Commit a174c0a2 authored by Nikolay Borisov's avatar Nikolay Borisov Committed by David Sterba
Browse files

btrfs: allow device add if balance is paused 



Currently paused balance precludes adding a device since they are both
considered exclusive ops and we can have at most one running at a time.
This is problematic in case a filesystem encounters an ENOSPC situation
while balance is running, in this case the only thing the user can do
is mount the fs with "skip_balance" which pauses balance and delete some
data to free up space for balance. However, it should be possible to add
a new device when balance is paused.

Fix this by allowing device add to proceed when balance is paused.

Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 621a1ee1

fs/btrfs/ioctl.c

+18 −3
Original line number Diff line number Diff line
@@ -3174,14 +3174,26 @@ static int btrfs_ioctl_defrag(struct file *file, void __user *argp) 
static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg)

{

	struct btrfs_ioctl_vol_args *vol_args;

	bool restore_op = false;

	int ret;



	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;



	if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_ADD))

	if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_ADD)) {

		if (!btrfs_exclop_start_try_lock(fs_info, BTRFS_EXCLOP_DEV_ADD))

			return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;



		/*

		 * We can do the device add because we have a paused balanced,

		 * change the exclusive op type and remember we should bring

		 * back the paused balance

		 */

		fs_info->exclusive_operation = BTRFS_EXCLOP_DEV_ADD;

		btrfs_exclop_start_unlock(fs_info);

		restore_op = true;

	}



	vol_args = memdup_user(arg, sizeof(*vol_args));

	if (IS_ERR(vol_args)) {

		ret = PTR_ERR(vol_args);
@@ -3196,6 +3208,9 @@ static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg) 


	kfree(vol_args);

out:

	if (restore_op)

		btrfs_exclop_balance(fs_info, BTRFS_EXCLOP_BALANCE_PAUSED);

	else

		btrfs_exclop_finish(fs_info);

	return ret;

}