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Diffstat (limited to 'fs/btrfs/extent-tree.c')
-rw-r--r--fs/btrfs/extent-tree.c21
1 files changed, 20 insertions, 1 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 53294da0749d..857a859948a3 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5735,10 +5735,13 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
unpin = &fs_info->freed_extents[0];
while (1) {
+ mutex_lock(&fs_info->unused_bg_unpin_mutex);
ret = find_first_extent_bit(unpin, 0, &start, &end,
EXTENT_DIRTY, NULL);
- if (ret)
+ if (ret) {
+ mutex_unlock(&fs_info->unused_bg_unpin_mutex);
break;
+ }
if (btrfs_test_opt(root, DISCARD))
ret = btrfs_discard_extent(root, start,
@@ -5746,6 +5749,7 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
clear_extent_dirty(unpin, start, end, GFP_NOFS);
unpin_extent_range(root, start, end, true);
+ mutex_unlock(&fs_info->unused_bg_unpin_mutex);
cond_resched();
}
@@ -9561,18 +9565,33 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
*/
start = block_group->key.objectid;
end = start + block_group->key.offset - 1;
+ /*
+ * Hold the unused_bg_unpin_mutex lock to avoid racing with
+ * btrfs_finish_extent_commit(). If we are at transaction N,
+ * another task might be running finish_extent_commit() for the
+ * previous transaction N - 1, and have seen a range belonging
+ * to the block group in freed_extents[] before we were able to
+ * clear the whole block group range from freed_extents[]. This
+ * means that task can lookup for the block group after we
+ * unpinned it from freed_extents[] and removed it, leading to
+ * a BUG_ON() at btrfs_unpin_extent_range().
+ */
+ mutex_lock(&fs_info->unused_bg_unpin_mutex);
ret = clear_extent_bits(&fs_info->freed_extents[0], start, end,
EXTENT_DIRTY, GFP_NOFS);
if (ret) {
+ mutex_unlock(&fs_info->unused_bg_unpin_mutex);
btrfs_set_block_group_rw(root, block_group);
goto end_trans;
}
ret = clear_extent_bits(&fs_info->freed_extents[1], start, end,
EXTENT_DIRTY, GFP_NOFS);
if (ret) {
+ mutex_unlock(&fs_info->unused_bg_unpin_mutex);
btrfs_set_block_group_rw(root, block_group);
goto end_trans;
}
+ mutex_unlock(&fs_info->unused_bg_unpin_mutex);
/* Reset pinned so btrfs_put_block_group doesn't complain */
block_group->pinned = 0;