From 60630fe66ed28d43379382645ed349f7d3457330 Mon Sep 17 00:00:00 2001 From: Brian Foster Date: Mon, 8 Feb 2016 15:00:02 +1100 Subject: [PATCH] xfs: clean up unwritten buffers on write failure 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 $ mount /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 Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner --- 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 379c089fb051..4a13f5311a41 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); } } -- 2.20.1