From eed810076685c77dc9a8c5c3593e641c93caed1c Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 5 Sep 2013 14:39:11 +0200 Subject: vfs: check unlinked ancestors before mount 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. Nor do we prevent mounts to be added to the disconnected subtree using relative paths after the d_drop(). This patch fixes these issues by checking for unlinked (unhashed, non-root) ancestors before proceeding with the mount. This is done with rename seqlock taken for write and with ->d_lock grabbed on each ancestor in turn, including our dentry itself. This ensures that the only one of check_submounts_and_drop() or has_unlinked_ancestor() can succeed. Signed-off-by: Miklos Szeredi Signed-off-by: Al Viro --- fs/internal.h | 1 + 1 file changed, 1 insertion(+) (limited to 'fs/internal.h') diff --git a/fs/internal.h b/fs/internal.h index 7c5f01cf619d..d20893795526 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -126,6 +126,7 @@ extern int invalidate_inodes(struct super_block *, bool); * dcache.c */ extern struct dentry *__d_alloc(struct super_block *, const struct qstr *); +extern int d_set_mounted(struct dentry *dentry); /* * read_write.c -- cgit