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drbd: Clarify when activity log I/O is delegated to the worker thread

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Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Lars Ellenberg 2013-03-19 18:16:48 +01:00 committed by Jens Axboe
parent c04ccaa669
commit 56392d2f40
5 changed files with 31 additions and 26 deletions
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49
drivers/block/drbd/drbd_actlog.c
View File

@ -104,7 +104,7 @@ struct update_al_work {
int err;
};
static int al_write_transaction(struct drbd_conf *mdev);
static int al_write_transaction(struct drbd_conf *mdev, bool delegate);
void *drbd_md_get_buffer(struct drbd_conf *mdev)
{
@ -246,7 +246,10 @@ static struct lc_element *_al_get(struct drbd_conf *mdev, unsigned int enr)
return al_ext;
}
void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i)
/*
* @delegate: delegate activity log I/O to the worker thread
*/
void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i, bool delegate)
{
/* for bios crossing activity log extent boundaries,
* we may need to activate two extents in one go */
@ -255,6 +258,17 @@ void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i)
unsigned enr;
bool locked = false;
/* When called through generic_make_request(), we must delegate
* activity log I/O to the worker thread: a further request
* submitted via generic_make_request() within the same task
* would be queued on current->bio_list, and would only start
* after this function returns (see generic_make_request()).
*
* However, if we *are* the worker, we must not delegate to ourselves.
*/
if (delegate)
BUG_ON(current == mdev->tconn->worker.task);
D_ASSERT(first <= last);
D_ASSERT(atomic_read(&mdev->local_cnt) > 0);
@ -270,13 +284,6 @@ void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i)
(locked = lc_try_lock_for_transaction(mdev->act_log)));
if (locked) {
/* drbd_al_write_transaction(mdev,al_ext,enr);
* recurses into generic_make_request(), which
* disallows recursion, bios being serialized on the
* current->bio_tail list now.
* we have to delegate updates to the activity log
* to the worker thread. */
/* Double check: it may have been committed by someone else,
* while we have been waiting for the lock. */
if (mdev->act_log->pending_changes) {
@ -287,7 +294,7 @@ void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i)
rcu_read_unlock();
if (write_al_updates) {
al_write_transaction(mdev);
al_write_transaction(mdev, delegate);
mdev->al_writ_cnt++;
}
@ -495,20 +502,18 @@ static int w_al_write_transaction(struct drbd_work *w, int unused)
/* Calls from worker context (see w_restart_disk_io()) need to write the
transaction directly. Others came through generic_make_request(),
those need to delegate it to the worker. */
static int al_write_transaction(struct drbd_conf *mdev)
static int al_write_transaction(struct drbd_conf *mdev, bool delegate)
{
struct update_al_work al_work;
if (current == mdev->tconn->worker.task)
if (delegate) {
struct update_al_work al_work;
init_completion(&al_work.event);
al_work.w.cb = w_al_write_transaction;
al_work.w.mdev = mdev;
drbd_queue_work_front(&mdev->tconn->sender_work, &al_work.w);
wait_for_completion(&al_work.event);
return al_work.err;
} else
return _al_write_transaction(mdev);
init_completion(&al_work.event);
al_work.w.cb = w_al_write_transaction;
al_work.w.mdev = mdev;
drbd_queue_work_front(&mdev->tconn->sender_work, &al_work.w);
wait_for_completion(&al_work.event);
return al_work.err;
}
static int _try_lc_del(struct drbd_conf *mdev, struct lc_element *al_ext)

2
drivers/block/drbd/drbd_int.h
View File

@ -1598,7 +1598,7 @@ extern const char *drbd_conn_str(enum drbd_conns s);
extern const char *drbd_role_str(enum drbd_role s);
/* drbd_actlog.c */
extern void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i);
extern void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i, bool delegate);
extern void drbd_al_complete_io(struct drbd_conf *mdev, struct drbd_interval *i);
extern void drbd_rs_complete_io(struct drbd_conf *mdev, sector_t sector);
extern int drbd_rs_begin_io(struct drbd_conf *mdev, sector_t sector);

2
drivers/block/drbd/drbd_receiver.c
View File

@ -2265,7 +2265,7 @@ static int receive_Data(struct drbd_tconn *tconn, struct packet_info *pi)
drbd_set_out_of_sync(mdev, peer_req->i.sector, peer_req->i.size);
peer_req->flags |= EE_CALL_AL_COMPLETE_IO;
peer_req->flags &= ~EE_MAY_SET_IN_SYNC;
drbd_al_begin_io(mdev, &peer_req->i);
drbd_al_begin_io(mdev, &peer_req->i, true);
}
err = drbd_submit_peer_request(mdev, peer_req, rw, DRBD_FAULT_DT_WR);

2
drivers/block/drbd/drbd_req.c
View File

@ -1054,7 +1054,7 @@ void __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long
if (rw == WRITE && req->private_bio && req->i.size
&& !test_bit(AL_SUSPENDED, &mdev->flags)) {
req->rq_state |= RQ_IN_ACT_LOG;
drbd_al_begin_io(mdev, &req->i);
drbd_al_begin_io(mdev, &req->i, true);
}
spin_lock_irq(&mdev->tconn->req_lock);

2
drivers/block/drbd/drbd_worker.c
View File

@ -1411,7 +1411,7 @@ int w_restart_disk_io(struct drbd_work *w, int cancel)
struct drbd_conf *mdev = w->mdev;
if (bio_data_dir(req->master_bio) == WRITE && req->rq_state & RQ_IN_ACT_LOG)
drbd_al_begin_io(mdev, &req->i);
drbd_al_begin_io(mdev, &req->i, false);
drbd_req_make_private_bio(req, req->master_bio);
req->private_bio->bi_bdev = mdev->ldev->backing_bdev;