Rework the data flow in xfs_file_iomap_begin where we decide if we have
to break shared extents.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Don't pass raw iomap flags to xfs_reflink_allocate_cow; signal our
intention with a boolean argument.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
A previous commit removed the initialization of variable 'error' to zero,
and can cause a bogus error return. This occurs when error contains a
non-zero garbage value and the call to xchk_should_terminate detects a
pending fatal signal and checks for a zero error before setting it
to -EAGAIN. Fix the issue by initializing error to zero.
Fixes: b9454fe056 ("xfs: clean up the inode cluster checking in the inobt scrub")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Add a mode where XFS never overwrites existing blocks in place. This
is to aid debugging our COW code, and also put infatructure in place
for things like possible future support for zoned block devices, which
can't support overwrites.
This mode is enabled globally by doing a:
echo 1 > /sys/fs/xfs/debug/always_cow
Note that the parameter is global to allow running all tests in xfstests
easily in this mode, which would not easily be possible with a per-fs
sysfs file.
In always_cow mode persistent preallocations are disabled, and fallocate
will fail when called with a 0 mode (with our without
FALLOC_FL_KEEP_SIZE), and not create unwritten extent for zeroed space
when called with FALLOC_FL_ZERO_RANGE or FALLOC_FL_UNSHARE_RANGE.
There are a few interesting xfstests failures when run in always_cow
mode:
- generic/392 fails because the bytes used in the file used to test
hole punch recovery are less after the log replay. This is
because the blocks written and then punched out are only freed
with a delay due to the logging mechanism.
- xfs/170 will fail as the already fragile file streams mechanism
doesn't seem to interact well with the COW allocator
- xfs/180 xfs/182 xfs/192 xfs/198 xfs/204 and xfs/208 will claim
the file system is badly fragmented, but there is not much we
can do to avoid that when always writing out of place
- xfs/205 fails because overwriting a file in always_cow mode
will require new space allocation and the assumption in the
test thus don't work anymore.
- xfs/326 fails to modify the file at all in always_cow mode after
injecting the refcount error, leading to an unexpected md5sum
after the remount, but that again is expected
Signed-off-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>
No user of it in the iomap code at the moment, but we should not
actively report wrong information if we can trivially get it right.
Signed-off-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>
If we have racing buffered and direct I/O COW fork extents under
writeback can have been moved to the data fork by the time we call
xfs_reflink_convert_cow from xfs_submit_ioend. This would be mostly
harmless as the block numbers don't change by this move, except for
the fact that xfs_bmapi_write will crash or trigger asserts when
not finding existing extents, even despite trying to paper over this
with the XFS_BMAPI_CONVERT_ONLY flag.
Instead of special casing non-transaction conversions in the already
way too complicated xfs_bmapi_write just add a new helper for the much
simpler non-transactional COW fork case, which simplify ignores not
found extents.
Signed-off-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>
Besides simplifying the code a bit this allows to actually implement
the behavior of using COW preallocation for non-COW data mentioned
in the current comments.
Signed-off-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>
This only matters if we want to write data through the COW fork that is
not actually an overwrite of existing data. Reasons for that are
speculative COW fork allocations using the cowextsize, or a mode where
we always write through the COW fork. Currently both can't actually
happen, but I plan to enable them.
Signed-off-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>
While using delalloc for extsize hints is generally a good idea, the
current code that does so only for COW doesn't help us much and creates
a lot of special cases. Switch it to use real allocations like we
do for direct I/O.
Signed-off-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>
We speculatively allocate extents in the COW fork to reduce
fragmentation. But when we write data into such COW fork blocks that
do now shadow an allocation in the data fork SEEK_DATA will not
correctly report it, as it only looks at the data fork extents.
The only reason why that hasn't been an issue so far is because
we even use these speculative COW fork preallocations over holes in
the data fork at all for buffered writes, and blocks in the COW
fork that are written by direct writes are moved into the data
fork immediately at I/O completion time.
Add a new set of iomap_ops for SEEK_HOLE/SEEK_DATA which looks into
both the COW and data fork, and reports all COW extents as unwritten
to the iomap layer. While this isn't strictly true for COW fork
extents that were already converted to real extents, the practical
semantics that you can't read data from them until they are moved
into the data fork are very similar, and this will force the iomap
layer into probing the extents for actually present data.
Signed-off-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>
Move checking for invalid zero blocks and setting of various iomap flags
into this helper. Also make it deal with "raw" delalloc extents to
avoid clutter in the callers.
Signed-off-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>
Create a separate magic16 check function so that we don't run afoul of
static checkers.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
While we can only truncate a block under the page lock for the current
page, there is no high-level synchronization for moving extents from the
COW to the data fork. This means that for example we can have another
thread doing a direct I/O completion that moves extents from the COW to
the data fork race with writeback. While this race is very hard to hit
the always_cow seems to reproduce it reasonably well, and it also exists
without that. Because of that there is a chance that a delalloc
conversion for the COW fork might not find any extents to convert. In
that case we should retry the whole block lookup and now find the blocks
in the data fork.
Signed-off-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>
Now that we properly handle the race with truncate in the delalloc
allocator there is no need to short cut this exceptional case earlier
on.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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>
This function is a small wrapper only used by the writeback code, so
move it together with the writeback code and simplify it down to the
glorified do { } while loop that is now is.
A few bits intentionally got lost here: no need to call xfs_qm_dqattach
because quotas are always attached when we create the delalloc
reservation, and no need for the imap->br_startblock == 0 check given
that xfs_bmapi_convert_delalloc already has a WARN_ON_ONCE for exactly
that condition.
Signed-off-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>
This way we can actually count how many bytes got converted and how many
calls we need, unlike in the caller which doesn't have the detailed
view.
Note that this includes a slight change in behavior as the
xs_xstrat_quick is now bumped for every allocation instead of just the
one covering the requested writeback offset, which makes a lot more
sense.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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>
No need to deal with the transaction and the inode locking in the
caller. Note that we also switch to passing whichfork as the second
paramter, matching what most related functions do.
Signed-off-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>
Delalloc conversion has traditionally been part of our function to
allocate blocks on disk (first xfs_bmapi, then xfs_bmapi_write), but
delalloc conversion is a little special as we really do not want
to allocate blocks over holes, for which we don't have reservations.
Split the delalloc conversions into a separate helper to keep the
code simple and structured.
Signed-off-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>
We want to be able to reuse them for the upcoming dedidcated delalloc
convert routine.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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>
Move boilerplate code from the callers into xfs_bmap_btree_to_extents:
- exit early without failure if we don't need to convert to the
extent format
- assert that we have a btree cursor
- don't reinitialize the passed in logflags argument
Signed-off-by: Christoph Hellwig <hch@lst.de>
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>
We already ensure all data fits into s_maxbytes in the write / fault
path. The only reason we have them here is that they were copy and
pasted from xfs_bmapi_read when we stopped using that function.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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>
The io_type field contains what is basically a summary of information
from the inode fork and the imap. But we can just as easily use that
information directly, simplifying a few bits here and there and
improving the trace points.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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>
When XFS creates an O_TMPFILE file, the inode is created with nlink = 1,
put on the unlinked list, and then the VFS sets nlink = 0 in d_tmpfile.
If we crash before anything logs the inode (it's dirty incore but the
vfs doesn't tell us it's dirty so we never log that change), the iunlink
processing part of recovery will then explode with a pile of:
XFS: Assertion failed: VFS_I(ip)->i_nlink == 0, file:
fs/xfs/xfs_log_recover.c, line: 5072
Worse yet, since nlink is nonzero, the inodes also don't get cleaned up
and they just leak until the next xfs_repair run.
Therefore, change xfs_iunlink to require that inodes being put on the
unlinked list have nlink == 0, change the tmpfile callers to instantiate
nodes that way, and set the nlink to 1 just prior to calling d_tmpfile.
Fix the comment for xfs_iunlink while we're at it.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Log recovery frees all the inodes stored in the unlinked list, which can
cause expansion of the free inode btree. The ifree code skips block
reservations if it thinks there's a per-AG space reservation, but we
don't set up the reservation until after log recovery, which means that
a finobt expansion blows up in xfs_trans_mod_sb when we exceed the
transaction's block reservation.
To fix this, we set the "no finobt reservation" flag to true when we
create the xfs_mount and only set it to false if we confirm that every
AG had enough free space to put aside for the finobt.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Rename this flag variable to imply more strongly that it's related to
the free inode btree (finobt) operation. No functional changes.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
For VFS listxattr calls, xfs_xattr_put_listent calls
__xfs_xattr_put_listent twice if it sees an attribute
"trusted.SGI_ACL_FILE": once for that name, and again for
"system.posix_acl_access". Unfortunately, if we happen to run out of
buffer space while emitting the first name, we set count to -1 (so that
we can feed ERANGE to the caller). The second invocation doesn't check that
the context parameters make sense and overwrites the byte before the
buffer, triggering a KASAN report:
==================================================================
BUG: KASAN: slab-out-of-bounds in strncpy+0xb3/0xd0
Write of size 1 at addr ffff88807fbd317f by task syz/1113
CPU: 3 PID: 1113 Comm: syz Not tainted 5.0.0-rc6-xfsx #rc6
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-1ubuntu1 04/01/2014
Call Trace:
dump_stack+0xcc/0x180
print_address_description+0x6c/0x23c
kasan_report.cold.3+0x1c/0x35
strncpy+0xb3/0xd0
__xfs_xattr_put_listent+0x1a9/0x2c0 [xfs]
xfs_attr_list_int_ilocked+0x11af/0x1800 [xfs]
xfs_attr_list_int+0x20c/0x2e0 [xfs]
xfs_vn_listxattr+0x225/0x320 [xfs]
listxattr+0x11f/0x1b0
path_listxattr+0xbd/0x130
do_syscall_64+0x139/0x560
While we're at it we add an assert to the other put_listent to avoid
this sort of thing ever happening to the attrlist_by_handle code.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
The v5 superblock format added various metadata fields (such as crc,
metadata lsn, owner uuid, etc.) to v4 metadata headers or created
new v5 headers for blocks where no such headers existed on v4. Where
v4 headers did exist, the v5 structures are careful to place v4
metadata at the original location. For example, the magic value is
expected to be at the same location in certain blocks to facilitate
version detection.
While failure of this invariant is likely to cause severe and
obvious problems at runtime, we can detect this condition at compile
time via the more recently added on-disk format check
infrastructure. Since there is no runtime cost, add some offset
checks that start with v5 structure definitions, traverse down to
the first bit of common metadata with v4 and ensure that common
metadata is at the expected offset. Note that we don't care about
blocks which had no v4 header because there is no common metadata in
those cases. No functional changes.
Signed-off-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>
Now that we encode block magic numbers in all the buffer ops, use that
for block type detection in the ag header repair code instead of
encoding magics directly in the repair code.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Add dquot magic numbers to the buffer ops type, in case we ever want to
use them.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Use xfs_verify_magic to check the magic numbers of inodes.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
With the verifier magic value helper in place, we've left a bit more
duplicate code across the verifiers that involve struct
xfs_da3_blkinfo. This includes the da node, xattr leaf and dir leaf
verifiers, all of which perform similar checks for v4 and v5
filesystems.
Create a common helper to verify an xfs_da3_blkinfo structure,
taking care to only access v5 fields where appropriate, and refactor
the aforementioned verifiers to use the helper. No functional
changes.
Signed-off-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>
Most buffer verifiers have hardcoded magic value checks
conditionalized on the version of the filesystem. The magic value
field of the verifier structure facilitates abstraction of some of
this code. Populate the ->magic field of various verifiers to take
advantage of this abstraction. No functional changes.
Signed-off-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>
The dir2 leaf verifiers share the same underlying structure
verification code, but implement six accessor functions to multiplex
the code across the two verifiers. Further, the magic value isn't
sufficiently abstracted such that the common helper has to manually
fix up the magic from the caller on v5 filesystems.
Use the magic field in the verifier structure to eliminate the
duplicate code and clean this all up. No functional change.
Signed-off-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>
The allocation btree verifiers share code that is unable to detect
cross-tree magic value corruptions such as a bnobt block with a
cntbt magic value. Populate the b_ops->magic field of the associated
verifier structures such that the structure verifier can check the
magic value against the expected value based on tree type.
The btree level check requires knowledge of the tree type to
determine the appropriate maximum value. This was previously part of
the hardcoded magic value checks. With that code removed, peek at
the first magic value in the verifier to determine the expected tree
type of the current block.
Signed-off-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>
Similar to the inode btree verifier, the same allocation btree
verifier structure is shared between the by-bno (bnobt) and by-size
(cntbt) btrees. This prevents the ability to distinguish magic
values between them. Separate the verifier into two, one for each
tree, and assign them appropriately. No functional changes.
Signed-off-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>
The inode btree verifier code is shared between the inode btree and
free inode btree because the underlying metadata formats are
essentially equivalent. A side effect of this is that the verifier
cannot determine whether a particular btree block should have an
inobt or finobt magic value.
This logic allows an unfortunate xfs_repair bug to escape detection
where certain level > 0 nodes of the finobt are stamped with inobt
magic by xfs_repair finobt reconstruction. This is fortunately not a
severe problem since the inode btree magic values do not contribute
to any changes in kernel behavior, but we do need a means to detect
and prevent this problem in the future.
Add a field to xfs_buf_ops to store the v4 and v5 superblock magic
values expected by a particular verifier. Add a helper to check an
on-disk magic value against the value expected by the verifier. Call
the helper from the shared [f]inobt verifier code for magic value
verification. This ensures that the inode btree blocks each have the
appropriate magic value based on specific tree type and superblock
version.
Signed-off-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>
The inobt verifier is reused for the inobt and finobt, which
prevents the ability to distinguish between magic values on a
per-tree basis. Create a separate finobt structure in preparation
for changes to enforce the appropriate magic value for the
associated tree. This patch has no functional change.
Signed-off-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>
Most verifiers that check on-disk magic values convert the CPU
endian magic value constant to disk endian to facilitate compile
time optimization of the byte swap and reduce the need for runtime
byte swaps in buffer verifiers. Several buffer verifiers do not
follow this pattern. Update those verifiers for consistency.
Also fix up a random typo in the inode readahead verifier name.
Signed-off-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>
Improve the documentation around xfs_buf_ensure_ops, which is the
function that is responsible for cleaning up the b_ops state of buffers
that go through xrep_findroot_block but don't match anything. Rename
the function to xfs_buf_reverify.
[darrick: this started off as bfoster mods of a previous patch of mine,
but the renaming part is now this separate patch.]
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Brian Foster <bfoster@redhat.com>
Use a rhashtable to cache the unlinked list incore. This should speed
up unlinked processing considerably when there are a lot of inodes on
the unlinked list because iunlink_remove no longer has to traverse an
entire bucket list to find which inode points to the one being removed.
The incore list structure records "X.next_unlinked = Y" relations, with
the rhashtable using Y to index the records. This makes finding the
inode X that points to a inode Y very quick. If our cache fails to find
anything we can always fall back on the old method.
FWIW this drastically reduces the amount of time it takes to remove
inodes from the unlinked list. I wrote a program to open a lot of
O_TMPFILE files and then close them in the same order, which takes
a very long time if we have to traverse the unlinked lists. With the
ptach, I see:
+ /d/t/tmpfile/tmpfile
Opened 193531 files in 6.33s.
Closed 193531 files in 5.86s
real 0m12.192s
user 0m0.064s
sys 0m11.619s
+ cd /
+ umount /mnt
real 0m0.050s
user 0m0.004s
sys 0m0.030s
And without the patch:
+ /d/t/tmpfile/tmpfile
Opened 193588 files in 6.35s.
Closed 193588 files in 751.61s
real 12m38.853s
user 0m0.084s
sys 12m34.470s
+ cd /
+ umount /mnt
real 0m0.086s
user 0m0.000s
sys 0m0.060s
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Add tracepoints so we can associate high level operations with low level
updates. No functional changes.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
In xfs_iunlink_remove we have two identical calls to
xfs_iunlink_update_inode, so move it out of the if statement to simplify
the code some more.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
There's a loop that searches an unlinked bucket list to find the inode
that points to a given inode. Hoist this into a separate function;
later we'll use our iunlink backref cache to bypass the slow list
operation. No functional changes.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Hoist the functions that update an inode's unlinked pointer updates into
a helper. No functional changes.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Strengthen our checking of the AGI unlinked pointers when we start to
use them for updating the metadata.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Split the AGI unlinked bucket updates into a separate function. No
functional changes.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Add a new helper to check that a per-AG inode pointer is either null or
points somewhere valid within that AG.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Fix some indentation issues with the iunlink functions and reorganize
the tops of the functions to be identical. No functional changes.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
The writeback delalloc conversion code is racy with respect to
changes in the currently cached file mapping outside of the current
page. This is because the ilock is cycled between the time the
caller originally looked up the mapping and across each real
allocation of the provided file range. This code has collected
various hacks over the years to help combat the symptoms of these
races (i.e., truncate race detection, allocation into hole
detection, etc.), but none address the fundamental problem that the
imap may not be valid at allocation time.
Rather than continue to use race detection hacks, update writeback
delalloc conversion to a model that explicitly converts the delalloc
extent backing the current file offset being processed. The current
file offset is the only block we can trust to remain once the ilock
is dropped because any operation that can remove the block
(truncate, hole punch, etc.) must flush and discard pagecache pages
first.
Modify xfs_iomap_write_allocate() to use the xfs_bmapi_delalloc()
mechanism to request allocation of the entire delalloc extent
backing the current offset instead of assuming the extent passed by
the caller is unchanged. Record the range specified by the caller
and apply it to the resulting allocated extent so previous checks by
the caller for COW fork overlap are not lost. Finally, overload the
bmapi delalloc flag with the range reval flag behavior since this is
the only use case for both.
This ensures that writeback always picks up the correct
and current extent associated with the page, regardless of races
with other extent modifying operations. If operating on a data fork
and the COW overlap state has changed since the ilock was cycled,
the caller revalidates against the COW fork sequence number before
using the imap for the next block.
Signed-off-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>
The writeback delalloc conversion code is racy with respect to
changes in the currently cached file mapping. This stems from the
fact that the bmapi allocation code requires a file range to
allocate and the writeback conversion code assumes the range of the
currently cached mapping is still valid with respect to the fork. It
may not be valid, however, because the ilock is cycled (potentially
multiple times) between the time the cached mapping was populated
and the delalloc conversion occurs.
To facilitate a solution to this problem, create a new
xfs_bmapi_delalloc() wrapper to xfs_bmapi_write() that takes a file
(FSB) offset and attempts to allocate whatever delalloc extent backs
the offset. Use a new bmapi flag to cause xfs_bmapi_write() to set
the range based on the extent backing the bno parameter unless bno
lands in a hole. If bno does land in a hole, fall back to the
current behavior (which may result in an error or quietly skipping
holes in the specified range depending on other parameters). This
patch does not change behavior.
Signed-off-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>
