Btrfs: fix btrfs_search_slot_for_read backwards iteration
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Message ID 1389475734-19236-1-git-send-email-fdmanana@gmail.com
State Accepted
Headers show

Commit Message

Filipe Manana Jan. 11, 2014, 9:28 p.m. UTC
If the current path's leaf slot is 0, we do search for the previous
leaf (via btrfs_prev_leaf) and set the new path's leaf slot to a
value corresponding to the number of items - 1 of the former leaf.
Fix this by using the slot set by btrfs_prev_leaf, decrementing it
by 1 if it's equal to the leaf's number of items.

Use of btrfs_search_slot_for_read() for backward iteration is used in
particular by the send feature, which could miss items when the input
leaf has less items than its previous leaf.

This could be reproduced by running btrfs/007 from xfstests in a loop.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
---
 fs/btrfs/ctree.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Patch
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diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 9e9de68..7f4fe10 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -3142,7 +3142,9 @@  again:
 			if (ret < 0)
 				return ret;
 			if (!ret) {
-				p->slots[0] = btrfs_header_nritems(leaf) - 1;
+				leaf = p->nodes[0];
+				if (p->slots[0] == btrfs_header_nritems(leaf))
+					p->slots[0]--;
 				return 0;
 			}
 			if (!return_any)