Re: [PATCH 00/21] vfs: atomic open v6 (part 2)

From: Christoph Hellwig
Date: Mon Jun 18 2012 - 07:58:04 EST


On Sun, Jun 17, 2012 at 04:37:55PM -0400, Christoph Hellwig wrote:
> vfs.git#master fails xfstests 005 (Test symlinks & ELOOP) for me. I'll
> try to get it bisected tomorrow, unless anyone gets to it earlier.

this failure was caused by

"namei.c: let follow_link() do put_link() on failure"

and the reason was that we didn't do a proper path_put when failing
inside follow_link(). Fix that should be squashed in below. With this
xfstests 049 is still failing, I'll look into that next.


Index: linux-2.6/fs/namei.c
===================================================================
--- linux-2.6.orig/fs/namei.c 2012-06-18 12:17:08.084097978 +0200
+++ linux-2.6/fs/namei.c 2012-06-18 13:39:29.764224510 +0200
@@ -597,18 +591,19 @@ static inline void put_link(struct namei
static __always_inline int
follow_link(struct path *link, struct nameidata *nd, void **p)
{
- int error;
struct dentry *dentry = link->dentry;
+ int error;
+ char *s;

BUG_ON(nd->flags & LOOKUP_RCU);

if (link->mnt == nd->path.mnt)
mntget(link->mnt);

- if (unlikely(current->total_link_count >= 40)) {
- path_put(&nd->path);
- return -ELOOP;
- }
+ error = -ELOOP;
+ if (unlikely(current->total_link_count >= 40))
+ goto out_put_nd_path;
+
cond_resched();
current->total_link_count++;

@@ -616,31 +611,36 @@ follow_link(struct path *link, struct na
nd_set_link(nd, NULL);

error = security_inode_follow_link(link->dentry, nd);
- if (error) {
- path_put(&nd->path);
- return error;
- }
+ if (error)
+ goto out_put_nd_path;

nd->last_type = LAST_BIND;
*p = dentry->d_inode->i_op->follow_link(dentry, nd);
error = PTR_ERR(*p);
- if (!IS_ERR(*p)) {
- char *s = nd_get_link(nd);
- error = 0;
- if (s)
- error = __vfs_follow_link(nd, s);
- else if (nd->last_type == LAST_BIND) {
- nd->flags |= LOOKUP_JUMPED;
- nd->inode = nd->path.dentry->d_inode;
- if (nd->inode->i_op->follow_link) {
- /* stepped on a _really_ weird one */
- path_put(&nd->path);
- error = -ELOOP;
- }
+ if (IS_ERR(*p))
+ goto out_put_link;
+
+ error = 0;
+ s = nd_get_link(nd);
+ if (s) {
+ error = __vfs_follow_link(nd, s);
+ } else if (nd->last_type == LAST_BIND) {
+ nd->flags |= LOOKUP_JUMPED;
+ nd->inode = nd->path.dentry->d_inode;
+ if (nd->inode->i_op->follow_link) {
+ /* stepped on a _really_ weird one */
+ path_put(&nd->path);
+ error = -ELOOP;
}
- if (unlikely(error))
- put_link(nd, link, p);
}
+ if (unlikely(error))
+ put_link(nd, link, p);
+ return error;
+
+out_put_nd_path:
+ path_put(&nd->path);
+out_put_link:
+ path_put(link);
return error;
}

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