The xfs_vm_write_failed() handler is currently responsible for cleaning
up any delalloc blocks over the range of a failed write beyond EOF.
Failure to do so results in warning messages and other inconsistencies
between buffer and extent state. The ->releasepage() handler currently
warns in the event of a page being released with either unwritten or
delalloc buffers, as neither is ever expected by the time a page is
released.
As has been reproduced by generic/083 on a -bsize=1k fs, it is currently
possible to trigger the ->releasepage() warning for a page with
unwritten buffers when a filesystem is near ENOSPC. This is reproduced
by the following sequence:
The first pwrite command attempts a block unaligned write across an
unwritten block and a hole. The delalloc for the hole fails with ENOSPC
and the subsequent error handling does not clean up the unwritten buffer
that was instantiated during the first ->get_block() call.
The second pwrite triggers a warning as part of the inode mapping
invalidation that occurs prior to direct I/O. The releasepage() handler
detects the unwritten buffer at this time, warns and prevents the
release of the page.
To deal with this problem, update xfs_vm_write_failed() to clean up
unwritten as well as delalloc buffers that are beyond EOF and within the
range of the failed write.
Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>