We only pass this as 1 from __extent_writepage_io(). The parameter
basically means "pretend I didn't pass in a page". This is silly since
we can simply not pass in the page. Get rid of the parameter from
btrfs_get_extent(), and since it's used as a get_extent_t callback,
remove it from get_extent_t and btree_get_extent(), neither of which
need it.
While we're here, let's document btrfs_get_extent().
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
ordered->start, ordered->len, and ordered->disk_len correspond to
fi->disk_bytenr, fi->num_bytes, and fi->disk_num_bytes, respectively.
It's confusing to translate between the two naming schemes. Since a
btrfs_ordered_extent is basically a pending btrfs_file_extent_item,
let's make the former use the naming from the latter.
Note that I didn't touch the names in tracepoints just in case there are
scripts depending on the current naming.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When using the NO_HOLES feature if we clone a range that contains a hole
and a temporary ENOSPC happens while dropping extents from the target
inode's range, we can end up failing and aborting the transaction with
-EEXIST or with a corrupt file extent item, that has a length greater
than it should and overlaps with other extents. For example when cloning
the following range from inode A to inode B:
Inode A:
extent A1 extent A2
[ ----------- ] [ hole, implicit, 4MB length ] [ ------------- ]
0 1MB 5MB 6MB
Range to clone: [1MB, 6MB)
Inode B:
extent B1 extent B2 extent B3 extent B4
[ ---------- ] [ --------- ] [ ---------- ] [ ---------- ]
0 1MB 1MB 2MB 2MB 5MB 5MB 6MB
Target range: [1MB, 6MB) (same as source, to make it easier to explain)
The following can happen:
1) btrfs_punch_hole_range() gets -ENOSPC from __btrfs_drop_extents();
2) At that point, 'cur_offset' is set to 1MB and __btrfs_drop_extents()
set 'drop_end' to 2MB, meaning it was able to drop only extent B2;
3) We then compute 'clone_len' as 'drop_end' - 'cur_offset' = 2MB - 1MB =
1MB;
4) We then attempt to insert a file extent item at inode B with a file
offset of 5MB, which is the value of clone_info->file_offset. This
fails with error -EEXIST because there's already an extent at that
offset (extent B4);
5) We abort the current transaction with -EEXIST and return that error
to user space as well.
Another example, for extent corruption:
Inode A:
extent A1 extent A2
[ ----------- ] [ hole, implicit, 10MB length ] [ ------------- ]
0 1MB 11MB 12MB
Inode B:
extent B1 extent B2
[ ----------- ] [ --------- ] [ ----------------------------- ]
0 1MB 1MB 5MB 5MB 12MB
Target range: [1MB, 12MB) (same as source, to make it easier to explain)
1) btrfs_punch_hole_range() gets -ENOSPC from __btrfs_drop_extents();
2) At that point, 'cur_offset' is set to 1MB and __btrfs_drop_extents()
set 'drop_end' to 5MB, meaning it was able to drop only extent B2;
3) We then compute 'clone_len' as 'drop_end' - 'cur_offset' = 5MB - 1MB =
4MB;
4) We then insert a file extent item at inode B with a file offset of 11MB
which is the value of clone_info->file_offset, and a length of 4MB (the
value of 'clone_len'). So we get 2 extents items with ranges that
overlap and an extent length of 4MB, larger then the extent A2 from
inode A (1MB length);
5) After that we end the transaction, balance the btree dirty pages and
then start another or join the previous transaction. It might happen
that the transaction which inserted the incorrect extent was committed
by another task so we end up with extent corruption if a power failure
happens.
So fix this by making sure we attempt to insert the extent to clone at
the destination inode only if we are past dropping the sub-range that
corresponds to a hole.
Fixes: 690a5dbfc5 ("Btrfs: fix ENOSPC errors, leading to transaction aborts, when cloning extents")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We can now remove the bdev from extent_map. Previous patches made sure
that bio_set_dev is correctly in all places and that we don't need to
grab it from latest_bdev or pass it around inside the extent map.
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of using an input pointer parameter as the return value and have
an int as the return type of find_desired_extent, rework the function to
directly return the found offset. Doing that the 'ret' variable in
btrfs_llseek_file can be removed. Additional (subjective) benefit is
that btrfs' llseek function now resemebles those of the other major
filesystems.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Handle SEEK_END/SEEK_CUR in a single 'default' case by directly
returning from generic_file_llseek. This makes the 'out' label
redundant. Finally return directly the vale from vfs_setpos. No
semantic changes.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Modifying the file position is done on a per-file basis. This renders
holding the inode lock for writing useless and makes the performance of
concurrent llseek's abysmal.
Fix this by holding the inode for read. This provides protection against
concurrent truncates and find_desired_extent already includes proper
extent locking for the range which ensures proper locking against
concurrent writes. SEEK_CUR and SEEK_END can be done lockessly.
The former is synchronized by file::f_lock spinlock. SEEK_END is not
synchronized but atomic, but that's OK since there is not guarantee that
SEEK_END will always be at the end of the file in the face of tail
modifications.
This change brings ~82% performance improvement when doing a lot of
parallel fseeks. The workload essentially does:
for (d=0; d<num_seek_read; d++)
{
/* offset %= 16777216; */
fseek (f, 256 * d % 16777216, SEEK_SET);
fread (buffer, 64, 1, f);
}
Without patch:
num workprocesses = 16
num fseek/fread = 8000000
step = 256
fork 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
real 0m41.412s
user 0m28.777s
sys 2m16.510s
With patch:
num workprocesses = 16
num fseek/fread = 8000000
step = 256
fork 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
real 0m11.479s
user 0m27.629s
sys 0m21.040s
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing a buffered write it's possible to leave the subv_writers
counter of the root, used for synchronization between buffered nocow
writers and snapshotting. This happens in an exceptional case like the
following:
1) We fail to allocate data space for the write, since there's not
enough available data space nor enough unallocated space for allocating
a new data block group;
2) Because of that failure, we try to go to NOCOW mode, which succeeds
and therefore we set the local variable 'only_release_metadata' to true
and set the root's sub_writers counter to 1 through the call to
btrfs_start_write_no_snapshotting() made by check_can_nocow();
3) The call to btrfs_copy_from_user() returns zero, which is very unlikely
to happen but not impossible;
4) No pages are copied because btrfs_copy_from_user() returned zero;
5) We call btrfs_end_write_no_snapshotting() which decrements the root's
subv_writers counter to 0;
6) We don't set 'only_release_metadata' back to 'false' because we do
it only if 'copied', the value returned by btrfs_copy_from_user(), is
greater than zero;
7) On the next iteration of the while loop, which processes the same
page range, we are now able to allocate data space for the write (we
got enough data space released in the meanwhile);
8) After this if we fail at btrfs_delalloc_reserve_metadata(), because
now there isn't enough free metadata space, or in some other place
further below (prepare_pages(), lock_and_cleanup_extent_if_need(),
btrfs_dirty_pages()), we break out of the while loop with
'only_release_metadata' having a value of 'true';
9) Because 'only_release_metadata' is 'true' we end up decrementing the
root's subv_writers counter to -1 (through a call to
btrfs_end_write_no_snapshotting()), and we also end up not releasing the
data space previously reserved through btrfs_check_data_free_space().
As a consequence the mechanism for synchronizing NOCOW buffered writes
with snapshotting gets broken.
Fix this by always setting 'only_release_metadata' to false at the start
of each iteration.
Fixes: 8257b2dc3c ("Btrfs: introduce btrfs_{start, end}_nocow_write() for each subvolume")
Fixes: 7ee9e4405f ("Btrfs: check if we can nocow if we don't have data space")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The parameter is now always set to NULL and could be dropped. The last
user was get_default_root but that got reworked in 05dbe6837b ("Btrfs:
unify subvol= and subvolid= mounting") and the parameter became unused.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This is similar to 942491c9e6 ("xfs: fix AIM7 regression"). Apparently
our current rwsem code doesn't like doing the trylock, then lock for
real scheme. This causes extra contention on the lock and can be
measured eg. by AIM7 benchmark. So change our read/write methods to
just do the trylock for the RWF_NOWAIT case.
Fixes: edf064e7c6 ("btrfs: nowait aio support")
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
We were checking for the full fsync flag in the inode before locking the
inode, which is racy, since at that that time it might not be set but
after we acquire the inode lock some other task set it. One case where
this can happen is on a system low on memory and some concurrent task
failed to allocate an extent map and therefore set the full sync flag on
the inode, to force the next fsync to work in full mode.
A consequence of missing the full fsync flag set is hitting the problems
fixed by commit 0c713cbab6 ("Btrfs: fix race between ranged fsync and
writeback of adjacent ranges"), BUG_ON() when dropping extents from a log
tree, hitting assertion failures at tree-log.c:copy_items() or all sorts
of weird inconsistencies after replaying a log due to file extents items
representing ranges that overlap.
So just move the check such that it's done after locking the inode and
before starting writeback again.
Fixes: 0c713cbab6 ("Btrfs: fix race between ranged fsync and writeback of adjacent ranges")
CC: stable@vger.kernel.org # 5.2+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[Background]
Btrfs qgroup uses two types of reserved space for METADATA space,
PERTRANS and PREALLOC.
PERTRANS is metadata space reserved for each transaction started by
btrfs_start_transaction().
While PREALLOC is for delalloc, where we reserve space before joining a
transaction, and finally it will be converted to PERTRANS after the
writeback is done.
[Inconsistency]
However there is inconsistency in how we handle PREALLOC metadata space.
The most obvious one is:
In btrfs_buffered_write():
btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes, true);
We always free qgroup PREALLOC meta space.
While in btrfs_truncate_block():
btrfs_delalloc_release_extents(BTRFS_I(inode), blocksize, (ret != 0));
We only free qgroup PREALLOC meta space when something went wrong.
[The Correct Behavior]
The correct behavior should be the one in btrfs_buffered_write(), we
should always free PREALLOC metadata space.
The reason is, the btrfs_delalloc_* mechanism works by:
- Reserve metadata first, even it's not necessary
In btrfs_delalloc_reserve_metadata()
- Free the unused metadata space
Normally in:
btrfs_delalloc_release_extents()
|- btrfs_inode_rsv_release()
Here we do calculation on whether we should release or not.
E.g. for 64K buffered write, the metadata rsv works like:
/* The first page */
reserve_meta: num_bytes=calc_inode_reservations()
free_meta: num_bytes=0
total: num_bytes=calc_inode_reservations()
/* The first page caused one outstanding extent, thus needs metadata
rsv */
/* The 2nd page */
reserve_meta: num_bytes=calc_inode_reservations()
free_meta: num_bytes=calc_inode_reservations()
total: not changed
/* The 2nd page doesn't cause new outstanding extent, needs no new meta
rsv, so we free what we have reserved */
/* The 3rd~16th pages */
reserve_meta: num_bytes=calc_inode_reservations()
free_meta: num_bytes=calc_inode_reservations()
total: not changed (still space for one outstanding extent)
This means, if btrfs_delalloc_release_extents() determines to free some
space, then those space should be freed NOW.
So for qgroup, we should call btrfs_qgroup_free_meta_prealloc() other
than btrfs_qgroup_convert_reserved_meta().
The good news is:
- The callers are not that hot
The hottest caller is in btrfs_buffered_write(), which is already
fixed by commit 336a8bb8e3 ("btrfs: Fix wrong
btrfs_delalloc_release_extents parameter"). Thus it's not that
easy to cause false EDQUOT.
- The trans commit in advance for qgroup would hide the bug
Since commit f5fef45936 ("btrfs: qgroup: Make qgroup async transaction
commit more aggressive"), when btrfs qgroup metadata free space is slow,
it will try to commit transaction and free the wrongly converted
PERTRANS space, so it's not that easy to hit such bug.
[FIX]
So to fix the problem, remove the @qgroup_free parameter for
btrfs_delalloc_release_extents(), and always pass true to
btrfs_inode_rsv_release().
Reported-by: Filipe Manana <fdmanana@suse.com>
Fixes: 43b18595d6 ("btrfs: qgroup: Use separate meta reservation type for delalloc")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When we have a buffered write that starts at an offset greater than or
equals to the file's size happening concurrently with a full ranged
fiemap, we can end up leaking an extent state structure.
Suppose we have a file with a size of 1Mb, and before the buffered write
and fiemap are performed, it has a single extent state in its io tree
representing the range from 0 to 1Mb, with the EXTENT_DELALLOC bit set.
The following sequence diagram shows how the memory leak happens if a
fiemap a buffered write, starting at offset 1Mb and with a length of
4Kb, are performed concurrently.
CPU 1 CPU 2
extent_fiemap()
--> it's a full ranged fiemap
range from 0 to LLONG_MAX - 1
(9223372036854775807)
--> locks range in the inode's
io tree
--> after this we have 2 extent
states in the io tree:
--> 1 for range [0, 1Mb[ with
the bits EXTENT_LOCKED and
EXTENT_DELALLOC_BITS set
--> 1 for the range
[1Mb, LLONG_MAX[ with
the EXTENT_LOCKED bit set
--> start buffered write at offset
1Mb with a length of 4Kb
btrfs_file_write_iter()
btrfs_buffered_write()
--> cached_state is NULL
lock_and_cleanup_extent_if_need()
--> returns 0 and does not lock
range because it starts
at current i_size / eof
--> cached_state remains NULL
btrfs_dirty_pages()
btrfs_set_extent_delalloc()
(...)
__set_extent_bit()
--> splits extent state for range
[1Mb, LLONG_MAX[ and now we
have 2 extent states:
--> one for the range
[1Mb, 1Mb + 4Kb[ with
EXTENT_LOCKED set
--> another one for the range
[1Mb + 4Kb, LLONG_MAX[ with
EXTENT_LOCKED set as well
--> sets EXTENT_DELALLOC on the
extent state for the range
[1Mb, 1Mb + 4Kb[
--> caches extent state
[1Mb, 1Mb + 4Kb[ into
@cached_state because it has
the bit EXTENT_LOCKED set
--> btrfs_buffered_write() ends up
with a non-NULL cached_state and
never calls anything to release its
reference on it, resulting in a
memory leak
Fix this by calling free_extent_state() on cached_state if the range was
not locked by lock_and_cleanup_extent_if_need().
The same issue can happen if anything else other than fiemap locks a range
that covers eof and beyond.
This could be triggered, sporadically, by test case generic/561 from the
fstests suite, which makes duperemove run concurrently with fsstress, and
duperemove does plenty of calls to fiemap. When CONFIG_BTRFS_DEBUG is set
the leak is reported in dmesg/syslog when removing the btrfs module with
a message like the following:
[77100.039461] BTRFS: state leak: start 6574080 end 6582271 state 16402 in tree 0 refs 1
Otherwise (CONFIG_BTRFS_DEBUG not set) detectable with kmemleak.
CC: stable@vger.kernel.org # 4.16+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Since commit fee187d9d9 ("Btrfs: do not set EXTENT_DIRTY along with
EXTENT_DELALLOC"), we never set EXTENT_DIRTY in inode->io_tree, so we
can simplify and stop trying to clear it.
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>
The VFS indicates a synchronous write to ->write_iter() via
iocb->ki_flags. The IOCB_{,D}SYNC flags may be set based on the file
(see iocb_flags()) or the RWF_* flags passed to a syscall like
pwritev2() (see kiocb_set_rw_flags()).
However, in btrfs_file_write_iter(), we're checking if a write is
synchronous based only on the file; we use this to decide when to bump
the sync_writers counter and thus do CRCs synchronously. Make sure we do
this for all synchronous writes as determined by the VFS.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add const ]
Signed-off-by: David Sterba <dsterba@suse.com>
generic_write_checks() may modify iov_iter_count(), so we must get the
count after the call, not before. Using the wrong one has a couple of
consequences:
1. We check a longer range in check_can_nocow() for nowait than we're
actually writing.
2. We create extra hole extent maps in btrfs_cont_expand(). As far as I
can tell, this is harmless, but I might be missing something.
These issues are pretty minor, but let's fix it before something more
important trips on it.
Fixes: edf064e7c6 ("btrfs: nowait aio support")
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_calc_trunc_metadata_size differs from trans_metadata_size in that
it doesn't take into account any splitting at the levels, because
truncate will never split nodes. However truncate _and_ changing will
never split nodes, so rename btrfs_calc_trunc_metadata_size to
btrfs_calc_metadata_size. Also btrfs_calc_trans_metadata_size is purely
for inserting items, so rename this to btrfs_calc_insert_metadata_size.
Making these clearer will help when I start using them differently in
upcoming patches.
Reviewed-by: Nikolay Borisov <nborisov@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>
It's unlikely in-band dedupe is going to land so just remove any
leftovers - dedupe.h header as well as the 'dedupe' parameter to
btrfs_set_extent_delalloc.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When cloning extents (or deduplicating) we create a transaction with a
space reservation that considers we will drop or update a single file
extent item of the destination inode (that we modify a single leaf). That
is fine for the vast majority of scenarios, however it might happen that
we need to drop many file extent items, and adjust at most two file extent
items, in the destination root, which can span multiple leafs. This will
lead to either the call to btrfs_drop_extents() to fail with ENOSPC or
the subsequent calls to btrfs_insert_empty_item() or btrfs_update_inode()
(called through clone_finish_inode_update()) to fail with ENOSPC. Such
failure results in a transaction abort, leaving the filesystem in a
read-only mode.
In order to fix this we need to follow the same approach as the hole
punching code, where we create a local reservation with 1 unit and keep
ending and starting transactions, after balancing the btree inode,
when __btrfs_drop_extents() returns ENOSPC. So fix this by making the
extent cloning call calls the recently added btrfs_punch_hole_range()
helper, which is what does the mentioned work for hole punching, and
make sure whenever we drop extent items in a transaction, we also add a
replacing file extent item, to avoid corruption (a hole) if after ending
a transaction and before starting a new one, the old transaction gets
committed and a power failure happens before we finish cloning.
A test case for fstests follows soon.
Reported-by: David Goodwin <david@codepoets.co.uk>
Link: https://lore.kernel.org/linux-btrfs/a4a4cf31-9cf4-e52c-1f86-c62d336c9cd1@codepoets.co.uk/
Reported-by: Sam Tygier <sam@tygier.co.uk>
Link: https://lore.kernel.org/linux-btrfs/82aace9f-a1e3-1f0b-055f-3ea75f7a41a0@tygier.co.uk/
Fixes: b6f3409b21 ("Btrfs: reserve sufficient space for ioctl clone")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move the code that is responsible for dropping extents in a range out of
btrfs_punch_hole() into a new helper function, btrfs_punch_hole_range(),
so that later it can be used by the reflinking (extent cloning and dedup)
code to fix a ENOSPC bug.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have code for data and metadata reservations for delalloc. There's
quite a bit of code here, and it's used in a lot of places so I've
separated it out to it's own file. inode.c and file.c are already
pretty large, and this code is complicated enough to live in its own
space.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
A few more instances whre we don't need to specify the values as long as
they are the same that enum assigns automatically. All of the enums are
in-memory only and nothing relies on the exact values.
Signed-off-by: David Sterba <dsterba@suse.com>
If the range for which we are punching a hole covers only part of a page,
we end up updating the inode item but we skip the update of the inode's
iversion, mtime and ctime. Fix that by ensuring we update those properties
of the inode.
A patch for fstests test case generic/059 that tests this as been sent
along with this fix.
Fixes: 2aaa665581 ("Btrfs: add hole punching")
Fixes: e8c1c76e80 ("Btrfs: add missing inode update when punching hole")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The first thing code does in check_can_nocow is trying to block
concurrent snapshots. If this fails (due to snpashot already being in
progress) the function returns ENOSPC which makes no sense. Instead
return EAGAIN. Despite this return value not being propagated to callers
it's good practice to return the closest in terms of semantics error
code. No functional changes.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There several functions which open code
btrfs_lock_and_flush_ordered_range, just replace them with a call to the
function. No functional changes.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When we do a full fsync (the bit BTRFS_INODE_NEEDS_FULL_SYNC is set in the
inode) that happens to be ranged, which happens during a msync() or writes
for files opened with O_SYNC for example, we can end up with a corrupt log,
due to different file extent items representing ranges that overlap with
each other, or hit some assertion failures.
When doing a ranged fsync we only flush delalloc and wait for ordered
exents within that range. If while we are logging items from our inode
ordered extents for adjacent ranges complete, we end up in a race that can
make us insert the file extent items that overlap with others we logged
previously and the assertion failures.
For example, if tree-log.c:copy_items() receives a leaf that has the
following file extents items, all with a length of 4K and therefore there
is an implicit hole in the range 68K to 72K - 1:
(257 EXTENT_ITEM 64K), (257 EXTENT_ITEM 72K), (257 EXTENT_ITEM 76K), ...
It copies them to the log tree. However due to the need to detect implicit
holes, it may release the path, in order to look at the previous leaf to
detect an implicit hole, and then later it will search again in the tree
for the first file extent item key, with the goal of locking again the
leaf (which might have changed due to concurrent changes to other inodes).
However when it locks again the leaf containing the first key, the key
corresponding to the extent at offset 72K may not be there anymore since
there is an ordered extent for that range that is finishing (that is,
somewhere in the middle of btrfs_finish_ordered_io()), and it just
removed the file extent item but has not yet replaced it with a new file
extent item, so the part of copy_items() that does hole detection will
decide that there is a hole in the range starting from 68K to 76K - 1,
and therefore insert a file extent item to represent that hole, having
a key offset of 68K. After that we now have a log tree with 2 different
extent items that have overlapping ranges:
1) The file extent item copied before copy_items() released the path,
which has a key offset of 72K and a length of 4K, representing the
file range 72K to 76K - 1.
2) And a file extent item representing a hole that has a key offset of
68K and a length of 8K, representing the range 68K to 76K - 1. This
item was inserted after releasing the path, and overlaps with the
extent item inserted before.
The overlapping extent items can cause all sorts of unpredictable and
incorrect behaviour, either when replayed or if a fast (non full) fsync
happens later, which can trigger a BUG_ON() when calling
btrfs_set_item_key_safe() through __btrfs_drop_extents(), producing a
trace like the following:
[61666.783269] ------------[ cut here ]------------
[61666.783943] kernel BUG at fs/btrfs/ctree.c:3182!
[61666.784644] invalid opcode: 0000 [#1] PREEMPT SMP
(...)
[61666.786253] task: ffff880117b88c40 task.stack: ffffc90008168000
[61666.786253] RIP: 0010:btrfs_set_item_key_safe+0x7c/0xd2 [btrfs]
[61666.786253] RSP: 0018:ffffc9000816b958 EFLAGS: 00010246
[61666.786253] RAX: 0000000000000000 RBX: 000000000000000f RCX: 0000000000030000
[61666.786253] RDX: 0000000000000000 RSI: ffffc9000816ba4f RDI: ffffc9000816b937
[61666.786253] RBP: ffffc9000816b998 R08: ffff88011dae2428 R09: 0000000000001000
[61666.786253] R10: 0000160000000000 R11: 6db6db6db6db6db7 R12: ffff88011dae2418
[61666.786253] R13: ffffc9000816ba4f R14: ffff8801e10c4118 R15: ffff8801e715c000
[61666.786253] FS: 00007f6060a18700(0000) GS:ffff88023f5c0000(0000) knlGS:0000000000000000
[61666.786253] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[61666.786253] CR2: 00007f6060a28000 CR3: 0000000213e69000 CR4: 00000000000006e0
[61666.786253] Call Trace:
[61666.786253] __btrfs_drop_extents+0x5e3/0xaad [btrfs]
[61666.786253] ? time_hardirqs_on+0x9/0x14
[61666.786253] btrfs_log_changed_extents+0x294/0x4e0 [btrfs]
[61666.786253] ? release_extent_buffer+0x38/0xb4 [btrfs]
[61666.786253] btrfs_log_inode+0xb6e/0xcdc [btrfs]
[61666.786253] ? lock_acquire+0x131/0x1c5
[61666.786253] ? btrfs_log_inode_parent+0xee/0x659 [btrfs]
[61666.786253] ? arch_local_irq_save+0x9/0xc
[61666.786253] ? btrfs_log_inode_parent+0x1f5/0x659 [btrfs]
[61666.786253] btrfs_log_inode_parent+0x223/0x659 [btrfs]
[61666.786253] ? arch_local_irq_save+0x9/0xc
[61666.786253] ? lockref_get_not_zero+0x2c/0x34
[61666.786253] ? rcu_read_unlock+0x3e/0x5d
[61666.786253] btrfs_log_dentry_safe+0x60/0x7b [btrfs]
[61666.786253] btrfs_sync_file+0x317/0x42c [btrfs]
[61666.786253] vfs_fsync_range+0x8c/0x9e
[61666.786253] SyS_msync+0x13c/0x1c9
[61666.786253] entry_SYSCALL_64_fastpath+0x18/0xad
A sample of a corrupt log tree leaf with overlapping extents I got from
running btrfs/072:
item 14 key (295 108 200704) itemoff 2599 itemsize 53
extent data disk bytenr 0 nr 0
extent data offset 0 nr 458752 ram 458752
item 15 key (295 108 659456) itemoff 2546 itemsize 53
extent data disk bytenr 4343541760 nr 770048
extent data offset 606208 nr 163840 ram 770048
item 16 key (295 108 663552) itemoff 2493 itemsize 53
extent data disk bytenr 4343541760 nr 770048
extent data offset 610304 nr 155648 ram 770048
item 17 key (295 108 819200) itemoff 2440 itemsize 53
extent data disk bytenr 4334788608 nr 4096
extent data offset 0 nr 4096 ram 4096
The file extent item at offset 659456 (item 15) ends at offset 823296
(659456 + 163840) while the next file extent item (item 16) starts at
offset 663552.
Another different problem that the race can trigger is a failure in the
assertions at tree-log.c:copy_items(), which expect that the first file
extent item key we found before releasing the path exists after we have
released path and that the last key we found before releasing the path
also exists after releasing the path:
$ cat -n fs/btrfs/tree-log.c
4080 if (need_find_last_extent) {
4081 /* btrfs_prev_leaf could return 1 without releasing the path */
4082 btrfs_release_path(src_path);
4083 ret = btrfs_search_slot(NULL, inode->root, &first_key,
4084 src_path, 0, 0);
4085 if (ret < 0)
4086 return ret;
4087 ASSERT(ret == 0);
(...)
4103 if (i >= btrfs_header_nritems(src_path->nodes[0])) {
4104 ret = btrfs_next_leaf(inode->root, src_path);
4105 if (ret < 0)
4106 return ret;
4107 ASSERT(ret == 0);
4108 src = src_path->nodes[0];
4109 i = 0;
4110 need_find_last_extent = true;
4111 }
(...)
The second assertion implicitly expects that the last key before the path
release still exists, because the surrounding while loop only stops after
we have found that key. When this assertion fails it produces a stack like
this:
[139590.037075] assertion failed: ret == 0, file: fs/btrfs/tree-log.c, line: 4107
[139590.037406] ------------[ cut here ]------------
[139590.037707] kernel BUG at fs/btrfs/ctree.h:3546!
[139590.038034] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC PTI
[139590.038340] CPU: 1 PID: 31841 Comm: fsstress Tainted: G W 5.0.0-btrfs-next-46 #1
(...)
[139590.039354] RIP: 0010:assfail.constprop.24+0x18/0x1a [btrfs]
(...)
[139590.040397] RSP: 0018:ffffa27f48f2b9b0 EFLAGS: 00010282
[139590.040730] RAX: 0000000000000041 RBX: ffff897c635d92c8 RCX: 0000000000000000
[139590.041105] RDX: 0000000000000000 RSI: ffff897d36a96868 RDI: ffff897d36a96868
[139590.041470] RBP: ffff897d1b9a0708 R08: 0000000000000000 R09: 0000000000000000
[139590.041815] R10: 0000000000000008 R11: 0000000000000000 R12: 0000000000000013
[139590.042159] R13: 0000000000000227 R14: ffff897cffcbba88 R15: 0000000000000001
[139590.042501] FS: 00007f2efc8dee80(0000) GS:ffff897d36a80000(0000) knlGS:0000000000000000
[139590.042847] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[139590.043199] CR2: 00007f8c064935e0 CR3: 0000000232252002 CR4: 00000000003606e0
[139590.043547] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[139590.043899] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[139590.044250] Call Trace:
[139590.044631] copy_items+0xa3f/0x1000 [btrfs]
[139590.045009] ? generic_bin_search.constprop.32+0x61/0x200 [btrfs]
[139590.045396] btrfs_log_inode+0x7b3/0xd70 [btrfs]
[139590.045773] btrfs_log_inode_parent+0x2b3/0xce0 [btrfs]
[139590.046143] ? do_raw_spin_unlock+0x49/0xc0
[139590.046510] btrfs_log_dentry_safe+0x4a/0x70 [btrfs]
[139590.046872] btrfs_sync_file+0x3b6/0x440 [btrfs]
[139590.047243] btrfs_file_write_iter+0x45b/0x5c0 [btrfs]
[139590.047592] __vfs_write+0x129/0x1c0
[139590.047932] vfs_write+0xc2/0x1b0
[139590.048270] ksys_write+0x55/0xc0
[139590.048608] do_syscall_64+0x60/0x1b0
[139590.048946] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[139590.049287] RIP: 0033:0x7f2efc4be190
(...)
[139590.050342] RSP: 002b:00007ffe743243a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[139590.050701] RAX: ffffffffffffffda RBX: 0000000000008d58 RCX: 00007f2efc4be190
[139590.051067] RDX: 0000000000008d58 RSI: 00005567eca0f370 RDI: 0000000000000003
[139590.051459] RBP: 0000000000000024 R08: 0000000000000003 R09: 0000000000008d60
[139590.051863] R10: 0000000000000078 R11: 0000000000000246 R12: 0000000000000003
[139590.052252] R13: 00000000003d3507 R14: 00005567eca0f370 R15: 0000000000000000
(...)
[139590.055128] ---[ end trace 193f35d0215cdeeb ]---
So fix this race between a full ranged fsync and writeback of adjacent
ranges by flushing all delalloc and waiting for all ordered extents to
complete before logging the inode. This is the simplest way to solve the
problem because currently the full fsync path does not deal with ranges
at all (it assumes a full range from 0 to LLONG_MAX) and it always needs
to look at adjacent ranges for hole detection. For use cases of ranged
fsyncs this can make a few fsyncs slower but on the other hand it can
make some following fsyncs to other ranges do less work or no need to do
anything at all. A full fsync is rare anyway and happens only once after
loading/creating an inode and once after less common operations such as a
shrinking truncate.
This is an issue that exists for a long time, and was often triggered by
generic/127, because it does mmap'ed writes and msync (which triggers a
ranged fsync). Adding support for the tree checker to detect overlapping
extents (next patch in the series) and trigger a WARN() when such cases
are found, and then calling btrfs_check_leaf_full() at the end of
btrfs_insert_file_extent() made the issue much easier to detect. Running
btrfs/072 with that change to the tree checker and making fsstress open
files always with O_SYNC made it much easier to trigger the issue (as
triggering it with generic/127 is very rare).
CC: stable@vger.kernel.org # 3.16+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we have an error writing out a delalloc range in
btrfs_punch_hole_lock_range we'll unlock the inode and then goto
out_only_mutex, where we will again unlock the inode. This is bad,
don't do this.
Fixes: f27451f229 ("Btrfs: add support for fallocate's zero range operation")
CC: stable@vger.kernel.org # 4.19+
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>
Similar to btrfs_inc_extent_ref(), use btrfs_ref to replace the long
parameter list and the confusing @owner parameter.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Use the new btrfs_ref structure and replace parameter list to clean up
the usage of owner and level to distinguish the extent types.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing fallocate, we first add the range to the reserve_list and
then reserve the quota. If quota reservation fails, we'll release all
reserved parts of reserve_list.
However, cur_offset is not updated to indicate that this range is
already been inserted into the list. Therefore, the same range is freed
twice. Once at list_for_each_entry loop, and once at the end of the
function. This will result in WARN_ON on bytes_may_use when we free the
remaining space.
At the end, under the 'out' label we have a call to:
btrfs_free_reserved_data_space(inode, data_reserved, alloc_start, alloc_end - cur_offset);
The start offset, third argument, should be cur_offset.
Everything from alloc_start to cur_offset was freed by the
list_for_each_entry_safe_loop.
Fixes: 18513091af ("btrfs: update btrfs_space_info's bytes_may_use timely")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Robbie Ko <robbieko@synology.com>
Signed-off-by: David Sterba <dsterba@suse.com>
BUG_ON(1) leads to bogus warnings from clang when
CONFIG_PROFILE_ANNOTATED_BRANCHES is set:
fs/btrfs/volumes.c:5041:3: error: variable 'max_chunk_size' is used uninitialized whenever 'if' condition is false
[-Werror,-Wsometimes-uninitialized]
BUG_ON(1);
^~~~~~~~~
include/asm-generic/bug.h:61:36: note: expanded from macro 'BUG_ON'
#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
^~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:48:23: note: expanded from macro 'unlikely'
# define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x)))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs/btrfs/volumes.c:5046:9: note: uninitialized use occurs here
max_chunk_size);
^~~~~~~~~~~~~~
include/linux/kernel.h:860:36: note: expanded from macro 'min'
#define min(x, y) __careful_cmp(x, y, <)
^
include/linux/kernel.h:853:17: note: expanded from macro '__careful_cmp'
__cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), op))
^
include/linux/kernel.h:847:25: note: expanded from macro '__cmp_once'
typeof(y) unique_y = (y); \
^
fs/btrfs/volumes.c:5041:3: note: remove the 'if' if its condition is always true
BUG_ON(1);
^
include/asm-generic/bug.h:61:32: note: expanded from macro 'BUG_ON'
#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
^
fs/btrfs/volumes.c:4993:20: note: initialize the variable 'max_chunk_size' to silence this warning
u64 max_chunk_size;
^
= 0
Change it to BUG() so clang can see that this code path can never
continue.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit db2462a6ad ("btrfs: don't run delayed refs in the end transaction
logic") removed its last use, so now it does absolutely nothing, therefore
remove it.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This function is a simple wrapper over btrfs_get_extent that returns
either:
a) A real extent in the passed range or
b) Adjusted extent based on whether delalloc bytes are found backing up
a hole.
To support these semantics it doesn't need the page/pg_offset/create
arguments which are passed to btrfs_get_extent in case an extent is to
be created. So simplify the function by removing the unused arguments.
No functional changes.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The typos accumulate over time so once in a while time they get fixed in
a large patch.
Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Constructs like 'var & (PAGE_SIZE - 1)' or 'var & ~PAGE_MASK' can denote an
offset into a page.
So replace them by the offset_in_page() macro instead of open-coding it if
they're not used as an alignment check.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The io_err field of struct btrfs_log_ctx is no longer used after the
recent simplification of the fast fsync path, where we now wait for
ordered extents to complete before logging the inode. We did this in
commit b5e6c3e170 ("btrfs: always wait on ordered extents at fsync
time") and commit a2120a473a ("btrfs: clean up the left over
logged_list usage") removed its last use.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-4.20-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"Some of these bugs are being hit during testing so we'd like to get
them merged, otherwise there are usual stability fixes for stable
trees"
* tag 'for-4.20-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: relocation: set trans to be NULL after ending transaction
Btrfs: fix race between enabling quotas and subvolume creation
Btrfs: send, fix infinite loop due to directory rename dependencies
Btrfs: ensure path name is null terminated at btrfs_control_ioctl
Btrfs: fix rare chances for data loss when doing a fast fsync
btrfs: Always try all copies when reading extent buffers
After the simplification of the fast fsync patch done recently by commit
b5e6c3e170 ("btrfs: always wait on ordered extents at fsync time") and
commit e7175a6927 ("btrfs: remove the wait ordered logic in the
log_one_extent path"), we got a very short time window where we can get
extents logged without writeback completing first or extents logged
without logging the respective data checksums. Both issues can only happen
when doing a non-full (fast) fsync.
As soon as we enter btrfs_sync_file() we trigger writeback, then lock the
inode and then wait for the writeback to complete before starting to log
the inode. However before we acquire the inode's lock and after we started
writeback, it's possible that more writes happened and dirtied more pages.
If that happened and those pages get writeback triggered while we are
logging the inode (for example, the VM subsystem triggering it due to
memory pressure, or another concurrent fsync), we end up seeing the
respective extent maps in the inode's list of modified extents and will
log matching file extent items without waiting for the respective
ordered extents to complete, meaning that either of the following will
happen:
1) We log an extent after its writeback finishes but before its checksums
are added to the csum tree, leading to -EIO errors when attempting to
read the extent after a log replay.
2) We log an extent before its writeback finishes.
Therefore after the log replay we will have a file extent item pointing
to an unwritten extent (and without the respective data checksums as
well).
This could not happen before the fast fsync patch simplification, because
for any extent we found in the list of modified extents, we would wait for
its respective ordered extent to finish writeback or collect its checksums
for logging if it did not complete yet.
Fix this by triggering writeback again after acquiring the inode's lock
and before waiting for ordered extents to complete.
Fixes: e7175a6927 ("btrfs: remove the wait ordered logic in the log_one_extent path")
Fixes: b5e6c3e170 ("btrfs: always wait on ordered extents at fsync time")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Rework the vfs_clone_file_range and vfs_dedupe_file_range infrastructure to use
a common .remap_file_range method and supply generic bounds and sanity checking
functions that are shared with the data write path. The current VFS
infrastructure has problems with rlimit, LFS file sizes, file time stamps,
maximum filesystem file sizes, stripping setuid bits, etc and so they are
addressed in these commits.
We also introduce the ability for the ->remap_file_range methods to return short
clones so that clones for vfs_copy_file_range() don't get rejected if the entire
range can't be cloned. It also allows filesystems to sliently skip deduplication
of partial EOF blocks if they are not capable of doing so without requiring
errors to be thrown to userspace.
All existing filesystems are converted to user the new .remap_file_range method,
and both XFS and ocfs2 are modified to make use of the new generic checking
infrastructure.
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Merge tag 'xfs-4.20-merge-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull vfs dedup fixes from Dave Chinner:
"This reworks the vfs data cloning infrastructure.
We discovered many issues with these interfaces late in the 4.19 cycle
- the worst of them (data corruption, setuid stripping) were fixed for
XFS in 4.19-rc8, but a larger rework of the infrastructure fixing all
the problems was needed. That rework is the contents of this pull
request.
Rework the vfs_clone_file_range and vfs_dedupe_file_range
infrastructure to use a common .remap_file_range method and supply
generic bounds and sanity checking functions that are shared with the
data write path. The current VFS infrastructure has problems with
rlimit, LFS file sizes, file time stamps, maximum filesystem file
sizes, stripping setuid bits, etc and so they are addressed in these
commits.
We also introduce the ability for the ->remap_file_range methods to
return short clones so that clones for vfs_copy_file_range() don't get
rejected if the entire range can't be cloned. It also allows
filesystems to sliently skip deduplication of partial EOF blocks if
they are not capable of doing so without requiring errors to be thrown
to userspace.
Existing filesystems are converted to user the new remap_file_range
method, and both XFS and ocfs2 are modified to make use of the new
generic checking infrastructure"
* tag 'xfs-4.20-merge-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (28 commits)
xfs: remove [cm]time update from reflink calls
xfs: remove xfs_reflink_remap_range
xfs: remove redundant remap partial EOF block checks
xfs: support returning partial reflink results
xfs: clean up xfs_reflink_remap_blocks call site
xfs: fix pagecache truncation prior to reflink
ocfs2: remove ocfs2_reflink_remap_range
ocfs2: support partial clone range and dedupe range
ocfs2: fix pagecache truncation prior to reflink
ocfs2: truncate page cache for clone destination file before remapping
vfs: clean up generic_remap_file_range_prep return value
vfs: hide file range comparison function
vfs: enable remap callers that can handle short operations
vfs: plumb remap flags through the vfs dedupe functions
vfs: plumb remap flags through the vfs clone functions
vfs: make remap_file_range functions take and return bytes completed
vfs: remap helper should update destination inode metadata
vfs: pass remap flags to generic_remap_checks
vfs: pass remap flags to generic_remap_file_range_prep
vfs: combine the clone and dedupe into a single remap_file_range
...
Combine the clone_file_range and dedupe_file_range operations into a
single remap_file_range file operation dispatch since they're
fundamentally the same operation. The differences between the two can
be made in the prep functions.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
During buffered writes, we follow this basic series of steps:
again:
lock all the pages
wait for writeback on all the pages
Take the extent range lock
wait for ordered extents on the whole range
clean all the pages
if (copy_from_user_in_atomic() hits a fault) {
drop our locks
goto again;
}
dirty all the pages
release all the locks
The extra waiting, cleaning and locking are there to make sure we don't
modify pages in flight to the drive, after they've been crc'd.
If some of the pages in the range were already dirty when the write
began, and we need to goto again, we create a window where a dirty page
has been cleaned and unlocked. It may be reclaimed before we're able to
lock it again, which means we'll read the old contents off the drive and
lose any modifications that had been pending writeback.
We don't actually need to clean the pages. All of the other locking in
place makes sure we don't start IO on the pages, so we can just leave
them dirty for the duration of the write.
Fixes: 73d59314e6 (the original btrfs merge)
CC: stable@vger.kernel.org # v4.4+
Signed-off-by: Chris Mason <clm@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Using true and false here is closer to the expected semantic than using
0 and 1. No functional change.
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Functions that get btrfs inode can simply reach the fs_info by
dereferencing the root and this looks a bit more straightforward
compared to the btrfs_sb(...) indirection.
If the transaction handle is available and not NULL it's used instead.
Signed-off-by: David Sterba <dsterba@suse.com>
struct kiocb carries the ki_pos, so there is no need to pass it as
a separate function parameter.
generic_file_direct_write() increments ki_pos, so we now assign pos
after the function.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
[ rename to btrfs_buffered_write ]
Signed-off-by: David Sterba <dsterba@suse.com>
We used to call btrfs_file_extent_inline_len() to get the uncompressed
data size of an inlined extent.
However this function is hiding evil, for compressed extent, it has no
choice but to directly read out ram_bytes from btrfs_file_extent_item.
While for uncompressed extent, it uses item size to calculate the real
data size, and ignoring ram_bytes completely.
In fact, for corrupted ram_bytes, due to above behavior kernel
btrfs_print_leaf() can't even print correct ram_bytes to expose the bug.
Since we have the tree-checker to verify all EXTENT_DATA, such mismatch
can be detected pretty easily, thus we can trust ram_bytes without the
evil btrfs_file_extent_inline_len().
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The logic to check if the inode is already in the log can now be
simplified since we always wait for the ordered extents to complete
before deciding whether the inode needs to be logged. The big comment
about it can go away too.
CC: Filipe Manana <fdmanana@suse.com>
Suggested-by: Filipe Manana <fdmanana@suse.com>
[ code and changelog copied from mail discussion ]
Signed-off-by: David Sterba <dsterba@suse.com>
There's a priority inversion that exists currently with btrfs fsync. In
some cases we will collect outstanding ordered extents onto a list and
only wait on them at the very last second. However this "very last
second" falls inside of a transaction handle, so if we are in a lower
priority cgroup we can end up holding the transaction open for longer
than needed, so if a high priority cgroup is also trying to fsync()
it'll see latency.
Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
