1 files changed, 72 insertions, 8 deletions

diff --git a/fs/super.c b/fs/super.c
index 2761d3e22ed9..19eb70b374bc 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -54,7 +54,7 @@ DEFINE_SPINLOCK(sb_lock);
 static struct super_block *alloc_super(struct file_system_type *type)
 {
         struct super_block *s = kzalloc(sizeof(struct super_block),  GFP_USER);
-        static struct super_operations default_op;
+        static const struct super_operations default_op;
 
         if (s) {
                 if (security_sb_alloc(s)) {
@@ -62,9 +62,6 @@ static struct super_block *alloc_super(struct file_system_type *type)
                         s = NULL;
                         goto out;
                 }
-                INIT_LIST_HEAD(&s->s_dirty);
-                INIT_LIST_HEAD(&s->s_io);
-                INIT_LIST_HEAD(&s->s_more_io);
                 INIT_LIST_HEAD(&s->s_files);
                 INIT_LIST_HEAD(&s->s_instances);
                 INIT_HLIST_HEAD(&s->s_anon);
@@ -171,7 +168,7 @@ int __put_super_and_need_restart(struct super_block *sb)
  *      Drops a temporary reference, frees superblock if there's no
  *      references left.
  */
-static void put_super(struct super_block *sb)
+void put_super(struct super_block *sb)
 {
         spin_lock(&sb_lock);
         __put_super(sb);
@@ -468,6 +465,48 @@ rescan:
 }
 
 EXPORT_SYMBOL(get_super);
+
+/**
+ * get_active_super - get an active reference to the superblock of a device
+ * @bdev: device to get the superblock for
+ *
+ * Scans the superblock list and finds the superblock of the file system
+ * mounted on the device given.  Returns the superblock with an active
+ * reference and s_umount held exclusively or %NULL if none was found.
+ */
+struct super_block *get_active_super(struct block_device *bdev)
+{
+        struct super_block *sb;
+
+        if (!bdev)
+                return NULL;
+
+        spin_lock(&sb_lock);
+        list_for_each_entry(sb, &super_blocks, s_list) {
+                if (sb->s_bdev != bdev)
+                        continue;
+
+                sb->s_count++;
+                spin_unlock(&sb_lock);
+                down_write(&sb->s_umount);
+                if (sb->s_root) {
+                        spin_lock(&sb_lock);
+                        if (sb->s_count > S_BIAS) {
+                                atomic_inc(&sb->s_active);
+                                sb->s_count--;
+                                spin_unlock(&sb_lock);
+                                return sb;
+                        }
+                        spin_unlock(&sb_lock);
+                }
+                up_write(&sb->s_umount);
+                put_super(sb);
+                yield();
+                spin_lock(&sb_lock);
+        }
+        spin_unlock(&sb_lock);
+        return NULL;
+}
  
 struct super_block * user_get_super(dev_t dev)
 {
@@ -530,11 +569,15 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
 {
         int retval;
         int remount_rw;
-        
+
+        if (sb->s_frozen != SB_UNFROZEN)
+                return -EBUSY;
+
 #ifdef CONFIG_BLOCK
         if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
                 return -EACCES;
 #endif
+
         if (flags & MS_RDONLY)
                 acct_auto_close(sb);
         shrink_dcache_sb(sb);
@@ -710,6 +753,12 @@ static int set_bdev_super(struct super_block *s, void *data)
 {
         s->s_bdev = data;
         s->s_dev = s->s_bdev->bd_dev;
+
+        /*
+         * We set the bdi here to the queue backing, file systems can
+         * overwrite this in ->fill_super()
+         */
+        s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info;
         return 0;
 }
 
@@ -740,9 +789,14 @@ int get_sb_bdev(struct file_system_type *fs_type,
          * will protect the lockfs code from trying to start a snapshot
          * while we are mounting
          */
-        down(&bdev->bd_mount_sem);
+        mutex_lock(&bdev->bd_fsfreeze_mutex);
+        if (bdev->bd_fsfreeze_count > 0) {
+                mutex_unlock(&bdev->bd_fsfreeze_mutex);
+                error = -EBUSY;
+                goto error_bdev;
+        }
         s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
-        up(&bdev->bd_mount_sem);
+        mutex_unlock(&bdev->bd_fsfreeze_mutex);
         if (IS_ERR(s))
                 goto error_s;
 
@@ -889,6 +943,16 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void
         if (error)
                 goto out_sb;
 
+        /*
+         * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
+         * but s_maxbytes was an unsigned long long for many releases. Throw
+         * this warning for a little while to try and catch filesystems that
+         * violate this rule. This warning should be either removed or
+         * converted to a BUG() in 2.6.34.
+         */
+        WARN((mnt->mnt_sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
+                "negative value (%lld)\n", type->name, mnt->mnt_sb->s_maxbytes);
+
         mnt->mnt_mountpoint = mnt->mnt_root;
         mnt->mnt_parent = mnt;
         up_write(&mnt->mnt_sb->s_umount);