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Commit 26e81b31 authored by Ian Kent's avatar Ian Kent Committed by Linus Torvalds
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autofs4: fix pending checks 



There are two cases for which a dentry that has a pending mount request
does not wait for completion.  One is via autofs4_revalidate() and the
other via autofs4_follow_link().

In revalidate, after the mount point directory is created, but before the
mount is done, the check in try_to_fill_dentry() can can fail to send the
dentry to the wait queue since the dentry is positive and the lookup flags
may contain only LOOKUP_FOLLOW.  Although we don't trigger a mount for the
LOOKUP_FOLLOW flag, if ther's one pending we might as well wait and use
the mounted dentry for the lookup.

In autofs4_follow_link() the dentry is not checked to see if it is pending
so it may fail to call try_to_fill_dentry() and not wait for mount
completion.

A dentry that is pending must always be sent to the wait queue.

Signed-off-by: default avatarIan Kent <raven@themaw.net>
Reviewed-by: default avatarJeff Moyer <jmoyer@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ff9cd499

fs/autofs4/root.c

+6 −3
Original line number Diff line number Diff line
@@ -177,7 +177,8 @@ static int try_to_fill_dentry(struct dentry *dentry, int flags) 
			return status;

		}

	/* Trigger mount for path component or follow link */

	} else if (flags & (TRIGGER_FLAGS | TRIGGER_INTENTS) ||

	} else if (dentry->d_flags & DCACHE_AUTOFS_PENDING ||

			flags & (TRIGGER_FLAGS | TRIGGER_INTENTS) ||

			current->link_count) {

		DPRINTK("waiting for mount name=%.*s",

			dentry->d_name.len, dentry->d_name.name);
@@ -223,7 +224,8 @@ static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd) 


	/* If it's our master or we shouldn't trigger a mount we're done */

	lookup_type = nd->flags & (TRIGGER_FLAGS | TRIGGER_INTENTS);

	if (oz_mode || !lookup_type)

	if (oz_mode ||

	    !(lookup_type || dentry->d_flags & DCACHE_AUTOFS_PENDING))

		goto done;



	/* If an expire request is pending wait for it. */
@@ -242,7 +244,8 @@ static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd) 
	 * don't try to mount it again.

	 */

	spin_lock(&dcache_lock);

	if (!d_mountpoint(dentry) && __simple_empty(dentry)) {

	if (dentry->d_flags & DCACHE_AUTOFS_PENDING ||

	    (!d_mountpoint(dentry) && __simple_empty(dentry))) {

		spin_unlock(&dcache_lock);



		status = try_to_fill_dentry(dentry, 0);