Re: [autofs] [RFC:VFS] autofs4 needs to force fail returnrevalidate

[Jeff Moyer]

==> Regarding [autofs] [RFC:VFS] autofs4 needs to force fail return revalidate; Ian Kent <raven@xxxxxxxxxx> adds:

raven> Hi all,

raven> For a long time now I have had a problem with not being able to
raven> return a lookup failure on an existsing directory. In autofs this
raven> corresponds to a mount failure on a autofs managed mount entry that
raven> is browsable (and so the mount point directory exists).

raven> While this problem has been present for a long time I've avoided
raven> resolving it because it was not very visible. But now that autofs v5
raven> has "mount and expire on demand" of nested multiple mounts, such as
raven> is found when mounting an export list from a server, solving the
raven> problem cannot be avoided any longer.

raven> I've tried very hard to find a way to do this entirely within the
raven> autofs4 module but have not been able to find a satisfactory way to
raven> achieve it.

raven> So, I need to propose a change to the VFS.

raven> Please offer comments and suggestions or if anyone has an idea how
raven> this could be done within the autofs4 filesystem then I'm all ears.

> --- linux-2.6.17/include/linux/dcache.h.dcache-revalidate-return-fail	2006-06-19 13:26:27.000000000 +0800
> +++ linux-2.6.17/include/linux/dcache.h	2006-06-19 13:29:25.000000000 +0800
> @@ -163,6 +163,7 @@ d_iput:		no		no		no       yes
>  #define DCACHE_UNHASHED		0x0010	

>  #define DCACHE_INOTIFY_PARENT_WATCHED	0x0020 /* Parent inode is watched */
> +#define DCACHE_REVAL_FORCE_FAIL 0x0040	/* Force revalidate fail on valid dentry */

>  extern spinlock_t dcache_lock;

This looks like the right approach to me.  I'd ack it.

-Jeff
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