diff options
| -rw-r--r-- | fs/namei.c | 29 | ||||
| -rw-r--r-- | fs/namespace.c | 40 |
2 files changed, 37 insertions, 32 deletions
diff --git a/fs/namei.c b/fs/namei.c index db6565c99825..626eddb33508 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1208,11 +1208,9 @@ EXPORT_SYMBOL(follow_up); * - return -EISDIR to tell follow_managed() to stop and return the path we * were called with. */ -static int follow_automount(struct path *path, struct nameidata *nd, - bool *need_mntput) +static int follow_automount(struct path *path, struct nameidata *nd) { struct vfsmount *mnt; - int err; if (!path->dentry->d_op || !path->dentry->d_op->d_automount) return -EREMOTE; @@ -1253,29 +1251,10 @@ static int follow_automount(struct path *path, struct nameidata *nd, return PTR_ERR(mnt); } - if (!mnt) /* mount collision */ - return 0; - - if (!*need_mntput) { - /* lock_mount() may release path->mnt on error */ - mntget(path->mnt); - *need_mntput = true; - } - err = finish_automount(mnt, path); - - switch (err) { - case -EBUSY: - /* Someone else made a mount here whilst we were busy */ + if (!mnt) return 0; - case 0: - path_put(path); - path->mnt = mnt; - path->dentry = dget(mnt->mnt_root); - return 0; - default: - return err; - } + return finish_automount(mnt, path); } /* @@ -1333,7 +1312,7 @@ static int follow_managed(struct path *path, struct nameidata *nd) /* Handle an automount point */ if (flags & DCACHE_NEED_AUTOMOUNT) { - ret = follow_automount(path, nd, &need_mntput); + ret = follow_automount(path, nd); if (ret < 0) break; continue; diff --git a/fs/namespace.c b/fs/namespace.c index dcd015fafe01..777c3116e62e 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2823,6 +2823,7 @@ static int do_new_mount(struct path *path, const char *fstype, int sb_flags, int finish_automount(struct vfsmount *m, struct path *path) { + struct dentry *dentry = path->dentry; struct mount *mnt = real_mount(m); struct mountpoint *mp; int err; @@ -2832,21 +2833,46 @@ int finish_automount(struct vfsmount *m, struct path *path) BUG_ON(mnt_get_count(mnt) < 2); if (m->mnt_sb == path->mnt->mnt_sb && - m->mnt_root == path->dentry) { + m->mnt_root == dentry) { err = -ELOOP; - goto fail; + goto discard; } - mp = lock_mount(path); + /* + * we don't want to use lock_mount() - in this case finding something + * that overmounts our mountpoint to be means "quitely drop what we've + * got", not "try to mount it on top". + */ + inode_lock(dentry->d_inode); + namespace_lock(); + if (unlikely(cant_mount(dentry))) { + err = -ENOENT; + goto discard_locked; + } + rcu_read_lock(); + if (unlikely(__lookup_mnt(path->mnt, dentry))) { + rcu_read_unlock(); + err = 0; + goto discard_locked; + } + rcu_read_unlock(); + mp = get_mountpoint(dentry); if (IS_ERR(mp)) { err = PTR_ERR(mp); - goto fail; + goto discard_locked; } + err = do_add_mount(mnt, mp, path, path->mnt->mnt_flags | MNT_SHRINKABLE); unlock_mount(mp); - if (!err) - return 0; -fail: + if (unlikely(err)) + goto discard; + mntput(m); + return 0; + +discard_locked: + namespace_unlock(); + inode_unlock(dentry->d_inode); +discard: /* remove m from any expiration list it may be on */ if (!list_empty(&mnt->mnt_expire)) { namespace_lock(); |