X-Git-Url: http://ftp.safe.ca/?p=safe%2Fjmp%2Flinux-2.6;a=blobdiff_plain;f=fs%2Fsuper.c;h=19eb70b374bcb3239cd7a75ee901336f942b02e4;hp=54fd331f0cabef972746b0adba7a7f758b06ddbc;hb=1557aca7904ed6fadd22cdc3364754070bb3d3c3;hpb=a9e220f8322e2b0e0b8903fe00265461cffad3f0

diff --git a/fs/super.c b/fs/super.c
index 54fd331..19eb70b 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);
@@ -309,7 +306,6 @@ void generic_shutdown_super(struct super_block *sb)
 
 		/* bad name - it should be evict_inodes() */
 		invalidate_inodes(sb);
-		lock_kernel();
 
 		if (sop->put_super)
 			sop->put_super(sb);
@@ -320,8 +316,6 @@ void generic_shutdown_super(struct super_block *sb)
 			   "Self-destruct in 5 seconds.  Have a nice day...\n",
 			   sb->s_id);
 		}
-
-		unlock_kernel();
 		put_fs_excl();
 	}
 	spin_lock(&sb_lock);
@@ -423,10 +417,8 @@ restart:
 			spin_unlock(&sb_lock);
 
 			down_read(&sb->s_umount);
-			lock_super(sb);
 			if (sb->s_root && sb->s_dirt)
 				sb->s_op->write_super(sb);
-			unlock_super(sb);
 			up_read(&sb->s_umount);
 
 			spin_lock(&sb_lock);
@@ -473,6 +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)
 {
@@ -535,11 +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);
@@ -559,9 +597,7 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
 	remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY);
 
 	if (sb->s_op->remount_fs) {
-		lock_super(sb);
 		retval = sb->s_op->remount_fs(sb, &flags, data);
-		unlock_super(sb);
 		if (retval)
 			return retval;
 	}
@@ -586,9 +622,7 @@ static void do_emergency_remount(struct work_struct *work)
 			 *
 			 * What lock protects sb->s_flags??
 			 */
-			lock_kernel();
 			do_remount_sb(sb, MS_RDONLY, NULL, 1);
-			unlock_kernel();
 		}
 		up_write(&sb->s_umount);
 		put_super(sb);
@@ -617,6 +651,7 @@ void emergency_remount(void)
 
 static DEFINE_IDA(unnamed_dev_ida);
 static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
+static int unnamed_dev_start = 0; /* don't bother trying below it */
 
 int set_anon_super(struct super_block *s, void *data)
 {
@@ -627,7 +662,9 @@ int set_anon_super(struct super_block *s, void *data)
 	if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)
 		return -ENOMEM;
 	spin_lock(&unnamed_dev_lock);
-	error = ida_get_new(&unnamed_dev_ida, &dev);
+	error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);
+	if (!error)
+		unnamed_dev_start = dev + 1;
 	spin_unlock(&unnamed_dev_lock);
 	if (error == -EAGAIN)
 		/* We raced and lost with another CPU. */
@@ -638,6 +675,8 @@ int set_anon_super(struct super_block *s, void *data)
 	if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
 		spin_lock(&unnamed_dev_lock);
 		ida_remove(&unnamed_dev_ida, dev);
+		if (unnamed_dev_start > dev)
+			unnamed_dev_start = dev;
 		spin_unlock(&unnamed_dev_lock);
 		return -EMFILE;
 	}
@@ -654,6 +693,8 @@ void kill_anon_super(struct super_block *sb)
 	generic_shutdown_super(sb);
 	spin_lock(&unnamed_dev_lock);
 	ida_remove(&unnamed_dev_ida, slot);
+	if (slot < unnamed_dev_start)
+		unnamed_dev_start = slot;
 	spin_unlock(&unnamed_dev_lock);
 }
 
@@ -712,6 +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;
 }
 
@@ -742,9 +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;
 
@@ -891,6 +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);