[PATCH 3/7] Btrfs: check if extent buffer is aligned to sectorsize

[Liu Bo <bo.li.liu@oracle.com>]

Thanks to fuzz testing, we can pass an invalid bytenr to extent buffer
via alloc_extent_buffer().  An unaligned eb can have more pages than it
should have, which ends up extent buffer's leak or some corrupted content
in extent buffer.

This adds a warning to let us quickly know what was happening.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
---
 fs/btrfs/extent_io.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d247fc0..e601e0f 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4868,6 +4868,10 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
 	int uptodate = 1;
 	int ret;
 
+	WARN_ONCE(!IS_ALIGNED(start, fs_info->tree_root->sectorsize),
+		  KERN_WARNING "eb->start(%llu) is not aligned to root->sectorsize(%u)\n",
+		  start, fs_info->tree_root->sectorsize);
+
 	eb = find_extent_buffer(fs_info, start);
 	if (eb)
 		return eb;
-- 
2.5.5