Commit 80de1912 authored by Ilya Dryomov's avatar Ilya Dryomov
Browse files

rbd: lock_on_read map option 



Add a per-device option to acquire exclusive lock on reads (in addition
to writes and discards).  The use case is iSCSI, where it will be used
to prevent execution of stale writes after the implicit failover.

Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
Tested-by: default avatarMike Christie <mchristi@redhat.com>
parent 0276dca6

drivers/block/rbd.c

+12 −1
Original line number Diff line number Diff line
@@ -795,6 +795,7 @@ enum { 
	/* string args above */

	Opt_read_only,

	Opt_read_write,

	Opt_lock_on_read,

	Opt_err

};
@@ -806,16 +807,19 @@ static match_table_t rbd_opts_tokens = { 
	{Opt_read_only, "ro"},		/* Alternate spelling */

	{Opt_read_write, "read_write"},

	{Opt_read_write, "rw"},		/* Alternate spelling */

	{Opt_lock_on_read, "lock_on_read"},

	{Opt_err, NULL}

};



struct rbd_options {

	int	queue_depth;

	bool	read_only;

	bool	lock_on_read;

};



#define RBD_QUEUE_DEPTH_DEFAULT	BLKDEV_MAX_RQ

#define RBD_READ_ONLY_DEFAULT	false

#define RBD_LOCK_ON_READ_DEFAULT false



static int parse_rbd_opts_token(char *c, void *private)

{
@@ -851,6 +855,9 @@ static int parse_rbd_opts_token(char *c, void *private) 
	case Opt_read_write:

		rbd_opts->read_only = false;

		break;

	case Opt_lock_on_read:

		rbd_opts->lock_on_read = true;

		break;

	default:

		/* libceph prints "bad option" msg */

		return -EINVAL;
@@ -4105,7 +4112,7 @@ static void rbd_queue_workfn(struct work_struct *work) 
	u64 length = blk_rq_bytes(rq);

	enum obj_operation_type op_type;

	u64 mapping_size;

	bool must_be_locked = false;

	bool must_be_locked;

	int result;



	if (rq->cmd_type != REQ_TYPE_FS) {
@@ -4168,6 +4175,9 @@ static void rbd_queue_workfn(struct work_struct *work) 
		snapc = rbd_dev->header.snapc;

		ceph_get_snap_context(snapc);

		must_be_locked = rbd_is_lock_supported(rbd_dev);

	} else {

		must_be_locked = rbd_dev->opts->lock_on_read &&

					rbd_is_lock_supported(rbd_dev);

	}

	up_read(&rbd_dev->header_rwsem);
@@ -5757,6 +5767,7 @@ static int rbd_add_parse_args(const char *buf, 


	rbd_opts->read_only = RBD_READ_ONLY_DEFAULT;

	rbd_opts->queue_depth = RBD_QUEUE_DEPTH_DEFAULT;

	rbd_opts->lock_on_read = RBD_LOCK_ON_READ_DEFAULT;



	copts = ceph_parse_options(options, mon_addrs,

					mon_addrs + mon_addrs_size - 1,

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