autofs4: always use lookup for lookup

We need to be able to cope with the directory mutex being held during
->d_revalidate() in some cases, but not all cases, and not necessarily by
us.  Because we need to release the mutex when we call back to the daemon
to do perform a mount we must be sure that it is us who holds the mutex so
we must redirect mount requests to ->lookup() if the mutex is held.

Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Sage Weil <sage@newdream.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Andreas Dilger <adilger@sun.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Yehuda Saheh <yehuda@newdream.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index 3d283ab..0118d67 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -60,6 +60,11 @@ do {							\
 		current->pid, __func__, ##args);	\
 } while (0)
 
+struct rehash_entry {
+	struct task_struct *task;
+	struct list_head list;
+};
+
 /* Unified info structure.  This is pointed to by both the dentry and
    inode structures.  Each file in the filesystem has an instance of this
    structure.  It holds a reference to the dentry, so dentries are never
@@ -76,6 +81,7 @@ struct autofs_info {
 
 	struct list_head active;
 	int active_count;
+	struct list_head rehash_list;
 
 	struct list_head expiring;
 
@@ -98,6 +104,7 @@ struct autofs_info {
 #define AUTOFS_INF_EXPIRING	(1<<0) /* dentry is in the process of expiring */
 #define AUTOFS_INF_MOUNTPOINT	(1<<1) /* mountpoint status for direct expire */
 #define AUTOFS_INF_PENDING	(1<<2) /* dentry pending mount */
+#define AUTOFS_INF_REHASH	(1<<3) /* dentry in transit to ->lookup() */
 
 struct autofs_wait_queue {
 	wait_queue_head_t queue;