share some code between get_sb_bdev and xfs log/rtdev handling

fs/block_dev.c

@@ -22,6 +22,7 @@
 #include <linux/mpage.h>
 #include <linux/mount.h>
 #include <linux/uio.h>
+#include <linux/namei.h>
 #include <asm/uaccess.h>
 
 
@@ -796,3 +797,82 @@ const char *__bdevname(dev_t dev)
 	sprintf(buffer, "%s(%d,%d)", name, MAJOR(dev), MINOR(dev));
 	return buffer;
 }
+
+/**
+ * open_bdev_excl  -  open a block device by name and set it up for use
+ *
+ * @path:	special file representing the block device
+ * @flags:	%MS_RDONLY for opening read-only
+ * @kind:	usage (same as the 4th paramter to blkdev_get)
+ * @holder:	owner for exclusion
+ *
+ * Open the blockdevice described by the special file at @path, claim it
+ * for the @holder and properly set it up for @kind usage.
+ */
+struct block_device *open_bdev_excl(const char *path, int flags,
+				    int kind, void *holder)
+{
+	struct inode *inode;
+	struct block_device *bdev;
+	struct nameidata nd;
+	mode_t mode = FMODE_READ;
+	int error = 0;
+
+	if (!path || !*path)
+		return ERR_PTR(-EINVAL);
+
+	error = path_lookup(path, LOOKUP_FOLLOW, &nd);
+	if (error)
+		return ERR_PTR(error);
+
+	inode = nd.dentry->d_inode;
+	error = -ENOTBLK;
+	if (!S_ISBLK(inode->i_mode))
+		goto path_release;
+	error = -EACCES;
+	if (nd.mnt->mnt_flags & MNT_NODEV)
+		goto path_release;
+	error = bd_acquire(inode);
+	if (error)
+		goto path_release;
+	bdev = inode->i_bdev;
+
+	/* Done with lookups */
+	path_release(&nd);
+
+	if (!(flags & MS_RDONLY))
+		mode |= FMODE_WRITE;
+	error = blkdev_get(bdev, mode, 0, kind);
+	if (error)
+		return ERR_PTR(error);
+	error = -EACCES;
+	if (!(flags & MS_RDONLY) && bdev_read_only(bdev))
+		goto blkdev_put;
+	error = bd_claim(bdev, holder);
+	if (error)
+		goto blkdev_put;
+
+	return bdev;
+	
+blkdev_put:
+	blkdev_put(bdev, BDEV_FS);
+	return ERR_PTR(error);
+
+path_release:
+	path_release(&nd);
+	return ERR_PTR(error);
+}
+
+/**
+ * close_bdev_excl  -  release a blockdevice openen by open_bdev_excl()
+ *
+ * @bdev:	blockdevice to close
+ * @kind:	usage (same as the 4th paramter to blkdev_get)
+ *
+ * This is the counterpart to open_bdev_excl().
+ */
+void close_bdev_excl(struct block_device *bdev, int kind)
+{
+	bd_release(bdev);
+	blkdev_put(bdev, kind);
+}

fs/super.c

@@ -463,55 +463,25 @@ struct super_block *get_sb_bdev(struct file_system_type *fs_type,
 	int flags, char *dev_name, void * data,
 	int (*fill_super)(struct super_block *, void *, int))
 {
-	struct inode *inode;
 	struct block_device *bdev;
-	struct super_block * s;
-	struct nameidata nd;
+	struct super_block *s;
 	int error = 0;
-	mode_t mode = FMODE_READ; /* we always need it ;-) */
 
-	/* What device it is? */
-	if (!dev_name || !*dev_name)
-		return ERR_PTR(-EINVAL);
-	error = path_lookup(dev_name, LOOKUP_FOLLOW, &nd);
-	if (error)
-		return ERR_PTR(error);
-	inode = nd.dentry->d_inode;
-	error = -ENOTBLK;
-	if (!S_ISBLK(inode->i_mode))
-		goto out;
-	error = -EACCES;
-	if (nd.mnt->mnt_flags & MNT_NODEV)
-		goto out;
-	error = bd_acquire(inode);
-	if (error)
-		goto out;
-	bdev = inode->i_bdev;
-	/* Done with lookups, semaphore down */
-	if (!(flags & MS_RDONLY))
-		mode |= FMODE_WRITE;
-	error = blkdev_get(bdev, mode, 0, BDEV_FS);
-	if (error)
-		goto out;
-	error = -EACCES;
-	if (!(flags & MS_RDONLY) && bdev_read_only(bdev))
-		goto out1;
-	error = bd_claim(bdev, fs_type);
-	if (error)
-		goto out1;
+	bdev = open_bdev_excl(dev_name, flags, BDEV_FS, fs_type);
+	if (IS_ERR(bdev))
+		return (struct super_block *)bdev;
 
 	s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
-	if (IS_ERR(s)) {
-		bd_release(bdev);
-		blkdev_put(bdev, BDEV_FS);
-	} else if (s->s_root) {
+	if (IS_ERR(s))
+		goto out;
+
+	if (s->s_root) {
 		if ((flags ^ s->s_flags) & MS_RDONLY) {
 			up_write(&s->s_umount);
 			deactivate_super(s);
 			s = ERR_PTR(-EBUSY);
 		}
-		bd_release(bdev);
-		blkdev_put(bdev, BDEV_FS);
+		goto out;
 	} else {
 		s->s_flags = flags;
 		strncpy(s->s_id, bdevname(bdev), sizeof(s->s_id));
@@ -525,14 +495,12 @@ struct super_block *get_sb_bdev(struct file_system_type *fs_type,
 		} else
 			s->s_flags |= MS_ACTIVE;
 	}
-	path_release(&nd);
+
 	return s;
 
-out1:
-	blkdev_put(bdev, BDEV_FS);
 out:
-	path_release(&nd);
-	return ERR_PTR(error);
+	close_bdev_excl(bdev, BDEV_FS);
+	return s;
 }
 
 void kill_block_super(struct super_block *sb)
@@ -540,8 +508,7 @@ void kill_block_super(struct super_block *sb)
 	struct block_device *bdev = sb->s_bdev;
 	generic_shutdown_super(sb);
 	set_blocksize(bdev, sb->s_old_blocksize);
-	bd_release(bdev);
-	blkdev_put(bdev, BDEV_FS);
+	close_bdev_excl(bdev, BDEV_FS);
 }
 
 struct super_block *get_sb_nodev(struct file_system_type *fs_type,

fs/xfs/linux/xfs_super.c

@@ -466,31 +466,20 @@ xfs_initialize_vnode(
 	}
 }
 
-/*ARGSUSED*/
 int
 xfs_blkdev_get(
 	xfs_mount_t		*mp,
 	const char		*name,
 	struct block_device	**bdevp)
 {
-	struct nameidata	nd;
-	int			error;
+	int			error = 0;
 
-	error = path_lookup(name, LOOKUP_FOLLOW, &nd);
-	if (error) {
+	*bdevp = open_bdev_excl(name, 0, BDEV_FS, mp);
+	if (IS_ERR(*bdevp)) {
+		error = PTR_ERR(*bdevp);
 		printk("XFS: Invalid device [%s], error=%d\n", name, error);
-		return -error;
-	}
-
-	/* I think we actually want bd_acquire here..  --hch */
-	*bdevp = bdget(kdev_t_to_nr(nd.dentry->d_inode->i_rdev));
-	if (*bdevp) {
-		error = blkdev_get(*bdevp, FMODE_READ|FMODE_WRITE, 0, BDEV_FS);
-	} else {
-		error = -ENOMEM;
 	}
 
-	path_release(&nd);
 	return -error;
 }
 
@@ -499,7 +488,7 @@ xfs_blkdev_put(
 	struct block_device	*bdev)
 {
 	if (bdev)
-		blkdev_put(bdev, BDEV_FS);
+		close_bdev_excl(bdev, BDEV_FS);
 }
 
 void

include/linux/fs.h

@@ -1096,15 +1096,20 @@ extern int bd_claim(struct block_device *, void *);
 extern void bd_release(struct block_device *);
 extern void blk_run_queues(void);
 
-/* fs/devices.c */
+/* fs/char_dev.c */
 extern int register_chrdev(unsigned int, const char *, struct file_operations *);
 extern int unregister_chrdev(unsigned int, const char *);
 extern int chrdev_open(struct inode *, struct file *);
+
+/* fs/block_dev.c */
 extern const char *__bdevname(dev_t);
 extern inline const char *bdevname(struct block_device *bdev)
 {
 	return __bdevname(bdev->bd_dev);
 }
+extern struct block_device *open_bdev_excl(const char *, int, int, void *);
+extern void close_bdev_excl(struct block_device *, int);
+
 extern const char * cdevname(kdev_t);
 extern const char * kdevname(kdev_t);
 extern void init_special_inode(struct inode *, umode_t, dev_t);

kernel/ksyms.c

@@ -203,6 +203,8 @@ EXPORT_SYMBOL(bdget);
 EXPORT_SYMBOL(bdput);
 EXPORT_SYMBOL(bd_claim);
 EXPORT_SYMBOL(bd_release);
+EXPORT_SYMBOL(open_bdev_excl);
+EXPORT_SYMBOL(close_bdev_excl);
 EXPORT_SYMBOL(__brelse);
 EXPORT_SYMBOL(__bforget);
 EXPORT_SYMBOL(ll_rw_block);