From 848ac114e847af3f1f9141c90a39ebe79bdb13b3 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 5 Sep 2013 11:44:36 +0200 Subject: vfs: check submounts and drop atomically We check submounts before doing d_drop() on a non-empty directory dentry in NFS (have_submounts()), but we do not exclude a racing mount. Process A: have_submounts() -> returns false Process B: mount() -> success Process A: d_drop() This patch prepares the ground for the fix by doing the following operations all under the same rename lock: have_submounts() shrink_dcache_parent() d_drop() This is actually an optimization since have_submounts() and shrink_dcache_parent() both traverse the same dentry tree separately. Signed-off-by: Miklos Szeredi CC: David Howells CC: Steven Whitehouse CC: Trond Myklebust CC: Greg Kroah-Hartman Signed-off-by: Al Viro --- include/linux/dcache.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/dcache.h') diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 9169b91ea2d2..c6d3fe50ff96 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -253,6 +253,7 @@ extern void d_prune_aliases(struct inode *); /* test whether we have any submounts in a subdir tree */ extern int have_submounts(struct dentry *); +extern int check_submounts_and_drop(struct dentry *); /* * This adds the entry to the hash queues. -- cgit v1.2.3