Commit c6b0b656 authored by Jeff Layton's avatar Jeff Layton Committed by Ilya Dryomov

ceph: clean up unsafe d_parent accesses in build_dentry_path

While we hold a reference to the dentry when build_dentry_path is
called, we could end up racing with a rename that changes d_parent.
Handle that situation correctly, by using the rcu_read_lock to
ensure that the parent dentry and inode stick around long enough
to safely check ceph_snap and ceph_ino.

Link: default avatarJeff Layton <>
Reviewed-by: default avatarYan, Zheng <>
Signed-off-by: default avatarIlya Dryomov <>
parent 30c71233
......@@ -1800,13 +1800,18 @@ static int build_dentry_path(struct dentry *dentry,
int *pfreepath)
char *path;
struct inode *dir;
if (ceph_snap(d_inode(dentry->d_parent)) == CEPH_NOSNAP) {
*pino = ceph_ino(d_inode(dentry->d_parent));
dir = d_inode_rcu(dentry->d_parent);
if (dir && ceph_snap(dir) == CEPH_NOSNAP) {
*pino = ceph_ino(dir);
*ppath = dentry->;
*ppathlen = dentry->d_name.len;
return 0;
path = ceph_mdsc_build_path(dentry, ppathlen, pino, 1);
if (IS_ERR(path))
return PTR_ERR(path);
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