On Sat, 2011-06-18 at 01:11 +0100, David Howells wrote:
> autofs4_d_automount() returns 0 if it detects that the calling process is in
> Oz
> mode (ie. it's the autofs userspace daemon). This return, however, is meant
> to
> indicate to follow_automount() that the caller should retry the check on the
> the current path point. In the Oz mode case, this is a bad idea because
> nothing has changed on the path, and follow_managed() will just repeat until
> follow_automount() hits the total_link_count limit and returns -ELOOP.
>
> What it should do is return -EISDIR to indicate to the callers that actually
> it
> wants the daemon to see this directory as an ordinary directory.
No, not unless the check below can be changed to somehow not trigger
when LOOKUP_CONTINUE is set for autofs automount dentrys that don't
actually end up with a mount on them, but are automount triggers never
the less:
if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_CONTINUE))
return -EREMOTE;
return PTR_ERR(mnt);
Fact is in our discussions on this we could never reach agreement so I
worked around it by breaking out of the follow_managed() loop using
->d_managed() instead, thinking that the above check must remain to
satisfy the needs of other kernel users.
>
>
> Now, given that change outlined above, it is then unnecessary for
> autofs4_d_manage() to return -EISDIR if the current path point is not a
> mountpoint. If it returns 0 instead, and the path point isn't a mountpoint,
> then follow_managed() will skip the attempt to transit to the mounted
> filesystem and proceed to call autofs4_d_automount(), which will return
> -EISDIR.
>
> Signed-off-by: David Howells <[email protected]>
> ---
>
> fs/autofs4/root.c | 9 ++-------
> 1 files changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
> index f55ae23..a6dc11c 100644
> --- a/fs/autofs4/root.c
> +++ b/fs/autofs4/root.c
> @@ -334,7 +334,7 @@ static struct vfsmount *autofs4_d_automount(struct path
> *path)
>
> /* The daemon never triggers a mount. */
> if (autofs4_oz_mode(sbi))
> - return NULL;
> + return ERR_PTR(-EISDIR);
>
> /*
> * If an expire request is pending everyone must wait.
> @@ -435,13 +435,8 @@ int autofs4_d_manage(struct dentry *dentry, bool
> rcu_walk)
> dentry, dentry->d_name.len, dentry->d_name.name);
>
> /* The daemon never waits. */
> - if (autofs4_oz_mode(sbi)) {
> - if (rcu_walk)
> - return 0;
> - if (!d_mountpoint(dentry))
> - return -EISDIR;
> + if (autofs4_oz_mode(sbi))
> return 0;
> - }
>
> /* We need to sleep, so we need pathwalk to be in ref-mode */
> if (rcu_walk)
>
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