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From: Al Viro <viro@ZenIV.linux.org.uk>
To: NeilBrown <neilb@suse.de>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 01/13] VFS: replace {, total_}link_count in task_struct with pointer to nameidata
Date: Mon, 16 Mar 2015 19:46:22 +0000 [thread overview]
Message-ID: <20150316194622.GA29656@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20150316044319.23648.13820.stgit@notabene.brown>
On Mon, Mar 16, 2015 at 03:43:19PM +1100, NeilBrown wrote:
> - if (unlikely(current->total_link_count >= 40))
> + if (unlikely(current->nameidata->total_link_count >= 40))
Huh? nd->total_link_count, please.
>
> - current->total_link_count++;
> + current->nameidata->total_link_count++;
Similar.
> @@ -991,8 +1008,8 @@ static int follow_automount(struct path *path, unsigned flags,
> path->dentry->d_inode)
> return -EISDIR;
>
> - current->total_link_count++;
> - if (current->total_link_count >= 40)
> + current->nameidata->total_link_count++;
> + if (current->nameidata->total_link_count >= 40)
> return -ELOOP;
We probably ought to pass nd through follow_mount / follow_automount, instead
of nd->flags, and use nd->total_link_count here.
> - if (unlikely(current->link_count >= MAX_NESTED_LINKS)) {
> + if (unlikely(current->nameidata->link_count >= MAX_NESTED_LINKS)) {
Again, nd->link_count.
> @@ -1948,7 +1965,7 @@ static int path_init(int dfd, const char *name, unsigned int flags,
> rcu_read_unlock();
> return -ECHILD;
> done:
> - current->total_link_count = 0;
> + current->nameidata->total_link_count = 0;
... and again.
> return link_path_walk(name, nd);
> }
>
> @@ -2027,7 +2044,9 @@ static int path_lookupat(int dfd, const char *name,
> static int filename_lookup(int dfd, struct filename *name,
> unsigned int flags, struct nameidata *nd)
> {
> - int retval = path_lookupat(dfd, name->name, flags | LOOKUP_RCU, nd);
> + int retval;
> + struct nameidata *saved_nd = set_nameidata(nd);
I'm not sure it's the right place ;-/ I'll play with that a bit and see
if I can get it cleaner...
> - struct nameidata nd;
> + struct nameidata nd, *saved = set_nameidata(&nd);
> void *cookie;
> int res;
>
> @@ -4441,6 +4465,7 @@ int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
> res = readlink_copy(buffer, buflen, nd_get_link(&nd));
> if (dentry->d_inode->i_op->put_link)
> dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
> + set_nameidata(saved);
> return res;
Now, _that_ is broken - get ERR_PTR(...) from ->follow_link() and you've
leaked nameidata.
next prev parent reply other threads:[~2015-03-16 19:46 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-16 4:43 [PATCH 00/13] Support follow_link in RCU-walk. - V2 NeilBrown
2015-03-16 4:43 ` [PATCH 01/13] VFS: replace {, total_}link_count in task_struct with pointer to nameidata NeilBrown
2015-03-16 19:46 ` Al Viro [this message]
2015-03-16 4:43 ` [PATCH 02/13] VFS: make all ->follow_link handlers aware for LOOKUP_RCU NeilBrown
2015-03-16 4:43 ` [PATCH 04/13] security/selinux: check for LOOKUP_RCU in _follow_link NeilBrown
2015-03-16 21:00 ` Al Viro
2015-03-20 4:39 ` NeilBrown
2015-03-20 5:12 ` Al Viro
2015-03-16 4:43 ` [PATCH 03/13] VFS: remove nameidata args from ->follow_link and ->put_link NeilBrown
2015-03-16 20:47 ` Al Viro
2015-03-16 4:43 ` [PATCH 05/13] VFS/namei: use terminate_walk when symlink lookup fails NeilBrown
2015-03-16 4:43 ` [PATCH 12/13] XFS: allow follow_link to often succeed in RCU-walk NeilBrown
2015-03-16 22:37 ` Al Viro
2015-03-16 4:43 ` [PATCH 10/13] VFS/namei: handle LOOKUP_RCU in page_follow_link_light NeilBrown
2015-03-16 22:50 ` Al Viro
2015-03-19 22:38 ` NeilBrown
2015-03-19 23:46 ` Al Viro
2015-03-16 4:43 ` [PATCH 11/13] xfs: use RCU to free 'struct xfs_mount' NeilBrown
2015-03-16 4:43 ` [PATCH 13/13] NFS: support LOOKUP_RCU in nfs_follow_link NeilBrown
2015-03-16 4:43 ` [PATCH 06/13] VFS/namei: new flag to support RCU symlinks: LOOKUP_LINK_RCU NeilBrown
2015-03-16 22:33 ` Al Viro
2015-03-17 0:59 ` Al Viro
2015-03-16 4:43 ` [PATCH 07/13] VFS/namei: abort RCU-walk on symlink if atime needs updating NeilBrown
2015-03-16 4:43 ` [PATCH 08/13] VFS/namei: enhance follow_link to support RCU-walk NeilBrown
2015-03-16 4:43 ` [PATCH 09/13] VFS/namei: enable RCU-walk when following symlinks NeilBrown
2015-03-16 22:44 ` Al Viro
2015-03-16 19:14 ` [PATCH 00/13] Support follow_link in RCU-walk. - V2 Al Viro
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