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 10/13] VFS/namei: handle LOOKUP_RCU in page_follow_link_light.
Date: Thu, 19 Mar 2015 23:46:28 +0000 [thread overview]
Message-ID: <20150319234625.GT29656@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20150320093833.25603da2@notabene.brown>
On Fri, Mar 20, 2015 at 09:38:33AM +1100, NeilBrown wrote:
> Ahhh - that's what nd->inode is for. I wondered.
>
> Am I correct in thinking that dentry->d_inode can only become NULL - it cannot
> then become some other inode?
It can - consider somebody doing mkdir on that name right under you.
_All_ we are guaranteed is that at some moment nd->inode matched the
pathname this far and so was (at the same moment) path->dentry. We
are not promised that these inode and dentry will remain associated
with each other, etc.
We ought to check ->d_seq after checking ->d_flags, BTW. _That_ will confirm
that inode remained corresponding to that dentry until the time we'd
observed d_is_symlink(dentry), i.e. make sure that inode *is* a symlink one.
And yes, we probably would have to pass dentry and inode separately, more's
the pity.
next prev parent reply other threads:[~2015-03-19 23:46 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 02/13] VFS: make all ->follow_link handlers aware for LOOKUP_RCU NeilBrown
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 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 01/13] VFS: replace {, total_}link_count in task_struct with pointer to nameidata NeilBrown
2015-03-16 19:46 ` 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 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 08/13] VFS/namei: enhance follow_link to support RCU-walk 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 09/13] VFS/namei: enable RCU-walk when following symlinks NeilBrown
2015-03-16 22:44 ` Al Viro
2015-03-16 4:43 ` [PATCH 13/13] NFS: support LOOKUP_RCU in nfs_follow_link NeilBrown
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 [this message]
2015-03-16 4:43 ` [PATCH 11/13] xfs: use RCU to free 'struct xfs_mount' NeilBrown
2015-03-16 4:43 ` [PATCH 07/13] VFS/namei: abort RCU-walk on symlink if atime needs updating NeilBrown
2015-03-16 19:14 ` [PATCH 00/13] Support follow_link in RCU-walk. - V2 Al Viro
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