From: David Sterba Date: Tue, 20 Mar 2018 22:44:50 +0000 (+0100) Subject: btrfs: remove wrong use of volume_mutex from btrfs_dev_replace_start X-Git-Tag: v4.19~584^2~152 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=a0fecc23718aa9ef020b8c86173a0b783ed37dcf;p=platform%2Fkernel%2Flinux-rpi.git btrfs: remove wrong use of volume_mutex from btrfs_dev_replace_start The volume mutex does not protect against anything in this case, the comment about scrub is right but not related to locking and looks confusing. The comment in btrfs_find_device_missing_or_by_path is wrong and confusing too. The device_list_mutex is not held here to protect device lookup, but in this case device replace cannot run in parallel with device removal (due to exclusive op protection), so we don't need further locking here. Reviewed-by: Anand Jain Signed-off-by: David Sterba --- diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c index 9fe7be7..d097701 100644 --- a/fs/btrfs/dev-replace.c +++ b/fs/btrfs/dev-replace.c @@ -414,18 +414,13 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, struct btrfs_device *tgt_device = NULL; struct btrfs_device *src_device = NULL; - /* the disk copy procedure reuses the scrub code */ - mutex_lock(&fs_info->volume_mutex); ret = btrfs_find_device_by_devspec(fs_info, srcdevid, srcdev_name, &src_device); - if (ret) { - mutex_unlock(&fs_info->volume_mutex); + if (ret) return ret; - } ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name, src_device, &tgt_device); - mutex_unlock(&fs_info->volume_mutex); if (ret) return ret; diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 07706c0..9e5d27d 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -2218,10 +2218,6 @@ int btrfs_find_device_missing_or_by_path(struct btrfs_fs_info *fs_info, struct btrfs_device *tmp; devices = &fs_info->fs_devices->devices; - /* - * It is safe to read the devices since the volume_mutex - * is held by the caller. - */ list_for_each_entry(tmp, devices, dev_list) { if (test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &tmp->dev_state) && !tmp->bdev) {