autofs4: always use lookup for lookup
authorIan Kent <raven@themaw.net>
Wed, 16 Dec 2009 00:45:51 +0000 (16:45 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 16 Dec 2009 15:19:58 +0000 (07:19 -0800)
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>
fs/autofs4/autofs_i.h
fs/autofs4/expire.c
fs/autofs4/inode.c
fs/autofs4/root.c

index 3d283abf67d7bb0aae5affddee58fdf504706df1..0118d67221b218672c622fdd1927289c1d9459ed 100644 (file)
@@ -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;
index a796c9417fb16f5b4b27ce56586753d3c5b7e948..74bc9aa6df310d4ccdf0d312dd43976c02f93d1e 100644 (file)
@@ -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);
index 4670a7818eac1c5feb953a1dbc0d019cce6087a5..d0a3de247458aae03f045bf6788b64e5045ad950 100644 (file)
@@ -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);
index a015b49891df6347f70f6c318666b63a74638dc8..30cc9ddf4b708454c772ca95fc848c5c83ca92df 100644 (file)
@@ -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)