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authorJosef Bacik <jbacik@fusionio.com>2012-12-18 20:39:19 +0400
committerJosef Bacik <jbacik@fusionio.com>2013-01-24 21:49:49 +0400
commitb0175117b9376a69978bbe80af26fb95dddbd53e (patch)
tree1748791c73aae22587be21f2b3ee127d858c3432
parent201a90389424d6771d24fc5d72f7e34cb4a8f967 (diff)
downloadlinux-b0175117b9376a69978bbe80af26fb95dddbd53e.tar.xz
Btrfs: fix panic when recovering tree log
A user reported a BUG_ON(ret) that occured during tree log replay. Ret was -EAGAIN, so what I think happened is that we removed an extent that covered a bitmap entry and an extent entry. We remove the part from the bitmap and return -EAGAIN and then search for the next piece we want to remove, which happens to be an entire extent entry, so we just free the sucker and return. The problem is ret is still set to -EAGAIN so we trip the BUG_ON(). The user used btrfs-zero-log so I'm not 100% sure this is what happened so I've added a WARN_ON() to catch the other possibility. Thanks, Reported-by: Jan Steffens <jan.steffens@gmail.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
-rw-r--r--fs/btrfs/free-space-cache.c20
1 files changed, 12 insertions, 8 deletions
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 59ea2e4349c9..0be7a8742a43 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1862,11 +1862,13 @@ int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
{
struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
struct btrfs_free_space *info;
- int ret = 0;
+ int ret;
+ bool re_search = false;
spin_lock(&ctl->tree_lock);
again:
+ ret = 0;
if (!bytes)
goto out_lock;
@@ -1879,17 +1881,17 @@ again:
info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
1, 0);
if (!info) {
- /* the tree logging code might be calling us before we
- * have fully loaded the free space rbtree for this
- * block group. So it is possible the entry won't
- * be in the rbtree yet at all. The caching code
- * will make sure not to put it in the rbtree if
- * the logging code has pinned it.
+ /*
+ * If we found a partial bit of our free space in a
+ * bitmap but then couldn't find the other part this may
+ * be a problem, so WARN about it.
*/
+ WARN_ON(re_search);
goto out_lock;
}
}
+ re_search = false;
if (!info->bitmap) {
unlink_free_space(ctl, info);
if (offset == info->offset) {
@@ -1935,8 +1937,10 @@ again:
}
ret = remove_from_bitmap(ctl, info, &offset, &bytes);
- if (ret == -EAGAIN)
+ if (ret == -EAGAIN) {
+ re_search = true;
goto again;
+ }
BUG_ON(ret); /* logic error */
out_lock:
spin_unlock(&ctl->tree_lock);