[PATCH] (1/3) fs/super.c cleanups

* missing yield() added to grab_super() (on failure exit).  Without
  that we have a nasty race - if get_sb_bdev() happens just before
  we grab ->s_umount in kill_super(), we are going to have
  get_sb_bdev() spinning indefinitely long without yielding CPU,
  so that kill_super() could make progress (and break the loop).

* in kill_super() code that does actual superblock shutdown is
  wrapped in if (sb->s_root) {}.  That condition is true for
  all old callers of kill_super(), so we don't change existing
  behaviour.

* instances of deactivate_super()/remove_super() (after failed
  call of foo_fill_super()) are replaced with
	up_write(&s->s_umount);
	kill_super(s);
  - now it becomes legitimate (kill_super() works on such guys and
  does exactly what we want).

diff --git a/fs/super.c b/fs/super.c
index 2b4162e4b2834cd37330f476be7a19b4b5f5878b..5295c6a5d3363141c98779ba8e13cb15b1836bcc 100644 (file)
--- a/fs/super.c
+++ b/fs/super.c
@@ -355,6 +355,7 @@ static int grab_super(struct super_block *s)
        }
        up_write(&s->s_umount);
        put_super(s);
+       yield();
        return 0;
 }
  
@@ -724,8 +725,8 @@ restart:
        return s;
 
 failed:
-       deactivate_super(s);
-       remove_super(s);
+       up_write(&s->s_umount);
+       kill_super(s);
        goto out;
 out1:
        blkdev_put(bdev, BDEV_FS);
@@ -748,8 +749,8 @@ struct super_block *get_sb_nodev(struct file_system_type *fs_type,
 
        error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
        if (error) {
-               deactivate_super(s);
-               remove_super(s);
+               up_write(&s->s_umount);
+               kill_super(s);
                return ERR_PTR(error);
        }
        s->s_flags |= MS_ACTIVE;
@@ -774,8 +775,8 @@ struct super_block *get_sb_single(struct file_system_type *fs_type,
                s->s_flags = flags;
                error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
                if (error) {
-                       deactivate_super(s);
-                       remove_super(s);
+                       up_write(&s->s_umount);
+                       kill_super(s);
                        return ERR_PTR(error);
                }
                s->s_flags |= MS_ACTIVE;
@@ -826,32 +827,35 @@ void kill_super(struct super_block *sb)
                return;
 
        down_write(&sb->s_umount);
-       sb->s_root = NULL;
-       /* Need to clean after the sucker */
-       if (fs->fs_flags & FS_LITTER)
-               d_genocide(root);
-       shrink_dcache_parent(root);
-       dput(root);
-       fsync_super(sb);
-       lock_super(sb);
-       lock_kernel();
-       sb->s_flags &= ~MS_ACTIVE;
-       invalidate_inodes(sb);  /* bad name - it should be evict_inodes() */
-       if (sop) {
-               if (sop->write_super && sb->s_dirt)
-                       sop->write_super(sb);
-               if (sop->put_super)
-                       sop->put_super(sb);
-       }
+       if (sb->s_root) {
+               sb->s_root = NULL;
+               /* Need to clean after the sucker */
+               if (fs->fs_flags & FS_LITTER)
+                       d_genocide(root);
+               shrink_dcache_parent(root);
+               dput(root);
+               fsync_super(sb);
+               lock_super(sb);
+               lock_kernel();
+               sb->s_flags &= ~MS_ACTIVE;
+               /* bad name - it should be evict_inodes() */
+               invalidate_inodes(sb);
+               if (sop) {
+                       if (sop->write_super && sb->s_dirt)
+                               sop->write_super(sb);
+                       if (sop->put_super)
+                               sop->put_super(sb);
+               }
 
-       /* Forget any remaining inodes */
-       if (invalidate_inodes(sb)) {
-               printk("VFS: Busy inodes after unmount. "
-                       "Self-destruct in 5 seconds.  Have a nice day...\n");
-       }
+               /* Forget any remaining inodes */
+               if (invalidate_inodes(sb)) {
+                       printk("VFS: Busy inodes after unmount. "
+                          "Self-destruct in 5 seconds.  Have a nice day...\n");
+               }
 
-       unlock_kernel();
-       unlock_super(sb);
+               unlock_kernel();
+               unlock_super(sb);
+       }
        remove_super(sb);
 }