Directory entry removal must always succeed; Hence XFS does the
following during low disk space scenario:
1. Data/Free blocks linger until a future remove operation.
2. Dabtree blocks would be swapped with the last block in the leaf space
and then the new last block will be unmapped.
This facility is reused during low inode extent count scenario i.e. this
commit causes xfs_bmap_del_extent_real() to return -ENOSPC error code so
that the above mentioned behaviour is exercised causing no change to the
directory's extent count.
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Directory entry addition can cause the following,
1. Data block can be added/removed.
A new extent can cause extent count to increase by 1.
2. Free disk block can be added/removed.
Same behaviour as described above for Data block.
3. Dabtree blocks.
XFS_DA_NODE_MAXDEPTH blocks can be added. Each of these
can be new extents. Hence extent count can increase by
XFS_DA_NODE_MAXDEPTH.
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
The extent mapping the file offset at which a hole has to be
inserted will be split into two extents causing extent count to
increase by 1.
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
When adding a new data extent (without modifying an inode's existing
extents) the extent count increases only by 1. This commit checks for
extent count overflow in such cases.
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
XFS does not check for possible overflow of per-inode extent counter
fields when adding extents to either data or attr fork.
For e.g.
1. Insert 5 million xattrs (each having a value size of 255 bytes) and
then delete 50% of them in an alternating manner.
2. On a 4k block sized XFS filesystem instance, the above causes 98511
extents to be created in the attr fork of the inode.
xfsaild/loop0 2008 [003] 1475.127209: probe:xfs_inode_to_disk: (ffffffffa43fb6b0) if_nextents=98511 i_ino=131
3. The incore inode fork extent counter is a signed 32-bit
quantity. However the on-disk extent counter is an unsigned 16-bit
quantity and hence cannot hold 98511 extents.
4. The following incorrect value is stored in the attr extent counter,
# xfs_db -f -c 'inode 131' -c 'print core.naextents' /dev/loop0
core.naextents = -32561
This commit adds a new helper function (i.e.
xfs_iext_count_may_overflow()) to check for overflow of the per-inode
data and xattr extent counters. Future patches will use this function to
make sure that an FS operation won't cause the extent counter to
overflow.
Suggested-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
When overlayfs is running on top of xfs and the user unlinks a file in
the overlay, overlayfs will create a whiteout inode and ask xfs to
"rename" the whiteout file atop the one being unlinked. If the file
being unlinked loses its one nlink, we then have to put the inode on the
unlinked list.
This requires us to grab the AGI buffer of the whiteout inode to take it
off the unlinked list (which is where whiteouts are created) and to grab
the AGI buffer of the file being deleted. If the whiteout was created
in a higher numbered AG than the file being deleted, we'll lock the AGIs
in the wrong order and deadlock.
Therefore, grab all the AGI locks we think we'll need ahead of time, and
in order of increasing AG number per the locking rules.
Reported-by: wenli xie <wlxie7296@gmail.com>
Fixes: 93597ae8da ("xfs: Fix deadlock between AGI and AGF when target_ip exists in xfs_rename()")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Prepare for kernel xfs_buf alignment by getting rid of the
xfs_buf_t typedef from userspace.
[darrick: This patch is a port of a userspace patch removing the
xfs_buf_t typedef in preparation to make the userspace xfs_buf code
behave more like its kernel counterpart.]
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Replace a comma between expression statements by a semicolon.
Signed-off-by: Zheng Yongjun <zhengyongjun3@huawei.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
It's enough to just use return code, and get rid of an argument.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This patch explicitly separates free inode chunk allocation and
inode allocation into two individual high level operations.
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Get rid of the confusing ialloc_context and failure handling around
xfs_dialloc() by moving xfs_dialloc_roll() into xfs_dialloc().
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Introduce a helper to make the on-disk inode allocation rolling
logic clearer in preparation of the following cleanup.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Boolean is preferred for such use.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
We don't yet support dax on reflinked files, but that is in the works.
Further, having the flag set does not automatically mean that the inode
is actually "in the CPU direct access state," which depends on several
other conditions in addition to the flag being set.
As such, we should not catch this as corruption in the verifier - simply
not actually enabling S_DAX on reflinked files is enough for now.
Fixes: 4f435ebe7d ("xfs: don't mix reflink and DAX mode for now")
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
[darrick: fix the scrubber too]
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Since *init_cursor() can always return a valid cursor, the NULL check
in caller is unneeded. So clean them up.
This also keeps the behavior consistent with other callers.
Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Introduce a common helper to consolidate stripe validation process.
Also make kernel code xfs_validate_sb_common() use it first.
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
There are no callers of the XFS_B_FSB_OFFSET macro, so remove it.
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Nowadays the only things that the XFS_TRANS_DQ_DIRTY flag seems to do
are indicates the tp->t_dqinfo->dqs[XFS_QM_TRANS_{USR,GRP,PRJ}] values
changed and check in xfs_trans_apply_dquot_deltas() and the unreserve
variant xfs_trans_unreserve_and_mod_dquots(). Actually, we also can
use the tp->t_dqinfo value instead of the XFS_TRANS_DQ_DIRTY flag, that
is to say, we allocate the new tp->t_dqinfo only when the qtrx values
changed, so the tp->t_dqinfo value isn't NULL equals the XFS_TRANS_DQ_DIRTY
flag is set, we only need to check if tp->t_dqinfo == NULL in
xfs_trans_apply_dquot_deltas() and its unreserve variant to determine
whether lock all of the dquots and join them to the transaction.
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Refactor all the open-coded validation of file block ranges into a
single helper, and teach the bmap scrubber to check the ranges.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Refactor all the open-coded validation of realtime device extents into a
single helper.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Refactor all the open-coded validation of non-static data device extents
into a single helper.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Detect file block mappings with a blockcount that's either so large that
integer overflows occur or are zero, because neither are valid in the
filesystem. Worse yet, attempting directory modifications causes the
iext code to trip over the bmbt key handling and takes the filesystem
down. We can fix most of this by preventing the bad metadata from
entering the incore structures in the first place.
Found by setting blockcount=0 in a directory data fork mapping and
watching the fireworks.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Make it so that libxfs recognizes the needsrepair feature. Note that
the kernel will still refuse to mount these.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Define an incompat feature flag to indicate that the filesystem needs to
be repaired. While libxfs will recognize this feature, the kernel will
refuse to mount if the feature flag is set, and only xfs_repair will be
able to clear the flag. The goal here is to force the admin to run
xfs_repair to completion after upgrading the filesystem, or if we
otherwise detect anomalies.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
A couple of the superblock validation checks apply only to the kernel,
so move them to xfs_fc_fill_super before we add the needsrepair "feature",
which will prevent the kernel (but not xfsprogs) from mounting the
filesystem. This also reduces the diff between kernel and userspace
libxfs.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
This reverts commit 6ff646b2ce.
Your maintainer committed a major braino in the rmap code by adding the
attr fork, bmbt, and unwritten extent usage bits into rmap record key
comparisons. While XFS uses the usage bits *in the rmap records* for
cross-referencing metadata in xfs_scrub and xfs_repair, it only needs
the owner and offset information to distinguish between reverse mappings
of the same physical extent into the data fork of a file at multiple
offsets. The other bits are not important for key comparisons for index
lookups, and never have been.
Eric Sandeen reports that this causes regressions in generic/299, so
undo this patch before it does more damage.
Reported-by: Eric Sandeen <sandeen@sandeen.net>
Fixes: 6ff646b2ce ("xfs: fix rmap key and record comparison functions")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Currently, commit e9e2eae89d dropped a (int) decoration from
XFS_LITINO(mp), and since sizeof() expression is also involved,
the result of XFS_LITINO(mp) is simply as the size_t type
(commonly unsigned long).
Considering the expression in xfs_attr_shortform_bytesfit():
offset = (XFS_LITINO(mp) - bytes) >> 3;
let "bytes" be (int)340, and
"XFS_LITINO(mp)" be (unsigned long)336.
on 64-bit platform, the expression is
offset = ((unsigned long)336 - (int)340) >> 3 =
(int)(0xfffffffffffffffcUL >> 3) = -1
but on 32-bit platform, the expression is
offset = ((unsigned long)336 - (int)340) >> 3 =
(int)(0xfffffffcUL >> 3) = 0x1fffffff
instead.
so offset becomes a large positive number on 32-bit platform, and
cause xfs_attr_shortform_bytesfit() returns maxforkoff rather than 0.
Therefore, one result is
"ASSERT(new_size <= XFS_IFORK_SIZE(ip, whichfork));"
assertion failure in xfs_idata_realloc(), which was also the root
cause of the original bugreport from Dennis, see:
https://bugzilla.redhat.com/show_bug.cgi?id=1894177
And it can also be manually triggered with the following commands:
$ touch a;
$ setfattr -n user.0 -v "`seq 0 80`" a;
$ setfattr -n user.1 -v "`seq 0 80`" a
on 32-bit platform.
Fix the case in xfs_attr_shortform_bytesfit() by bailing out
"XFS_LITINO(mp) < bytes" in advance suggested by Eric and a misleading
comment together with this bugfix suggested by Darrick. It seems the
other users of XFS_LITINO(mp) are not impacted.
Fixes: e9e2eae89d ("xfs: only check the superblock version for dinode size calculation")
Cc: <stable@vger.kernel.org> # 5.7+
Reported-and-tested-by: Dennis Gilmore <dgilmore@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Keys for extent interval records in the reverse mapping btree are
supposed to be computed as follows:
(physical block, owner, fork, is_btree, is_unwritten, offset)
This provides users the ability to look up a reverse mapping from a bmbt
record -- start with the physical block; then if there are multiple
records for the same block, move on to the owner; then the inode fork
type; and so on to the file offset.
However, the key comparison functions incorrectly remove the
fork/btree/unwritten information that's encoded in the on-disk offset.
This means that lookup comparisons are only done with:
(physical block, owner, offset)
This means that queries can return incorrect results. On consistent
filesystems this hasn't been an issue because blocks are never shared
between forks or with bmbt blocks; and are never unwritten. However,
this bug means that online repair cannot always detect corruption in the
key information in internal rmapbt nodes.
Found by fuzzing keys[1].attrfork = ones on xfs/371.
Fixes: 4b8ed67794 ("xfs: add rmap btree operations")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Pass the same oldext argument (which contains the existing rmapping's
unwritten state) to xfs_rmap_lookup_le_range at the start of
xfs_rmap_convert_shared. At this point in the code, flags is zero,
which means that we perform lookups using the wrong key.
Fixes: 3f165b334e ("xfs: convert unwritten status of reverse mappings for shared files")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Make sure that we actually initialize xefi_discard when we're scheduling
a deferred free of an AGFL block. This was (eventually) found by the
UBSAN while I was banging on realtime rmap problems, but it exists in
the upstream codebase. While we're at it, rearrange the structure to
reduce the struct size from 64 to 56 bytes.
Fixes: fcb762f5de ("xfs: add bmapi nodiscard flag")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Fix some off-by-one errors in xfs_rtalloc_query_range. The highest key
in the realtime bitmap is always one less than the number of rt extents,
which means that the key clamp at the start of the function is wrong.
The 4th argument to xfs_rtfind_forw is the highest rt extent that we
want to probe, which means that passing 1 less than the high key is
wrong. Finally, drop the rem variable that controls the loop because we
can compare the iteration point (rtstart) against the high key directly.
The sordid history of this function is that the original commit (fb3c3)
incorrectly passed (high_rec->ar_startblock - 1) as the 'limit' parameter
to xfs_rtfind_forw. This was wrong because the "high key" is supposed
to be the largest key for which the caller wants result rows, not the
key for the first row that could possibly be outside the range that the
caller wants to see.
A subsequent attempt (8ad56) to strengthen the parameter checking added
incorrect clamping of the parameters to the number of rt blocks in the
system (despite the bitmap functions all taking units of rt extents) to
avoid querying ranges past the end of rt bitmap file but failed to fix
the incorrect _rtfind_forw parameter. The original _rtfind_forw
parameter error then survived the conversion of the startblock and
blockcount fields to rt extents (a0e5c), and the most recent off-by-one
fix (a3a37) thought it was patching a problem when the end of the rt
volume is not in use, but none of these fixes actually solved the
original problem that the author was confused about the "limit" argument
to xfs_rtfind_forw.
Sadly, all four of these patches were written by this author and even
his own usage of this function and rt testing were inadequate to get
this fixed quickly.
Original-problem: fb3c3de2f6 ("xfs: add a couple of queries to iterate free extents in the rtbitmap")
Not-fixed-by: 8ad560d256 ("xfs: strengthen rtalloc query range checks")
Not-fixed-by: a0e5c435ba ("xfs: fix xfs_rtalloc_rec units")
Fixes: a3a374bf18 ("xfs: fix off-by-one error in xfs_rtalloc_query_range")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Now that we have the ability to ask the log how far the tail needs to be
pushed to maintain its free space targets, augment the decision to relog
an intent item so that we only do it if the log has hit the 75% full
threshold. There's no point in relogging an intent into the same
checkpoint, and there's no need to relog if there's plenty of free space
in the log.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
There's a subtle design flaw in the deferred log item code that can lead
to pinning the log tail. Taking up the defer ops chain examples from
the previous commit, we can get trapped in sequences like this:
Caller hands us a transaction t0 with D0-D3 attached. The defer ops
chain will look like the following if the transaction rolls succeed:
t1: D0(t0), D1(t0), D2(t0), D3(t0)
t2: d4(t1), d5(t1), D1(t0), D2(t0), D3(t0)
t3: d5(t1), D1(t0), D2(t0), D3(t0)
...
t9: d9(t7), D3(t0)
t10: D3(t0)
t11: d10(t10), d11(t10)
t12: d11(t10)
In transaction 9, we finish d9 and try to roll to t10 while holding onto
an intent item for D3 that we logged in t0.
The previous commit changed the order in which we place new defer ops in
the defer ops processing chain to reduce the maximum chain length. Now
make xfs_defer_finish_noroll capable of relogging the entire chain
periodically so that we can always move the log tail forward. Most
chains will never get relogged, except for operations that generate very
long chains (large extents containing many blocks with different sharing
levels) or are on filesystems with small logs and a lot of ongoing
metadata updates.
Callers are now required to ensure that the transaction reservation is
large enough to handle logging done items and new intent items for the
maximum possible chain length. Most callers are careful to keep the
chain lengths low, so the overhead should be minimal.
The decision to relog an intent item is made based on whether the intent
was logged in a previous checkpoint, since there's no point in relogging
an intent into the same checkpoint.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
The defer ops code has been finishing items in the wrong order -- if a
top level defer op creates items A and B, and finishing item A creates
more defer ops A1 and A2, we'll put the new items on the end of the
chain and process them in the order A B A1 A2. This is kind of weird,
since it's convenient for programmers to be able to think of A and B as
an ordered sequence where all the sub-tasks for A must finish before we
move on to B, e.g. A A1 A2 D.
Right now, our log intent items are not so complex that this matters,
but this will become important for the atomic extent swapping patchset.
In order to maintain correct reference counting of extents, we have to
unmap and remap extents in that order, and we want to complete that work
before moving on to the next range that the user wants to swap. This
patch fixes defer ops to satsify that requirement.
The primary symptom of the incorrect order was noticed in an early
performance analysis of the atomic extent swap code. An astonishingly
large number of deferred work items accumulated when userspace requested
an atomic update of two very fragmented files. The cause of this was
traced to the same ordering bug in the inner loop of
xfs_defer_finish_noroll.
If the ->finish_item method of a deferred operation queues new deferred
operations, those new deferred ops are appended to the tail of the
pending work list. To illustrate, say that a caller creates a
transaction t0 with four deferred operations D0-D3. The first thing
defer ops does is roll the transaction to t1, leaving us with:
t1: D0(t0), D1(t0), D2(t0), D3(t0)
Let's say that finishing each of D0-D3 will create two new deferred ops.
After finish D0 and roll, we'll have the following chain:
t2: D1(t0), D2(t0), D3(t0), d4(t1), d5(t1)
d4 and d5 were logged to t1. Notice that while we're about to start
work on D1, we haven't actually completed all the work implied by D0
being finished. So far we've been careful (or lucky) to structure the
dfops callers such that D1 doesn't depend on d4 or d5 being finished,
but this is a potential logic bomb.
There's a second problem lurking. Let's see what happens as we finish
D1-D3:
t3: D2(t0), D3(t0), d4(t1), d5(t1), d6(t2), d7(t2)
t4: D3(t0), d4(t1), d5(t1), d6(t2), d7(t2), d8(t3), d9(t3)
t5: d4(t1), d5(t1), d6(t2), d7(t2), d8(t3), d9(t3), d10(t4), d11(t4)
Let's say that d4-d11 are simple work items that don't queue any other
operations, which means that we can complete each d4 and roll to t6:
t6: d5(t1), d6(t2), d7(t2), d8(t3), d9(t3), d10(t4), d11(t4)
t7: d6(t2), d7(t2), d8(t3), d9(t3), d10(t4), d11(t4)
...
t11: d10(t4), d11(t4)
t12: d11(t4)
<done>
When we try to roll to transaction #12, we're holding defer op d11,
which we logged way back in t4. This means that the tail of the log is
pinned at t4. If the log is very small or there are a lot of other
threads updating metadata, this means that we might have wrapped the log
and cannot get roll to t11 because there isn't enough space left before
we'd run into t4.
Let's shift back to the original failure. I mentioned before that I
discovered this flaw while developing the atomic file update code. In
that scenario, we have a defer op (D0) that finds a range of file blocks
to remap, creates a handful of new defer ops to do that, and then asks
to be continued with however much work remains.
So, D0 is the original swapext deferred op. The first thing defer ops
does is rolls to t1:
t1: D0(t0)
We try to finish D0, logging d1 and d2 in the process, but can't get all
the work done. We log a done item and a new intent item for the work
that D0 still has to do, and roll to t2:
t2: D0'(t1), d1(t1), d2(t1)
We roll and try to finish D0', but still can't get all the work done, so
we log a done item and a new intent item for it, requeue D0 a second
time, and roll to t3:
t3: D0''(t2), d1(t1), d2(t1), d3(t2), d4(t2)
If it takes 48 more rolls to complete D0, then we'll finally dispense
with D0 in t50:
t50: D<fifty primes>(t49), d1(t1), ..., d102(t50)
We then try to roll again to get a chain like this:
t51: d1(t1), d2(t1), ..., d101(t50), d102(t50)
...
t152: d102(t50)
<done>
Notice that in rolling to transaction #51, we're holding on to a log
intent item for d1 that was logged in transaction #1. This means that
the tail of the log is pinned at t1. If the log is very small or there
are a lot of other threads updating metadata, this means that we might
have wrapped the log and cannot roll to t51 because there isn't enough
space left before we'd run into t1. This is of course problem #2 again.
But notice the third problem with this scenario: we have 102 defer ops
tied to this transaction! Each of these items are backed by pinned
kernel memory, which means that we risk OOM if the chains get too long.
Yikes. Problem #1 is a subtle logic bomb that could hit someone in the
future; problem #2 applies (rarely) to the current upstream, and problem
#3 applies to work under development.
This is not how incremental deferred operations were supposed to work.
The dfops design of logging in the same transaction an intent-done item
and a new intent item for the work remaining was to make it so that we
only have to juggle enough deferred work items to finish that one small
piece of work. Deferred log item recovery will find that first
unfinished work item and restart it, no matter how many other intent
items might follow it in the log. Therefore, it's ok to put the new
intents at the start of the dfops chain.
For the first example, the chains look like this:
t2: d4(t1), d5(t1), D1(t0), D2(t0), D3(t0)
t3: d5(t1), D1(t0), D2(t0), D3(t0)
...
t9: d9(t7), D3(t0)
t10: D3(t0)
t11: d10(t10), d11(t10)
t12: d11(t10)
For the second example, the chains look like this:
t1: D0(t0)
t2: d1(t1), d2(t1), D0'(t1)
t3: d2(t1), D0'(t1)
t4: D0'(t1)
t5: d1(t4), d2(t4), D0''(t4)
...
t148: D0<50 primes>(t147)
t149: d101(t148), d102(t148)
t150: d102(t148)
<done>
This actually sucks more for pinning the log tail (we try to roll to t10
while holding an intent item that was logged in t1) but we've solved
problem #1. We've also reduced the maximum chain length from:
sum(all the new items) + nr_original_items
to:
max(new items that each original item creates) + nr_original_items
This solves problem #3 by sharply reducing the number of defer ops that
can be attached to a transaction at any given time. The change makes
the problem of log tail pinning worse, but is improvement we need to
solve problem #2. Actually solving #2, however, is left to the next
patch.
Note that a subsequent analysis of some hard-to-trigger reflink and COW
livelocks on extremely fragmented filesystems (or systems running a lot
of IO threads) showed the same symptoms -- uncomfortably large numbers
of incore deferred work items and occasional stalls in the transaction
grant code while waiting for log reservations. I think this patch and
the next one will also solve these problems.
As originally written, the code used list_splice_tail_init instead of
list_splice_init, so change that, and leave a short comment explaining
our actions.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
In xfs_bui_item_recover, there exists a use-after-free bug with regards
to the inode that is involved in the bmap replay operation. If the
mapping operation does not complete, we call xfs_bmap_unmap_extent to
create a deferred op to finish the unmapping work, and we retain a
pointer to the incore inode.
Unfortunately, the very next thing we do is commit the transaction and
drop the inode. If reclaim tears down the inode before we try to finish
the defer ops, we dereference garbage and blow up. Therefore, create a
way to join inodes to the defer ops freezer so that we can maintain the
xfs_inode reference until we're done with the inode.
Note: This imposes the requirement that there be enough memory to keep
every incore inode in memory throughout recovery.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
When xfs_defer_capture extracts the deferred ops and transaction state
from a transaction, it should record the transaction reservation type
from the old transaction so that when we continue the dfops chain, we
still use the same reservation parameters.
Doing this means that the log item recovery functions get to determine
the transaction reservation instead of abusing tr_itruncate in yet
another part of xfs.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
When xfs_defer_capture extracts the deferred ops and transaction state
from a transaction, it should record the remaining block reservations so
that when we continue the dfops chain, we can reserve the same number of
blocks to use. We capture the reservations for both data and realtime
volumes.
This adds the requirement that every log intent item recovery function
must be careful to reserve enough blocks to handle both itself and all
defer ops that it can queue. On the other hand, this enables us to do
away with the handwaving block estimation nonsense that was going on in
xlog_finish_defer_ops.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
When we replay unfinished intent items that have been recovered from the
log, it's possible that the replay will cause the creation of more
deferred work items. As outlined in commit 509955823c ("xfs: log
recovery should replay deferred ops in order"), later work items have an
implicit ordering dependency on earlier work items. Therefore, recovery
must replay the items (both recovered and created) in the same order
that they would have been during normal operation.
For log recovery, we enforce this ordering by using an empty transaction
to collect deferred ops that get created in the process of recovering a
log intent item to prevent them from being committed before the rest of
the recovered intent items. After we finish committing all the
recovered log items, we allocate a transaction with an enormous block
reservation, splice our huge list of created deferred ops into that
transaction, and commit it, thereby finishing all those ops.
This is /really/ hokey -- it's the one place in XFS where we allow
nested transactions; the splicing of the defer ops list is is inelegant
and has to be done twice per recovery function; and the broken way we
handle inode pointers and block reservations cause subtle use-after-free
and allocator problems that will be fixed by this patch and the two
patches after it.
Therefore, replace the hokey empty transaction with a structure designed
to capture each chain of deferred ops that are created as part of
recovering a single unfinished log intent. Finally, refactor the loop
that replays those chains to do so using one transaction per chain.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Remove this one-line helper since the assert is trivially true in one
call site and the rest obscures a bitmask operation.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
During code review, I noticed that the rmap code uses the (slower)
shared mappings rmap functions for any extent of a reflinked file, even
if those extents are for the attr fork, which doesn't support sharing.
We can speed up rmap a tiny bit by optimizing out this case.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cleanup the typedef usage, the unnecessary parentheses, the unnecessary
backslash and use the open-coded round_up call in
xfs_attr_leaf_entsize_{remote,local}.
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
We already check whether the crc feature is enabled before calling
xfs_attr3_rmt_verify(), so remove the redundant feature check in that
function.
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Fix the comments to help people understand the code.
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
[darrick: fix the indenting problems too]
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
We have already defined the project ID type prid_t, so maybe should
use it here.
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
During a code inspection, I found a serious bug in the log intent item
recovery code when an intent item cannot complete all the work and
decides to requeue itself to get that done. When this happens, the
item recovery creates a new incore deferred op representing the
remaining work and attaches it to the transaction that it allocated. At
the end of _item_recover, it moves the entire chain of deferred ops to
the dummy parent_tp that xlog_recover_process_intents passed to it, but
fail to log a new intent item for the remaining work before committing
the transaction for the single unit of work.
xlog_finish_defer_ops logs those new intent items once recovery has
finished dealing with the intent items that it recovered, but this isn't
sufficient. If the log is forced to disk after a recovered log item
decides to requeue itself and the system goes down before we call
xlog_finish_defer_ops, the second log recovery will never see the new
intent item and therefore has no idea that there was more work to do.
It will finish recovery leaving the filesystem in a corrupted state.
The same logic applies to /any/ deferred ops added during intent item
recovery, not just the one handling the remaining work.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
When callers pass XFS_BMAPI_REMAP into xfs_bunmapi, they want the extent
to be unmapped from the given file fork without the extent being freed.
We do this for non-rt files, but we forgot to do this for realtime
files. So far this isn't a big deal since nobody makes a bunmapi call
to a rt file with the REMAP flag set, but don't leave a logic bomb.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
xfs_attr_sf_totsize() requires access to xfs_inode structure, so, once
xfs_attr_shortform_addname() is its only user, move it to xfs_attr.c
instead of playing with more #includes.
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
nameval is a variable-size array, so, define it as it, and remove all
the -1 magic number subtractions
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
