bdev: rename freeze and thaw helpers

We have bdev_mark_dead() etc and we're going to move block device
freezing to holder ops in the next patch. Make the naming consistent:

* freeze_bdev() -> bdev_freeze()
* thaw_bdev()   -> bdev_thaw()

Also document the return code.

Link: https://lore.kernel.org/r/20231024-vfs-super-freeze-v2-2-599c19f4faac@kernel.org
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

block/bdev.c

@@ -207,18 +207,20 @@ int sync_blockdev_range(struct block_device *bdev, loff_t lstart, loff_t lend)
 EXPORT_SYMBOL(sync_blockdev_range);
 
 /**
- * freeze_bdev - lock a filesystem and force it into a consistent state
+ * bdev_freeze - lock a filesystem and force it into a consistent state
  * @bdev:	blockdevice to lock
  *
  * If a superblock is found on this device, we take the s_umount semaphore
  * on it to make sure nobody unmounts until the snapshot creation is done.
  * The reference counter (bd_fsfreeze_count) guarantees that only the last
  * unfreeze process can unfreeze the frozen filesystem actually when multiple
- * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
- * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
+ * freeze requests arrive simultaneously. It counts up in bdev_freeze() and
+ * count down in bdev_thaw(). When it becomes 0, thaw_bdev() will unfreeze
  * actually.
+ *
+ * Return: On success zero is returned, negative error code on failure.
  */
-int freeze_bdev(struct block_device *bdev)
+int bdev_freeze(struct block_device *bdev)
 {
 	struct super_block *sb;
 	int error = 0;
@@ -248,15 +250,17 @@ done:
 	mutex_unlock(&bdev->bd_fsfreeze_mutex);
 	return error;
 }
-EXPORT_SYMBOL(freeze_bdev);
+EXPORT_SYMBOL(bdev_freeze);
 
 /**
- * thaw_bdev - unlock filesystem
+ * bdev_thaw - unlock filesystem
  * @bdev:	blockdevice to unlock
  *
- * Unlocks the filesystem and marks it writeable again after freeze_bdev().
+ * Unlocks the filesystem and marks it writeable again after bdev_freeze().
+ *
+ * Return: On success zero is returned, negative error code on failure.
  */
-int thaw_bdev(struct block_device *bdev)
+int bdev_thaw(struct block_device *bdev)
 {
 	struct super_block *sb;
 	int error = -EINVAL;
@@ -285,7 +289,7 @@ out:
 	mutex_unlock(&bdev->bd_fsfreeze_mutex);
 	return error;
 }
-EXPORT_SYMBOL(thaw_bdev);
+EXPORT_SYMBOL(bdev_thaw);
 
 /*
  * pseudo-fs

drivers/md/dm.c

@@ -2675,7 +2675,7 @@ static int lock_fs(struct mapped_device *md)
 
 	WARN_ON(test_bit(DMF_FROZEN, &md->flags));
 
-	r = freeze_bdev(md->disk->part0);
+	r = bdev_freeze(md->disk->part0);
 	if (!r)
 		set_bit(DMF_FROZEN, &md->flags);
 	return r;
@@ -2685,7 +2685,7 @@ static void unlock_fs(struct mapped_device *md)
 {
 	if (!test_bit(DMF_FROZEN, &md->flags))
 		return;
-	thaw_bdev(md->disk->part0);
+	bdev_thaw(md->disk->part0);
 	clear_bit(DMF_FROZEN, &md->flags);
 }
 

fs/bcachefs/fs-ioctl.c

@@ -291,14 +291,14 @@ static int bch2_ioc_goingdown(struct bch_fs *c, u32 __user *arg)
 
 	switch (flags) {
 	case FSOP_GOING_FLAGS_DEFAULT:
-		ret = freeze_bdev(c->vfs_sb->s_bdev);
+		ret = bdev_freeze(c->vfs_sb->s_bdev);
 		if (ret)
 			goto err;
 
 		bch2_journal_flush(&c->journal);
 		c->vfs_sb->s_flags |= SB_RDONLY;
 		bch2_fs_emergency_read_only(c);
-		thaw_bdev(c->vfs_sb->s_bdev);
+		bdev_thaw(c->vfs_sb->s_bdev);
 		break;
 
 	case FSOP_GOING_FLAGS_LOGFLUSH:

fs/ext4/ioctl.c

@@ -819,11 +819,11 @@ int ext4_force_shutdown(struct super_block *sb, u32 flags)
 
 	switch (flags) {
 	case EXT4_GOING_FLAGS_DEFAULT:
-		ret = freeze_bdev(sb->s_bdev);
+		ret = bdev_freeze(sb->s_bdev);
 		if (ret)
 			return ret;
 		set_bit(EXT4_FLAGS_SHUTDOWN, &sbi->s_ext4_flags);
-		thaw_bdev(sb->s_bdev);
+		bdev_thaw(sb->s_bdev);
 		break;
 	case EXT4_GOING_FLAGS_LOGFLUSH:
 		set_bit(EXT4_FLAGS_SHUTDOWN, &sbi->s_ext4_flags);

fs/f2fs/file.c

@@ -2239,11 +2239,11 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
 
 	switch (in) {
 	case F2FS_GOING_DOWN_FULLSYNC:
-		ret = freeze_bdev(sb->s_bdev);
+		ret = bdev_freeze(sb->s_bdev);
 		if (ret)
 			goto out;
 		f2fs_stop_checkpoint(sbi, false, STOP_CP_REASON_SHUTDOWN);
-		thaw_bdev(sb->s_bdev);
+		bdev_thaw(sb->s_bdev);
 		break;
 	case F2FS_GOING_DOWN_METASYNC:
 		/* do checkpoint only */

fs/super.c

@@ -1224,7 +1224,7 @@ static void do_thaw_all_callback(struct super_block *sb)
 
 	if (locked && sb->s_root) {
 		if (IS_ENABLED(CONFIG_BLOCK))
-			while (sb->s_bdev && !thaw_bdev(sb->s_bdev))
+			while (sb->s_bdev && !bdev_thaw(sb->s_bdev))
 				pr_warn("Emergency Thaw on %pg\n", sb->s_bdev);
 		thaw_super_locked(sb, FREEZE_HOLDER_USERSPACE);
 		return;
@@ -1532,7 +1532,7 @@ int setup_bdev_super(struct super_block *sb, int sb_flags,
 	/*
 	 * Until SB_BORN flag is set, there can be no active superblock
 	 * references and thus no filesystem freezing. get_active_super() will
-	 * just loop waiting for SB_BORN so even freeze_bdev() cannot proceed.
+	 * just loop waiting for SB_BORN so even bdev_freeze() cannot proceed.
 	 *
 	 * It is enough to check bdev was not frozen before we set s_bdev.
 	 */

fs/xfs/xfs_fsops.c

@@ -482,9 +482,9 @@ xfs_fs_goingdown(
 {
 	switch (inflags) {
 	case XFS_FSOP_GOING_FLAGS_DEFAULT: {
-		if (!freeze_bdev(mp->m_super->s_bdev)) {
+		if (!bdev_freeze(mp->m_super->s_bdev)) {
 			xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
-			thaw_bdev(mp->m_super->s_bdev);
+			bdev_thaw(mp->m_super->s_bdev);
 		}
 		break;
 	}

include/linux/blkdev.h

@@ -1541,8 +1541,8 @@ static inline int early_lookup_bdev(const char *pathname, dev_t *dev)
 }
 #endif /* CONFIG_BLOCK */
 
-int freeze_bdev(struct block_device *bdev);
-int thaw_bdev(struct block_device *bdev);
+int bdev_freeze(struct block_device *bdev);
+int bdev_thaw(struct block_device *bdev);
 
 struct io_comp_batch {
 	struct request *req_list;