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: $ mkfs.xfs -f -b size=1k -d size=100m <dev> $ mount <dev> /mnt/ $ $ xfs_io -fc "falloc -k 0 1k" /mnt/file $ dd if=/dev/zero of=/mnt/enospc conv=notrunc oflag=append $ $ xfs_io -c "pwrite 512 1k" /mnt/file $ xfs_io -d -c "pwrite 16k 1k" /mnt/file 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@xxxxxxxxxx> --- The alternative to this approach was to just kill the releasepage() unwritten buffer warning, but this seemed more consistent and cautious in that we can retain the warning to catch any other potential problems in the future. I'm open to either approach, along with any other ideas of course.. As it is, this survives xfstests with 1k and 4k blocks without any explosions and many iterations of generic/083 w/ bsize=1k, which was the original reproducer. Brian fs/xfs/xfs_aops.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index 7d6e368..c8c74d0 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -1783,14 +1783,22 @@ xfs_vm_write_failed( if (block_start >= to) break; - if (!buffer_delay(bh)) + /* + * Process delalloc and unwritten buffers beyond EOF. We can + * encounter unwritten buffers in the event that a file has + * post-EOF unwritten extents and an extending write happens to + * fail (e.g., an unaligned write that also involves a delalloc + * to the same page). + */ + if (!buffer_delay(bh) && !buffer_unwritten(bh)) continue; if (!buffer_new(bh) && block_offset < i_size_read(inode)) continue; - xfs_vm_kill_delalloc_range(inode, block_offset, - block_offset + bh->b_size); + if (buffer_delay(bh)) + xfs_vm_kill_delalloc_range(inode, block_offset, + block_offset + bh->b_size); /* * This buffer does not contain data anymore. make sure anyone @@ -1801,6 +1809,7 @@ xfs_vm_write_failed( clear_buffer_mapped(bh); clear_buffer_new(bh); clear_buffer_dirty(bh); + clear_buffer_unwritten(bh); } } -- 2.4.3 _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
