Commit 578bda9e authored by David Sterba's avatar David Sterba
Browse files

btrfs: introduce try-lock semantics for exclusive op start 



Add try-lock for exclusive operation start to allow callers to do more
checks. The same operation must already be running. The try-lock and
unlock must pair and are a substitute for btrfs_exclop_start, thus it
must also pair with btrfs_exclop_finish to release the exclop context.

Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Reviewed-by: default avatarAnand Jain <anand.jain@oracle.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 907d2710

fs/btrfs/ctree.h

+3 −0
Original line number Diff line number Diff line
@@ -3233,6 +3233,9 @@ void btrfs_update_ioctl_balance_args(struct btrfs_fs_info *fs_info, 
			       struct btrfs_ioctl_balance_args *bargs);

bool btrfs_exclop_start(struct btrfs_fs_info *fs_info,

			enum btrfs_exclusive_operation type);

bool btrfs_exclop_start_try_lock(struct btrfs_fs_info *fs_info,

				 enum btrfs_exclusive_operation type);

void btrfs_exclop_start_unlock(struct btrfs_fs_info *fs_info);

void btrfs_exclop_finish(struct btrfs_fs_info *fs_info);



/* file.c */

fs/btrfs/ioctl.c

+26 −0
Original line number Diff line number Diff line
@@ -371,6 +371,32 @@ bool btrfs_exclop_start(struct btrfs_fs_info *fs_info, 
	return ret;

}



/*

 * Conditionally allow to enter the exclusive operation in case it's compatible

 * with the running one.  This must be paired with btrfs_exclop_start_unlock and

 * btrfs_exclop_finish.

 *

 * Compatibility:

 * - the same type is already running

 * - not BTRFS_EXCLOP_NONE - this is intentionally incompatible and the caller

 *   must check the condition first that would allow none -> @type

 */

bool btrfs_exclop_start_try_lock(struct btrfs_fs_info *fs_info,

				 enum btrfs_exclusive_operation type)

{

	spin_lock(&fs_info->super_lock);

	if (fs_info->exclusive_operation == type)

		return true;



	spin_unlock(&fs_info->super_lock);

	return false;

}



void btrfs_exclop_start_unlock(struct btrfs_fs_info *fs_info)

{

	spin_unlock(&fs_info->super_lock);

}



void btrfs_exclop_finish(struct btrfs_fs_info *fs_info)

{

	spin_lock(&fs_info->super_lock);