Permalink
Browse files

Btrfs: do not allow logged extents to be merged or removed

We drop the extent map tree lock while we're logging extents, so somebody
could come in and merge another extent into this one and screw up our
logging, or they could even remove us from the list which would keep us from
logging the extent or freeing our ref on it, so we need to make sure to not
clear LOGGING until after the extent is logged, and then we can merge it to
adjacent extents.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
  • Loading branch information...
Josef Bacik
Josef Bacik committed Jan 24, 2013
1 parent a105bb8 commit 201a90389424d6771d24fc5d72f7e34cb4a8f967
Showing with 16 additions and 3 deletions.
  1. +12 −1 fs/btrfs/extent_map.c
  2. +1 −0 fs/btrfs/extent_map.h
  3. +3 −2 fs/btrfs/tree-log.c
View
@@ -171,6 +171,10 @@ static int mergable_maps(struct extent_map *prev, struct extent_map *next)
if (test_bit(EXTENT_FLAG_COMPRESSED, &prev->flags))
return 0;
+ if (test_bit(EXTENT_FLAG_LOGGING, &prev->flags) ||
+ test_bit(EXTENT_FLAG_LOGGING, &next->flags))
+ return 0;
+
if (extent_map_end(prev) == next->start &&
prev->flags == next->flags &&
prev->bdev == next->bdev &&
@@ -256,7 +260,8 @@ int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len,
if (!em)
goto out;
- list_move(&em->list, &tree->modified_extents);
+ if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags))
+ list_move(&em->list, &tree->modified_extents);
em->generation = gen;
clear_bit(EXTENT_FLAG_PINNED, &em->flags);
em->mod_start = em->start;
@@ -281,6 +286,12 @@ int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len,
}
+void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
+{
+ clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
+ try_merge_map(tree, em);
+}
+
/**
* add_extent_mapping - add new extent map to the extent tree
* @tree: tree to insert new map in
View
@@ -69,6 +69,7 @@ void free_extent_map(struct extent_map *em);
int __init extent_map_init(void);
void extent_map_exit(void);
int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len, u64 gen);
+void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em);
struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
u64 start, u64 len);
#endif
View
@@ -3410,22 +3410,23 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
em = list_entry(extents.next, struct extent_map, list);
list_del_init(&em->list);
- clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
/*
* If we had an error we just need to delete everybody from our
* private list.
*/
if (ret) {
+ clear_em_logging(tree, em);
free_extent_map(em);
continue;
}
write_unlock(&tree->lock);
ret = log_one_extent(trans, inode, root, em, path);
- free_extent_map(em);
write_lock(&tree->lock);
+ clear_em_logging(tree, em);
+ free_extent_map(em);
}
WARN_ON(!list_empty(&extents));
write_unlock(&tree->lock);

0 comments on commit 201a903

Please sign in to comment.