Commit aa144bfe authored by David Sterba's avatar David Sterba
Browse files

btrfs: dev-replace: avoid useless lock on error handling path 



The exit sequence in btrfs_dev_replace_start does not allow to simply
add a label to the right place so the error handling after starting
transaction failure jumps there. Currently there's a lock that pairs
with the unlock in the section, which is unnecessary and only raises
questions.  Add a variable to track the locking status and avoid the
extra locking.

Reviewed-by: default avatarOmar Sandoval <osandov@fb.com>
Reviewed-by: default avatarAnand Jain <anand.jain@oracle.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 9f6cbcbb

fs/btrfs/dev-replace.c

+6 −1
Original line number Diff line number Diff line
@@ -400,6 +400,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, 
	int ret;

	struct btrfs_device *tgt_device = NULL;

	struct btrfs_device *src_device = NULL;

	bool need_unlock;



	src_device = btrfs_find_device_by_devspec(fs_info, srcdevid,

						  srcdev_name);
@@ -424,6 +425,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, 
		return PTR_ERR(trans);

	}



	need_unlock = true;

	btrfs_dev_replace_write_lock(dev_replace);

	switch (dev_replace->replace_state) {

	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
@@ -463,6 +465,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, 
	atomic64_set(&dev_replace->num_write_errors, 0);

	atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);

	btrfs_dev_replace_write_unlock(dev_replace);

	need_unlock = false;



	ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);

	if (ret)
@@ -474,6 +477,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, 
	trans = btrfs_start_transaction(root, 0);

	if (IS_ERR(trans)) {

		ret = PTR_ERR(trans);

		need_unlock = true;

		btrfs_dev_replace_write_lock(dev_replace);

		dev_replace->replace_state =

			BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
@@ -500,6 +504,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, 
	return ret;



leave:

	if (need_unlock)

		btrfs_dev_replace_write_unlock(dev_replace);

	btrfs_destroy_dev_replace_tgtdev(tgt_device);

	return ret;

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