autofs4: reorganize expire pending wait function calls
Ian Kent [Thu, 24 Jul 2008 04:30:28 +0000 (21:30 -0700)]
This patch re-orgnirzes the checking for and waiting on active expires and
elininates redundant checks.

Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Jeff Moyer <jmoyer@redhat.com>
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/root.c

index 4b40cbc..69a2f5c 100644 (file)
@@ -163,6 +163,7 @@ void autofs4_free_ino(struct autofs_info *);
 
 /* Expiration */
 int is_autofs4_dentry(struct dentry *);
+int autofs4_expire_wait(struct dentry *dentry);
 int autofs4_expire_run(struct super_block *, struct vfsmount *,
                        struct autofs_sb_info *,
                        struct autofs_packet_expire __user *);
index 705b9f0..cdabb79 100644 (file)
@@ -402,6 +402,35 @@ found:
        return expired;
 }
 
+int autofs4_expire_wait(struct dentry *dentry)
+{
+       struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
+       struct autofs_info *ino = autofs4_dentry_ino(dentry);
+       int status;
+
+       /* Block on any pending expire */
+       spin_lock(&sbi->fs_lock);
+       if (ino->flags & AUTOFS_INF_EXPIRING) {
+               spin_unlock(&sbi->fs_lock);
+
+               DPRINTK("waiting for expire %p name=%.*s",
+                        dentry, dentry->d_name.len, dentry->d_name.name);
+
+               status = autofs4_wait(sbi, dentry, NFY_NONE);
+               wait_for_completion(&ino->expire_complete);
+
+               DPRINTK("expire done status=%d", status);
+
+               if (d_unhashed(dentry))
+                       return -EAGAIN;
+
+               return status;
+       }
+       spin_unlock(&sbi->fs_lock);
+
+       return 0;
+}
+
 /* Perform an expiry operation */
 int autofs4_expire_run(struct super_block *sb,
                      struct vfsmount *mnt,
index e062ee5..ae22bde 100644 (file)
@@ -130,34 +130,6 @@ static int try_to_fill_dentry(struct dentry *dentry, int flags)
        struct autofs_info *ino = autofs4_dentry_ino(dentry);
        int status;
 
-       /* Block on any pending expiry here; invalidate the dentry
-           when expiration is done to trigger mount request with a new
-           dentry */
-       spin_lock(&sbi->fs_lock);
-       if (ino->flags & AUTOFS_INF_EXPIRING) {
-               spin_unlock(&sbi->fs_lock);
-
-               DPRINTK("waiting for expire %p name=%.*s",
-                        dentry, dentry->d_name.len, dentry->d_name.name);
-
-               status = autofs4_wait(sbi, dentry, NFY_NONE);
-               wait_for_completion(&ino->expire_complete);
-
-               DPRINTK("expire done status=%d", status);
-
-               /*
-                * If the directory still exists the mount request must
-                * continue otherwise it can't be followed at the right
-                * time during the walk.
-                */
-               status = d_invalidate(dentry);
-               if (status != -EBUSY)
-                       return -EAGAIN;
-
-               goto cont;
-       }
-       spin_unlock(&sbi->fs_lock);
-cont:
        DPRINTK("dentry=%p %.*s ino=%p",
                 dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
 
@@ -248,22 +220,8 @@ static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
        }
 
        /* If an expire request is pending everyone must wait. */
-       spin_lock(&sbi->fs_lock);
-       if (ino->flags & AUTOFS_INF_EXPIRING) {
-               spin_unlock(&sbi->fs_lock);
-
-               DPRINTK("waiting for active request %p name=%.*s",
-                       dentry, dentry->d_name.len, dentry->d_name.name);
-
-               status = autofs4_wait(sbi, dentry, NFY_NONE);
-               wait_for_completion(&ino->expire_complete);
+       autofs4_expire_wait(dentry);
 
-               DPRINTK("request done status=%d", status);
-
-               goto cont;
-       }
-       spin_unlock(&sbi->fs_lock);
-cont:
        /* We trigger a mount for almost all flags */
        lookup_type = nd->flags & (TRIGGER_FLAGS | TRIGGER_INTENTS);
        if (!(lookup_type || dentry->d_flags & DCACHE_AUTOFS_PENDING))
@@ -332,6 +290,14 @@ static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
                        return 1;
 
                /*
+                * If the directory has gone away due to an expire
+                * we have been called as ->d_revalidate() and so
+                * we need to return false and proceed to ->lookup().
+                */
+               if (autofs4_expire_wait(dentry) == -EAGAIN)
+                       return 0;
+
+               /*
                 * A zero status is success otherwise we have a
                 * negative error code.
                 */
@@ -339,15 +305,6 @@ static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
                if (status == 0)
                        return 1;
 
-               /*
-                * A status of EAGAIN here means that the dentry has gone
-                * away while waiting for an expire to complete. If we are
-                * racing with expire lookup will wait for it so this must
-                * be a revalidate and we need to send it to lookup.
-                */
-               if (status == -EAGAIN)
-                       return 0;
-
                return status;
        }
        spin_unlock(&sbi->fs_lock);
@@ -557,19 +514,7 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
                 * so it must have been successful, so just wait for it.
                 */
                ino = autofs4_dentry_ino(expiring);
-               spin_lock(&sbi->fs_lock);
-               if (ino->flags & AUTOFS_INF_EXPIRING) {
-                       spin_unlock(&sbi->fs_lock);
-                       DPRINTK("wait for incomplete expire %p name=%.*s",
-                               expiring, expiring->d_name.len,
-                               expiring->d_name.name);
-                       autofs4_wait(sbi, expiring, NFY_NONE);
-                       wait_for_completion(&ino->expire_complete);
-                       DPRINTK("request completed");
-                       goto cont;
-               }
-               spin_unlock(&sbi->fs_lock);
-cont:
+               autofs4_expire_wait(expiring);
                spin_lock(&sbi->lookup_lock);
                if (!list_empty(&ino->expiring))
                        list_del_init(&ino->expiring);