Commit 1da73967 authored by Anand Jain's avatar Anand Jain Committed by David Sterba
Browse files

btrfs: add helper to obtain number of devices with ongoing dev-replace 



When the replace is running the fs_devices::num_devices also includes
the replaced device, however in some operations like device delete and
balance it needs the actual num_devices without the repalced devices.
The function btrfs_num_devices() just provides that.

And here is a scenario how balance and repalce items could co-exist:

Consider balance is started and paused, now start the replace followed
by a unmount or system power-cycle. During following mount, the
open_ctree() first restarts the balance so it must check for the device
replace otherwise our num_devices calculation will be wrong.

Signed-off-by: default avatarAnand Jain <anand.jain@oracle.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 16220c46

fs/btrfs/volumes.c

+21 −14
Original line number Diff line number Diff line
@@ -1854,6 +1854,24 @@ void btrfs_assign_next_active_device(struct btrfs_device *device, 
		fs_info->fs_devices->latest_bdev = next_device->bdev;

}



/*

 * Return btrfs_fs_devices::num_devices excluding the device that's being

 * currently replaced.

 */

static u64 btrfs_num_devices(struct btrfs_fs_info *fs_info)

{

	u64 num_devices = fs_info->fs_devices->num_devices;



	btrfs_dev_replace_read_lock(&fs_info->dev_replace);

	if (btrfs_dev_replace_is_ongoing(&fs_info->dev_replace)) {

		ASSERT(num_devices > 1);

		num_devices--;

	}

	btrfs_dev_replace_read_unlock(&fs_info->dev_replace);



	return num_devices;

}



int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,

		u64 devid)

{
@@ -1865,13 +1883,7 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path, 


	mutex_lock(&uuid_mutex);



	num_devices = fs_devices->num_devices;

	btrfs_dev_replace_read_lock(&fs_info->dev_replace);

	if (btrfs_dev_replace_is_ongoing(&fs_info->dev_replace)) {

		ASSERT(num_devices > 1);

		num_devices--;

	}

	btrfs_dev_replace_read_unlock(&fs_info->dev_replace);

	num_devices = btrfs_num_devices(fs_info);



	ret = btrfs_check_raid_min_devices(fs_info, num_devices - 1);

	if (ret)
@@ -3740,13 +3752,8 @@ int btrfs_balance(struct btrfs_fs_info *fs_info, 
		}

	}



	num_devices = fs_info->fs_devices->num_devices;

	btrfs_dev_replace_read_lock(&fs_info->dev_replace);

	if (btrfs_dev_replace_is_ongoing(&fs_info->dev_replace)) {

		ASSERT(num_devices > 1);

		num_devices--;

	}

	btrfs_dev_replace_read_unlock(&fs_info->dev_replace);

	num_devices = btrfs_num_devices(fs_info);



	allowed = BTRFS_AVAIL_ALLOC_BIT_SINGLE | BTRFS_BLOCK_GROUP_DUP;

	if (num_devices > 1)

		allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1);

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