This bio is usually one of the compressed bio's, and we don't actually
need it in this function, so remove the argument and stop passing it
around.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit c09abff87f ("btrfs: cloned bios must not be iterated by
bio_for_each_segment_all") added ASSERT()'s to make sure we weren't
calling bio_for_each_segment_all() on a RAID5/6 bio. However it was
checking the bio that the compression code passed in, not the
cb->orig_bio that we actually iterate over, so adjust this ASSERT() to
check the correct bio.
Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently any error we get while trying to lookup csums during reads
shows up as a missing csum, and then on the read completion side we
print an error saying there was a csum mismatch and we increase the
device corruption count.
However we could have gotten an EIO from the lookup. We could also be
inside of a memory constrained container and gotten a ENOMEM while
trying to do the read. In either case we don't want to make this look
like a file system corruption problem, we want to make it look like the
actual error it is. Capture any negative value, convert it to the
appropriate blk_status_t, free the csum array if we have one and bail.
Note: a possible improvement would be to make the relocation code look
up the owning inode and see if it's marked as NODATASUM and set
EXTENT_NODATASUM there, that way if there's corruption and there isn't a
checksum when we want it we can fail here rather than later.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We can either fail to find a csum entry at all and return -ENOENT, or we
can find a range that is close, but return -EFBIG. In essence these
both mean the same thing when we are doing a lookup for a csum in an
existing range, we didn't find a csum. We want to treat both of these
errors the same way, complain loudly that there wasn't a csum. This
currently happens anyway because we do
count = search_csum_tree();
if (count <= 0) {
// reloc and error handling
}
However it forces us to incorrectly treat EIO or ENOMEM errors as on
disk corruption. Fix this by returning 0 if we get either -ENOENT or
-EFBIG from btrfs_lookup_csum() so we can do proper error handling.
Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The implementation resembles direct I/O: we have to flush any ordered
extents, invalidate the page cache, and do the io tree/delalloc/extent
map/ordered extent dance. From there, we can reuse the compression code
with a minor modification to distinguish the write from writeback. This
also creates inline extents when possible.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There are 4 main cases:
1. Inline extents: we copy the data straight out of the extent buffer.
2. Hole/preallocated extents: we fill in zeroes.
3. Regular, uncompressed extents: we read the sectors we need directly
from disk.
4. Regular, compressed extents: we read the entire compressed extent
from disk and indicate what subset of the decompressed extent is in
the file.
This initial implementation simplifies a few things that can be improved
in the future:
- Cases 1, 3, and 4 allocate temporary memory to read into before
copying out to userspace.
- We don't do read repair, because it turns out that read repair is
currently broken for compressed data.
- We hold the inode lock during the operation.
Note that we don't need to hold the mmap lock. We may race with
btrfs_page_mkwrite() and read the old data from before the page was
dirtied:
btrfs_page_mkwrite btrfs_encoded_read
---------------------------------------------------
(enter) (enter)
btrfs_wait_ordered_range
lock_extent_bits
btrfs_page_set_dirty
unlock_extent_cached
(exit)
lock_extent_bits
read extent (dirty page hasn't been flushed,
so this is the old data)
unlock_extent_cached
(exit)
we read the old data from before the page was dirtied. But, that's true
even if we were to hold the mmap lock:
btrfs_page_mkwrite btrfs_encoded_read
-------------------------------------------------------------------
(enter) (enter)
btrfs_inode_lock(BTRFS_ILOCK_MMAP)
down_read(i_mmap_lock) (blocked)
btrfs_wait_ordered_range
lock_extent_bits
read extent (page hasn't been dirtied,
so this is the old data)
unlock_extent_cached
btrfs_inode_unlock(BTRFS_ILOCK_MMAP)
down_read(i_mmap_lock) returns
lock_extent_bits
btrfs_page_set_dirty
unlock_extent_cached
In other words, this is inherently racy, so it's fine that we return the
old data in this tiny window.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently, an inline extent is always created after i_size is extended
from btrfs_dirty_pages(). However, for encoded writes, we only want to
update i_size after we successfully created the inline extent. Add an
update_i_size parameter to cow_file_range_inline() and
insert_inline_extent() and pass in the size of the extent rather than
determining it from i_size.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ reformat comment ]
Signed-off-by: David Sterba <dsterba@suse.com>
The start parameter to cow_file_range_inline() (and
insert_inline_extent()) is always 0, so get rid of it and simplify the
logic in those two functions. Pass btrfs_inode to insert_inline_extent()
and remove the redundant root parameter. Also document the requirements
for creating an inline extent. No functional change.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently, we always reserve the same extent size in the file and extent
size on disk for delalloc because the former is the worst case for the
latter. For BTRFS_IOC_ENCODED_WRITE writes, we know the exact size of
the extent on disk, which may be less than or greater than (for
bookends) the size in the file. Add a disk_num_bytes parameter to
btrfs_delalloc_reserve_metadata() so that we can reserve the correct
amount of csum bytes. No functional change.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently, we only create ordered extents when ram_bytes == num_bytes
and offset == 0. However, BTRFS_IOC_ENCODED_WRITE writes may create
extents which only refer to a subset of the full unencoded extent, so we
need to plumb these fields through the ordered extent infrastructure and
pass them down to insert_reserved_file_extent().
Since we're changing the btrfs_add_ordered_extent* signature, let's get
rid of the trivial wrappers and add a kernel-doc.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_csum_one_bio() loops over each filesystem block in the bio while
keeping a cursor of its current logical position in the file in order to
look up the ordered extent to add the checksums to. However, this
doesn't make much sense for compressed extents, as a sector on disk does
not correspond to a sector of decompressed file data. It happens to work
because:
1) the compressed bio always covers one ordered extent
2) the size of the bio is always less than the size of the ordered
extent
However, the second point will not always be true for encoded writes.
Let's add a boolean parameter to btrfs_csum_one_bio() to indicate that
it can assume that the bio only covers one ordered extent. Since we're
already changing the signature, let's get rid of the contig parameter
and make it implied by the offset parameter, similar to the change we
recently made to btrfs_lookup_bio_sums(). Additionally, let's rename
nr_sectors to blockcount to make it clear that it's the number of
filesystem blocks, not the number of 512-byte sectors.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
These comments are old, outdated and not very specific. It seems that it
doesn't help to inspire anybody to work on that. So we remove them.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Sidong Yang <realwakka@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Removes duplicated check when adding qgroup relations.
btrfs_add_qgroup_relations function adds relations by calling
add_relation_rb(). add_relation_rb() checks that member/parentid exists
in current qgroup_tree. But it already checked before calling the
function. It seems that we don't need to double check.
Add new function __add_relation_rb() that adds relations with
qgroup structures and makes old function use the new one. And it makes
btrfs_add_qgroup_relation() function work without double checks by
calling the new function.
Signed-off-by: Sidong Yang <realwakka@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add comments ]
Signed-off-by: David Sterba <dsterba@suse.com>
It makes it more readable for length checking and is be used repeatedly.
Signed-off-by: Dāvis Mosāns <davispuh@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When btrfs_get_extent() tries to get some file extent from disk, it
never populates extent_map::generation, leaving the value to be 0.
On the other hand, for extent map generated by IO, it will get its
generation properly set at finish_ordered_io()
finish_ordered_io()
|- unpin_extent_cache(gen = trans->transid)
|- em->generation = gen;
[CAUSE]
Since extent_map::generation is mostly used by fsync code, and for fsync
they only care about modified extents, which all have their
em::generation > 0.
Thus it's fine to not populate em read from disk for fsync.
[CORNER CASE]
However autodefrag also relies on em::generation to determine if one
extent needs to be defragged.
This unpopulated extent_map::generation can prevent the following
autodefrag case from working:
mkfs.btrfs -f $dev
mount $dev $mnt -o autodefrag
# initial write to queue the inode for autodefrag
xfs_io -f -c "pwrite 0 4k" $mnt/file
sync
# Real fragmented write
xfs_io -f -s -c "pwrite -b 4096 0 32k" $mnt/file
sync
echo "=== before autodefrag ==="
xfs_io -c "fiemap -v" $mnt/file
# Drop cache to force em to be read from disk
echo 3 > /proc/sys/vm/drop_caches
mount -o remount,commit=1 $mnt
sleep 3
sync
echo "=== After autodefrag ==="
xfs_io -c "fiemap -v" $mnt/file
umount $mnt
The result looks like this:
=== before autodefrag ===
/mnt/btrfs/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..15]: 26672..26687 16 0x0
1: [16..31]: 26656..26671 16 0x0
2: [32..47]: 26640..26655 16 0x0
3: [48..63]: 26624..26639 16 0x1
=== After autodefrag ===
/mnt/btrfs/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..15]: 26672..26687 16 0x0
1: [16..31]: 26656..26671 16 0x0
2: [32..47]: 26640..26655 16 0x0
3: [48..63]: 26624..26639 16 0x1
This fragmented 32K will not be defragged by autodefrag.
[FIX]
To make things less weird, just populate extent_map::generation when
reading file extents from disk.
This would make above fragmented extents to be properly defragged:
== before autodefrag ===
/mnt/btrfs/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..15]: 26672..26687 16 0x0
1: [16..31]: 26656..26671 16 0x0
2: [32..47]: 26640..26655 16 0x0
3: [48..63]: 26624..26639 16 0x1
=== After autodefrag ===
/mnt/btrfs/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..63]: 26688..26751 64 0x1
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Removing or replacing an extent map requires holding a write lock on the
extent map's tree. We currently do that everywhere, except in one of the
self tests, where it's harmless since there's no concurrency.
In order to catch possible races in the future, assert that we are holding
a write lock on the extent map tree before removing or replacing an extent
map in the tree, and update the self test to obtain a write lock before
removing extent maps.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
After commit 92082d4097 ("btrfs: integrate page status update for
data read path into begin/end_page_read"), the 'nr' counter at
btrfs_do_readpage() is no longer used, we increment it but we never
read from it. So just remove it.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
At btrfs_do_readpage(), if we get an error when trying to lookup for an
extent map, we end up marking the page with the error bit, clearing
the uptodate bit on it, and doing everything else that should be done.
However we return success (0) to the caller, when we should return the
error encoded in the extent map pointer. So fix that by returning the
error encoded in the pointer.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
At extent_io.c, in the read page and write page code paths, we are testing
if the return value from btrfs_get_extent() can be NULL. However that is
not possible, as btrfs_get_extent() always returns either an error pointer
or a (non-NULL) pointer to an extent map structure.
Everywhere else outside extent_io.c we never check for NULL, we always
treat any returned value as a non-NULL pointer if it does not encode an
error.
So check only for the IS_ERR() case at extent_io.c.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When we want to log an extent, in the fast fsync path, we obtain a path
to the leaf that will hold the file extent item either through a deletion
search, via btrfs_drop_extents(), or through an insertion search using
btrfs_insert_empty_item(). After that we fill the file extent item's
fields one by one directly on the leaf.
Instead of doing that, we could prepare the file extent item before
obtaining a btree path, and then copy the prepared extent item with a
single operation once we get the path. This helps avoid some contention
on the log tree, since we are holding write locks for longer than
necessary, especially in the case where the path is obtained via
btrfs_drop_extents() through a deletion search, which always keeps a
write lock on the nodes at levels 1 and 2 (besides the leaf).
This change does that, we prepare the file extent item that is going to
be inserted before acquiring a path, and then copy it into a leaf using
a single copy operation once we get a path.
This change if part of a patchset that is comprised of the following
patches:
1/6 btrfs: remove unnecessary leaf free space checks when pushing items
2/6 btrfs: avoid unnecessary COW of leaves when deleting items from a leaf
3/6 btrfs: avoid unnecessary computation when deleting items from a leaf
4/6 btrfs: remove constraint on number of visited leaves when replacing extents
5/6 btrfs: remove useless path release in the fast fsync path
6/6 btrfs: prepare extents to be logged before locking a log tree path
The following test was run to measure the impact of the whole patchset:
$ cat test.sh
#!/bin/bash
DEV=/dev/sdi
MNT=/mnt/sdi
MOUNT_OPTIONS="-o ssd"
MKFS_OPTIONS="-R free-space-tree -O no-holes"
NUM_JOBS=8
FILE_SIZE=128M
RUN_TIME=200
cat <<EOF > /tmp/fio-job.ini
[writers]
rw=randwrite
fsync=1
fallocate=none
group_reporting=1
direct=0
bssplit=4k/20:8k/20:16k/20:32k/10:64k/10:128k/5:256k/5:512k/5:1m/5
ioengine=sync
filesize=$FILE_SIZE
runtime=$RUN_TIME
time_based
directory=$MNT
numjobs=$NUM_JOBS
thread
EOF
echo "performance" | \
tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
echo
echo "Using config:"
echo
cat /tmp/fio-job.ini
echo
umount $MNT &> /dev/null
mkfs.btrfs -f $MKFS_OPTIONS $DEV
mount $MOUNT_OPTIONS $DEV $MNT
fio /tmp/fio-job.ini
umount $MNT
The test ran inside a VM (8 cores, 32G of RAM) with the target disk
mapping to a raw NVMe device, and using a non-debug kernel config
(Debian's default config).
Before the patchset:
WRITE: bw=116MiB/s (122MB/s), 116MiB/s-116MiB/s (122MB/s-122MB/s), io=22.7GiB (24.4GB), run=200013-200013msec
After the patchset:
WRITE: bw=125MiB/s (131MB/s), 125MiB/s-125MiB/s (131MB/s-131MB/s), io=24.3GiB (26.1GB), run=200007-200007msec
A 7.8% gain on throughput and +7.0% more IO done in the same period of
time (200 seconds).
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There's no point in calling btrfs_release_path() after finishing the loop
that logs the modified extents, since log_one_extent() returns with the
path released. In case the list of extents is empty, the path is already
released, so there's no need for that case as well.
So just remove that unnecessary btrfs_release_path() call.
This change if part of a patchset that is comprised of the following
patches:
1/6 btrfs: remove unnecessary leaf free space checks when pushing items
2/6 btrfs: avoid unnecessary COW of leaves when deleting items from a leaf
3/6 btrfs: avoid unnecessary computation when deleting items from a leaf
4/6 btrfs: remove constraint on number of visited leaves when replacing extents
5/6 btrfs: remove useless path release in the fast fsync path
6/6 btrfs: prepare extents to be logged before locking a log tree path
The last patch in the series has some performance test result in its
changelog.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
At btrfs_drop_extents(), we try to replace a range of file extent items
with a new file extent in a single btree search, to avoid the need to do
a search for deletion, followed by a path release and followed by yet
another search for insertion.
When I originally added that optimization, in commit 1acae57b16
("Btrfs: faster file extent item replace operations"), I left a constraint
to do the fast replace only if we visited a single leaf. That was because
in the most common case we find all file extent items that need to be
deleted (or trimmed) in a single leaf, however it can work for other
common cases like when we need to delete a few file extent items located
at the end of a leaf and a few more located at the beginning of the next
leaf. The key for the new file extent item is greater than the key of
any deleted or trimmed file extent item from previous leaves, so we are
fine to use the last leaf that we found as long as we are holding a
write lock on it - even if the new key ends up at slot 0, as if that's
the case, the btree search has obtained a write lock on any upper nodes
that need to have a key pointer updated.
So removed the constraint that limits the optimization to the case where
we visited only a single leaf.
This change if part of a patchset that is comprised of the following
patches:
1/6 btrfs: remove unnecessary leaf free space checks when pushing items
2/6 btrfs: avoid unnecessary COW of leaves when deleting items from a leaf
3/6 btrfs: avoid unnecessary computation when deleting items from a leaf
4/6 btrfs: remove constraint on number of visited leaves when replacing extents
5/6 btrfs: remove useless path release in the fast fsync path
6/6 btrfs: prepare extents to be logged before locking a log tree path
The last patch in the series has some performance test result in its
changelog.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When deleting items from a leaf, we always compute the sum of the data
sizes of the items that are going to be deleted. However we only use
that sum when the last item to delete is behind the last item in the
leaf. This unnecessarily wastes CPU time when we are deleting either
the whole leaf or from some slot > 0 up to the last item in the leaf,
and both of these cases are common (e.g. truncation operation, either
as a result of truncate(2) or when logging inodes, deleting checksums
after removing a large enough extent, etc).
So compute only the sum of the data sizes if the last item to be
deleted does not match the last item in the leaf.
This change if part of a patchset that is comprised of the following
patches:
1/6 btrfs: remove unnecessary leaf free space checks when pushing items
2/6 btrfs: avoid unnecessary COW of leaves when deleting items from a leaf
3/6 btrfs: avoid unnecessary computation when deleting items from a leaf
4/6 btrfs: remove constraint on number of visited leaves when replacing extents
5/6 btrfs: remove useless path release in the fast fsync path
6/6 btrfs: prepare extents to be logged before locking a log tree path
The last patch in the series has some performance test result in its
changelog.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When we delete items from a leaf, if we end up with more than two thirds
of unused leaf space, we try to delete the leaf by moving all its items
into its left and right neighbour leaves. Sometimes that is not possible
because there is not enough free space in the left and right leaves, and
in that case we end up not deleting our leaf.
The way we are doing this is not ideal and can be improved in the
following ways:
1) When we call push_leaf_left(), we pass a value of 1 byte to the data
size parameter of push_leaf_left(). This is not realistic value because
no item can have a size less than 25 bytes, which is the size of struct
btrfs_item. This means that means that if the left leaf has not enough
free space to push any item, we end up COWing it even if we end up not
changing its content at all.
COWing that leaf means allocating a new metadata extent, marking it
dirty and doing more IO when committing a transaction or when syncing a
log tree. For a log tree case, it's particularly more important to
avoid the useless COW operation, as more IO can imply a higher latency
for an fsync operation.
So instead of passing 1 as the minimum data size for push_leaf_left(),
pass the size of the first item in our leaf, as we don't want to COW
the left leaf if we can't at least push the first item of our leaf;
2) When we call push_leaf_right(), we also pass a value of 1 byte as the
data size parameter of push_leaf_right(). Like the previous case, it
will also result in COWing the right leaf even if we are not able to
move any items into it, since there can't be any item with a size
smaller than 25 bytes (the size of struct btrfs_item).
So instead of passing 1 as the minimum data size to push_leaf_right(),
pass a size that corresponds to the sum of the size of all the
remaining items in our leaf. We are not interested in moving less than
that, because if we do, we are not able to delete our leaf and we have
COWed the right leaf for nothing. Plus, moving only some of the items
of our leaf, it means an even less balanced tree.
Just like the previous case, we want to avoid the useless COW of the
right leaf, this way we don't have to spend time allocating one new
metadata extent, and doing more IO when committing a transaction or
syncing a log tree. For the log tree case it's specially more important
because more IO can result in a higher latency for a fsync operation.
So adjust the minimum data size passed to push_leaf_left() and
push_leaf_right() as mentioned above.
This change if part of a patchset that is comprised of the following
patches:
1/6 btrfs: remove unnecessary leaf free space checks when pushing items
2/6 btrfs: avoid unnecessary COW of leaves when deleting items from a leaf
3/6 btrfs: avoid unnecessary computation when deleting items from a leaf
4/6 btrfs: remove constraint on number of visited leaves when replacing extents
5/6 btrfs: remove useless path release in the fast fsync path
6/6 btrfs: prepare extents to be logged before locking a log tree path
Not being able to delete a leaf that became less than 1/3 full after
deleting items from it is actually common. For example, for the fio test
mentioned in the changelog of patch 6/6, we are only able to delete a
leaf at btrfs_del_items() about 5.3% of the time, due to its left and
right neighbour leaves not having enough free space to push all the
remaining items into them.
The last patch in the series has some performance test result in its
changelog.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When trying to push items from a leaf into its left and right neighbours,
we lock the left or right leaf, check if it has the required minimum free
space, COW the leaf and then check again if it has the minimum required
free space. This second check is pointless:
1) Most and foremost because it's not needed. We have a write lock on the
leaf and on its parent node, so no one can come in and change either
the pre-COW or post-COW version of the leaf for the whole duration of
the push_leaf_left() and push_leaf_right() calls;
2) The call to btrfs_leaf_free_space() is not trivial, it has a fair
amount of arithmetic operations and access to fields in the leaf's
header and items, so it's not very cheap.
So remove the duplicated free space checks.
This change if part of a patchset that is comprised of the following
patches:
1/6 btrfs: remove unnecessary leaf free space checks when pushing items
2/6 btrfs: avoid unnecessary COW of leaves when deleting items from a leaf
3/6 btrfs: avoid unnecessary computation when deleting items from a leaf
4/6 btrfs: remove constraint on number of visited leaves when replacing extents
5/6 btrfs: remove useless path release in the fast fsync path
6/6 btrfs: prepare extents to be logged before locking a log tree path
The last patch in the series has some performance test result in its
changelog.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In get_extent_skip_holes() we're checking the return of
btrfs_get_extent_fiemap() for an error pointer or NULL, but
btrfs_get_extent_fiemap() will never return NULL, only error pointers or
a valid extent_map.
The other caller of btrfs_get_extent_fiemap(), find_desired_extent(),
correctly only checks for error-pointers.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Remove the redundant assignment to zone_info variable in
btrfs_check_zoned_mode function.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The static_assert introduced in 6bab69c650 ("build_bug.h: add wrapper
for _Static_assert") has been supported by compilers for a long time
(gcc 4.6, clang 3.0) and can be used in header files. We don't need to
put BUILD_BUG_ON to random functions but rather keep it next to the
definition.
The exception here is the UAPI header btrfs_tree.h that could be
potentially included by userspace code and the static assert is not
defined (nor used in any other header).
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Allow creating or reading block-groups on a zoned device with DUP as a
meta-data profile.
This works because we're using the zoned_meta_io_lock and REQ_OP_WRITE
operations for meta-data on zoned btrfs, so all writes to meta-data zones
are aligned to the zone's write-pointer.
Upon loading of the block-group, it is ensured both zones do have the same
zone capacity and write-pointer offsets, so no extra machinery is needed
to keep the write-pointers in sync for the meta-data zones. If this
prerequisite is not met, loading of the block-group is refused.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Allow for a block-group to be placed on more than one physical zone.
This is a preparation for allowing DUP profiles for meta-data on a zoned
file-system.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently finishing of a zone only works if the block group isn't
spanning more than one zone.
This limitation is purely artificial and can be easily expanded to block
groups being places across multiple zones.
This is a preparation for allowing DUP and later more complex block-group
profiles on zoned btrfs.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently activation of a zone only works if the block group isn't
spanning more than one zone.
This limitation is purely artificial and can be easily expanded to block
groups being places across multiple zones.
This is a preparation for allowing DUP and later more complex block-group
profiles on zoned btrfs.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
With extent tree v2 you will be able to create multiple csum, extent,
and free space trees. They will be used based on the block group, which
will now use the block_group_item->chunk_objectid to point to the set of
global roots that it will use. When allocating new block groups we'll
simply mod the gigabyte offset of the block group against the number of
global roots we have and that will be the block groups global id.
>From there we can take the bytenr that we're modifying in the respective
tree, look up the block group and get that block groups corresponding
global root id. From there we can get to the appropriate global root
for that bytenr.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This code adds the on disk structures for the block group root, which
will hold the block group items for extent tree v2.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We're going to be adding more roots that need to be loaded from the
super block, so abstract out the code to read the tree_root from the
super block, and use this helper for the chunk root as well. This will
make it simpler to load the new trees in the future.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For extent tree v2 we can definitely have empty extent roots, so skip
this particular check if we have that set.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We cannot fall back on the slow caching for extent tree v2, which means
we can't just arbitrarily clear the free space trees at mount time.
Furthermore we can't do v1 space cache with extent tree v2. Simply
ignore these mount options for extent tree v2 as they aren't relevant.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When we stop tracking metadata blocks all of snapshotting will break, so
disable it until I add the snapshot root and drop tree support.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Scrub depends on extent references for every block, and with extent tree
v2 we won't have that, so disable scrub until we can add back the proper
code to handle extent-tree-v2.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Backref lookups are going to be drastically different with extent tree
v2, disable qgroups until we do the work to add this support for extent
tree v2.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Device add, remove, and replace all require balance, which doesn't work
right now on extent tree v2, so disable these for now.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
With global root id's it makes it problematic to do backref lookups for
balance. This isn't hard to deal with, but future changes are going to
make it impossible to lookup backrefs on any COWonly roots, so go ahead
and disable balance for now on extent tree v2 until we can add balance
support back in future patches.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This adds the initial definition of the EXTENT_TREE_V2 incompat feature
flag. This also hides the support behind CONFIG_BTRFS_DEBUG.
THIS IS A IN DEVELOPMENT FORMAT CHANGE, DO NOT USE UNLESS YOU ARE A
DEVELOPER OR A TESTER.
The format is in flux and will be added in stages, any fs will need to
be re-made between updates to the format.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
At btrfs_log_inode(), we have two variables to track errors and the
return value of the function, named 'ret' and 'err'. In some places we
use 'ret' and if gets a non-zero value we assign its value to 'err'
and then jump to the 'out' label, while in other places we use 'err'
directly without 'ret' as an intermediary. This is inconsistent, error
prone and not necessary. So change that to use only the 'ret' variable,
making this consistent with most functions in btrfs.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
During a rename or link operation, we need to determine if an inode was
previously logged or not, and if it was, do some update to the logged
inode. We used to rely exclusively on the logged_trans field of struct
btrfs_inode to determine that, but that was not reliable because the
value of that field is not persisted in the inode item, so it's lost
when an inode is evicted and loaded back again. That led to several
issues in the past, such as not persisting deletions (such as the case
fixed by commit 803f0f64d1 ("Btrfs: fix fsync not persisting dentry
deletions due to inode evictions")), or resulting in losing a file
after an inode eviction followed by a rename (commit ecc64fab7d
("btrfs: fix lost inode on log replay after mix of fsync, rename and
inode eviction")), besides other issues.
So the inode_logged() helper was introduced and used to determine if an
inode was possibly logged before in the current transaction, with the
caveat that it could return false positives, in the sense that even if an
inode was not logged before in the current transaction, it could still
return true, but never to return false in case the inode was logged.
>From a functional point of view that is fine, but from a performance
perspective it can introduce significant latencies to rename and link
operations, as they will end up doing inode logging even when it is not
necessary.
Recently on a 5.15 kernel, an openSUSE Tumbleweed user reported package
installations and upgrades, with the zypper tool, were often taking a
long time to complete. With strace it could be observed that zypper was
spending about 99% of its time on rename operations, and then with
further analysis we checked that directory logging was happening too
frequently. Taking into account that installation/upgrade of some of the
packages needed a few thousand file renames, the slowdown was very
noticeable for the user.
The issue was caused indirectly due to an excessive number of inode
evictions on a 5.15 kernel, about 100x more compared to a 5.13, 5.14 or
a 5.16-rc8 kernel. While triggering the inode evictions if something
outside btrfs' control, btrfs could still behave better by eliminating
the false positives from the inode_logged() helper.
So change inode_logged() to actually eliminate such false positives caused
by inode eviction and when an inode was never logged since the filesystem
was mounted, as both cases relate to when the logged_trans field of struct
btrfs_inode has a value of zero. When it can not determine if the inode
was logged based only on the logged_trans value, lookup for the existence
of the inode item in the log tree - if it's there then we known the inode
was logged, if it's not there then it can not have been logged in the
current transaction. Once we determine if the inode was logged, update
the logged_trans value to avoid future calls to have to search in the log
tree again.
Alternatively, we could start storing logged_trans in the on disk inode
item structure (struct btrfs_inode_item) in the unused space it still has,
but that would be a bit odd because:
1) We only care about logged_trans since the filesystem was mounted, we
don't care about its value from a previous mount. Having it persisted
in the inode item structure would not make the best use of the precious
unused space;
2) In order to get logged_trans persisted before inode eviction, we would
have to update the delayed inode when we finish logging the inode and
update its logged_trans in struct btrfs_inode, which makes it a bit
cumbersome since we need to check if the delayed inode exists, if not
create it and populate it and deal with any errors (-ENOMEM mostly).
This change is part of a patchset comprised of the following patches:
1/5 btrfs: add helper to delete a dir entry from a log tree
2/5 btrfs: pass the dentry to btrfs_log_new_name() instead of the inode
3/5 btrfs: avoid logging all directory changes during renames
4/5 btrfs: stop doing unnecessary log updates during a rename
5/5 btrfs: avoid inode logging during rename and link when possible
The following test script mimics part of what the zypper tool does during
package installations/upgrades. It does not triggers inode evictions, but
it's similar because it triggers false positives from the inode_logged()
helper, because the inodes have a logged_trans of 0, there's a log tree
due to a fsync of an unrelated file and the directory inode has its
last_trans field set to the current transaction:
$ cat test.sh
#!/bin/bash
DEV=/dev/nvme0n1
MNT=/mnt/nvme0n1
NUM_FILES=10000
mkfs.btrfs -f $DEV
mount $DEV $MNT
mkdir $MNT/testdir
for ((i = 1; i <= $NUM_FILES; i++)); do
echo -n > $MNT/testdir/file_$i
done
sync
# Now do some change to an unrelated file and fsync it.
# This is just to create a log tree to make sure that inode_logged()
# does not return false when called against "testdir".
xfs_io -f -c "pwrite 0 4K" -c "fsync" $MNT/foo
# Do some change to testdir. This is to make sure inode_logged()
# will return true when called against "testdir", because its
# logged_trans is 0, it was changed in the current transaction
# and there's a log tree.
echo -n > $MNT/testdir/file_$((NUM_FILES + 1))
echo "Renaming $NUM_FILES files..."
start=$(date +%s%N)
for ((i = 1; i <= $NUM_FILES; i++)); do
mv $MNT/testdir/file_$i $MNT/testdir/file_$i-RPMDELETE
done
end=$(date +%s%N)
dur=$(( (end - start) / 1000000 ))
echo "Renames took $dur milliseconds"
umount $MNT
Testing this change on a box using a non-debug kernel (Debian's default
kernel config) gave the following results:
NUM_FILES=10000, before patchset: 27837 ms
NUM_FILES=10000, after patches 1/5 to 4/5 applied: 9236 ms (-66.8%)
NUM_FILES=10000, after whole patchset applied: 8902 ms (-68.0%)
NUM_FILES=5000, before patchset: 9127 ms
NUM_FILES=5000, after patches 1/5 to 4/5 applied: 4640 ms (-49.2%)
NUM_FILES=5000, after whole patchset applied: 4441 ms (-51.3%)
NUM_FILES=2000, before patchset: 2528 ms
NUM_FILES=2000, after patches 1/5 to 4/5 applied: 1983 ms (-21.6%)
NUM_FILES=2000, after whole patchset applied: 1747 ms (-30.9%)
NUM_FILES=1000, before patchset: 1085 ms
NUM_FILES=1000, after patches 1/5 to 4/5 applied: 893 ms (-17.7%)
NUM_FILES=1000, after whole patchset applied: 867 ms (-20.1%)
Running dbench on the same physical machine with the following script:
$ cat run-dbench.sh
#!/bin/bash
NUM_JOBS=$(nproc --all)
DEV=/dev/nvme0n1
MNT=/mnt/nvme0n1
MOUNT_OPTIONS="-o ssd"
MKFS_OPTIONS="-O no-holes -R free-space-tree"
echo "performance" | \
tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
mkfs.btrfs -f $MKFS_OPTIONS $DEV
mount $MOUNT_OPTIONS $DEV $MNT
dbench -D $MNT -t 120 $NUM_JOBS
umount $MNT
Before patchset:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 3761352 0.032 143.843
Close 2762770 0.002 2.273
Rename 159304 0.291 67.037
Unlink 759784 0.207 143.998
Deltree 72 4.028 15.977
Mkdir 36 0.003 0.006
Qpathinfo 3409780 0.013 9.678
Qfileinfo 596772 0.001 0.878
Qfsinfo 625189 0.003 1.245
Sfileinfo 306443 0.006 1.840
Find 1318106 0.063 19.798
WriteX 1871137 0.021 8.532
ReadX 5897325 0.003 3.567
LockX 12252 0.003 0.258
UnlockX 12252 0.002 0.100
Flush 263666 3.327 155.632
Throughput 980.047 MB/sec 12 clients 12 procs max_latency=155.636 ms
After whole patchset applied:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX 4195584 0.033 107.742
Close 3081932 0.002 1.935
Rename 177641 0.218 14.905
Unlink 847333 0.166 107.822
Deltree 118 5.315 15.247
Mkdir 59 0.004 0.048
Qpathinfo 3802612 0.014 10.302
Qfileinfo 666748 0.001 1.034
Qfsinfo 697329 0.003 0.944
Sfileinfo 341712 0.006 2.099
Find 1470365 0.065 9.359
WriteX 2093921 0.021 8.087
ReadX 6576234 0.003 3.407
LockX 13660 0.003 0.308
UnlockX 13660 0.002 0.114
Flush 294090 2.906 115.539
Throughput 1093.11 MB/sec 12 clients 12 procs max_latency=115.544 ms
+11.5% throughput -25.8% max latency rename max latency -77.8%
Link: https://bugzilla.opensuse.org/show_bug.cgi?id=1193549
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
During a rename, we call __btrfs_unlink_inode(), which will call
btrfs_del_inode_ref_in_log() and btrfs_del_dir_entries_in_log(), in order
to remove an inode reference and a directory entry from the log. These
are necessary when __btrfs_unlink_inode() is called from the unlink path,
but not necessary when it's called from a rename context, because:
1) For the btrfs_del_inode_ref_in_log() call, it's pointless to delete the
inode reference related to the old name, because later in the rename
path we call btrfs_log_new_name(), which will drop all inode references
from the log and copy all inode references from the subvolume tree to
the log tree. So we are doing one unnecessary btree operation which
adds additional latency and lock contention in case there are other
tasks accessing the log tree;
2) For the btrfs_del_dir_entries_in_log() call, we are now doing the
equivalent at btrfs_log_new_name() since the previous patch in the
series, that has the subject "btrfs: avoid logging all directory
changes during renames". In fact, having __btrfs_unlink_inode() call
this function not only adds additional latency and lock contention due
to the extra btree operation, but also can make btrfs_log_new_name()
unnecessarily log a range item to track the deletion of the old name,
since it has no way to known that the directory entry related to the
old name was previously logged and already deleted by
__btrfs_unlink_inode() through its call to
btrfs_del_dir_entries_in_log().
So skip those calls at __btrfs_unlink_inode() when we are doing a rename.
Skipping them also allows us now to reduce the duration of time we are
pinning a log transaction during renames, which is always beneficial as
it's not delaying so much other tasks trying to sync the log tree, in
particular we end up not holding the log transaction pinned while adding
the new name (adding inode ref, directory entry, etc).
This change is part of a patchset comprised of the following patches:
1/5 btrfs: add helper to delete a dir entry from a log tree
2/5 btrfs: pass the dentry to btrfs_log_new_name() instead of the inode
3/5 btrfs: avoid logging all directory changes during renames
4/5 btrfs: stop doing unnecessary log updates during a rename
5/5 btrfs: avoid inode logging during rename and link when possible
Just like the previous patch in the series, "btrfs: avoid logging all
directory changes during renames", the following script mimics part of
what a package installation/upgrade with zypper does, which is basically
renaming a lot of files, in some directory under /usr, to a name with a
suffix of "-RPMDELETE":
$ cat test.sh
#!/bin/bash
DEV=/dev/nvme0n1
MNT=/mnt/nvme0n1
NUM_FILES=10000
mkfs.btrfs -f $DEV
mount $DEV $MNT
mkdir $MNT/testdir
for ((i = 1; i <= $NUM_FILES; i++)); do
echo -n > $MNT/testdir/file_$i
done
sync
# Do some change to testdir and fsync it.
echo -n > $MNT/testdir/file_$((NUM_FILES + 1))
xfs_io -c "fsync" $MNT/testdir
echo "Renaming $NUM_FILES files..."
start=$(date +%s%N)
for ((i = 1; i <= $NUM_FILES; i++)); do
mv $MNT/testdir/file_$i $MNT/testdir/file_$i-RPMDELETE
done
end=$(date +%s%N)
dur=$(( (end - start) / 1000000 ))
echo "Renames took $dur milliseconds"
umount $MNT
Testing this change on box a using a non-debug kernel (Debian's default
kernel config) gave the following results:
NUM_FILES=10000, before patchset: 27399 ms
NUM_FILES=10000, after patches 1/5 to 3/5 applied: 9093 ms (-66.8%)
NUM_FILES=10000, after patches 1/5 to 4/5 applied: 9016 ms (-67.1%)
NUM_FILES=5000, before patchset: 9241 ms
NUM_FILES=5000, after patches 1/5 to 3/5 applied: 4642 ms (-49.8%)
NUM_FILES=5000, after patches 1/5 to 4/5 applied: 4553 ms (-50.7%)
NUM_FILES=2000, before patchset: 2550 ms
NUM_FILES=2000, after patches 1/5 to 3/5 applied: 1788 ms (-29.9%)
NUM_FILES=2000, after patches 1/5 to 4/5 applied: 1767 ms (-30.7%)
NUM_FILES=1000, before patchset: 1088 ms
NUM_FILES=1000, after patches 1/5 to 3/5 applied: 905 ms (-16.9%)
NUM_FILES=1000, after patches 1/5 to 4/5 applied: 883 ms (-18.8%)
The next patch in the series (5/5), also contains dbench results after
applying to whole patchset.
Link: https://bugzilla.opensuse.org/show_bug.cgi?id=1193549
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing a rename of a file, if the file or its old parent directory
were logged before, we log the new name of the file and then make sure
we log the old parent directory, to ensure that after a log replay the
old name of the file is deleted and the new name added.
The logging of the old parent directory can take some time, because it
will scan all leaves modified in the current transaction, check which
directory entries were already logged, copy the ones that were not
logged before, etc. In this rename context all we need to do is make
sure that the old name of the file is deleted on log replay, so instead
of triggering a directory log operation, we can just delete the old
directory entry from the log if it's there, or in case it isn't there,
just log a range item to signal log replay that the old name must be
deleted. So change btrfs_log_new_name() to do that.
This scenario is actually not uncommon to trigger, and recently on a
5.15 kernel, an openSUSE Tumbleweed user reported package installations
and upgrades, with the zypper tool, were often taking a long time to
complete, much more than usual. With strace it could be observed that
zypper was spending over 99% of its time on rename operations, and then
with further analysis we checked that directory logging was happening
too frequently and causing high latencies for the rename operations.
Taking into account that installation/upgrade of some of these packages
needed about a few thousand file renames, the slowdown was very noticeable
for the user.
The issue was caused indirectly due to an excessive number of inode
evictions on a 5.15 kernel, about 100x more compared to a 5.13, 5.14
or a 5.16-rc8 kernel. After an inode eviction we can't tell for sure,
in an efficient way, if an inode was previously logged in the current
transaction, so we are pessimistic and assume it was, because in case
it was we need to update the logged inode. More details on that in one
of the patches in the same series (subject "btrfs: avoid inode logging
during rename and link when possible"). Either way, in case the parent
directory was logged before, we currently do more work then necessary
during a rename, and this change minimizes that amount of work.
The following script mimics part of what a package installation/upgrade
with zypper does, which is basically renaming a lot of files, in some
directory under /usr, to a name with a suffix of "-RPMDELETE":
$ cat test.sh
#!/bin/bash
DEV=/dev/nvme0n1
MNT=/mnt/nvme0n1
NUM_FILES=10000
mkfs.btrfs -f $DEV
mount $DEV $MNT
mkdir $MNT/testdir
for ((i = 1; i <= $NUM_FILES; i++)); do
echo -n > $MNT/testdir/file_$i
done
sync
# Do some change to testdir and fsync it.
echo -n > $MNT/testdir/file_$((NUM_FILES + 1))
xfs_io -c "fsync" $MNT/testdir
echo "Renaming $NUM_FILES files..."
start=$(date +%s%N)
for ((i = 1; i <= $NUM_FILES; i++)); do
mv $MNT/testdir/file_$i $MNT/testdir/file_$i-RPMDELETE
done
end=$(date +%s%N)
dur=$(( (end - start) / 1000000 ))
echo "Renames took $dur milliseconds"
umount $MNT
Testing this change on box using a non-debug kernel (Debian's default
kernel config) gave the following results:
NUM_FILES=10000, before this patch: 27399 ms
NUM_FILES=10000, after this patch: 9093 ms (-66.8%)
NUM_FILES=5000, before this patch: 9241 ms
NUM_FILES=5000, after this patch: 4642 ms (-49.8%)
NUM_FILES=2000, before this patch: 2550 ms
NUM_FILES=2000, after this patch: 1788 ms (-29.9%)
NUM_FILES=1000, before this patch: 1088 ms
NUM_FILES=1000, after this patch: 905 ms (-16.9%)
Link: https://bugzilla.opensuse.org/show_bug.cgi?id=1193549
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In the next patch in the series, there will be the need to access the old
name, and its length, of an inode when logging the inode during a rename.
So instead of passing the inode to btrfs_log_new_name() pass the dentry,
because from the dentry we can get the inode, the name and its length.
This will avoid passing 3 new parameters to btrfs_log_new_name() in the
next patch - the name, its length and an index number. This way we end
up passing only 1 new parameter, the index number.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move the code that finds and deletes a logged dir entry out of
btrfs_del_dir_entries_in_log() into a helper function. This new helper
function will be used by another patch in the same series, and serves
to avoid having duplicated logic.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Return value from fs_path_add_path() directly instead of taking this in
another redundant variable.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn>
Signed-off-by: CGEL ZTE <cgel.zte@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of having 2 places that short circuit the qgroup leaf scan have
everything in the qgroup_rescan_leaf function. In addition to that, also
ensure that the inconsistent qgroup flag is set when rescan_should_stop
returns true. This both retains the old behavior when -EINTR was set in
the body of the loop and at the same time also extends this behavior
when scanning is interrupted due to remount or unmount operations.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
increment is being initialized to map->stripe_len but this is never
read as increment is overwritten later on. Remove the redundant
initialization.
Cleans up the following clang-analyzer warning:
fs/btrfs/scrub.c:3193:6: warning: Value stored to 'increment' during its
initialization is never read [clang-analyzer-deadcode.DeadStores].
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
to_add is being initialized to len but this is never read as to_add is
overwritten later on. Remove the redundant initialization.
Cleans up the following clang-analyzer warning:
fs/btrfs/extent-tree.c:2769:8: warning: Value stored to 'to_add' during
its initialization is never read [clang-analyzer-deadcode.DeadStores].
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The pointer to struct request_queue is used only to get device type
rotating or the non-rotating. So use it directly.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit "btrfs: add device major-minor info in the struct btrfs_device"
saved the device major-minor number in the struct btrfs_device upon
discovering it.
So no need to lookup_bdev() again just match, which means
device_matched() can go away.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Internally it is common to use the major-minor number to identify a
device and, at a few locations in btrfs, we use the major-minor number
to match the device.
So when we identify a new btrfs device through device add or device
replace or device-scan/ready save the device's major-minor (dev_t) in the
struct btrfs_device so that we don't have to call lookup_bdev() again.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
After the commit "btrfs: harden identification of the stale device", we
don't have to match the device path anymore. Instead, we match the dev_t.
So pass in the dev_t instead of the device path, in the call chain
btrfs_forget_devices()->btrfs_free_stale_devices().
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Identifying and removing the stale device from the fs_uuids list is done
by btrfs_free_stale_devices(). btrfs_free_stale_devices() in turn
depends on device_path_matched() to check if the device appears in more
than one btrfs_device structure.
The matching of the device happens by its path, the device path. However,
when device mapper is in use, the dm device paths are nothing but a link
to the actual block device, which leads to the device_path_matched()
failing to match.
Fix this by matching the dev_t as provided by lookup_bdev() instead of
plain string compare of the device paths.
Reported-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In btrfs_init_dev_replace_tgtdev() we dereference fs_info to get
fs_devices many times, instead save a point to the fs_devices.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_ioctl extracts inode from file so we can pass that into the
callbacks.
Signed-off-by: Sahil Kang <sahil.kang@asilaycomputing.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This simplifies the code flow in read_one_chunk and makes error handling
when handling missing devices a bit simpler by reducing it to a single
check if something went wrong. No functional changes.
Reviewed-by: Su Yue <l@damenly.su>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When logging a directory we are trying to log subdirectories that were
changed in the current transaction and created in a past transaction.
This type of behaviour was introduced by commit 2f2ff0ee5e ("Btrfs:
fix metadata inconsistencies after directory fsync"), to fix some metadata
inconsistencies that in the meanwhile no longer need this behaviour due to
numerous other changes that happened throughout the years.
This behaviour, besides not needed anymore, it's also undesirable because:
1) It's not reliable because it's only triggered for the directories
of dentries (dir items) that happen to be present on a leaf that
was changed in the current transaction. If a dentry that points to
a directory resides on a leaf that was not changed in the current
transaction, then it's not logged, as at log_dir_items() and
log_new_dir_dentries() we use btrfs_search_forward();
2) It's not required by posix or any standard, it's undefined territory.
The only way to guarantee a subdirectory is logged, it to explicitly
fsync it;
Making the behaviour guaranteed would require scanning all directory
items, check which point to a directory, and then fsync each subdirectory
which was modified in the current transaction. This could be very
expensive for large directories with many subdirectories and/or large
subdirectories.
So remove that obsolete logic.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When logging a directory, we go over every leaf of the subvolume tree that
was changed in the current transaction and copy all its dir index keys to
the log tree.
That includes copying dir index keys created in past transactions. This is
done mostly for simplicity, as after logging the keys we log an item that
specifies the start and end ranges of the keys we logged. That item is
then used during log replay to figure out which keys need to be deleted -
every key in that range that we find in the subvolume tree and is not in
the log tree, needs to be deleted.
Now that we log only dir index keys, and not dir item keys anymore, when
we remove dentries from a directory (due to unlink and rename operations),
we can get entire leaves that we changed only for deleting old dir index
keys, or that have few dir index keys that are new - this is due to the
fact that the offset for new index keys comes from a monotonically
increasing counter.
We can avoid logging dir index keys from past transactions, and in order
to track the deletions, only log range items (BTRFS_DIR_LOG_INDEX_KEY key
type) when we find gaps between consecutive index keys. This massively
reduces the amount of logged metadata when we have deleted directory
entries, even if it's a small percentage of the total number of entries.
The reduction comes from both less items that are logged and instead of
logging many dir index items (struct btrfs_dir_item), which have a size
of 30 bytes plus a file name, we typically log just a few range items
(struct btrfs_dir_log_item), which take only 8 bytes each.
Even if no entries were deleted from a directory and only new entries
were added, we typically still get a reduction on the amount of logged
metadata, because it's very likely the first leaf that got the new
dir index entries also has several old dir index entries.
So change the logging logic to not log dir index keys created in past
transactions and log a range item for every gap it finds between each
pair of consecutive index keys, to ensure deletions are tracked and
replayed on log replay.
This patch is part of a patchset comprised of the following patches:
1/4 btrfs: don't log unnecessary boundary keys when logging directory
2/4 btrfs: put initial index value of a directory in a constant
3/4 btrfs: stop copying old dir items when logging a directory
4/4 btrfs: stop trying to log subdirectories created in past transactions
The following test was run on a branch without this patchset and on a
branch with the first three patches applied:
$ cat test.sh
#!/bin/bash
DEV=/dev/nvme0n1
MNT=/mnt/nvme0n1
NUM_FILES=1000000
NUM_FILE_DELETES=10000
MKFS_OPTIONS="-O no-holes -R free-space-tree"
MOUNT_OPTIONS="-o ssd"
mkfs.btrfs -f $MKFS_OPTIONS $DEV
mount $MOUNT_OPTIONS $DEV $MNT
mkdir $MNT/testdir
for ((i = 1; i <= $NUM_FILES; i++)); do
echo -n > $MNT/testdir/file_$i
done
sync
del_inc=$(( $NUM_FILES / $NUM_FILE_DELETES ))
for ((i = 1; i <= $NUM_FILES; i += $del_inc)); do
rm -f $MNT/testdir/file_$i
done
start=$(date +%s%N)
xfs_io -c "fsync" $MNT/testdir
end=$(date +%s%N)
dur=$(( (end - start) / 1000000 ))
echo "dir fsync took $dur ms after deleting $NUM_FILE_DELETES files"
echo
umount $MNT
The test was run on a non-debug kernel (Debian's default kernel config),
and the results were the following for various values of NUM_FILES and
NUM_FILE_DELETES:
** before, NUM_FILES = 1 000 000, NUM_FILE_DELETES = 10 000 **
dir fsync took 585 ms after deleting 10000 files
** after, NUM_FILES = 1 000 000, NUM_FILE_DELETES = 10 000 **
dir fsync took 34 ms after deleting 10000 files (-94.2%)
** before, NUM_FILES = 100 000, NUM_FILE_DELETES = 1 000 **
dir fsync took 50 ms after deleting 1000 files
** after, NUM_FILES = 100 000, NUM_FILE_DELETES = 1 000 **
dir fsync took 7 ms after deleting 1000 files (-86.0%)
** before, NUM_FILES = 10 000, NUM_FILE_DELETES = 100 **
dir fsync took 9 ms after deleting 100 files
** after, NUM_FILES = 10 000, NUM_FILE_DELETES = 100 **
dir fsync took 5 ms after deleting 100 files (-44.4%)
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
At btrfs_set_inode_index_count() we refer twice to the number 2 as the
initial index value for a directory (when it's empty), with a proper
comment explaining the reason for that value. In the next patch I'll
have to use that magic value in the directory logging code, so put
the value in a #define at btrfs_inode.h, to avoid hardcoding the
magic value again at tree-log.c.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Before we start to log dir index keys from a leaf, we check if there is a
previous index key, which normally is at the end of a leaf that was not
changed in the current transaction. Then we log that key and set the start
of logged range (item of type BTRFS_DIR_LOG_INDEX_KEY) to the offset of
that key. This is to ensure that if there were deleted index keys between
that key and the first key we are going to log, those deletions are
replayed in case we need to replay to the log after a power failure.
However we really don't need to log that previous key, we can just set the
start of the logged range to that key's offset plus 1. This achieves the
same and avoids logging one dir index key.
The same logic is performed when we finish logging the index keys of a
leaf and we find that the next leaf has index keys and was not changed in
the current transaction. We are logging the first key of that next leaf
and use its offset as the end of range we log. This is just to ensure that
if there were deleted index keys between the last index key we logged and
the first key of that next leaf, those index keys are deleted if we end
up replaying the log. However that is not necessary, we can avoid logging
that first index key of the next leaf and instead set the end of the
logged range to match the offset of that index key minus 1.
So avoid logging those index keys at the boundaries and adjust the start
and end offsets of the logged ranges as described above.
This patch is part of a patchset comprised of the following patches:
1/4 btrfs: don't log unnecessary boundary keys when logging directory
2/4 btrfs: put initial index value of a directory in a constant
3/4 btrfs: stop copying old dir items when logging a directory
4/4 btrfs: stop trying to log subdirectories created in past transactions
Performance test results are listed in the changelog of patch 3/4.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_ioctl already contains pointers to the inode and btrfs_root
structs, so we can pass them into the subfunctions instead of the
toplevel struct file.
Signed-off-by: Sahil Kang <sahil.kang@asilaycomputing.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The ->write and ->wait fields of struct walk_control, used for log trees,
are not used since 2008, more specifically since commit d0c803c404
("Btrfs: Record dirty pages tree-log pages in an extent_io tree") and
since commit d0c803c404 ("Btrfs: Record dirty pages tree-log pages in
an extent_io tree"). So just remove them, along with the function
btrfs_write_tree_block(), which is also not used anymore after removing
the ->write member.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
As a preparation for moving to -std=gnu11, turn off the
-Wshift-negative-value option. This warning is enabled by gcc when
building with -Wextra for c99 or higher, but not for c89. Since
the kernel already relies on well-defined overflow behavior,
the warning is not helpful and can simply be disabled in
all locations that use -Wextra.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13.0.0 (x86-64)
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
With the NVMe support for this gone, there are no consumers of these hints
left, so remove them.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220304175556.407719-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'for-5.17-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"A few more fixes for various problems that have user visible effects
or seem to be urgent:
- fix corruption when combining DIO and non-blocking io_uring over
multiple extents (seen on MariaDB)
- fix relocation crash due to premature return from commit
- fix quota deadlock between rescan and qgroup removal
- fix item data bounds checks in tree-checker (found on a fuzzed
image)
- fix fsync of prealloc extents after EOF
- add missing run of delayed items after unlink during log replay
- don't start relocation until snapshot drop is finished
- fix reversed condition for subpage writers locking
- fix warning on page error"
* tag 'for-5.17-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: fallback to blocking mode when doing async dio over multiple extents
btrfs: add missing run of delayed items after unlink during log replay
btrfs: qgroup: fix deadlock between rescan worker and remove qgroup
btrfs: fix relocation crash due to premature return from btrfs_commit_transaction()
btrfs: do not start relocation until in progress drops are done
btrfs: tree-checker: use u64 for item data end to avoid overflow
btrfs: do not WARN_ON() if we have PageError set
btrfs: fix lost prealloc extents beyond eof after full fsync
btrfs: subpage: fix a wrong check on subpage->writers
Some users recently reported that MariaDB was getting a read corruption
when using io_uring on top of btrfs. This started to happen in 5.16,
after commit 51bd9563b6 ("btrfs: fix deadlock due to page faults
during direct IO reads and writes"). That changed btrfs to use the new
iomap flag IOMAP_DIO_PARTIAL and to disable page faults before calling
iomap_dio_rw(). This was necessary to fix deadlocks when the iovector
corresponds to a memory mapped file region. That type of scenario is
exercised by test case generic/647 from fstests.
For this MariaDB scenario, we attempt to read 16K from file offset X
using IOCB_NOWAIT and io_uring. In that range we have 4 extents, each
with a size of 4K, and what happens is the following:
1) btrfs_direct_read() disables page faults and calls iomap_dio_rw();
2) iomap creates a struct iomap_dio object, its reference count is
initialized to 1 and its ->size field is initialized to 0;
3) iomap calls btrfs_dio_iomap_begin() with file offset X, which finds
the first 4K extent, and setups an iomap for this extent consisting
of a single page;
4) At iomap_dio_bio_iter(), we are able to access the first page of the
buffer (struct iov_iter) with bio_iov_iter_get_pages() without
triggering a page fault;
5) iomap submits a bio for this 4K extent
(iomap_dio_submit_bio() -> btrfs_submit_direct()) and increments
the refcount on the struct iomap_dio object to 2; The ->size field
of the struct iomap_dio object is incremented to 4K;
6) iomap calls btrfs_iomap_begin() again, this time with a file
offset of X + 4K. There we setup an iomap for the next extent
that also has a size of 4K;
7) Then at iomap_dio_bio_iter() we call bio_iov_iter_get_pages(),
which tries to access the next page (2nd page) of the buffer.
This triggers a page fault and returns -EFAULT;
8) At __iomap_dio_rw() we see the -EFAULT, but we reset the error
to 0 because we passed the flag IOMAP_DIO_PARTIAL to iomap and
the struct iomap_dio object has a ->size value of 4K (we submitted
a bio for an extent already). The 'wait_for_completion' variable
is not set to true, because our iocb has IOCB_NOWAIT set;
9) At the bottom of __iomap_dio_rw(), we decrement the reference count
of the struct iomap_dio object from 2 to 1. Because we were not
the only ones holding a reference on it and 'wait_for_completion' is
set to false, -EIOCBQUEUED is returned to btrfs_direct_read(), which
just returns it up the callchain, up to io_uring;
10) The bio submitted for the first extent (step 5) completes and its
bio endio function, iomap_dio_bio_end_io(), decrements the last
reference on the struct iomap_dio object, resulting in calling
iomap_dio_complete_work() -> iomap_dio_complete().
11) At iomap_dio_complete() we adjust the iocb->ki_pos from X to X + 4K
and return 4K (the amount of io done) to iomap_dio_complete_work();
12) iomap_dio_complete_work() calls the iocb completion callback,
iocb->ki_complete() with a second argument value of 4K (total io
done) and the iocb with the adjust ki_pos of X + 4K. This results
in completing the read request for io_uring, leaving it with a
result of 4K bytes read, and only the first page of the buffer
filled in, while the remaining 3 pages, corresponding to the other
3 extents, were not filled;
13) For the application, the result is unexpected because if we ask
to read N bytes, it expects to get N bytes read as long as those
N bytes don't cross the EOF (i_size).
MariaDB reports this as an error, as it's not expecting a short read,
since it knows it's asking for read operations fully within the i_size
boundary. This is typical in many applications, but it may also be
questionable if they should react to such short reads by issuing more
read calls to get the remaining data. Nevertheless, the short read
happened due to a change in btrfs regarding how it deals with page
faults while in the middle of a read operation, and there's no reason
why btrfs can't have the previous behaviour of returning the whole data
that was requested by the application.
The problem can also be triggered with the following simple program:
/* Get O_DIRECT */
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <liburing.h>
int main(int argc, char *argv[])
{
char *foo_path;
struct io_uring ring;
struct io_uring_sqe *sqe;
struct io_uring_cqe *cqe;
struct iovec iovec;
int fd;
long pagesize;
void *write_buf;
void *read_buf;
ssize_t ret;
int i;
if (argc != 2) {
fprintf(stderr, "Use: %s <directory>\n", argv[0]);
return 1;
}
foo_path = malloc(strlen(argv[1]) + 5);
if (!foo_path) {
fprintf(stderr, "Failed to allocate memory for file path\n");
return 1;
}
strcpy(foo_path, argv[1]);
strcat(foo_path, "/foo");
/*
* Create file foo with 2 extents, each with a size matching
* the page size. Then allocate a buffer to read both extents
* with io_uring, using O_DIRECT and IOCB_NOWAIT. Before doing
* the read with io_uring, access the first page of the buffer
* to fault it in, so that during the read we only trigger a
* page fault when accessing the second page of the buffer.
*/
fd = open(foo_path, O_CREAT | O_TRUNC | O_WRONLY |
O_DIRECT, 0666);
if (fd == -1) {
fprintf(stderr,
"Failed to create file 'foo': %s (errno %d)",
strerror(errno), errno);
return 1;
}
pagesize = sysconf(_SC_PAGE_SIZE);
ret = posix_memalign(&write_buf, pagesize, 2 * pagesize);
if (ret) {
fprintf(stderr, "Failed to allocate write buffer\n");
return 1;
}
memset(write_buf, 0xab, pagesize);
memset(write_buf + pagesize, 0xcd, pagesize);
/* Create 2 extents, each with a size matching page size. */
for (i = 0; i < 2; i++) {
ret = pwrite(fd, write_buf + i * pagesize, pagesize,
i * pagesize);
if (ret != pagesize) {
fprintf(stderr,
"Failed to write to file, ret = %ld errno %d (%s)\n",
ret, errno, strerror(errno));
return 1;
}
ret = fsync(fd);
if (ret != 0) {
fprintf(stderr, "Failed to fsync file\n");
return 1;
}
}
close(fd);
fd = open(foo_path, O_RDONLY | O_DIRECT);
if (fd == -1) {
fprintf(stderr,
"Failed to open file 'foo': %s (errno %d)",
strerror(errno), errno);
return 1;
}
ret = posix_memalign(&read_buf, pagesize, 2 * pagesize);
if (ret) {
fprintf(stderr, "Failed to allocate read buffer\n");
return 1;
}
/*
* Fault in only the first page of the read buffer.
* We want to trigger a page fault for the 2nd page of the
* read buffer during the read operation with io_uring
* (O_DIRECT and IOCB_NOWAIT).
*/
memset(read_buf, 0, 1);
ret = io_uring_queue_init(1, &ring, 0);
if (ret != 0) {
fprintf(stderr, "Failed to create io_uring queue\n");
return 1;
}
sqe = io_uring_get_sqe(&ring);
if (!sqe) {
fprintf(stderr, "Failed to get io_uring sqe\n");
return 1;
}
iovec.iov_base = read_buf;
iovec.iov_len = 2 * pagesize;
io_uring_prep_readv(sqe, fd, &iovec, 1, 0);
ret = io_uring_submit_and_wait(&ring, 1);
if (ret != 1) {
fprintf(stderr,
"Failed at io_uring_submit_and_wait()\n");
return 1;
}
ret = io_uring_wait_cqe(&ring, &cqe);
if (ret < 0) {
fprintf(stderr, "Failed at io_uring_wait_cqe()\n");
return 1;
}
printf("io_uring read result for file foo:\n\n");
printf(" cqe->res == %d (expected %d)\n", cqe->res, 2 * pagesize);
printf(" memcmp(read_buf, write_buf) == %d (expected 0)\n",
memcmp(read_buf, write_buf, 2 * pagesize));
io_uring_cqe_seen(&ring, cqe);
io_uring_queue_exit(&ring);
return 0;
}
When running it on an unpatched kernel:
$ gcc io_uring_test.c -luring
$ mkfs.btrfs -f /dev/sda
$ mount /dev/sda /mnt/sda
$ ./a.out /mnt/sda
io_uring read result for file foo:
cqe->res == 4096 (expected 8192)
memcmp(read_buf, write_buf) == -205 (expected 0)
After this patch, the read always returns 8192 bytes, with the buffer
filled with the correct data. Although that reproducer always triggers
the bug in my test vms, it's possible that it will not be so reliable
on other environments, as that can happen if the bio for the first
extent completes and decrements the reference on the struct iomap_dio
object before we do the atomic_dec_and_test() on the reference at
__iomap_dio_rw().
Fix this in btrfs by having btrfs_dio_iomap_begin() return -EAGAIN
whenever we try to satisfy a non blocking IO request (IOMAP_NOWAIT flag
set) over a range that spans multiple extents (or a mix of extents and
holes). This avoids returning success to the caller when we only did
partial IO, which is not optimal for writes and for reads it's actually
incorrect, as the caller doesn't expect to get less bytes read than it has
requested (unless EOF is crossed), as previously mentioned. This is also
the type of behaviour that xfs follows (xfs_direct_write_iomap_begin()),
even though it doesn't use IOMAP_DIO_PARTIAL.
A test case for fstests will follow soon.
Link: https://lore.kernel.org/linux-btrfs/CABVffEM0eEWho+206m470rtM0d9J8ue85TtR-A_oVTuGLWFicA@mail.gmail.com/
Link: https://lore.kernel.org/linux-btrfs/CAHF2GV6U32gmqSjLe=XKgfcZAmLCiH26cJ2OnHGp5x=VAH4OHQ@mail.gmail.com/
CC: stable@vger.kernel.org # 5.16+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
During log replay, whenever we need to check if a name (dentry) exists in
a directory we do searches on the subvolume tree for inode references or
or directory entries (BTRFS_DIR_INDEX_KEY keys, and BTRFS_DIR_ITEM_KEY
keys as well, before kernel 5.17). However when during log replay we
unlink a name, through btrfs_unlink_inode(), we may not delete inode
references and dir index keys from a subvolume tree and instead just add
the deletions to the delayed inode's delayed items, which will only be
run when we commit the transaction used for log replay. This means that
after an unlink operation during log replay, if we attempt to search for
the same name during log replay, we will not see that the name was already
deleted, since the deletion is recorded only on the delayed items.
We run delayed items after every unlink operation during log replay,
except at unlink_old_inode_refs() and at add_inode_ref(). This was due
to an overlook, as delayed items should be run after evert unlink, for
the reasons stated above.
So fix those two cases.
Fixes: 0d836392ca ("Btrfs: fix mount failure after fsync due to hard link recreation")
Fixes: 1f250e929a ("Btrfs: fix log replay failure after unlink and link combination")
CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The commit e804861bd4 ("btrfs: fix deadlock between quota disable and
qgroup rescan worker") by Kawasaki resolves deadlock between quota
disable and qgroup rescan worker. But also there is a deadlock case like
it. It's about enabling or disabling quota and creating or removing
qgroup. It can be reproduced in simple script below.
for i in {1..100}
do
btrfs quota enable /mnt &
btrfs qgroup create 1/0 /mnt &
btrfs qgroup destroy 1/0 /mnt &
btrfs quota disable /mnt &
done
Here's why the deadlock happens:
1) The quota rescan task is running.
2) Task A calls btrfs_quota_disable(), locks the qgroup_ioctl_lock
mutex, and then calls btrfs_qgroup_wait_for_completion(), to wait for
the quota rescan task to complete.
3) Task B calls btrfs_remove_qgroup() and it blocks when trying to lock
the qgroup_ioctl_lock mutex, because it's being held by task A. At that
point task B is holding a transaction handle for the current transaction.
4) The quota rescan task calls btrfs_commit_transaction(). This results
in it waiting for all other tasks to release their handles on the
transaction, but task B is blocked on the qgroup_ioctl_lock mutex
while holding a handle on the transaction, and that mutex is being held
by task A, which is waiting for the quota rescan task to complete,
resulting in a deadlock between these 3 tasks.
To resolve this issue, the thread disabling quota should unlock
qgroup_ioctl_lock before waiting rescan completion. Move
btrfs_qgroup_wait_for_completion() after unlock of qgroup_ioctl_lock.
Fixes: e804861bd4 ("btrfs: fix deadlock between quota disable and qgroup rescan worker")
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Sidong Yang <realwakka@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We hit a bug with a recovering relocation on mount for one of our file
systems in production. I reproduced this locally by injecting errors
into snapshot delete with balance running at the same time. This
presented as an error while looking up an extent item
WARNING: CPU: 5 PID: 1501 at fs/btrfs/extent-tree.c:866 lookup_inline_extent_backref+0x647/0x680
CPU: 5 PID: 1501 Comm: btrfs-balance Not tainted 5.16.0-rc8+ #8
RIP: 0010:lookup_inline_extent_backref+0x647/0x680
RSP: 0018:ffffae0a023ab960 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 000000000000000c RDI: 0000000000000000
RBP: ffff943fd2a39b60 R08: 0000000000000000 R09: 0000000000000001
R10: 0001434088152de0 R11: 0000000000000000 R12: 0000000001d05000
R13: ffff943fd2a39b60 R14: ffff943fdb96f2a0 R15: ffff9442fc923000
FS: 0000000000000000(0000) GS:ffff944e9eb40000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1157b1fca8 CR3: 000000010f092000 CR4: 0000000000350ee0
Call Trace:
<TASK>
insert_inline_extent_backref+0x46/0xd0
__btrfs_inc_extent_ref.isra.0+0x5f/0x200
? btrfs_merge_delayed_refs+0x164/0x190
__btrfs_run_delayed_refs+0x561/0xfa0
? btrfs_search_slot+0x7b4/0xb30
? btrfs_update_root+0x1a9/0x2c0
btrfs_run_delayed_refs+0x73/0x1f0
? btrfs_update_root+0x1a9/0x2c0
btrfs_commit_transaction+0x50/0xa50
? btrfs_update_reloc_root+0x122/0x220
prepare_to_merge+0x29f/0x320
relocate_block_group+0x2b8/0x550
btrfs_relocate_block_group+0x1a6/0x350
btrfs_relocate_chunk+0x27/0xe0
btrfs_balance+0x777/0xe60
balance_kthread+0x35/0x50
? btrfs_balance+0xe60/0xe60
kthread+0x16b/0x190
? set_kthread_struct+0x40/0x40
ret_from_fork+0x22/0x30
</TASK>
Normally snapshot deletion and relocation are excluded from running at
the same time by the fs_info->cleaner_mutex. However if we had a
pending balance waiting to get the ->cleaner_mutex, and a snapshot
deletion was running, and then the box crashed, we would come up in a
state where we have a half deleted snapshot.
Again, in the normal case the snapshot deletion needs to complete before
relocation can start, but in this case relocation could very well start
before the snapshot deletion completes, as we simply add the root to the
dead roots list and wait for the next time the cleaner runs to clean up
the snapshot.
Fix this by setting a bit on the fs_info if we have any DEAD_ROOT's that
had a pending drop_progress key. If they do then we know we were in the
middle of the drop operation and set a flag on the fs_info. Then
balance can wait until this flag is cleared to start up again.
If there are DEAD_ROOT's that don't have a drop_progress set then we're
safe to start balance right away as we'll be properly protected by the
cleaner_mutex.
CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
User reported there is an array-index-out-of-bounds access while
mounting the crafted image:
[350.411942 ] loop0: detected capacity change from 0 to 262144
[350.427058 ] BTRFS: device fsid a62e00e8-e94e-4200-8217-12444de93c2e devid 1 transid 8 /dev/loop0 scanned by systemd-udevd (1044)
[350.428564 ] BTRFS info (device loop0): disk space caching is enabled
[350.428568 ] BTRFS info (device loop0): has skinny extents
[350.429589 ]
[350.429619 ] UBSAN: array-index-out-of-bounds in fs/btrfs/struct-funcs.c:161:1
[350.429636 ] index 1048096 is out of range for type 'page *[16]'
[350.429650 ] CPU: 0 PID: 9 Comm: kworker/u8:1 Not tainted 5.16.0-rc4
[350.429652 ] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014
[350.429653 ] Workqueue: btrfs-endio-meta btrfs_work_helper [btrfs]
[350.429772 ] Call Trace:
[350.429774 ] <TASK>
[350.429776 ] dump_stack_lvl+0x47/0x5c
[350.429780 ] ubsan_epilogue+0x5/0x50
[350.429786 ] __ubsan_handle_out_of_bounds+0x66/0x70
[350.429791 ] btrfs_get_16+0xfd/0x120 [btrfs]
[350.429832 ] check_leaf+0x754/0x1a40 [btrfs]
[350.429874 ] ? filemap_read+0x34a/0x390
[350.429878 ] ? load_balance+0x175/0xfc0
[350.429881 ] validate_extent_buffer+0x244/0x310 [btrfs]
[350.429911 ] btrfs_validate_metadata_buffer+0xf8/0x100 [btrfs]
[350.429935 ] end_bio_extent_readpage+0x3af/0x850 [btrfs]
[350.429969 ] ? newidle_balance+0x259/0x480
[350.429972 ] end_workqueue_fn+0x29/0x40 [btrfs]
[350.429995 ] btrfs_work_helper+0x71/0x330 [btrfs]
[350.430030 ] ? __schedule+0x2fb/0xa40
[350.430033 ] process_one_work+0x1f6/0x400
[350.430035 ] ? process_one_work+0x400/0x400
[350.430036 ] worker_thread+0x2d/0x3d0
[350.430037 ] ? process_one_work+0x400/0x400
[350.430038 ] kthread+0x165/0x190
[350.430041 ] ? set_kthread_struct+0x40/0x40
[350.430043 ] ret_from_fork+0x1f/0x30
[350.430047 ] </TASK>
[350.430047 ]
[350.430077 ] BTRFS warning (device loop0): bad eb member start: ptr 0xffe20f4e start 20975616 member offset 4293005178 size 2
btrfs check reports:
corrupt leaf: root=3 block=20975616 physical=20975616 slot=1, unexpected
item end, have 4294971193 expect 3897
The first slot item offset is 4293005033 and the size is 1966160.
In check_leaf, we use btrfs_item_end() to check item boundary versus
extent_buffer data size. However, return type of btrfs_item_end() is u32.
(u32)(4293005033 + 1966160) == 3897, overflow happens and the result 3897
equals to leaf data size reasonably.
Fix it by use u64 variable to store item data end in check_leaf() to
avoid u32 overflow.
This commit does solve the invalid memory access showed by the stack
trace. However, its metadata profile is DUP and another copy of the
leaf is fine. So the image can be mounted successfully. But when umount
is called, the ASSERT btrfs_mark_buffer_dirty() will be triggered
because the only node in extent tree has 0 item and invalid owner. It's
solved by another commit
"btrfs: check extent buffer owner against the owner rootid".
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215299
Reported-by: Wenqing Liu <wenqingliu0120@gmail.com>
CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Su Yue <l@damenly.su>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Whenever we do any extent buffer operations we call
assert_eb_page_uptodate() to complain loudly if we're operating on an
non-uptodate page. Our overnight tests caught this warning earlier this
week
WARNING: CPU: 1 PID: 553508 at fs/btrfs/extent_io.c:6849 assert_eb_page_uptodate+0x3f/0x50
CPU: 1 PID: 553508 Comm: kworker/u4:13 Tainted: G W 5.17.0-rc3+ #564
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
Workqueue: btrfs-cache btrfs_work_helper
RIP: 0010:assert_eb_page_uptodate+0x3f/0x50
RSP: 0018:ffffa961440a7c68 EFLAGS: 00010246
RAX: 0017ffffc0002112 RBX: ffffe6e74453f9c0 RCX: 0000000000001000
RDX: ffffe6e74467c887 RSI: ffffe6e74453f9c0 RDI: ffff8d4c5efc2fc0
RBP: 0000000000000d56 R08: ffff8d4d4a224000 R09: 0000000000000000
R10: 00015817fa9d1ef0 R11: 000000000000000c R12: 00000000000007b1
R13: ffff8d4c5efc2fc0 R14: 0000000001500000 R15: 0000000001cb1000
FS: 0000000000000000(0000) GS:ffff8d4dbbd00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff31d3448d8 CR3: 0000000118be8004 CR4: 0000000000370ee0
Call Trace:
extent_buffer_test_bit+0x3f/0x70
free_space_test_bit+0xa6/0xc0
load_free_space_tree+0x1f6/0x470
caching_thread+0x454/0x630
? rcu_read_lock_sched_held+0x12/0x60
? rcu_read_lock_sched_held+0x12/0x60
? rcu_read_lock_sched_held+0x12/0x60
? lock_release+0x1f0/0x2d0
btrfs_work_helper+0xf2/0x3e0
? lock_release+0x1f0/0x2d0
? finish_task_switch.isra.0+0xf9/0x3a0
process_one_work+0x26d/0x580
? process_one_work+0x580/0x580
worker_thread+0x55/0x3b0
? process_one_work+0x580/0x580
kthread+0xf0/0x120
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x1f/0x30
This was partially fixed by c2e3930529 ("btrfs: clear extent buffer
uptodate when we fail to write it"), however all that fix did was keep
us from finding extent buffers after a failed writeout. It didn't keep
us from continuing to use a buffer that we already had found.
In this case we're searching the commit root to cache the block group,
so we can start committing the transaction and switch the commit root
and then start writing. After the switch we can look up an extent
buffer that hasn't been written yet and start processing that block
group. Then we fail to write that block out and clear Uptodate on the
page, and then we start spewing these errors.
Normally we're protected by the tree lock to a certain degree here. If
we read a block we have that block read locked, and we block the writer
from locking the block before we submit it for the write. However this
isn't necessarily fool proof because the read could happen before we do
the submit_bio and after we locked and unlocked the extent buffer.
Also in this particular case we have path->skip_locking set, so that
won't save us here. We'll simply get a block that was valid when we
read it, but became invalid while we were using it.
What we really want is to catch the case where we've "read" a block but
it's not marked Uptodate. On read we ClearPageError(), so if we're
!Uptodate and !Error we know we didn't do the right thing for reading
the page.
Fix this by checking !Uptodate && !Error, this way we will not complain
if our buffer gets invalidated while we're using it, and we'll maintain
the spirit of the check which is to make sure we have a fully in-cache
block while we're messing with it.
CC: stable@vger.kernel.org # 5.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing a full fsync, if we have prealloc extents beyond (or at) eof,
and the leaves that contain them were not modified in the current
transaction, we end up not logging them. This results in losing those
extents when we replay the log after a power failure, since the inode is
truncated to the current value of the logged i_size.
Just like for the fast fsync path, we need to always log all prealloc
extents starting at or beyond i_size. The fast fsync case was fixed in
commit 471d557afe ("Btrfs: fix loss of prealloc extents past i_size
after fsync log replay") but it missed the full fsync path. The problem
exists since the very early days, when the log tree was added by
commit e02119d5a7 ("Btrfs: Add a write ahead tree log to optimize
synchronous operations").
Example reproducer:
$ mkfs.btrfs -f /dev/sdc
$ mount /dev/sdc /mnt
# Create our test file with many file extent items, so that they span
# several leaves of metadata, even if the node/page size is 64K. Use
# direct IO and not fsync/O_SYNC because it's both faster and it avoids
# clearing the full sync flag from the inode - we want the fsync below
# to trigger the slow full sync code path.
$ xfs_io -f -d -c "pwrite -b 4K 0 16M" /mnt/foo
# Now add two preallocated extents to our file without extending the
# file's size. One right at i_size, and another further beyond, leaving
# a gap between the two prealloc extents.
$ xfs_io -c "falloc -k 16M 1M" /mnt/foo
$ xfs_io -c "falloc -k 20M 1M" /mnt/foo
# Make sure everything is durably persisted and the transaction is
# committed. This makes all created extents to have a generation lower
# than the generation of the transaction used by the next write and
# fsync.
sync
# Now overwrite only the first extent, which will result in modifying
# only the first leaf of metadata for our inode. Then fsync it. This
# fsync will use the slow code path (inode full sync bit is set) because
# it's the first fsync since the inode was created/loaded.
$ xfs_io -c "pwrite 0 4K" -c "fsync" /mnt/foo
# Extent list before power failure.
$ xfs_io -c "fiemap -v" /mnt/foo
/mnt/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..7]: 2178048..2178055 8 0x0
1: [8..16383]: 26632..43007 16376 0x0
2: [16384..32767]: 2156544..2172927 16384 0x0
3: [32768..34815]: 2172928..2174975 2048 0x800
4: [34816..40959]: hole 6144
5: [40960..43007]: 2174976..2177023 2048 0x801
<power fail>
# Mount fs again, trigger log replay.
$ mount /dev/sdc /mnt
# Extent list after power failure and log replay.
$ xfs_io -c "fiemap -v" /mnt/foo
/mnt/foo:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..7]: 2178048..2178055 8 0x0
1: [8..16383]: 26632..43007 16376 0x0
2: [16384..32767]: 2156544..2172927 16384 0x1
# The prealloc extents at file offsets 16M and 20M are missing.
So fix this by calling btrfs_log_prealloc_extents() when we are doing a
full fsync, so that we always log all prealloc extents beyond eof.
A test case for fstests will follow soon.
CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When looping btrfs/074 with 64K page size and 4K sectorsize, there is a
low chance (1/50~1/100) to crash with the following ASSERT() triggered
in btrfs_subpage_start_writer():
ret = atomic_add_return(nbits, &subpage->writers);
ASSERT(ret == nbits); <<< This one <<<
[CAUSE]
With more debugging output on the parameters of
btrfs_subpage_start_writer(), it shows a very concerning error:
ret=29 nbits=13 start=393216 len=53248
For @nbits it's correct, but @ret which is the returned value from
atomic_add_return(), it's not only larger than nbits, but also larger
than max sectors per page value (for 64K page size and 4K sector size,
it's 16).
This indicates that some call sites are not properly decreasing the value.
And that's exactly the case, in btrfs_page_unlock_writer(), due to the
fact that we can have page locked either by lock_page() or
process_one_page(), we have to check if the subpage has any writer.
If no writers, it's locked by lock_page() and we only need to unlock it.
But unfortunately the check for the writers are completely opposite:
if (atomic_read(&subpage->writers))
/* No writers, locked by plain lock_page() */
return unlock_page(page);
We directly unlock the page if it has writers, which is the completely
opposite what we want.
Thankfully the affected call site is only limited to
extent_write_locked_range(), so it's mostly affecting compressed write.
[FIX]
Just fix the wrong check condition to fix the bug.
Fixes: e55a0de185 ("btrfs: rework page locking in __extent_writepage()")
CC: stable@vger.kernel.org # 5.16
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-5.17-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"This is a hopefully last batch of fixes for defrag that got broken in
5.16, all stable material.
The remaining reported problem is excessive IO with autodefrag due to
various conditions in the defrag code not met or missing"
* tag 'for-5.17-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: reduce extent threshold for autodefrag
btrfs: autodefrag: only scan one inode once
btrfs: defrag: don't use merged extent map for their generation check
btrfs: defrag: bring back the old file extent search behavior
btrfs: defrag: remove an ambiguous condition for rejection
btrfs: defrag: don't defrag extents which are already at max capacity
btrfs: defrag: don't try to merge regular extents with preallocated extents
btrfs: defrag: allow defrag_one_cluster() to skip large extent which is not a target
btrfs: prevent copying too big compressed lzo segment
There is a big gap between inode_should_defrag() and autodefrag extent
size threshold. For inode_should_defrag() it has a flexible
@small_write value. For compressed extent is 16K, and for non-compressed
extent it's 64K.
However for autodefrag extent size threshold, it's always fixed to the
default value (256K).
This means, the following write sequence will trigger autodefrag to
defrag ranges which didn't trigger autodefrag:
pwrite 0 8k
sync
pwrite 8k 128K
sync
The latter 128K write will also be considered as a defrag target (if
other conditions are met). While only that 8K write is really
triggering autodefrag.
Such behavior can cause extra IO for autodefrag.
Close the gap, by copying the @small_write value into inode_defrag, so
that later autodefrag can use the same @small_write value which
triggered autodefrag.
With the existing transid value, this allows autodefrag really to scan
the ranges which triggered autodefrag.
Although this behavior change is mostly reducing the extent_thresh value
for autodefrag, I believe in the future we should allow users to specify
the autodefrag extent threshold through mount options, but that's an
other problem to consider in the future.
CC: stable@vger.kernel.org # 5.16+
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Although we have btrfs_requeue_inode_defrag(), for autodefrag we are
still just exhausting all inode_defrag items in the tree.
This means, it doesn't make much difference to requeue an inode_defrag,
other than scan the inode from the beginning till its end.
Change the behaviour to always scan from offset 0 of an inode, and till
the end.
By this we get the following benefit:
- Straight-forward code
- No more re-queue related check
- Fewer members in inode_defrag
We still keep the same btrfs_get_fs_root() and btrfs_iget() check for
each loop, and added extra should_auto_defrag() check per-loop.
Note: the patch needs to be backported and is intentionally written
to minimize the diff size, code will be cleaned up later.
CC: stable@vger.kernel.org # 5.16
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For extent maps, if they are not compressed extents and are adjacent by
logical addresses and file offsets, they can be merged into one larger
extent map.
Such merged extent map will have the higher generation of all the
original ones.
But this brings a problem for autodefrag, as it relies on accurate
extent_map::generation to determine if one extent should be defragged.
For merged extent maps, their higher generation can mark some older
extents to be defragged while the original extent map doesn't meet the
minimal generation threshold.
Thus this will cause extra IO.
So solve the problem, here we introduce a new flag, EXTENT_FLAG_MERGED,
to indicate if the extent map is merged from one or more ems.
And for autodefrag, if we find a merged extent map, and its generation
meets the generation requirement, we just don't use this one, and go
back to defrag_get_extent() to read extent maps from subvolume trees.
This could cause more read IO, but should result less defrag data write,
so in the long run it should be a win for autodefrag.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For defrag, we don't really want to use btrfs_get_extent() to iterate
all extent maps of an inode.
The reasons are:
- btrfs_get_extent() can merge extent maps
And the result em has the higher generation of the two, causing defrag
to mark unnecessary part of such merged large extent map.
This in fact can result extra IO for autodefrag in v5.16+ kernels.
However this patch is not going to completely solve the problem, as
one can still using read() to trigger extent map reading, and got
them merged.
The completely solution for the extent map merging generation problem
will come as an standalone fix.
- btrfs_get_extent() caches the extent map result
Normally it's fine, but for defrag the target range may not get
another read/write for a long long time.
Such cache would only increase the memory usage.
- btrfs_get_extent() doesn't skip older extent map
Unlike the old find_new_extent() which uses btrfs_search_forward() to
skip the older subtree, thus it will pick up unnecessary extent maps.
This patch will fix the regression by introducing defrag_get_extent() to
replace the btrfs_get_extent() call.
This helper will:
- Not cache the file extent we found
It will search the file extent and manually convert it to em.
- Use btrfs_search_forward() to skip entire ranges which is modified in
the past
This should reduce the IO for autodefrag.
Reported-by: Filipe Manana <fdmanana@suse.com>
Fixes: 7b508037d4 ("btrfs: defrag: use defrag_one_cluster() to implement btrfs_defrag_file()")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
From the very beginning of btrfs defrag, there is a check to reject
extents which meet both conditions:
- Physically adjacent
We may want to defrag physically adjacent extents to reduce the number
of extents or the size of subvolume tree.
- Larger than 128K
This may be there for compressed extents, but unfortunately 128K is
exactly the max capacity for compressed extents.
And the check is > 128K, thus it never rejects compressed extents.
Furthermore, the compressed extent capacity bug is fixed by previous
patch, there is no reason for that check anymore.
The original check has a very small ranges to reject (the target extent
size is > 128K, and default extent threshold is 256K), and for
compressed extent it doesn't work at all.
So it's better just to remove the rejection, and allow us to defrag
physically adjacent extents.
CC: stable@vger.kernel.org # 5.16
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
For compressed extents, defrag ioctl will always try to defrag any
compressed extents, wasting not only IO but also CPU time to
compress/decompress:
mkfs.btrfs -f $DEV
mount -o compress $DEV $MNT
xfs_io -f -c "pwrite -S 0xab 0 128K" $MNT/foobar
sync
xfs_io -f -c "pwrite -S 0xcd 128K 128K" $MNT/foobar
sync
echo "=== before ==="
xfs_io -c "fiemap -v" $MNT/foobar
btrfs filesystem defrag $MNT/foobar
sync
echo "=== after ==="
xfs_io -c "fiemap -v" $MNT/foobar
Then it shows the 2 128K extents just get COW for no extra benefit, with
extra IO/CPU spent:
=== before ===
/mnt/btrfs/file1:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..255]: 26624..26879 256 0x8
1: [256..511]: 26632..26887 256 0x9
=== after ===
/mnt/btrfs/file1:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..255]: 26640..26895 256 0x8
1: [256..511]: 26648..26903 256 0x9
This affects not only v5.16 (after the defrag rework), but also v5.15
(before the defrag rework).
[CAUSE]
From the very beginning, btrfs defrag never checks if one extent is
already at its max capacity (128K for compressed extents, 128M
otherwise).
And the default extent size threshold is 256K, which is already beyond
the compressed extent max size.
This means, by default btrfs defrag ioctl will mark all compressed
extent which is not adjacent to a hole/preallocated range for defrag.
[FIX]
Introduce a helper to grab the maximum extent size, and then in
defrag_collect_targets() and defrag_check_next_extent(), reject extents
which are already at their max capacity.
Reported-by: Filipe Manana <fdmanana@suse.com>
CC: stable@vger.kernel.org # 5.16
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
With older kernels (before v5.16), btrfs will defrag preallocated extents.
While with newer kernels (v5.16 and newer) btrfs will not defrag
preallocated extents, but it will defrag the extent just before the
preallocated extent, even it's just a single sector.
This can be exposed by the following small script:
mkfs.btrfs -f $dev > /dev/null
mount $dev $mnt
xfs_io -f -c "pwrite 0 4k" -c sync -c "falloc 4k 16K" $mnt/file
xfs_io -c "fiemap -v" $mnt/file
btrfs fi defrag $mnt/file
sync
xfs_io -c "fiemap -v" $mnt/file
The output looks like this on older kernels:
/mnt/btrfs/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..7]: 26624..26631 8 0x0
1: [8..39]: 26632..26663 32 0x801
/mnt/btrfs/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..39]: 26664..26703 40 0x1
Which defrags the single sector along with the preallocated extent, and
replace them with an regular extent into a new location (caused by data
COW).
This wastes most of the data IO just for the preallocated range.
On the other hand, v5.16 is slightly better:
/mnt/btrfs/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..7]: 26624..26631 8 0x0
1: [8..39]: 26632..26663 32 0x801
/mnt/btrfs/file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..7]: 26664..26671 8 0x0
1: [8..39]: 26632..26663 32 0x801
The preallocated range is not defragged, but the sector before it still
gets defragged, which has no need for it.
[CAUSE]
One of the function reused by the old and new behavior is
defrag_check_next_extent(), it will determine if we should defrag
current extent by checking the next one.
It only checks if the next extent is a hole or inlined, but it doesn't
check if it's preallocated.
On the other hand, out of the function, both old and new kernel will
reject preallocated extents.
Such inconsistent behavior causes above behavior.
[FIX]
- Also check if next extent is preallocated
If so, don't defrag current extent.
- Add comments for each branch why we reject the extent
This will reduce the IO caused by defrag ioctl and autodefrag.
CC: stable@vger.kernel.org # 5.16
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In the rework of btrfs_defrag_file(), we always call
defrag_one_cluster() and increase the offset by cluster size, which is
only 256K.
But there are cases where we have a large extent (e.g. 128M) which
doesn't need to be defragged at all.
Before the refactor, we can directly skip the range, but now we have to
scan that extent map again and again until the cluster moves after the
non-target extent.
Fix the problem by allow defrag_one_cluster() to increase
btrfs_defrag_ctrl::last_scanned to the end of an extent, if and only if
the last extent of the cluster is not a target.
The test script looks like this:
mkfs.btrfs -f $dev > /dev/null
mount $dev $mnt
# As btrfs ioctl uses 32M as extent_threshold
xfs_io -f -c "pwrite 0 64M" $mnt/file1
sync
# Some fragemented range to defrag
xfs_io -s -c "pwrite 65548k 4k" \
-c "pwrite 65544k 4k" \
-c "pwrite 65540k 4k" \
-c "pwrite 65536k 4k" \
$mnt/file1
sync
echo "=== before ==="
xfs_io -c "fiemap -v" $mnt/file1
echo "=== after ==="
btrfs fi defrag $mnt/file1
sync
xfs_io -c "fiemap -v" $mnt/file1
umount $mnt
With extra ftrace put into defrag_one_cluster(), before the patch it
would result tons of loops:
(As defrag_one_cluster() is inlined, the function name is its caller)
btrfs-126062 [005] ..... 4682.816026: btrfs_defrag_file: r/i=5/257 start=0 len=262144
btrfs-126062 [005] ..... 4682.816027: btrfs_defrag_file: r/i=5/257 start=262144 len=262144
btrfs-126062 [005] ..... 4682.816028: btrfs_defrag_file: r/i=5/257 start=524288 len=262144
btrfs-126062 [005] ..... 4682.816028: btrfs_defrag_file: r/i=5/257 start=786432 len=262144
btrfs-126062 [005] ..... 4682.816028: btrfs_defrag_file: r/i=5/257 start=1048576 len=262144
...
btrfs-126062 [005] ..... 4682.816043: btrfs_defrag_file: r/i=5/257 start=67108864 len=262144
But with this patch there will be just one loop, then directly to the
end of the extent:
btrfs-130471 [014] ..... 5434.029558: defrag_one_cluster: r/i=5/257 start=0 len=262144
btrfs-130471 [014] ..... 5434.029559: defrag_one_cluster: r/i=5/257 start=67108864 len=16384
CC: stable@vger.kernel.org # 5.16
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-5.17-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
- yield CPU more often when defragmenting a large file
- skip defragmenting extents already under writeback
- improve error message when send fails to write file data
- get rid of warning when mounted with 'flushoncommit'
* tag 'for-5.17-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: send: in case of IO error log it
btrfs: get rid of warning on transaction commit when using flushoncommit
btrfs: defrag: don't try to defrag extents which are under writeback
btrfs: don't hold CPU for too long when defragging a file
Currently if we get IO error while doing send then we abort without
logging information about which file caused issue. So log it to help
with debugging.
CC: stable@vger.kernel.org # 4.9+
Signed-off-by: Dāvis Mosāns <davispuh@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When using the flushoncommit mount option, during almost every transaction
commit we trigger a warning from __writeback_inodes_sb_nr():
$ cat fs/fs-writeback.c:
(...)
static void __writeback_inodes_sb_nr(struct super_block *sb, ...
{
(...)
WARN_ON(!rwsem_is_locked(&sb->s_umount));
(...)
}
(...)
The trace produced in dmesg looks like the following:
[947.473890] WARNING: CPU: 5 PID: 930 at fs/fs-writeback.c:2610 __writeback_inodes_sb_nr+0x7e/0xb3
[947.481623] Modules linked in: nfsd nls_cp437 cifs asn1_decoder cifs_arc4 fscache cifs_md4 ipmi_ssif
[947.489571] CPU: 5 PID: 930 Comm: btrfs-transacti Not tainted 95.16.3-srb-asrock-00001-g36437ad63879 #186
[947.497969] RIP: 0010:__writeback_inodes_sb_nr+0x7e/0xb3
[947.502097] Code: 24 10 4c 89 44 24 18 c6 (...)
[947.519760] RSP: 0018:ffffc90000777e10 EFLAGS: 00010246
[947.523818] RAX: 0000000000000000 RBX: 0000000000963300 RCX: 0000000000000000
[947.529765] RDX: 0000000000000000 RSI: 000000000000fa51 RDI: ffffc90000777e50
[947.535740] RBP: ffff888101628a90 R08: ffff888100955800 R09: ffff888100956000
[947.541701] R10: 0000000000000002 R11: 0000000000000001 R12: ffff888100963488
[947.547645] R13: ffff888100963000 R14: ffff888112fb7200 R15: ffff888100963460
[947.553621] FS: 0000000000000000(0000) GS:ffff88841fd40000(0000) knlGS:0000000000000000
[947.560537] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[947.565122] CR2: 0000000008be50c4 CR3: 000000000220c000 CR4: 00000000001006e0
[947.571072] Call Trace:
[947.572354] <TASK>
[947.573266] btrfs_commit_transaction+0x1f1/0x998
[947.576785] ? start_transaction+0x3ab/0x44e
[947.579867] ? schedule_timeout+0x8a/0xdd
[947.582716] transaction_kthread+0xe9/0x156
[947.585721] ? btrfs_cleanup_transaction.isra.0+0x407/0x407
[947.590104] kthread+0x131/0x139
[947.592168] ? set_kthread_struct+0x32/0x32
[947.595174] ret_from_fork+0x22/0x30
[947.597561] </TASK>
[947.598553] ---[ end trace 644721052755541c ]---
This is because we started using writeback_inodes_sb() to flush delalloc
when committing a transaction (when using -o flushoncommit), in order to
avoid deadlocks with filesystem freeze operations. This change was made
by commit ce8ea7cc6e ("btrfs: don't call btrfs_start_delalloc_roots
in flushoncommit"). After that change we started producing that warning,
and every now and then a user reports this since the warning happens too
often, it spams dmesg/syslog, and a user is unsure if this reflects any
problem that might compromise the filesystem's reliability.
We can not just lock the sb->s_umount semaphore before calling
writeback_inodes_sb(), because that would at least deadlock with
filesystem freezing, since at fs/super.c:freeze_super() sync_filesystem()
is called while we are holding that semaphore in write mode, and that can
trigger a transaction commit, resulting in a deadlock. It would also
trigger the same type of deadlock in the unmount path. Possibly, it could
also introduce some other locking dependencies that lockdep would report.
To fix this call try_to_writeback_inodes_sb() instead of
writeback_inodes_sb(), because that will try to read lock sb->s_umount
and then will only call writeback_inodes_sb() if it was able to lock it.
This is fine because the cases where it can't read lock sb->s_umount
are during a filesystem unmount or during a filesystem freeze - in those
cases sb->s_umount is write locked and sync_filesystem() is called, which
calls writeback_inodes_sb(). In other words, in all cases where we can't
take a read lock on sb->s_umount, writeback is already being triggered
elsewhere.
An alternative would be to call btrfs_start_delalloc_roots() with a
number of pages different from LONG_MAX, for example matching the number
of delalloc bytes we currently have, in which case we would end up
starting all delalloc with filemap_fdatawrite_wbc() and not with an
async flush via filemap_flush() - that is only possible after the rather
recent commit e076ab2a2c ("btrfs: shrink delalloc pages instead of
full inodes"). However that creates a whole new can of worms due to new
lock dependencies, which lockdep complains, like for example:
[ 8948.247280] ======================================================
[ 8948.247823] WARNING: possible circular locking dependency detected
[ 8948.248353] 5.17.0-rc1-btrfs-next-111 #1 Not tainted
[ 8948.248786] ------------------------------------------------------
[ 8948.249320] kworker/u16:18/933570 is trying to acquire lock:
[ 8948.249812] ffff9b3de1591690 (sb_internal#2){.+.+}-{0:0}, at: find_free_extent+0x141e/0x1590 [btrfs]
[ 8948.250638]
but task is already holding lock:
[ 8948.251140] ffff9b3e09c717d8 (&root->delalloc_mutex){+.+.}-{3:3}, at: start_delalloc_inodes+0x78/0x400 [btrfs]
[ 8948.252018]
which lock already depends on the new lock.
[ 8948.252710]
the existing dependency chain (in reverse order) is:
[ 8948.253343]
-> #2 (&root->delalloc_mutex){+.+.}-{3:3}:
[ 8948.253950] __mutex_lock+0x90/0x900
[ 8948.254354] start_delalloc_inodes+0x78/0x400 [btrfs]
[ 8948.254859] btrfs_start_delalloc_roots+0x194/0x2a0 [btrfs]
[ 8948.255408] btrfs_commit_transaction+0x32f/0xc00 [btrfs]
[ 8948.255942] btrfs_mksubvol+0x380/0x570 [btrfs]
[ 8948.256406] btrfs_mksnapshot+0x81/0xb0 [btrfs]
[ 8948.256870] __btrfs_ioctl_snap_create+0x17f/0x190 [btrfs]
[ 8948.257413] btrfs_ioctl_snap_create_v2+0xbb/0x140 [btrfs]
[ 8948.257961] btrfs_ioctl+0x1196/0x3630 [btrfs]
[ 8948.258418] __x64_sys_ioctl+0x83/0xb0
[ 8948.258793] do_syscall_64+0x3b/0xc0
[ 8948.259146] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 8948.259709]
-> #1 (&fs_info->delalloc_root_mutex){+.+.}-{3:3}:
[ 8948.260330] __mutex_lock+0x90/0x900
[ 8948.260692] btrfs_start_delalloc_roots+0x97/0x2a0 [btrfs]
[ 8948.261234] btrfs_commit_transaction+0x32f/0xc00 [btrfs]
[ 8948.261766] btrfs_set_free_space_cache_v1_active+0x38/0x60 [btrfs]
[ 8948.262379] btrfs_start_pre_rw_mount+0x119/0x180 [btrfs]
[ 8948.262909] open_ctree+0x1511/0x171e [btrfs]
[ 8948.263359] btrfs_mount_root.cold+0x12/0xde [btrfs]
[ 8948.263863] legacy_get_tree+0x30/0x50
[ 8948.264242] vfs_get_tree+0x28/0xc0
[ 8948.264594] vfs_kern_mount.part.0+0x71/0xb0
[ 8948.265017] btrfs_mount+0x11d/0x3a0 [btrfs]
[ 8948.265462] legacy_get_tree+0x30/0x50
[ 8948.265851] vfs_get_tree+0x28/0xc0
[ 8948.266203] path_mount+0x2d4/0xbe0
[ 8948.266554] __x64_sys_mount+0x103/0x140
[ 8948.266940] do_syscall_64+0x3b/0xc0
[ 8948.267300] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 8948.267790]
-> #0 (sb_internal#2){.+.+}-{0:0}:
[ 8948.268322] __lock_acquire+0x12e8/0x2260
[ 8948.268733] lock_acquire+0xd7/0x310
[ 8948.269092] start_transaction+0x44c/0x6e0 [btrfs]
[ 8948.269591] find_free_extent+0x141e/0x1590 [btrfs]
[ 8948.270087] btrfs_reserve_extent+0x14b/0x280 [btrfs]
[ 8948.270588] cow_file_range+0x17e/0x490 [btrfs]
[ 8948.271051] btrfs_run_delalloc_range+0x345/0x7a0 [btrfs]
[ 8948.271586] writepage_delalloc+0xb5/0x170 [btrfs]
[ 8948.272071] __extent_writepage+0x156/0x3c0 [btrfs]
[ 8948.272579] extent_write_cache_pages+0x263/0x460 [btrfs]
[ 8948.273113] extent_writepages+0x76/0x130 [btrfs]
[ 8948.273573] do_writepages+0xd2/0x1c0
[ 8948.273942] filemap_fdatawrite_wbc+0x68/0x90
[ 8948.274371] start_delalloc_inodes+0x17f/0x400 [btrfs]
[ 8948.274876] btrfs_start_delalloc_roots+0x194/0x2a0 [btrfs]
[ 8948.275417] flush_space+0x1f2/0x630 [btrfs]
[ 8948.275863] btrfs_async_reclaim_data_space+0x108/0x1b0 [btrfs]
[ 8948.276438] process_one_work+0x252/0x5a0
[ 8948.276829] worker_thread+0x55/0x3b0
[ 8948.277189] kthread+0xf2/0x120
[ 8948.277506] ret_from_fork+0x22/0x30
[ 8948.277868]
other info that might help us debug this:
[ 8948.278548] Chain exists of:
sb_internal#2 --> &fs_info->delalloc_root_mutex --> &root->delalloc_mutex
[ 8948.279601] Possible unsafe locking scenario:
[ 8948.280102] CPU0 CPU1
[ 8948.280508] ---- ----
[ 8948.280915] lock(&root->delalloc_mutex);
[ 8948.281271] lock(&fs_info->delalloc_root_mutex);
[ 8948.281915] lock(&root->delalloc_mutex);
[ 8948.282487] lock(sb_internal#2);
[ 8948.282800]
*** DEADLOCK ***
[ 8948.283333] 4 locks held by kworker/u16:18/933570:
[ 8948.283750] #0: ffff9b3dc00a9d48 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1d2/0x5a0
[ 8948.284609] #1: ffffa90349dafe70 ((work_completion)(&fs_info->async_data_reclaim_work)){+.+.}-{0:0}, at: process_one_work+0x1d2/0x5a0
[ 8948.285637] #2: ffff9b3e14db5040 (&fs_info->delalloc_root_mutex){+.+.}-{3:3}, at: btrfs_start_delalloc_roots+0x97/0x2a0 [btrfs]
[ 8948.286674] #3: ffff9b3e09c717d8 (&root->delalloc_mutex){+.+.}-{3:3}, at: start_delalloc_inodes+0x78/0x400 [btrfs]
[ 8948.287596]
stack backtrace:
[ 8948.287975] CPU: 3 PID: 933570 Comm: kworker/u16:18 Not tainted 5.17.0-rc1-btrfs-next-111 #1
[ 8948.288677] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
[ 8948.289649] Workqueue: events_unbound btrfs_async_reclaim_data_space [btrfs]
[ 8948.290298] Call Trace:
[ 8948.290517] <TASK>
[ 8948.290700] dump_stack_lvl+0x59/0x73
[ 8948.291026] check_noncircular+0xf3/0x110
[ 8948.291375] ? start_transaction+0x228/0x6e0 [btrfs]
[ 8948.291826] __lock_acquire+0x12e8/0x2260
[ 8948.292241] lock_acquire+0xd7/0x310
[ 8948.292714] ? find_free_extent+0x141e/0x1590 [btrfs]
[ 8948.293241] ? lock_is_held_type+0xea/0x140
[ 8948.293601] start_transaction+0x44c/0x6e0 [btrfs]
[ 8948.294055] ? find_free_extent+0x141e/0x1590 [btrfs]
[ 8948.294518] find_free_extent+0x141e/0x1590 [btrfs]
[ 8948.294957] ? _raw_spin_unlock+0x29/0x40
[ 8948.295312] ? btrfs_get_alloc_profile+0x124/0x290 [btrfs]
[ 8948.295813] btrfs_reserve_extent+0x14b/0x280 [btrfs]
[ 8948.296270] cow_file_range+0x17e/0x490 [btrfs]
[ 8948.296691] btrfs_run_delalloc_range+0x345/0x7a0 [btrfs]
[ 8948.297175] ? find_lock_delalloc_range+0x247/0x270 [btrfs]
[ 8948.297678] writepage_delalloc+0xb5/0x170 [btrfs]
[ 8948.298123] __extent_writepage+0x156/0x3c0 [btrfs]
[ 8948.298570] extent_write_cache_pages+0x263/0x460 [btrfs]
[ 8948.299061] extent_writepages+0x76/0x130 [btrfs]
[ 8948.299495] do_writepages+0xd2/0x1c0
[ 8948.299817] ? sched_clock_cpu+0xd/0x110
[ 8948.300160] ? lock_release+0x155/0x4a0
[ 8948.300494] filemap_fdatawrite_wbc+0x68/0x90
[ 8948.300874] ? do_raw_spin_unlock+0x4b/0xa0
[ 8948.301243] start_delalloc_inodes+0x17f/0x400 [btrfs]
[ 8948.301706] ? lock_release+0x155/0x4a0
[ 8948.302055] btrfs_start_delalloc_roots+0x194/0x2a0 [btrfs]
[ 8948.302564] flush_space+0x1f2/0x630 [btrfs]
[ 8948.302970] btrfs_async_reclaim_data_space+0x108/0x1b0 [btrfs]
[ 8948.303510] process_one_work+0x252/0x5a0
[ 8948.303860] ? process_one_work+0x5a0/0x5a0
[ 8948.304221] worker_thread+0x55/0x3b0
[ 8948.304543] ? process_one_work+0x5a0/0x5a0
[ 8948.304904] kthread+0xf2/0x120
[ 8948.305184] ? kthread_complete_and_exit+0x20/0x20
[ 8948.305598] ret_from_fork+0x22/0x30
[ 8948.305921] </TASK>
It all comes from the fact that btrfs_start_delalloc_roots() takes the
delalloc_root_mutex, in the transaction commit path we are holding a
read lock on one of the superblock's freeze semaphores (via
sb_start_intwrite()), the async reclaim task can also do a call to
btrfs_start_delalloc_roots(), which ends up triggering writeback with
calls to filemap_fdatawrite_wbc(), resulting in extent allocation which
in turn can call btrfs_start_transaction(), which will result in taking
the freeze semaphore via sb_start_intwrite(), forming a nasty dependency
on all those locks which can be taken in different orders by different
code paths.
So just adopt the simple approach of calling try_to_writeback_inodes_sb()
at btrfs_start_delalloc_flush().
Link: https://lore.kernel.org/linux-btrfs/20220130005258.GA7465@cuci.nl/
Link: https://lore.kernel.org/linux-btrfs/43acc426-d683-d1b6-729d-c6bc4a2fff4d@gmail.com/
Link: https://lore.kernel.org/linux-btrfs/6833930a-08d7-6fbc-0141-eb9cdfd6bb4d@gmail.com/
Link: https://lore.kernel.org/linux-btrfs/20190322041731.GF16651@hungrycats.org/
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
[ add more link reports ]
Signed-off-by: David Sterba <dsterba@suse.com>
Once we start writeback (have called btrfs_run_delalloc_range()), we
allocate an extent, create an extent map point to that extent, with a
generation of (u64)-1, created the ordered extent and then clear the
DELALLOC bit from the range in the inode's io tree.
Such extent map can pass the first call of defrag_collect_targets(), as
its generation is (u64)-1, meets any possible minimal generation check.
And the range will not have DELALLOC bit, also passing the DELALLOC bit
check.
It will only be re-checked in the second call of
defrag_collect_targets(), which will wait for writeback.
But at that stage we have already spent our time waiting for some IO we
may or may not want to defrag.
Let's reject such extents early so we won't waste our time.
CC: stable@vger.kernel.org # 5.16
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There is a user report about "btrfs filesystem defrag" causing 120s
timeout problem.
For btrfs_defrag_file() it will iterate all file extents if called from
defrag ioctl, thus it can take a long time.
There is no reason not to release the CPU during such a long operation.
Add cond_resched() after defragged one cluster.
CC: stable@vger.kernel.org # 5.16
Link: https://lore.kernel.org/linux-btrfs/10e51417-2203-f0a4-2021-86c8511cc367@gmx.com
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-5.17-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"A few fixes and error handling improvements:
- fix deadlock between quota disable and qgroup rescan worker
- fix use-after-free after failure to create a snapshot
- skip warning on unmount after log cleanup failure
- don't start transaction for scrub if the fs is mounted read-only
- tree checker verifies item sizes"
* tag 'for-5.17-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: skip reserved bytes warning on unmount after log cleanup failure
btrfs: fix use of uninitialized variable at rm device ioctl
btrfs: fix use-after-free after failure to create a snapshot
btrfs: tree-checker: check item_size for dev_item
btrfs: tree-checker: check item_size for inode_item
btrfs: fix deadlock between quota disable and qgroup rescan worker
btrfs: don't start transaction for scrub if the fs is mounted read-only
Pass a block_device to bio_clone_fast and __bio_clone_fast and give
the functions more suitable names.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20220202160109.108149-14-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pass the block_device that we plan to use this bio for and the
operation to bio_reset to optimize the assigment. A NULL block_device
can be passed, both for the passthrough case on a raw request_queue and
to temporarily avoid refactoring some nasty code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220124091107.642561-20-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pass the block_device and operation that we plan to use this bio for to
bio_alloc to optimize the assignment. NULL/0 can be passed, both for the
passthrough case on a raw request_queue and to temporarily avoid
refactoring some nasty code.
Also move the gfp_mask argument after the nr_vecs argument for a much
more logical calling convention matching what most of the kernel does.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220124091107.642561-18-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pass the block_device and operation that we plan to use this bio for to
bio_alloc_bioset to optimize the assigment. NULL/0 can be passed, both
for the passthrough case on a raw request_queue and to temporarily avoid
refactoring some nasty code.
Also move the gfp_mask argument after the nr_vecs argument for a much
more logical calling convention matching what most of the kernel does.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220124091107.642561-16-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
