f2fs: don't let the orphan inode counter underflow

Accounting errors from buggy code calling the acquire/release/remove
orphan inode interfaces can cause n_orphans to underflow, which will
then cause acquire_orphan_inode() to return -ENOSPC on the next
operation.  This commit guards against that condition.

Signed-off-by: Russ Knize <rknize@motorola.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index bb31220..ca39442 100644 (file)
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -206,6 +206,7 @@ int acquire_orphan_inode(struct f2fs_sb_info *sbi)
 void release_orphan_inode(struct f2fs_sb_info *sbi)
 {
        mutex_lock(&sbi->orphan_inode_mutex);
+       BUG_ON(sbi->n_orphans == 0);
        sbi->n_orphans--;
        mutex_unlock(&sbi->orphan_inode_mutex);
 }
@@ -253,6 +254,7 @@ void remove_orphan_inode(struct f2fs_sb_info *sbi, nid_t ino)
                if (orphan->ino == ino) {
                        list_del(&orphan->list);
                        kmem_cache_free(orphan_entry_slab, orphan);
+                       BUG_ON(sbi->n_orphans == 0);
                        sbi->n_orphans--;
                        break;
                }