Hi Andrew,
Here is an update to this patch to address your concern below.
Basicly, I wait for pending operations to complete, the main concern is an
expire operation causing directories to be removed. As we hold a reference
to the vfsmount and the dentry that shouldn't happen once any that are in
progress have completed.
At least that's what I expect.
On Fri, 10 Mar 2006, Andrew Morton wrote:
> Ian Kent <raven@xxxxxxxxxx> wrote:
> >
> > @@ -337,10 +340,34 @@ static void *autofs4_follow_link(struct
> > if (oz_mode || !lookup_type)
> > goto done;
> >
> > + /*
> > + * If the dentry contains directories then it is an
> > + * autofs multi-mount with no root offset. So don't
> > + * try to mount it again.
> > + */
> > + spin_lock(&dcache_lock);
> > + if (!list_empty(&dentry->d_subdirs)) {
> > + spin_unlock(&dcache_lock);
> > + goto done;
> > + }
> > + spin_unlock(&dcache_lock);
> > +
>
> Can list_empty(&dentry->d_subdirs) become false right here, after the lock
> was dropped? If so, what happens?
>
>
> > status = try_to_fill_dentry(dentry, 0);
>
Signed-off-by: Ian Kent <raven@xxxxxxxxxx>
--
--- linux-2.6.16-mm1/fs/autofs4/root.c.follow_link-expire-check 2006-03-24 12:32:16.000000000 +0800
+++ linux-2.6.16-mm1/fs/autofs4/root.c 2006-03-24 15:01:15.000000000 +0800
@@ -341,38 +341,49 @@ static void *autofs4_follow_link(struct
goto done;
/*
- * If the dentry contains directories then it is an
- * autofs multi-mount with no root offset. So don't
- * try to mount it again.
+ * If a request is pending wait for it.
+ * If it's a mount then it won't be expired till at least
+ * a liitle later and if it's an expire then we might need
+ * to mount it again.
*/
- spin_lock(&dcache_lock);
- if (!list_empty(&dentry->d_subdirs)) {
- spin_unlock(&dcache_lock);
- goto done;
- }
- spin_unlock(&dcache_lock);
+ if (autofs4_ispending(dentry)) {
+ DPRINTK("waiting for active request %p name=%.*s",
+ dentry, dentry->d_name.len, dentry->d_name.name);
- status = try_to_fill_dentry(dentry, 0);
- if (status)
- goto out_error;
+ status = autofs4_wait(sbi, dentry, NFY_NONE);
+
+ DPRINTK("request done status=%d", status);
+ }
/*
- * The mount succeeded but if there is no root mount
- * and directories have been created then it must
- * be an autofs multi-mount with no root offset.
+ * If the dentry contains directories then it is an
+ * autofs multi-mount with no root mount offset. So
+ * don't try to mount it again.
*/
spin_lock(&dcache_lock);
- if (!d_mountpoint(dentry) && !list_empty(&dentry->d_subdirs)) {
+ if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
spin_unlock(&dcache_lock);
+
+ status = try_to_fill_dentry(dentry, 0);
+ if (status)
+ goto out_error;
+
+ /*
+ * The mount succeeded but if there is no root mount
+ * it must be an autofs multi-mount with no root offset
+ * so we don't need to follow the mount.
+ */
+ if (d_mountpoint(dentry)) {
+ if (!autofs4_follow_mount(&nd->mnt, &nd->dentry)) {
+ status = -ENOENT;
+ goto out_error;
+ }
+ }
+
goto done;
}
spin_unlock(&dcache_lock);
- if (!autofs4_follow_mount(&nd->mnt, &nd->dentry)) {
- status = -ENOENT;
- goto out_error;
- }
-
done:
return NULL;
-
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