Commit 171938e5 authored by David Sterba's avatar David Sterba
Browse files

btrfs: track exclusive filesystem operation in flags 



There are several operations, usually started from ioctls, that cannot
run concurrently. The status is tracked in
mutually_exclusive_operation_running as an atomic_t. We can easily track
the status as one of the per-filesystem flag bits with same
synchronization guarantees.

The conversion replaces:

* atomic_xchg(..., 1)    ->   test_and_set_bit(FLAG, ...)
* atomic_set(..., 0)     ->   clear_bit(FLAG, ...)

Reviewed-by: default avatarAnand Jain <anand.jain@oracle.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 48a89bc4

fs/btrfs/ctree.h

+5 −2
Original line number Diff line number Diff line
@@ -705,6 +705,11 @@ struct btrfs_delayed_root; 
#define BTRFS_FS_BTREE_ERR			11

#define BTRFS_FS_LOG1_ERR			12

#define BTRFS_FS_LOG2_ERR			13

/*

 * Indicate that a whole-filesystem exclusive operation is running

 * (device replace, resize, device add/delete, balance)

 */

#define BTRFS_FS_EXCL_OP			14



struct btrfs_fs_info {

	u8 fsid[BTRFS_FSID_SIZE];
@@ -1070,8 +1075,6 @@ struct btrfs_fs_info { 
	/* device replace state */

	struct btrfs_dev_replace dev_replace;



	atomic_t mutually_exclusive_operation_running;



	struct percpu_counter bio_counter;

	wait_queue_head_t replace_wait;

fs/btrfs/dev-replace.c

+2 −3
Original line number Diff line number Diff line
@@ -784,8 +784,7 @@ int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info) 
	}

	btrfs_dev_replace_unlock(dev_replace, 1);



	WARN_ON(atomic_xchg(

		&fs_info->mutually_exclusive_operation_running, 1));

	WARN_ON(test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));

	task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");

	return PTR_ERR_OR_ZERO(task);

}
@@ -814,7 +813,7 @@ static int btrfs_dev_replace_kthread(void *data) 
			(unsigned int)progress);

	}

	btrfs_dev_replace_continue_on_mount(fs_info);

	atomic_set(&fs_info->mutually_exclusive_operation_running, 0);

	clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);



	return 0;

}

fs/btrfs/ioctl.c

+15 −18
Original line number Diff line number Diff line
@@ -1504,7 +1504,7 @@ static noinline int btrfs_ioctl_resize(struct file *file, 
	if (ret)

		return ret;



	if (atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1)) {

	if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {

		mnt_drop_write_file(file);

		return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;

	}
@@ -1619,7 +1619,7 @@ out_free: 
	kfree(vol_args);

out:

	mutex_unlock(&fs_info->volume_mutex);

	atomic_set(&fs_info->mutually_exclusive_operation_running, 0);

	clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);

	mnt_drop_write_file(file);

	return ret;

}
@@ -2661,7 +2661,7 @@ static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg) 
	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;



	if (atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1))

	if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags))

		return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;



	mutex_lock(&fs_info->volume_mutex);
@@ -2680,7 +2680,7 @@ static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg) 
	kfree(vol_args);

out:

	mutex_unlock(&fs_info->volume_mutex);

	atomic_set(&fs_info->mutually_exclusive_operation_running, 0);

	clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);

	return ret;

}
@@ -2708,7 +2708,7 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg) 
	if (vol_args->flags & ~BTRFS_VOL_ARG_V2_FLAGS_SUPPORTED)

		return -EOPNOTSUPP;



	if (atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1)) {

	if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {

		ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;

		goto out;

	}
@@ -2721,7 +2721,7 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg) 
		ret = btrfs_rm_device(fs_info, vol_args->name, 0);

	}

	mutex_unlock(&fs_info->volume_mutex);

	atomic_set(&fs_info->mutually_exclusive_operation_running, 0);

	clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);



	if (!ret) {

		if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID)
@@ -2752,7 +2752,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg) 
	if (ret)

		return ret;



	if (atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1)) {

	if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {

		ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;

		goto out_drop_write;

	}
@@ -2772,7 +2772,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg) 
		btrfs_info(fs_info, "disk deleted %s", vol_args->name);

	kfree(vol_args);

out:

	atomic_set(&fs_info->mutually_exclusive_operation_running, 0);

	clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);

out_drop_write:

	mnt_drop_write_file(file);
@@ -4442,13 +4442,11 @@ static long btrfs_ioctl_dev_replace(struct btrfs_fs_info *fs_info, 
			ret = -EROFS;

			goto out;

		}

		if (atomic_xchg(

			&fs_info->mutually_exclusive_operation_running, 1)) {

		if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {

			ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;

		} else {

			ret = btrfs_dev_replace_by_ioctl(fs_info, p);

			atomic_set(

			 &fs_info->mutually_exclusive_operation_running, 0);

			clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);

		}

		break;

	case BTRFS_IOCTL_DEV_REPLACE_CMD_STATUS:
@@ -4643,7 +4641,7 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg) 
		return ret;



again:

	if (!atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1)) {

	if (!test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {

		mutex_lock(&fs_info->volume_mutex);

		mutex_lock(&fs_info->balance_mutex);

		need_unlock = true;
@@ -4689,7 +4687,7 @@ again: 
	}



locked:

	BUG_ON(!atomic_read(&fs_info->mutually_exclusive_operation_running));

	BUG_ON(!test_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));



	if (arg) {

		bargs = memdup_user(arg, sizeof(*bargs));
@@ -4745,11 +4743,10 @@ locked: 


do_balance:

	/*

	 * Ownership of bctl and mutually_exclusive_operation_running

	 * Ownership of bctl and filesystem flag BTRFS_FS_EXCL_OP

	 * goes to to btrfs_balance.  bctl is freed in __cancel_balance,

	 * or, if restriper was paused all the way until unmount, in

	 * free_fs_info.  mutually_exclusive_operation_running is

	 * cleared in __cancel_balance.

	 * free_fs_info.  The flag is cleared in __cancel_balance.

	 */

	need_unlock = false;
@@ -4769,7 +4766,7 @@ out_unlock: 
	mutex_unlock(&fs_info->balance_mutex);

	mutex_unlock(&fs_info->volume_mutex);

	if (need_unlock)

		atomic_set(&fs_info->mutually_exclusive_operation_running, 0);

		clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);

out:

	mnt_drop_write_file(file);

	return ret;

fs/btrfs/volumes.c

+3 −3
Original line number Diff line number Diff line
@@ -3761,7 +3761,7 @@ static void __cancel_balance(struct btrfs_fs_info *fs_info) 
	if (ret)

		btrfs_handle_fs_error(fs_info, ret, NULL);



	atomic_set(&fs_info->mutually_exclusive_operation_running, 0);

	clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);

}



/* Non-zero return value signifies invalidity */
@@ -3941,7 +3941,7 @@ out: 
		__cancel_balance(fs_info);

	else {

		kfree(bctl);

		atomic_set(&fs_info->mutually_exclusive_operation_running, 0);

		clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);

	}

	return ret;

}
@@ -4031,7 +4031,7 @@ int btrfs_recover_balance(struct btrfs_fs_info *fs_info) 
	btrfs_balance_sys(leaf, item, &disk_bargs);

	btrfs_disk_balance_args_to_cpu(&bctl->sys, &disk_bargs);



	WARN_ON(atomic_xchg(&fs_info->mutually_exclusive_operation_running, 1));

	WARN_ON(test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));



	mutex_lock(&fs_info->volume_mutex);

	mutex_lock(&fs_info->balance_mutex);

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