fix EOPENSTALE bug in do_last()

EOPENSTALE occuring at the last component of a trailing symlink ends up
with do_last() retrying its lookup.  After the symlink body has been
discarded.  The thing is, all this retry_lookup logics in there is not
needed at all - the upper layers will do the right thing if we simply
return that -EOPENSTALE as we would with any other error.  Trying to
microoptimize in do_last() is a lot of headache for no good reason.

Cc: stable@vger.kernel.org # v4.2+
Tested-by: Oleg Drokin <green@linuxhacker.ru>
Reviewed-and-Tested-by: Jeff Layton <jlayton@poochiereds.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namei.c b/fs/namei.c
index 4c4f95ac8aa5d535c1e919b4bbc9c394010bd88d..3d9511e656ab9f90ffbb03c1462e03e1623b79aa 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3166,9 +3166,7 @@ static int do_last(struct nameidata *nd,
        int acc_mode = op->acc_mode;
        unsigned seq;
        struct inode *inode;
-       struct path save_parent = { .dentry = NULL, .mnt = NULL };
        struct path path;
-       bool retried = false;
        int error;
 
        nd->flags &= ~LOOKUP_PARENT;
@@ -3211,7 +3209,6 @@ static int do_last(struct nameidata *nd,
                        return -EISDIR;
        }
 
-retry_lookup:
        if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {
                error = mnt_want_write(nd->path.mnt);
                if (!error)
@@ -3292,23 +3289,14 @@ finish_lookup:
        if (unlikely(error))
                return error;
 
-       if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) {
-               path_to_nameidata(&path, nd);
-       } else {
-               save_parent.dentry = nd->path.dentry;
-               save_parent.mnt = mntget(path.mnt);
-               nd->path.dentry = path.dentry;
-
-       }
+       path_to_nameidata(&path, nd);
        nd->inode = inode;
        nd->seq = seq;
        /* Why this, you ask?  _Now_ we might have grown LOOKUP_JUMPED... */
 finish_open:
        error = complete_walk(nd);
-       if (error) {
-               path_put(&save_parent);
+       if (error)
                return error;
-       }
        audit_inode(nd->name, nd->path.dentry, 0);
        error = -EISDIR;
        if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry))
@@ -3331,13 +3319,9 @@ finish_open_created:
                goto out;
        BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
        error = vfs_open(&nd->path, file, current_cred());
-       if (!error) {
-               *opened |= FILE_OPENED;
-       } else {
-               if (error == -EOPENSTALE)
-                       goto stale_open;
+       if (error)
                goto out;
-       }
+       *opened |= FILE_OPENED;
 opened:
        error = open_check_o_direct(file);
        if (!error)
@@ -3353,26 +3337,7 @@ out:
        }
        if (got_write)
                mnt_drop_write(nd->path.mnt);
-       path_put(&save_parent);
        return error;
-
-stale_open:
-       /* If no saved parent or already retried then can't retry */
-       if (!save_parent.dentry || retried)
-               goto out;
-
-       BUG_ON(save_parent.dentry != dir);
-       path_put(&nd->path);
-       nd->path = save_parent;
-       nd->inode = dir->d_inode;
-       save_parent.mnt = NULL;
-       save_parent.dentry = NULL;
-       if (got_write) {
-               mnt_drop_write(nd->path.mnt);
-               got_write = false;
-       }
-       retried = true;
-       goto retry_lookup;
 }
 
 static int do_tmpfile(struct nameidata *nd, unsigned flags,