New code for 5.5:
- Fill out the build string
- Prevent inode fork extent count overflows
- Refactor the allocator to reduce long tail latency
- Rework incore log locking a little to reduce spinning
- Break up the xfs_iomap_begin functions into smaller more cohesive
parts
- Fix allocation alignment being dropped too early when the allocation
request is for more blocks than an AG is large
- Other small cleanups
- Clean up file buftarg retrieval helpers
- Hoist the resvsp and unresvsp ioctls to the vfs
- Deprecate the undocumented biosize mount option
- Clean up some of the mount option printing and parsing
- Enhance attr leaf verifier to check block structure
- Check dirent and attr names for invalid characters before passing them
to the vfs
- Refactor open-coded bmbt walking
- Fix a few places where we return EIO instead of EFSCORRUPTED after
failing metadata sanity checks
- Fix a synchronization problem between fallocate and aio dio corrupting
the file length
xfs: properly serialise fallocate against AIO+DIO
AIO+DIO can extend the file size on IO completion, and it holds
no inode locks while the IO is in flight. Therefore, a race
condition exists in file size updates if we do something like this:
aio-thread fallocate-thread
lock inode
submit IO beyond inode->i_size
unlock inode
.....
lock inode
break layouts
if (off + len > inode->i_size)
new_size = off + len
.....
inode_dio_wait()
<blocks>
.....
completes
inode->i_size updated
inode_dio_done()
....
<wakes>
<does stuff no long beyond EOF>
if (new_size)
xfs_vn_setattr(inode, new_size)
Yup, that attempt to extend the file size in the fallocate code
turns into a truncate - it removes the whatever the aio write
allocated and put to disk, and reduced the inode size back down to
where the fallocate operation ends.
Fundamentally, xfs_file_fallocate() not compatible with racing
AIO+DIO completions, so we need to move the inode_dio_wait() call
up to where the lock the inode and break the layouts.
Secondly, storing the inode size and then using it unchecked without
holding the ILOCK is not safe; we can only do such a thing if we've
locked out and drained all IO and other modification operations,
which we don't do initially in xfs_file_fallocate.
It should be noted that some of the fallocate operations are
compound operations - they are made up of multiple manipulations
that may zero data, and so we may need to flush and invalidate the
file multiple times during an operation. However, we only need to
lock out IO and other space manipulation operations once, as that
lockout is maintained until the entire fallocate operation has been
completed.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-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>
3 files changed
