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 <rkn...@motorola.com>
---
  fs/f2fs/checkpoint.c |    2 ++
  1 file changed, 2 insertions(+)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index f2a7c98..2afa32b 100644
--- 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;
                }
-- 
1.7.9.5


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