Commit 485290a7 authored Oct 29, 2015 by Qu Wenruo Committed by Chris Mason Nov 03, 2015

btrfs: Fix a data space underflow warning



Even with quota disabled, generic/127 will trigger a kernel warning by
underflow data space info.

The bug is caused by buffered write, which in case of short copy, the
start parameter for btrfs_delalloc_release_space() is wrong, and
round_up/down() in btrfs_delalloc_release() extents the range to page
aligned, decreasing one more page than expected.

This patch will fix it by passing correct start.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

parent 90ce321d

fs/btrfs/file.c

+8 −3

Original line number	Diff line number	Diff line
		@@ -1604,13 +1604,18 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
		BTRFS_I(inode)->outstanding_extents++;
		spin_unlock(&BTRFS_I(inode)->lock);
		}
		if (only_release_metadata)
		if (only_release_metadata) {
		btrfs_delalloc_release_metadata(inode,
		release_bytes);
		else
		btrfs_delalloc_release_space(inode, pos,
		} else {
		u64 __pos;

		__pos = round_down(pos, root->sectorsize) +
		(dirty_pages << PAGE_CACHE_SHIFT);
		btrfs_delalloc_release_space(inode, __pos,
		release_bytes);
		}
		}

		release_bytes = dirty_pages << PAGE_CACHE_SHIFT;