3.8.13.5 -stable review patch. If anyone has any objections, please let me know.
------------------
From: Jan Schmidt <list.btrfs@xxxxxxxxxxxxx>
commit 47fb091fb787420cd195e66f162737401cce023f upstream.
When tree_mod_log_rewind decides to make a copy of the current tree buffer
for its modifications, it subsequently freed the buffer before unlocking it.
Obviously, those operations are required in reverse order.
Signed-off-by: Jan Schmidt <list.btrfs@xxxxxxxxxxxxx>
Signed-off-by: Josef Bacik <jbacik@xxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
fs/btrfs/ctree.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index ce1c169..f28b330 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1189,6 +1189,13 @@ __tree_mod_log_rewind(struct extent_buffer *eb, u64 time_seq,
btrfs_set_header_nritems(eb, n);
}
+/*
+ * Called with eb read locked. If the buffer cannot be rewinded, the same buffer
+ * is returned. If rewind operations happen, a fresh buffer is returned. The
+ * returned buffer is always read-locked. If the returned buffer is not the
+ * input buffer, the lock on the input buffer is released and the input buffer
+ * is freed (its refcount is decremented).
+ */
static struct extent_buffer *
tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
u64 time_seq)
@@ -1222,8 +1229,11 @@ tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
}
extent_buffer_get(eb_rewin);
+ btrfs_tree_read_unlock(eb);
free_extent_buffer(eb);
+ extent_buffer_get(eb_rewin);
+ btrfs_tree_read_lock(eb_rewin);
__tree_mod_log_rewind(eb_rewin, time_seq, tm);
WARN_ON(btrfs_header_nritems(eb_rewin) >
BTRFS_NODEPTRS_PER_BLOCK(fs_info->fs_root));
@@ -2800,15 +2810,9 @@ again:
btrfs_clear_path_blocking(p, b,
BTRFS_READ_LOCK);
}
+ b = tree_mod_log_rewind(root->fs_info, b, time_seq);
p->locks[level] = BTRFS_READ_LOCK;
p->nodes[level] = b;
- b = tree_mod_log_rewind(root->fs_info, b, time_seq);
- if (b != p->nodes[level]) {
- btrfs_tree_unlock_rw(p->nodes[level],
- p->locks[level]);
- p->locks[level] = 0;
- p->nodes[level] = b;
- }
} else {
p->slots[level] = slot;
unlock_up(p, level, lowest_unlock, 0, NULL);
--
1.8.1.2
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