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>

4 files changed, 330 insertions, 158 deletions

diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index 3d283abf67d7..0118d67221b2 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;
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index a796c9417fb1..74bc9aa6df31 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -279,6 +279,7 @@ struct dentry *autofs4_expire_direct(struct super_block *sb,
                         root->d_mounted--;
                 }
                 ino->flags |= AUTOFS_INF_EXPIRING;
+                autofs4_add_expiring(root);
                 init_completion(&ino->expire_complete);
                 spin_unlock(&sbi->fs_lock);
                 return root;
@@ -406,6 +407,7 @@ found:
                 expired, (int)expired->d_name.len, expired->d_name.name);
         ino = autofs4_dentry_ino(expired);
         ino->flags |= AUTOFS_INF_EXPIRING;
+        autofs4_add_expiring(expired);
         init_completion(&ino->expire_complete);
         spin_unlock(&sbi->fs_lock);
         spin_lock(&dcache_lock);
@@ -433,7 +435,7 @@ int autofs4_expire_wait(struct dentry *dentry)
 
                 DPRINTK("expire done status=%d", status);
 
-                if (d_unhashed(dentry))
+                if (d_unhashed(dentry) && IS_DEADDIR(dentry->d_inode))
                         return -EAGAIN;
 
                 return status;
@@ -473,6 +475,7 @@ int autofs4_expire_run(struct super_block *sb,
         spin_lock(&sbi->fs_lock);
         ino = autofs4_dentry_ino(dentry);
         ino->flags &= ~AUTOFS_INF_EXPIRING;
+        autofs4_del_expiring(dentry);
         complete_all(&ino->expire_complete);
         spin_unlock(&sbi->fs_lock);
 
@@ -503,6 +506,7 @@ int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
                         ino->flags &= ~AUTOFS_INF_MOUNTPOINT;
                 }
                 ino->flags &= ~AUTOFS_INF_EXPIRING;
+                autofs4_del_expiring(dentry);
                 complete_all(&ino->expire_complete);
                 spin_unlock(&sbi->fs_lock);
                 dput(dentry);
diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
index 4670a7818eac..d0a3de247458 100644
--- a/fs/autofs4/inode.c
+++ b/fs/autofs4/inode.c
@@ -49,6 +49,7 @@ struct autofs_info *autofs4_init_ino(struct autofs_info *ino,
                 ino->dentry = NULL;
                 ino->size = 0;
                 INIT_LIST_HEAD(&ino->active);
+                INIT_LIST_HEAD(&ino->rehash_list);
                 ino->active_count = 0;
                 INIT_LIST_HEAD(&ino->expiring);
                 atomic_set(&ino->count, 0);
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index a015b49891df..30cc9ddf4b70 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -104,6 +104,99 @@ static void autofs4_del_active(struct dentry *dentry)
         return;
 }
 
+static void autofs4_add_rehash_entry(struct autofs_info *ino,
+                                     struct rehash_entry *entry)
+{
+        entry->task = current;
+        INIT_LIST_HEAD(&entry->list);
+        list_add(&entry->list, &ino->rehash_list);
+        return;
+}
+
+static void autofs4_remove_rehash_entry(struct autofs_info *ino)
+{
+        struct list_head *head = &ino->rehash_list;
+        struct rehash_entry *entry;
+        list_for_each_entry(entry, head, list) {
+                if (entry->task == current) {
+                        list_del(&entry->list);
+                        kfree(entry);
+                        break;
+                }
+        }
+        return;
+}
+
+static void autofs4_remove_rehash_entrys(struct autofs_info *ino)
+{
+        struct autofs_sb_info *sbi = ino->sbi;
+        struct rehash_entry *entry, *next;
+        struct list_head *head;
+
+        spin_lock(&sbi->fs_lock);
+        spin_lock(&sbi->lookup_lock);
+        if (!(ino->flags & AUTOFS_INF_REHASH)) {
+                spin_unlock(&sbi->lookup_lock);
+                spin_unlock(&sbi->fs_lock);
+                return;
+        }
+        ino->flags &= ~AUTOFS_INF_REHASH;
+        head = &ino->rehash_list;
+        list_for_each_entry_safe(entry, next, head, list) {
+                list_del(&entry->list);
+                kfree(entry);
+        }
+        spin_unlock(&sbi->lookup_lock);
+        spin_unlock(&sbi->fs_lock);
+        dput(ino->dentry);
+
+        return;
+}
+
+static void autofs4_revalidate_drop(struct dentry *dentry,
+                                    struct rehash_entry *entry)
+{
+        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
+        struct autofs_info *ino = autofs4_dentry_ino(dentry);
+        /*
+         * Add to the active list so we can pick this up in
+         * ->lookup(). Also add an entry to a rehash list so
+         * we know when there are no dentrys in flight so we
+         * know when we can rehash the dentry.
+         */
+        spin_lock(&sbi->lookup_lock);
+        if (list_empty(&ino->active))
+                list_add(&ino->active, &sbi->active_list);
+        autofs4_add_rehash_entry(ino, entry);
+        spin_unlock(&sbi->lookup_lock);
+        if (!(ino->flags & AUTOFS_INF_REHASH)) {
+                ino->flags |= AUTOFS_INF_REHASH;
+                dget(dentry);
+                spin_lock(&dentry->d_lock);
+                __d_drop(dentry);
+                spin_unlock(&dentry->d_lock);
+        }
+        return;
+}
+
+static void autofs4_revalidate_rehash(struct dentry *dentry)
+{
+        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
+        struct autofs_info *ino = autofs4_dentry_ino(dentry);
+        if (ino->flags & AUTOFS_INF_REHASH) {
+                spin_lock(&sbi->lookup_lock);
+                autofs4_remove_rehash_entry(ino);
+                if (list_empty(&ino->rehash_list)) {
+                        spin_unlock(&sbi->lookup_lock);
+                        ino->flags &= ~AUTOFS_INF_REHASH;
+                        d_rehash(dentry);
+                        dput(ino->dentry);
+                } else
+                        spin_unlock(&sbi->lookup_lock);
+        }
+        return;
+}
+
 static unsigned int autofs4_need_mount(unsigned int flags)
 {
         unsigned int res = 0;
@@ -143,7 +236,7 @@ out:
         return dcache_dir_open(inode, file);
 }
 
-static int try_to_fill_dentry(struct dentry *dentry, int flags)
+static int try_to_fill_dentry(struct dentry *dentry)
 {
         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
         struct autofs_info *ino = autofs4_dentry_ino(dentry);
@@ -156,55 +249,17 @@ static int try_to_fill_dentry(struct dentry *dentry, int flags)
          * Wait for a pending mount, triggering one if there
          * isn't one already
          */
-        if (dentry->d_inode == NULL) {
-                DPRINTK("waiting for mount name=%.*s",
-                         dentry->d_name.len, dentry->d_name.name);
+        DPRINTK("waiting for mount name=%.*s",
+                 dentry->d_name.len, dentry->d_name.name);
 
-                status = autofs4_wait(sbi, dentry, NFY_MOUNT);
+        status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 
-                DPRINTK("mount done status=%d", status);
-
-                /* Turn this into a real negative dentry? */
-                if (status == -ENOENT) {
-                        spin_lock(&sbi->fs_lock);
-                        ino->flags &= ~AUTOFS_INF_PENDING;
-                        spin_unlock(&sbi->fs_lock);
-                        return status;
-                } else if (status) {
-                        /* Return a negative dentry, but leave it "pending" */
-                        return status;
-                }
-        /* Trigger mount for path component or follow link */
-        } else if (ino->flags & AUTOFS_INF_PENDING ||
-                        autofs4_need_mount(flags) ||
-                        current->link_count) {
-                DPRINTK("waiting for mount name=%.*s",
-                        dentry->d_name.len, dentry->d_name.name);
+        DPRINTK("mount done status=%d", status);
 
-                spin_lock(&sbi->fs_lock);
-                ino->flags |= AUTOFS_INF_PENDING;
-                spin_unlock(&sbi->fs_lock);
-                status = autofs4_wait(sbi, dentry, NFY_MOUNT);
+        /* Update expiry counter */
+        ino->last_used = jiffies;
 
-                DPRINTK("mount done status=%d", status);
-
-                if (status) {
-                        spin_lock(&sbi->fs_lock);
-                        ino->flags &= ~AUTOFS_INF_PENDING;
-                        spin_unlock(&sbi->fs_lock);
-                        return status;
-                }
-        }
-
-        /* Initialize expiry counter after successful mount */
-        if (ino)
-                ino->last_used = jiffies;
-
-        spin_lock(&sbi->fs_lock);
-        ino->flags &= ~AUTOFS_INF_PENDING;
-        spin_unlock(&sbi->fs_lock);
-
-        return 0;
+        return status;
 }
 
 /* For autofs direct mounts the follow link triggers the mount */
@@ -258,10 +313,16 @@ static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
          */
         if (ino->flags & AUTOFS_INF_PENDING ||
             (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs))) {
+                ino->flags |= AUTOFS_INF_PENDING;
                 spin_unlock(&dcache_lock);
                 spin_unlock(&sbi->fs_lock);
 
-                status = try_to_fill_dentry(dentry, 0);
+                status = try_to_fill_dentry(dentry);
+
+                spin_lock(&sbi->fs_lock);
+                ino->flags &= ~AUTOFS_INF_PENDING;
+                spin_unlock(&sbi->fs_lock);
+
                 if (status)
                         goto out_error;
 
@@ -300,18 +361,47 @@ static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
 {
         struct inode *dir = dentry->d_parent->d_inode;
         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
-        int oz_mode = autofs4_oz_mode(sbi);
+        struct autofs_info *ino = autofs4_dentry_ino(dentry);
+        struct rehash_entry *entry;
         int flags = nd ? nd->flags : 0;
-        int status = 1;
+        unsigned int mutex_aquired;
+
+        DPRINTK("name = %.*s oz_mode = %d",
+                dentry->d_name.len, dentry->d_name.name, oz_mode);
+
+        /* Daemon never causes a mount to trigger */
+        if (autofs4_oz_mode(sbi))
+                return 1;
+
+        entry = kmalloc(sizeof(struct rehash_entry), GFP_KERNEL);
+        if (!entry)
+                return -ENOMEM;
+
+        mutex_aquired = mutex_trylock(&dir->i_mutex);
 
-        /* Pending dentry */
         spin_lock(&sbi->fs_lock);
+        spin_lock(&dcache_lock);
+        /* Pending dentry */
         if (autofs4_ispending(dentry)) {
-                /* The daemon never causes a mount to trigger */
-                spin_unlock(&sbi->fs_lock);
+                int status;
 
-                if (oz_mode)
-                        return 1;
+                /*
+                 * We can only unhash and send this to ->lookup() if
+                 * the directory mutex is held over d_revalidate() and
+                 * ->lookup(). This prevents the VFS from incorrectly
+                 * seeing the dentry as non-existent.
+                 */
+                ino->flags |= AUTOFS_INF_PENDING;
+                if (!mutex_aquired) {
+                        autofs4_revalidate_drop(dentry, entry);
+                        spin_unlock(&dcache_lock);
+                        spin_unlock(&sbi->fs_lock);
+                        return 0;
+                }
+                spin_unlock(&dcache_lock);
+                spin_unlock(&sbi->fs_lock);
+                mutex_unlock(&dir->i_mutex);
+                kfree(entry);
 
                 /*
                  * If the directory has gone away due to an expire
@@ -325,45 +415,82 @@ static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
                  * A zero status is success otherwise we have a
                  * negative error code.
                  */
-                status = try_to_fill_dentry(dentry, flags);
+                status = try_to_fill_dentry(dentry);
+
+                spin_lock(&sbi->fs_lock);
+                ino->flags &= ~AUTOFS_INF_PENDING;
+                spin_unlock(&sbi->fs_lock);
+
                 if (status == 0)
                         return 1;
 
                 return status;
         }
-        spin_unlock(&sbi->fs_lock);
-
-        /* Negative dentry.. invalidate if "old" */
-        if (dentry->d_inode == NULL)
-                return 0;
 
         /* Check for a non-mountpoint directory with no contents */
-        spin_lock(&dcache_lock);
         if (S_ISDIR(dentry->d_inode->i_mode) &&
             !d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
                 DPRINTK("dentry=%p %.*s, emptydir",
                          dentry, dentry->d_name.len, dentry->d_name.name);
-                spin_unlock(&dcache_lock);
 
-                /* The daemon never causes a mount to trigger */
-                if (oz_mode)
-                        return 1;
+                if (autofs4_need_mount(flags) || current->link_count) {
+                        int status;
 
-                /*
-                 * A zero status is success otherwise we have a
-                 * negative error code.
-                 */
-                status = try_to_fill_dentry(dentry, flags);
-                if (status == 0)
-                        return 1;
+                        /*
+                         * We can only unhash and send this to ->lookup() if
+                         * the directory mutex is held over d_revalidate() and
+                         * ->lookup(). This prevents the VFS from incorrectly
+                         * seeing the dentry as non-existent.
+                         */
+                        ino->flags |= AUTOFS_INF_PENDING;
+                        if (!mutex_aquired) {
+                                autofs4_revalidate_drop(dentry, entry);
+                                spin_unlock(&dcache_lock);
+                                spin_unlock(&sbi->fs_lock);
+                                return 0;
+                        }
+                        spin_unlock(&dcache_lock);
+                        spin_unlock(&sbi->fs_lock);
+                        mutex_unlock(&dir->i_mutex);
+                        kfree(entry);
 
-                return status;
+                        /*
+                         * A zero status is success otherwise we have a
+                         * negative error code.
+                         */
+                        status = try_to_fill_dentry(dentry);
+
+                        spin_lock(&sbi->fs_lock);
+                        ino->flags &= ~AUTOFS_INF_PENDING;
+                        spin_unlock(&sbi->fs_lock);
+
+                        if (status == 0)
+                                return 1;
+
+                        return status;
+                }
         }
         spin_unlock(&dcache_lock);
+        spin_unlock(&sbi->fs_lock);
+
+        if (mutex_aquired)
+                mutex_unlock(&dir->i_mutex);
+
+        kfree(entry);
 
         return 1;
 }
 
+static void autofs4_free_rehash_entrys(struct autofs_info *inf)
+{
+        struct list_head *head = &inf->rehash_list;
+        struct rehash_entry *entry, *next;
+        list_for_each_entry_safe(entry, next, head, list) {
+                list_del(&entry->list);
+                kfree(entry);
+        }
+}
+
 void autofs4_dentry_release(struct dentry *de)
 {
         struct autofs_info *inf;
@@ -382,6 +509,8 @@ void autofs4_dentry_release(struct dentry *de)
                                 list_del(&inf->active);
                         if (!list_empty(&inf->expiring))
                                 list_del(&inf->expiring);
+                        if (!list_empty(&inf->rehash_list))
+                                autofs4_free_rehash_entrys(inf);
                         spin_unlock(&sbi->lookup_lock);
                 }
 
@@ -414,6 +543,7 @@ static struct dentry *autofs4_lookup_active(struct dentry *dentry)
         const unsigned char *str = name->name;
         struct list_head *p, *head;
 
+restart:
         spin_lock(&dcache_lock);
         spin_lock(&sbi->lookup_lock);
         head = &sbi->active_list;
@@ -431,6 +561,19 @@ static struct dentry *autofs4_lookup_active(struct dentry *dentry)
                 if (atomic_read(&active->d_count) == 0)
                         goto next;
 
+                if (active->d_inode && IS_DEADDIR(active->d_inode)) {
+                        if (!list_empty(&ino->rehash_list)) {
+                                dget(active);
+                                spin_unlock(&active->d_lock);
+                                spin_unlock(&sbi->lookup_lock);
+                                spin_unlock(&dcache_lock);
+                                autofs4_remove_rehash_entrys(ino);
+                                dput(active);
+                                goto restart;
+                        }
+                        goto next;
+                }
+
                 qstr = &active->d_name;
 
                 if (active->d_name.hash != hash)
@@ -443,13 +586,11 @@ static struct dentry *autofs4_lookup_active(struct dentry *dentry)
                 if (memcmp(qstr->name, str, len))
                         goto next;
 
-                if (d_unhashed(active)) {
-                        dget(active);
-                        spin_unlock(&active->d_lock);
-                        spin_unlock(&sbi->lookup_lock);
-                        spin_unlock(&dcache_lock);
-                        return active;
-                }
+                dget(active);
+                spin_unlock(&active->d_lock);
+                spin_unlock(&sbi->lookup_lock);
+                spin_unlock(&dcache_lock);
+                return active;
 next:
                 spin_unlock(&active->d_lock);
         }
@@ -498,13 +639,11 @@ static struct dentry *autofs4_lookup_expiring(struct dentry *dentry)
                 if (memcmp(qstr->name, str, len))
                         goto next;
 
-                if (d_unhashed(expiring)) {
-                        dget(expiring);
-                        spin_unlock(&expiring->d_lock);
-                        spin_unlock(&sbi->lookup_lock);
-                        spin_unlock(&dcache_lock);
-                        return expiring;
-                }
+                dget(expiring);
+                spin_unlock(&expiring->d_lock);
+                spin_unlock(&sbi->lookup_lock);
+                spin_unlock(&dcache_lock);
+                return expiring;
 next:
                 spin_unlock(&expiring->d_lock);
         }
@@ -514,6 +653,48 @@ next:
         return NULL;
 }
 
+static struct autofs_info *init_new_dentry(struct autofs_sb_info *sbi,
+                                           struct dentry *dentry, int oz_mode)
+{
+        struct autofs_info *ino;
+
+        /*
+         * Mark the dentry incomplete but don't hash it. We do this
+         * to serialize our inode creation operations (symlink and
+         * mkdir) which prevents deadlock during the callback to
+         * the daemon. Subsequent user space lookups for the same
+         * dentry are placed on the wait queue while the daemon
+         * itself is allowed passage unresticted so the create
+         * operation itself can then hash the dentry. Finally,
+         * we check for the hashed dentry and return the newly
+         * hashed dentry.
+         */
+        dentry->d_op = &autofs4_root_dentry_operations;
+
+        /*
+         * And we need to ensure that the same dentry is used for
+         * all following lookup calls until it is hashed so that
+         * the dentry flags are persistent throughout the request.
+         */
+        ino = autofs4_init_ino(NULL, sbi, 0555);
+        if (!ino)
+                return ERR_PTR(-ENOMEM);
+
+        dentry->d_fsdata = ino;
+        ino->dentry = dentry;
+
+        /*
+         * Only set the mount pending flag for new dentrys not created
+         * by the daemon.
+         */
+        if (!oz_mode)
+                ino->flags |= AUTOFS_INF_PENDING;
+
+        d_instantiate(dentry, NULL);
+
+        return ino;
+}
+
 /* Lookups in the root directory */
 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 {
@@ -521,6 +702,7 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
         struct autofs_info *ino;
         struct dentry *expiring, *active;
         int oz_mode;
+        int status = 0;
 
         DPRINTK("name = %.*s",
                 dentry->d_name.len, dentry->d_name.name);
@@ -535,44 +717,26 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
         DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
                  current->pid, task_pgrp_nr(current), sbi->catatonic, oz_mode);
 
+        spin_lock(&sbi->fs_lock);
         active = autofs4_lookup_active(dentry);
         if (active) {
                 dentry = active;
                 ino = autofs4_dentry_ino(dentry);
+                /* If this came from revalidate, rehash it */
+                autofs4_revalidate_rehash(dentry);
+                spin_unlock(&sbi->fs_lock);
         } else {
-                /*
-                 * Mark the dentry incomplete but don't hash it. We do this
-                 * to serialize our inode creation operations (symlink and
-                 * mkdir) which prevents deadlock during the callback to
-                 * the daemon. Subsequent user space lookups for the same
-                 * dentry are placed on the wait queue while the daemon
-                 * itself is allowed passage unresticted so the create
-                 * operation itself can then hash the dentry. Finally,
-                 * we check for the hashed dentry and return the newly
-                 * hashed dentry.
-                 */
-                dentry->d_op = &autofs4_root_dentry_operations;
-
-                /*
-                 * And we need to ensure that the same dentry is used for
-                 * all following lookup calls until it is hashed so that
-                 * the dentry flags are persistent throughout the request.
-                 */
-                ino = autofs4_init_ino(NULL, sbi, 0555);
-                if (!ino)
-                        return ERR_PTR(-ENOMEM);
-
-                dentry->d_fsdata = ino;
-                ino->dentry = dentry;
-
-                autofs4_add_active(dentry);
-
-                d_instantiate(dentry, NULL);
+                spin_unlock(&sbi->fs_lock);
+                ino = init_new_dentry(sbi, dentry, oz_mode);
+                if (IS_ERR(ino))
+                        return (struct dentry *) ino;
         }
 
+        autofs4_add_active(dentry);
+
         if (!oz_mode) {
-                mutex_unlock(&dir->i_mutex);
                 expiring = autofs4_lookup_expiring(dentry);
+                mutex_unlock(&dir->i_mutex);
                 if (expiring) {
                         /*
                          * If we are racing with expire the request might not
@@ -580,23 +744,22 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
                          * so it must have been successful, so just wait for it.
                          */
                         autofs4_expire_wait(expiring);
-                        autofs4_del_expiring(expiring);
                         dput(expiring);
                 }
-
+                status = try_to_fill_dentry(dentry);
+                mutex_lock(&dir->i_mutex);
                 spin_lock(&sbi->fs_lock);
-                ino->flags |= AUTOFS_INF_PENDING;
+                ino->flags &= ~AUTOFS_INF_PENDING;
                 spin_unlock(&sbi->fs_lock);
-                if (dentry->d_op && dentry->d_op->d_revalidate)
-                        (dentry->d_op->d_revalidate)(dentry, nd);
-                mutex_lock(&dir->i_mutex);
         }
 
+        autofs4_del_active(dentry);
+
         /*
-         * If we are still pending, check if we had to handle
+         * If we had a mount fail, check if we had to handle
          * a signal. If so we can force a restart..
          */
-        if (ino->flags & AUTOFS_INF_PENDING) {
+        if (status) {
                 /* See if we were interrupted */
                 if (signal_pending(current)) {
                         sigset_t *sigset = &current->pending.signal;
@@ -608,43 +771,46 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
                             return ERR_PTR(-ERESTARTNOINTR);
                         }
                 }
-                if (!oz_mode) {
-                        spin_lock(&sbi->fs_lock);
-                        ino->flags &= ~AUTOFS_INF_PENDING;
-                        spin_unlock(&sbi->fs_lock);
-                }
         }
 
         /*
-         * If this dentry is unhashed, then we shouldn't honour this
-         * lookup.  Returning ENOENT here doesn't do the right thing
-         * for all system calls, but it should be OK for the operations
-         * we permit from an autofs.
+         * User space can (and has done in the past) remove and re-create
+         * this directory during the callback. This can leave us with an
+         * unhashed dentry, but a successful mount!  So we need to
+         * perform another cached lookup in case the dentry now exists.
          */
-        if (!oz_mode && d_unhashed(dentry)) {
-                /*
-                 * A user space application can (and has done in the past)
-                 * remove and re-create this directory during the callback.
-                 * This can leave us with an unhashed dentry, but a
-                 * successful mount!  So we need to perform another
-                 * cached lookup in case the dentry now exists.
-                 */
-                struct dentry *parent = dentry->d_parent;
-                struct dentry *new = d_lookup(parent, &dentry->d_name);
-                if (new != NULL)
-                        dentry = new;
-                else
-                        dentry = ERR_PTR(-ENOENT);
+        if (!oz_mode && !have_submounts(dentry)) {
+                struct dentry *new;
+                new = d_lookup(dentry->d_parent, &dentry->d_name);
+                if (new) {
+                        if (active)
+                                dput(active);
+                        return new;
+                } else {
+                        if (!status)
+                                status = -ENOENT;
+                }
+        }
 
+        /*
+         * If we had a mount failure, return status to user space.
+         * If the mount succeeded and we used a dentry from the active queue
+         * return it.
+         */
+        if (status) {
+                dentry = ERR_PTR(status);
                 if (active)
                         dput(active);
-
                 return dentry;
+        } else {
+                /*
+                 * Valid successful mount, return active dentry or NULL
+                 * for a new dentry.
+                 */
+                if (active)
+                        return active;
         }
 
-        if (active)
-                return active;
-
         return NULL;
 }
 
@@ -668,8 +834,6 @@ static int autofs4_dir_symlink(struct inode *dir,
         if (!ino)
                 return -ENOMEM;
 
-        autofs4_del_active(dentry);
-
         ino->size = strlen(symname);
         cp = kmalloc(ino->size + 1, GFP_KERNEL);
         if (!cp) {
@@ -746,7 +910,6 @@ static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
         dir->i_mtime = CURRENT_TIME;
 
         spin_lock(&dcache_lock);
-        autofs4_add_expiring(dentry);
         spin_lock(&dentry->d_lock);
         __d_drop(dentry);
         spin_unlock(&dentry->d_lock);
@@ -772,7 +935,6 @@ static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
                 spin_unlock(&dcache_lock);
                 return -ENOTEMPTY;
         }
-        autofs4_add_expiring(dentry);
         spin_lock(&dentry->d_lock);
         __d_drop(dentry);
         spin_unlock(&dentry->d_lock);
@@ -810,8 +972,6 @@ static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
         if (!ino)
                 return -ENOMEM;
 
-        autofs4_del_active(dentry);
-
         inode = autofs4_get_inode(dir->i_sb, ino);
         if (!inode) {
                 if (!dentry->d_fsdata)