f2fs: fix handling orphan inodes

This patch fixes mishandling of the sbi->n_orphans variable.

If users request lots of f2fs_unlink(), check_orphan_space() could be contended.
In such the case, sbi->n_orphans can be read incorrectly so that f2fs_unlink()
would fall into the wrong state which results in the failure of
add_orphan_inode().

So, let's increment sbi->n_orphans virtually prior to the actual orphan inode
stuffs. After that, let's release sbi->n_orphans by calling release_orphan_inode
or remove_orphan_inode.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index fe91773de130..c5a5c390a5cc 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -182,7 +182,7 @@ const struct address_space_operations f2fs_meta_aops = {
 	.set_page_dirty	= f2fs_set_meta_page_dirty,
 };
 
-int check_orphan_space(struct f2fs_sb_info *sbi)
+int acquire_orphan_inode(struct f2fs_sb_info *sbi)
 {
 	unsigned int max_orphans;
 	int err = 0;
@@ -197,10 +197,19 @@ int check_orphan_space(struct f2fs_sb_info *sbi)
 	mutex_lock(&sbi->orphan_inode_mutex);
 	if (sbi->n_orphans >= max_orphans)
 		err = -ENOSPC;
+	else
+		sbi->n_orphans++;
 	mutex_unlock(&sbi->orphan_inode_mutex);
 	return err;
 }
 
+void release_orphan_inode(struct f2fs_sb_info *sbi)
+{
+	mutex_lock(&sbi->orphan_inode_mutex);
+	sbi->n_orphans--;
+	mutex_unlock(&sbi->orphan_inode_mutex);
+}
+
 void add_orphan_inode(struct f2fs_sb_info *sbi, nid_t ino)
 {
 	struct list_head *head, *this;
@@ -229,8 +238,6 @@ retry:
 		list_add(&new->list, this->prev);
 	else
 		list_add_tail(&new->list, head);
-
-	sbi->n_orphans++;
 out:
 	mutex_unlock(&sbi->orphan_inode_mutex);
 }