btrfs: Catch locking failures in {set,clear,convert}_extent_bit

The *_state functions can only return 0 or -EEXIST. This patch addresses
the cases where those functions returning -EEXIST represent a locking
failure. It handles them by panicking with an appropriate error message.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index a55fbe6252ded4e41d9b76cb3bed1a9f98acd065..601f23bddea8dc7faa02e9653e7657f3b34c7520 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -53,6 +53,12 @@ struct extent_page_data {
        unsigned int sync_io:1;
 };
 
+static inline struct btrfs_fs_info *
+tree_fs_info(struct extent_io_tree *tree)
+{
+       return btrfs_sb(tree->mapping->host->i_sb);
+}
+
 int __init extent_io_init(void)
 {
        extent_state_cache = kmem_cache_create("extent_state",
@@ -439,6 +445,13 @@ alloc_extent_state_atomic(struct extent_state *prealloc)
        return prealloc;
 }
 
+void extent_io_tree_panic(struct extent_io_tree *tree, int err)
+{
+       btrfs_panic(tree_fs_info(tree), err, "Locking error: "
+                   "Extent tree was modified by another "
+                   "thread while locked.");
+}
+
 /*
  * clear some bits on a range in the tree.  This may require splitting
  * or inserting elements in the tree, so the gfp mask is used to
@@ -542,7 +555,9 @@ hit_next:
                prealloc = alloc_extent_state_atomic(prealloc);
                BUG_ON(!prealloc);
                err = split_state(tree, state, prealloc, start);
-               BUG_ON(err == -EEXIST);
+               if (err)
+                       extent_io_tree_panic(tree, err);
+
                prealloc = NULL;
                if (err)
                        goto out;
@@ -564,7 +579,9 @@ hit_next:
                prealloc = alloc_extent_state_atomic(prealloc);
                BUG_ON(!prealloc);
                err = split_state(tree, state, prealloc, end + 1);
-               BUG_ON(err == -EEXIST);
+               if (err)
+                       extent_io_tree_panic(tree, err);
+
                if (wake)
                        wake_up(&state->wq);
 
@@ -742,8 +759,10 @@ again:
                prealloc = alloc_extent_state_atomic(prealloc);
                BUG_ON(!prealloc);
                err = insert_state(tree, prealloc, start, end, &bits);
+               if (err)
+                       extent_io_tree_panic(tree, err);
+
                prealloc = NULL;
-               BUG_ON(err == -EEXIST);
                goto out;
        }
        state = rb_entry(node, struct extent_state, rb_node);
@@ -809,7 +828,9 @@ hit_next:
                prealloc = alloc_extent_state_atomic(prealloc);
                BUG_ON(!prealloc);
                err = split_state(tree, state, prealloc, start);
-               BUG_ON(err == -EEXIST);
+               if (err)
+                       extent_io_tree_panic(tree, err);
+
                prealloc = NULL;
                if (err)
                        goto out;
@@ -846,12 +867,9 @@ hit_next:
                 */
                err = insert_state(tree, prealloc, start, this_end,
                                   &bits);
-               BUG_ON(err == -EEXIST);
-               if (err) {
-                       free_extent_state(prealloc);
-                       prealloc = NULL;
-                       goto out;
-               }
+               if (err)
+                       extent_io_tree_panic(tree, err);
+
                cache_state(prealloc, cached_state);
                prealloc = NULL;
                start = this_end + 1;
@@ -873,7 +891,8 @@ hit_next:
                prealloc = alloc_extent_state_atomic(prealloc);
                BUG_ON(!prealloc);
                err = split_state(tree, state, prealloc, end + 1);
-               BUG_ON(err == -EEXIST);
+               if (err)
+                       extent_io_tree_panic(tree, err);
 
                set_state_bits(tree, prealloc, &bits);
                cache_state(prealloc, cached_state);
@@ -946,7 +965,8 @@ again:
                }
                err = insert_state(tree, prealloc, start, end, &bits);
                prealloc = NULL;
-               BUG_ON(err == -EEXIST);
+               if (err)
+                       extent_io_tree_panic(tree, err);
                goto out;
        }
        state = rb_entry(node, struct extent_state, rb_node);
@@ -1002,7 +1022,8 @@ hit_next:
                        goto out;
                }
                err = split_state(tree, state, prealloc, start);
-               BUG_ON(err == -EEXIST);
+               if (err)
+                       extent_io_tree_panic(tree, err);
                prealloc = NULL;
                if (err)
                        goto out;
@@ -1041,12 +1062,8 @@ hit_next:
                 */
                err = insert_state(tree, prealloc, start, this_end,
                                   &bits);
-               BUG_ON(err == -EEXIST);
-               if (err) {
-                       free_extent_state(prealloc);
-                       prealloc = NULL;
-                       goto out;
-               }
+               if (err)
+                       extent_io_tree_panic(tree, err);
                prealloc = NULL;
                start = this_end + 1;
                goto search_again;
@@ -1065,7 +1082,8 @@ hit_next:
                }
 
                err = split_state(tree, state, prealloc, end + 1);
-               BUG_ON(err == -EEXIST);
+               if (err)
+                       extent_io_tree_panic(tree, err);
 
                set_state_bits(tree, prealloc, &bits);
                clear_state_bit(tree, prealloc, &clear_bits, 0);