xfs: detect and correct directory tree problems
Historically, checking the tree-ness of the directory tree structure has
not been complete. Cycles of subdirectories break the tree properties,
as do subdirectories with multiple parents. It's easy enough for DFS to
detect problems as long as one of the participants is reachable from the
root, but this technique cannot find unconnected cycles.
Directory parent pointers change that, because we can discover all of
these problems from a simple walk from a subdirectory towards the root.
For each child we start with, if the walk terminates without reaching
the root, we know the path is disconnected and ought to be attached to
the lost and found. If we find ourselves, we know this is a cycle and
can delete an incoming edge. If we find multiple paths to the root, we
know to delete an incoming edge.
Even better, once we've finished walking paths, we've identified the
good ones and know which other path(s) to remove.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
* tag 'scrub-directory-tree-6.10_2024-04-23' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
xfs: fix corruptions in the directory tree
xfs: report directory tree corruption in the health information
xfs: invalidate dirloop scrub path data when concurrent updates happen
xfs: teach online scrub to find directory tree structure problems
xfs: online repair for parent pointers
This series implements online repair for directory parent pointer
metadata. The checking half is fairly straightforward -- for each
outgoing directory link (forward or backwards), grab the inode at the
other end, and confirm that there's a corresponding link. If we can't
grab an inode or lock it, we'll save that link for a slower loop that
cycles all the locks, confirms the continued existence of the link, and
rechecks the link if it's actually still there.
Repairs are a bit more involved -- for directories, we walk the entire
filesystem to rebuild the dirents from parent pointer information.
Parent pointer repairs do the same walk but rebuild the pptrs from the
dirent information, but with the added twist that it duplicates all the
xattrs so that it can use the atomic extent swapping code to commit the
repairs atomically.
This introduces an added twist to the xattr repair code -- we use dirent
hooks to detect a colliding update to the pptr data while we're not
holding the ILOCKs; if one is detected, we restart the xattr salvaging
process but this time hold all the ILOCKs until the end of the scan.
For offline repair, the phase6 directory connectivity scan generates an
index of all the expected parent pointers in the filesystem. Then it
walks each file and compares the parent pointers attached to that file
against the index generated, and resyncs the results as necessary.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
* tag 'repair-pptrs-6.10_2024-04-23' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
xfs: inode repair should ensure there's an attr fork to store parent pointers
xfs: repair link count of nondirectories after rebuilding parent pointers
xfs: adapt the orphanage code to handle parent pointers
xfs: actually rebuild the parent pointer xattrs
xfs: add a per-leaf block callback to xchk_xattr_walk
xfs: split xfs_bmap_add_attrfork into two pieces
xfs: remove pointless unlocked assertion
xfs: implement live updates for parent pointer repairs
xfs: repair directory parent pointers by scanning for dirents
xfs: replay unlocked parent pointer updates that accrue during xattr repair
xfs: implement live updates for directory repairs
xfs: repair directories by scanning directory parent pointers
xfs: add raw parent pointer apis to support repair
xfs: salvage parent pointers when rebuilding xattr structures
xfs: make the reserved block permission flag explicit in xfs_attr_set
xfs: remove some boilerplate from xfs_attr_set
xfs: scrubbing for parent pointers
Teach online fsck to use parent pointers to assist in checking
directories, parent pointers, extended attributes, and link counts.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
* tag 'scrub-pptrs-6.10_2024-04-23' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
xfs: check parent pointer xattrs when scrubbing
xfs: walk directory parent pointers to determine backref count
xfs: deferred scrub of parent pointers
xfs: scrub parent pointers
xfs: deferred scrub of dirents
xfs: check dirents have parent pointers
xfs: revert commit 44af6c7e59
xfs: Parent Pointers
This is the latest parent pointer attributes for xfs. The goal of this
patch set is to add a parent pointer attribute to each inode. The
attribute name containing the parent inode, generation, and directory
offset, while the attribute value contains the file name. This feature
will enable future optimizations for online scrub, shrink, nfs handles,
verity, or any other feature that could make use of quickly deriving an
inodes path from the mount point.
Directory parent pointers are stored as namespaced extended attributes
of a file. Because parent pointers are an indivisible tuple of
(dirent_name, parent_ino, parent_gen) we cannot use the usual attr name
lookup functions to find a parent pointer. This is solvable by
introducing a new lookup mode that checks both the name and the value of
the xattr.
Therefore, introduce this new name-value lookup mode that's gated on the
XFS_ATTR_PARENT namespace. This requires the introduction of new
opcodes for the extended attribute update log intent items, which
actually means that parent pointers (itself an INCOMPAT feature) does
not depend on the LOGGED_XATTRS log incompat feature bit.
To reduce collisions on the dirent names of parent pointers, introduce a
new attr hash mode that is the dir2 namehash of the dirent name xor'd
with the parent inode number.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
* tag 'pptrs-6.10_2024-04-23' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
xfs: enable parent pointers
xfs: drop compatibility minimum log size computations for reflink
xfs: fix unit conversion error in xfs_log_calc_max_attrsetm_res
xfs: add a incompat feature bit for parent pointers
xfs: don't remove the attr fork when parent pointers are enabled
xfs: add parent pointer ioctls
xfs: split out handle management helpers a bit
xfs: move handle ioctl code to xfs_handle.c
xfs: pass the attr value to put_listent when possible
xfs: don't return XFS_ATTR_PARENT attributes via listxattr
xfs: Add parent pointers to xfs_cross_rename
xfs: Add parent pointers to rename
xfs: remove parent pointers in unlink
xfs: add parent attributes to symlink
xfs: add parent attributes to link
xfs: parent pointer attribute creation
xfs: create a hashname function for parent pointers
xfs: extend transaction reservations for parent attributes
xfs: add parent pointer validator functions
xfs: Expose init_xattrs in xfs_create_tmpfile
xfs: record inode generation in xattr update log intent items
xfs: create attr log item opcodes and formats for parent pointers
xfs: refactor xfs_is_using_logged_xattrs checks in attr item recovery
xfs: allow xattr matching on name and value for parent pointers
xfs: define parent pointer ondisk extended attribute format
xfs: add parent pointer support to attribute code
xfs: create a separate hashname function for extended attributes
xfs: move xfs_attr_defer_add to xfs_attr_item.c
xfs: check the flags earlier in xfs_attr_match
xfs: rearrange xfs_attr_match parameters
xfs: improve extended attribute validation
Prior to introducing parent pointer extended attributes, let's spend
some time cleaning up the attr code and strengthening the validation
that it performs on attrs coming in from the disk.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
* tag 'improve-attr-validation-6.10_2024-04-23' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
xfs: enforce one namespace per attribute
xfs: refactor name/value iovec validation in xlog_recover_attri_commit_pass2
xfs: refactor name/length checks in xfs_attri_validate
xfs: use local variables for name and value length in _attri_commit_pass2
xfs: always set args->value in xfs_attri_item_recover
xfs: validate recovered name buffers when recovering xattr items
xfs: use helpers to extract xattr op from opflags
xfs: restructure xfs_attr_complete_op a bit
xfs: check shortform attr entry flags specifically
xfs: fix missing check for invalid attr flags
xfs: check opcode and iovec count match in xlog_recover_attri_commit_pass2
xfs: use an XFS_OPSTATE_ flag for detecting if logged xattrs are available
xfs: require XFS_SB_FEAT_INCOMPAT_LOG_XATTRS for attr log intent item recovery
xfs: attr fork iext must be loaded before calling xfs_attr_is_leaf
xfs: shrink struct xfs_da_args
Let's clean out some unused flags and fields from struct xfs_da_args.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
* tag 'shrink-dirattr-args-6.10_2024-04-23' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
xfs: rearrange xfs_da_args a bit to use less space
xfs: make attr removal an explicit operation
xfs: remove xfs_da_args.attr_flags
xfs: remove XFS_DA_OP_NOTIME
xfs: remove XFS_DA_OP_REMOVE
Repair corruptions in the directory tree itself. Cycles are broken by
removing an incoming parent->child link. Multiply-owned directories are
fixed by pruning the extra parent -> child links Disconnected subtrees
are reconnected to the lost and found.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Report directories that are the source of corruption in the directory
tree.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
The runtime parent pointer update code expects that any file being moved
around the directory tree already has an attr fork. However, if we had
to rebuild an inode core record, there's a chance that we zeroed forkoff
as part of the inode to pass the iget verifiers.
Therefore, if we performed any repairs on an inode core, ensure that the
inode has a nonzero forkoff before unlocking the inode.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Add a dirent update hook so that we can detect directory tree updates
that affect any of the paths found by this scrubber and force it to
rescan.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Since the parent pointer scrubber does not exhaustively search the
filesystem for missing parent pointers, it doesn't have a good way to
determine that there are pointers missing from an otherwise uncorrupt
xattr structure. Instead, for nondirectories it employs a heuristic of
comparing the file link count to the number of parent pointers found.
However, we don't want this heuristic flagging a false corruption after
a repair has actually scanned the entire filesystem to rebuild the
parent pointers. Therefore, reset the file link count in this one case
because we actually know the correct link count.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Create a new scrubber that detects corruptions within the directory tree
structure itself. It can detect directories with multiple parents;
loops within the directory tree; and directory loops not accessible from
the root.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Adapt the orphanage's adoption code to update the child file's parent
pointers as part of the reparenting process. Also ensure that the child
has an attr fork to receive the parent pointer update, since the runtime
code assumes one exists.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Once we've assembled all the parent pointers for a file, we need to
commit the new dataset atomically to that file. Parent pointer records
are embedded in the xattr structure, which means that we must write a
new extended attribute structure, again, atomically. Therefore, we must
copy the non-parent-pointer attributes from the file being repaired into
the temporary file's extended attributes and then call the atomic extent
swap mechanism to exchange the blocks.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Add a second callback function to xchk_xattr_walk so that we can do
something in between attr leaf blocks. This will be used by the next
patch to see if we should flush cached parent pointer updates to
constrain memory usage.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Split this function into two pieces -- one to make the actual changes to
the inode core to add the attr fork, and another one to deal with
getting the transaction and locking the inodes.
The next couple of patches will need this to be split into two. One
patch implements committing new parent pointer recordsets to damaged
files. If one file has an attr fork and the other does not, we have to
create the missing attr fork before the atomic swap transaction, and can
use the behavior encoded in the current xfs_bmap_add_attrfork.
The second patch adapts /lost+found adoptions to handle parent pointers
correctly. The adoption process will add a parent pointer to a child
that is being moved to /lost+found, but this requires that the attr fork
already exists. We don't know if we're actually going to commit the
adoption until we've already reserved a transaction and taken the
ILOCKs, which means that we must have a way to bypass the start of the
current xfs_bmap_add_attrfork.
Therefore, create xfs_attr_add_fork as the helper that creates a
transaction and takes locks; and make xfs_bmap_add_attrfork the function
that updates the inode core and allocates the incore attr fork.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Remove this assertion about the inode not having an attr fork from
xfs_bmap_add_attrfork because the function handles that case just fine.
Weirder still, the function actually /requires/ the caller not to hold
the ILOCK, which means that its accesses are not stabilized.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
While we're scanning the filesystem for dirents that we can turn into
parent pointers, we cannot hold the IOLOCK or ILOCK of the file being
repaired. Therefore, we need to set up a dirent hook so that we can
keep the temporary file's parent pionters up to date with the rest of
the filesystem. Hence we add the ability to *remove* pptrs from the
temporary file.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
If parent pointers are enabled on the filesystem, we can repair the
entire dataset by walking the directories of the filesystem looking for
dirents that we can turn into parent pointers. Once we have a full
incore dataset, we'll figure out what to do with it, but that's for a
subsequent patch.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
There are a few places where the extended attribute repair code drops
the ILOCK to apply stashed xattrs to the temporary file. Although
setxattr and removexattr are still locked out because we retain our hold
on the IOLOCK, this doesn't prevent renames from updating parent
pointers, because the VFS doesn't take i_rwsem on children that are
being moved.
Therefore, set up a dirent hook to capture parent pointer updates for
this file, and replay(?) the updates.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
While we're scanning the filesystem for parent pointers that we can turn
into dirents, we cannot hold the IOLOCK or ILOCK of the directory being
repaired. Therefore, we need to set up a dirent hook so that we can
keep the temporary directory up to date with the rest of the filesystem.
Hence we add the ability to *remove* entries from the temporary dir.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
For filesystems with parent pointers, scan the entire filesystem looking
for parent pointers that target the directory we're rebuilding instead
of trying to salvage whatever we can from the directory data blocks.
This will be more robust than salvaging, but there's more code to come.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Add a couple of utility functions to set or remove parent pointers from
a file. These functions will be used by repair code, hence they skip
the xattr logging that regular parent pointer updates use.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Check parent pointer xattrs as part of scrubbing xattrs.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
When we're salvaging extended attributes, make sure we validate the ones
that claim to be parent pointers before adding them to the salvage pile.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
If the filesystem has parent pointers enabled, walk the parent pointers
of subdirectories to determine the true backref count. In theory each
subdir should have a single parent reachable via dotdot, but in the case
of (corrupt) subdirs with multiple parents, we need to keep the link
counts high enough that the directory loop detector will be able to
correct the multiple parents problems.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Make the use of reserved blocks an explicit parameter to xfs_attr_set.
Userspace setting XFS_ATTR_ROOT attrs should continue to be able to use
it, but for online repairs we can back out and therefore do not care.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
In preparation for online/offline repair wanting to use xfs_attr_set,
move some of the boilerplate out of this function into the callers.
Repair can initialize the da_args completely, and the userspace flag
handling/twisting goes away once we move it to xfs_attr_change.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
If the trylock-based dirent check fails, retain those parent pointers
and check them at the end. This may involve dropping the locks on the
file being scanned, so yay.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
If the trylock-based parent pointer check fails, retain those dirents
and check them at the end. This may involve dropping the locks on the
file being scanned, so yay.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
If the fs has parent pointers, we need to check that each child dirent
points to a file that has a parent pointer pointing back at us.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
In my haste to fix what I thought was a performance problem in the attr
scrub code, I neglected to notice that the xfs_attr_get_ilocked also had
the effect of checking that attributes can actually be looked up through
the attr dabtree. Fix this.
Fixes: 44af6c7e59 ("xfs: don't load local xattr values during scrub")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Let's also drop the oversized minimum log computations for reflink and
rmap that were the result of bugs introduced many years ago.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Dave and I were discussing some recent test regressions as a result of
me turning on nrext64=1 on realtime filesystems, when we noticed that
the minimum log size of a 32M filesystem jumped from 954 blocks to 4287
blocks.
Digging through xfs_log_calc_max_attrsetm_res, Dave noticed that @size
contains the maximum estimated amount of space needed for a local format
xattr, in bytes, but we feed this quantity to XFS_NEXTENTADD_SPACE_RES,
which requires units of blocks. This has resulted in an overestimation
of the minimum log size over the years.
We should nominally correct this, but there's a backwards compatibility
problem -- if we enable it now, the minimum log size will decrease. If
a corrected mkfs formats a filesystem with this new smaller log size, a
user will encounter mount failures on an uncorrected kernel due to the
larger minimum log size computations there.
Therefore, turn this on for parent pointers because it wasn't merged at
all upstream when this issue was discovered.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
When an inode is removed, it may also cause the attribute fork to be
removed if it is the last attribute. This transaction gets flushed to
the log, but if the system goes down before we could inactivate the symlink,
the log recovery tries to inactivate this inode (since it is on the unlinked
list) but the verifier trips over the remote value and leaks it.
Hence we ended up with a file in this odd state on a "clean" mount. The
"obvious" fix is to prohibit erasure of the attr fork to avoid tripping
over the verifiers when pptrs are enabled.
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This patch adds a pair of new file ioctls to retrieve the parent pointer
of a given inode. They both return the same results, but one operates
on the file descriptor passed to ioctl() whereas the other allows the
caller to specify a file handle for which the caller wants results.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Split out the functions that generate file/fs handles and map them back
into dentries in preparation for the GETPARENTS ioctl next.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Move the handle managemnet code (and the attrmulti code that uses it) to
xfs_handle.c.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Pass the attr value to put_listent when we have local xattrs or
shortform xattrs. This will enable the GETPARENTS ioctl to use
xfs_attr_list as its backend.
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Parent pointers are internal filesystem metadata. They're not intended
to be directly visible to userspace, so filter them out of
xfs_xattr_put_listent so that they don't appear in listxattr.
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Inspired-by: Andrey Albershteyn <aalbersh@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
[djwong: change this to XFS_ATTR_PRIVATE_NSP_MASK per fsverity patchset]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cross renames are handled separately from standard renames, and
need different handling to update the parent attributes correctly.
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This patch removes the old parent pointer attribute during the rename
operation, and re-adds the updated parent pointer.
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
[djwong: adjust to new ondisk format]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This patch removes the parent pointer attribute during unlink
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
[djwong: adjust to new ondisk format, minor rebase fixes]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This patch modifies xfs_symlink to add a parent pointer to the inode.
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
[djwong: minor rebase fixups]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Add parent pointer attribute during xfs_create, and subroutines to
initialize attributes. Note that the xfs_attr_intent object contains a
pointer to the caller's xfs_da_args object, so the latter must persist
until transaction commit.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
[djwong: shorten names, adjust to new format, set init_xattrs for parent
pointers]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Although directory entry and parent pointer recordsets look very similar
(name -> ino), there's one major difference between them: a file can be
hardlinked from multiple parent directories with the same filename.
This is common in shared container environments where a base directory
tree might be hardlink-copied multiple times. IOWs the same 'ls'
program might be hardlinked to multiple /srv/*/bin/ls paths.
We don't want parent pointer operations to bog down on hash collisions
between the same dirent name, so create a special hash function that
mixes in the parent directory inode number.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
