If the block size of a filesystem is not at least PAGE_SIZEd, then
at this point in time DAX cannot be used due to the fact we can't
guarantee extents are page sized or aligned without further work.
Hence disallow setting the DAX flag on an inode if the block size is
too small. Also, be defensive and check the block size when reading
an inode in off disk.
In future, we want to allow DAX to work on any filesystem, so this
is temporary while we sort of the correct conbination of extent size
hints and allocation alignment configurations needed to guarantee
page sized and aligned extent allocation for DAX enabled files.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Only regular files can use DAX for data operations, so we should
restrict setting it on the VFS inode to regular files. Setting it on
metadata inodes may cause the VFS to do the wrong thing for such
inodes, so avoid potential problems by restricting the scope of the
flag to what we know is supported.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Move the di_mode value from the xfs_icdinode to the VFS inode, reducing
the xfs_icdinode byte another 2 bytes and collapsing another 2 byte hole
in the structure.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Pull another 4 bytes out of the xfs_icdinode.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
The VFS tracks the inode nlink just like the xfs_icdinode. We can
remove the variable from the icdinode and use the VFS inode variable
everywhere, reducing the size of the xfs_icdinode by a further 4
bytes.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
The struct xfs_inode has two copies of the current timestamps in it,
one in the vfs inode and one in the struct xfs_icdinode. Now that we
no longer log the struct xfs_icdinode directly, we don't need to
keep the timestamps in this structure. instead we can copy them
straight out of the VFS inode when formatting the inode log item or
the on-disk inode.
This reduces the struct xfs_inode in size by 24 bytes.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This update contains:
o promotion of XFS_IOC_FS[GS]ETXATTR ioctl to the vfs level so that
it can be shared with other filesystems. The ext4 project quota
functionality is the first target for this. The commits in this
series have not been updated with review or final SOB tags because
the branch they were originally published in was needed by ext4.
Those tags are:
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Dave Chinner <david@fromrobit.com>
o Revert a change that is causing suspend failures.
o Fix a use-after-free that can occur on log mount failures. Been
around forever, but now exposed by other changes to log recovery
made in the first 4.5 merge.
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Merge tag 'xfs-for-linus-4.5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs
Pull more xfs updates from Dave Chinner:
"This is the second update for XFS that I mentioned in the original
pull request last week.
It contains a revert for a suspend regression in 4.4 and a fix for a
long standing log recovery issue that has been further exposed by all
the log recovery changes made in the original 4.5 merge.
There is one more thing in this pull request - one that I forgot to
merge into the origin. That is, pulling the XFS_IOC_FS[GS]ETXATTR
ioctl up to the VFS level so that other filesystems can also use it
for modifying project quota IDs
Summary:
- promotion of XFS_IOC_FS[GS]ETXATTR ioctl to the vfs level so that
it can be shared with other filesystems. The ext4 project quota
functionality is the first target for this. The commits in this
series have not been updated with review or final SOB tags because
the branch they were originally published in was needed by ext4.
Those tags are:
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Dave Chinner <david@fromrobit.com>
- Revert a change that is causing suspend failures.
- Fix a use-after-free that can occur on log mount failures. Been
around forever, but now exposed by other changes to log recovery
made in the first 4.5 merge"
* tag 'xfs-for-linus-4.5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs:
xfs: log mount failures don't wait for buffers to be released
Revert "xfs: clear PF_NOFREEZE for xfsaild kthread"
xfs: introduce per-inode DAX enablement
xfs: use FS_XFLAG definitions directly
fs: XFS_IOC_FS[SG]SETXATTR to FS_IOC_FS[SG]ETXATTR promotion
Rather than just being able to turn DAX on and off via a mount
option, some applications may only want to enable DAX for certain
performance critical files in a filesystem.
This patch introduces a new inode flag to enable DAX in the v3 inode
di_flags2 field. It adds support for setting and clearing flags in
the di_flags2 field via the XFS_IOC_FSSETXATTR ioctl, and sets the
S_DAX inode flag appropriately when it is seen.
When this flag is set on a directory, it acts as an "inherit flag".
That is, inodes created in the directory will automatically inherit
the on-disk inode DAX flag, enabling administrators to set up
directory heirarchies that automatically use DAX. Setting this flag
on an empty root directory will make the entire filesystem use DAX
by default.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
new method: ->get_link(); replacement of ->follow_link(). The differences
are:
* inode and dentry are passed separately
* might be called both in RCU and non-RCU mode;
the former is indicated by passing it a NULL dentry.
* when called that way it isn't allowed to block
and should return ERR_PTR(-ECHILD) if it needs to be called
in non-RCU mode.
It's a flagday change - the old method is gone, all in-tree instances
converted. Conversion isn't hard; said that, so far very few instances
do not immediately bail out when called in RCU mode. That'll change
in the next commits.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This patch modifies the stats counting macros and the callers
to those macros to properly increment, decrement, and add-to
the xfs stats counts. The counts for global and per-fs stats
are correctly advanced, and cleared by writing a "1" to the
corresponding clear file.
global counts: /sys/fs/xfs/stats/stats
per-fs counts: /sys/fs/xfs/sda*/stats/stats
global clear: /sys/fs/xfs/stats/stats_clear
per-fs clear: /sys/fs/xfs/sda*/stats/stats_clear
[dchinner: cleaned up macro variables, removed CONFIG_FS_PROC around
stats structures and macros. ]
Signed-off-by: Bill O'Donnell <billodo@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
As the code stands today, if xfs_trans_reserve() fails, we
goto out_dqrele, which does not free the allocated transaction.
Fix up the goto targets to undo everything properly.
Addresses-Coverity-Id: 145571
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This update contains:
o A new sparse on-disk inode record format to allow small extents to
be used for inode allocation when free space is fragmented.
o DAX support. This includes minor changes to the DAX core code to
fix problems with lock ordering and bufferhead mapping abuse.
o transaction commit interface cleanup
o removal of various unnecessary XFS specific type definitions
o cleanup and optimisation of freelist preparation before allocation
o various minor cleanups
o bug fixes for
- transaction reservation leaks
- incorrect inode logging in unwritten extent conversion
- mmap lock vs freeze ordering
- remote symlink mishandling
- attribute fork removal issues.
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Merge tag 'xfs-for-linus-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs
Pul xfs updates from Dave Chinner:
"There's a couple of small API changes to the core DAX code which
required small changes to the ext2 and ext4 code bases, but otherwise
everything is within the XFS codebase.
This update contains:
- A new sparse on-disk inode record format to allow small extents to
be used for inode allocation when free space is fragmented.
- DAX support. This includes minor changes to the DAX core code to
fix problems with lock ordering and bufferhead mapping abuse.
- transaction commit interface cleanup
- removal of various unnecessary XFS specific type definitions
- cleanup and optimisation of freelist preparation before allocation
- various minor cleanups
- bug fixes for
- transaction reservation leaks
- incorrect inode logging in unwritten extent conversion
- mmap lock vs freeze ordering
- remote symlink mishandling
- attribute fork removal issues"
* tag 'xfs-for-linus-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs: (49 commits)
xfs: don't truncate attribute extents if no extents exist
xfs: clean up XFS_MIN_FREELIST macros
xfs: sanitise error handling in xfs_alloc_fix_freelist
xfs: factor out free space extent length check
xfs: xfs_alloc_fix_freelist() can use incore perag structures
xfs: remove xfs_caddr_t
xfs: use void pointers in log validation helpers
xfs: return a void pointer from xfs_buf_offset
xfs: remove inst_t
xfs: remove __psint_t and __psunsigned_t
xfs: fix remote symlinks on V5/CRC filesystems
xfs: fix xfs_log_done interface
xfs: saner xfs_trans_commit interface
xfs: remove the flags argument to xfs_trans_cancel
xfs: pass a boolean flag to xfs_trans_free_items
xfs: switch remaining xfs_trans_dup users to xfs_trans_roll
xfs: check min blks for random debug mode sparse allocations
xfs: fix sparse inodes 32-bit compile failure
xfs: add initial DAX support
xfs: add DAX IO path support
...
The flags argument to xfs_trans_commit is not useful for most callers, as
a commit of a transaction without a permanent log reservation must pass
0 here, and all callers for a transaction with a permanent log reservation
except for xfs_trans_roll must pass XFS_TRANS_RELEASE_LOG_RES. So remove
the flags argument from the public xfs_trans_commit interfaces, and
introduce low-level __xfs_trans_commit variant just for xfs_trans_roll
that regrants a log reservation instead of releasing it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
xfs_trans_cancel takes two flags arguments: XFS_TRANS_RELEASE_LOG_RES and
XFS_TRANS_ABORT. Both of them are a direct product of the transaction
state, and can be deducted:
- any dirty transaction needs XFS_TRANS_ABORT to be properly canceled,
and XFS_TRANS_ABORT is a noop for a transaction that is not dirty.
- any transaction with a permanent log reservation needs
XFS_TRANS_RELEASE_LOG_RES to be properly canceled, and passing
XFS_TRANS_RELEASE_LOG_RES for a transaction without a permanent
log reservation is invalid.
So just remove the flags argument and do the right thing.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Add initial DAX support to XFS. To do this we need a new mount
option to turn DAX on filesystem, and we need to propagate this into
the inode flags whenever an inode is instantiated so that the
per-inode checks throughout the code Do The Right Thing.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
When we truncate a DAX file, we need to call through the DAX page
truncation path rather than through block_truncate_page() so that
mappings and block zeroing are all handled correctly. Otherwise,
truncate does not need to change.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
a) instead of storing the symlink body (via nd_set_link()) and returning
an opaque pointer later passed to ->put_link(), ->follow_link() _stores_
that opaque pointer (into void * passed by address by caller) and returns
the symlink body. Returning ERR_PTR() on error, NULL on jump (procfs magic
symlinks) and pointer to symlink body for normal symlinks. Stored pointer
is ignored in all cases except the last one.
Storing NULL for opaque pointer (or not storing it at all) means no call
of ->put_link().
b) the body used to be passed to ->put_link() implicitly (via nameidata).
Now only the opaque pointer is. In the cases when we used the symlink body
to free stuff, ->follow_link() now should store it as opaque pointer in addition
to returning it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull fourth vfs update from Al Viro:
"d_inode() annotations from David Howells (sat in for-next since before
the beginning of merge window) + four assorted fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
RCU pathwalk breakage when running into a symlink overmounting something
fix I_DIO_WAKEUP definition
direct-io: only inc/dec inode->i_dio_count for file systems
fs/9p: fix readdir()
VFS: assorted d_backing_inode() annotations
VFS: fs/inode.c helpers: d_inode() annotations
VFS: fs/cachefiles: d_backing_inode() annotations
VFS: fs library helpers: d_inode() annotations
VFS: assorted weird filesystems: d_inode() annotations
VFS: normal filesystems (and lustre): d_inode() annotations
VFS: security/: d_inode() annotations
VFS: security/: d_backing_inode() annotations
VFS: net/: d_inode() annotations
VFS: net/unix: d_backing_inode() annotations
VFS: kernel/: d_inode() annotations
VFS: audit: d_backing_inode() annotations
VFS: Fix up some ->d_inode accesses in the chelsio driver
VFS: Cachefiles should perform fs modifications on the top layer only
VFS: AF_UNIX sockets should call mknod on the top layer only
that's the bulk of filesystem drivers dealing with inodes of their own
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We want to drop all I/O path locks when recalling layouts, and that includes
i_mutex for the write path. Without this we get stuck processe when recalls
take too long.
[dchinner: fix build with !CONFIG_PNFS]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Whiteouts are used by overlayfs - it has a crazy convention that a
whiteout is a character device inode with a major:minor of 0:0.
Because it's not documented anywhere, here's an example of what
RENAME_WHITEOUT does on ext4:
# echo foo > /mnt/scratch/foo
# echo bar > /mnt/scratch/bar
# ls -l /mnt/scratch
total 24
-rw-r--r-- 1 root root 4 Feb 11 20:22 bar
-rw-r--r-- 1 root root 4 Feb 11 20:22 foo
drwx------ 2 root root 16384 Feb 11 20:18 lost+found
# src/renameat2 -w /mnt/scratch/foo /mnt/scratch/bar
# ls -l /mnt/scratch
total 20
-rw-r--r-- 1 root root 4 Feb 11 20:22 bar
c--------- 1 root root 0, 0 Feb 11 20:23 foo
drwx------ 2 root root 16384 Feb 11 20:18 lost+found
# cat /mnt/scratch/bar
foo
#
In XFS rename terms, the operation that has been done is that source
(foo) has been moved to the target (bar), which is like a nomal
rename operation, but rather than the source being removed, it have
been replaced with a whiteout.
We can't allocate whiteout inodes within the rename transaction due
to allocation being a multi-commit transaction: rename needs to
be a single, atomic commit. Hence we have several options here, form
most efficient to least efficient:
- use DT_WHT in the target dirent and do no whiteout inode
allocation. The main issue with this approach is that we need
hooks in lookup to create a virtual chardev inode to present
to userspace and in places where we might need to modify the
dirent e.g. unlink. Overlayfs also needs to be taught about
DT_WHT. Most invasive change, lowest overhead.
- create a special whiteout inode in the root directory (e.g. a
".wino" dirent) and then hardlink every new whiteout to it.
This means we only need to create a single whiteout inode, and
rename simply creates a hardlink to it. We can use DT_WHT for
these, though using DT_CHR means we won't have to modify
overlayfs, nor anything in userspace. Downside is we have to
look up the whiteout inode on every operation and create it if
it doesn't exist.
- copy ext4: create a special whiteout chardev inode for every
whiteout. This is more complex than the above options because
of the lack of atomicity between inode creation and the rename
operation, requiring us to create a tmpfile inode and then
linking it into the directory structure during the rename. At
least with a tmpfile inode crashes between the create and
rename doesn't leave unreferenced inodes or directory
pollution around.
By far the simplest thing to do in the short term is to copy ext4.
While it is the most inefficient way of supporting whiteouts, but as
an initial implementation we can simply reuse existing functions and
add a small amount of extra code the the rename operation.
When we get full whiteout support in the VFS (via the dentry cache)
we can then look to supporting DT_WHT method outlined as the first
method of supporting whiteouts. But until then, we'll stick with
what overlayfs expects us to be: dumb and stupid.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Al Viro noticed a generic set of issues to do with filehandle lookup
racing with dentry cache setup. They involve a filehandle lookup
occurring while an inode is being created and the filehandle lookup
racing with the dentry creation for the real file. This can lead to
multiple dentries for the one path being instantiated. There are a
host of other issues around this same set of paths.
The underlying cause is that file handle lookup only waits on inode
cache instantiation rather than full dentry cache instantiation. XFS
is mostly immune to the problems discovered due to it's own internal
inode cache, but there are a couple of corner cases where races can
happen.
We currently clear the XFS_INEW flag when the inode is fully set up
after insertion into the cache. Newly allocated inodes are inserted
locked and so aren't usable until the allocation transaction
commits. This, however, occurs before the dentry and security
information is fully initialised and hence the inode is unlocked and
available for lookups to find too early.
To solve the problem, only clear the XFS_INEW flag for newly created
inodes once the dentry is fully instantiated. This means lookups
will retry until the XFS_INEW flag is removed from the inode and
hence avoids the race conditions in questions.
THis also means that xfs_create(), xfs_create_tmpfile() and
xfs_symlink() need to finish the setup of the inode in their error
paths if we had allocated the inode but failed later in the creation
process. xfs_symlink(), in particular, needed a lot of help to make
it's error handling match that of xfs_create().
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
A new fsync vs power fail test in xfstests indicated that XFS can
have unreliable data consistency when doing extending truncates that
require block zeroing. The blocks beyond EOF get zeroed in memory,
but we never force those changes to disk before we run the
transaction that extends the file size and exposes those blocks to
userspace. This can result in the blocks not being correctly zeroed
after a crash.
Because in-memory behaviour is correct, tools like fsx don't pick up
any coherency problems - it's not until the filesystem is shutdown
or the system crashes after writing the truncate transaction to the
journal but before the zeroed data in the page cache is flushed that
the issue is exposed.
Fix this by also flushing the dirty data in memory region between
the old size and new size when we've found blocks that need zeroing
in the truncate process.
Reported-by: Liu Bo <bo.li.liu@oracle.com>
cc: <stable@vger.kernel.org>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Now that truncate locks out new page faults, we no longer need to do
special writeback hacks in truncate to work around potential races
between page faults, page cache truncation and file size updates to
ensure we get write page faults for extending truncates on sub-page
block size filesystems. Hence we can remove the code in
xfs_setattr_size() that handles this and update the comments around
the code tha thandles page cache truncate and size updates to
reflect the new reality.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Now we have the i_mmap_lock being held across the page fault IO
path, we now add extent manipulation operation exclusion by adding
the lock to the paths that directly modify extent maps. This
includes truncate, hole punching and other fallocate based
operations. The operations will now take both the i_iolock and the
i_mmaplock in exclusive mode, thereby ensuring that all IO and page
faults block without holding any page locks while the extent
manipulation is in progress.
This gives us the lock order during truncate of i_iolock ->
i_mmaplock -> page_lock -> i_lock, hence providing the same
lock order as the iolock provides the normal IO path without
involving the mmap_sem.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Recall all outstanding pNFS layouts and truncates, writes and similar extent
list modifying operations.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Add operations to export pNFS block layouts from an XFS filesystem. See
the previous commit adding the operations for an explanation of them.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Adds a new function named xfs_cross_rename(), responsible for
handling requests from sys_renameat2() using RENAME_EXCHANGE flag.
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
To be able to support RENAME_EXCHANGE flag from renameat2() system
call, XFS must have its inode_operations updated, exporting .rename2
method, instead of .rename.
This patch just replaces the (now old) .rename method by .rename2,
using the same infra-structure, but checking rename flags. Calls to
.rename2 using RENAME_EXCHANGE flag, although now handled inside
XFS, still return -EINVAL.
RENAME_NOREPLACE is handled via VFS and we don't need to care about
it inside xfs_vn_rename.
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
These functions are needed in userspace for repair and mkfs to
do the right thing. Move them to libxfs so they can be easily
shared.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
More on-disk format consolidation.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
More on-disk format consolidation. A few declarations that weren't on-disk
format related move into better suitable spots.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
More consolidatation for the on-disk format defintions. Note that the
XFS_IS_REALTIME_INODE moves to xfs_linux.h instead as it is not related
to the on disk format, but depends on a CONFIG_ option.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
On a sub-page sized filesystem, truncating a mapped region down
leaves us in a world of hurt. We truncate the pagecache, zeroing the
newly unused tail, then punch blocks out from under the page. If we
then truncate the file back up immediately, we expose that unmapped
hole to a dirty page mapped into the user application, and that's
where it all goes wrong.
In truncating the page cache, we avoid unmapping the tail page of
the cache because it still contains valid data. The problem is that
it also contains a hole after the truncate, but nobody told the mm
subsystem that. Therefore, if the page is dirty before the truncate,
we'll never get a .page_mkwrite callout after we extend the file and
the application writes data into the hole on the page. Hence when
we come to writing that region of the page, it has no blocks and no
delayed allocation reservation and hence we toss the data away.
This patch adds code to the truncate up case to solve it, by
ensuring the partial page at the old EOF is always cleaned after we
do any zeroing and move the EOF upwards. We can't actually serialise
the page writeback and truncate against page faults (yes, that
problem AGAIN) so this is really just a best effort and assumes it
is extremely unlikely that someone is concurrently writing to the
page at the EOF while extending the file.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
The offset and length parameters are converted from bytes to basic
blocks by xfs_vn_fiemap(). The BTOBB() converter rounds the value up to
the nearest basic block. This leads to unexpected behavior when
unaligned offsets are provided to FIEMAP.
Fix the conversions of byte values to block values to cover the provided
offsets. Round down the start offset to the nearest basic block.
Calculate the end offset based on the provided values, round up and
calculate length based on the start block offset.
Reported-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Convert all the errors the core XFs code to negative error signs
like the rest of the kernel and remove all the sign conversion we
do in the interface layers.
Errors for conversion (and comparison) found via searches like:
$ git grep " E" fs/xfs
$ git grep "return E" fs/xfs
$ git grep " E[A-Z].*;$" fs/xfs
Negation points found via searches like:
$ git grep "= -[a-z,A-Z]" fs/xfs
$ git grep "return -[a-z,A-D,F-Z]" fs/xfs
$ git grep " -[a-z].*;" fs/xfs
[ with some bits I missed from Brian Foster ]
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
XFS_ERROR was designed long ago to trap return values, but it's not
runtime configurable, it's not consistently used, and we can do
similar error trapping with ftrace scripts and triggers from
userspace.
Just nuke XFS_ERROR and associated bits.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
truncate_setsize() removes pages from the page cache, and hence
requires page locks to be held. It is not valid to lock a page cache
page inside a transaction context as we can hold page locks when we
we reserve space for a transaction. If we do, then we expose an ABBA
deadlock between log space reservation and page locks.
That is, both the write path and writeback lock a page, then start a
transaction for block allocation, which means they can block waiting
for a log reservation with the page lock held. If we hold a log
reservation and then do something that locks a page (e.g.
truncate_setsize in xfs_setattr_size) then that page lock can block
on the page locked and waiting for a log reservation. If the
transaction that is waiting for the page lock is the only active
transaction in the system that can free log space via a commit,
then writeback will never make progress and so log space will never
free up.
This issue with xfs_setattr_size() was introduced back in 2010 by
commit fa9b227 ("xfs: new truncate sequence") which moved the page
cache truncate from outside the transaction context (what was
xfs_itruncate_data()) to inside the transaction context as a call to
truncate_setsize().
The reason truncate_setsize() was located where in this place was
that we can't shouldn't change the file size until after we are in
the transaction context and the operation will either succeed or
shut down the filesystem on failure. However, block_truncate_page()
already modifies the file contents before we enter the transaction
context, so we can't really fulfill this guarantee in any way. Hence
we may as well ensure that on success or failure, the in-memory
inode and data is truncated away and that the application cleans up
the mess appropriately.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Dave Chinner