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drbd: Replaced md_io_mutex by an atomic: md_io_in_use
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The new function drbd_md_get_buffer() aborts waiting for the buffer
in case the disk failes in the meantime.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
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Philipp Reisner committed May 9, 2012
1 parent cc94c65 commit e171173
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Showing 4 changed files with 51 additions and 19 deletions.
44 changes: 34 additions & 10 deletions drivers/block/drbd/drbd_actlog.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,23 @@ struct drbd_atodb_wait {

int w_al_write_transaction(struct drbd_conf *, struct drbd_work *, int);

void *drbd_md_get_buffer(struct drbd_conf *mdev)
{
int r;

wait_event(mdev->misc_wait,
(r = atomic_cmpxchg(&mdev->md_io_in_use, 0, 1)) == 0 ||
mdev->state.disk <= D_FAILED);

return r ? NULL : page_address(mdev->md_io_page);
}

void drbd_md_put_buffer(struct drbd_conf *mdev)
{
if (atomic_dec_and_test(&mdev->md_io_in_use))
wake_up(&mdev->misc_wait);
}

static int _drbd_md_sync_page_io(struct drbd_conf *mdev,
struct drbd_backing_dev *bdev,
struct page *page, sector_t sector,
Expand All @@ -90,6 +107,7 @@ static int _drbd_md_sync_page_io(struct drbd_conf *mdev,
bio->bi_end_io = drbd_md_io_complete;
bio->bi_rw = rw;

atomic_inc(&mdev->md_io_in_use); /* drbd_md_put_buffer() is in the completion handler */
if (drbd_insert_fault(mdev, (rw & WRITE) ? DRBD_FAULT_MD_WR : DRBD_FAULT_MD_RD))
bio_endio(bio, -EIO);
else
Expand All @@ -109,7 +127,7 @@ int drbd_md_sync_page_io(struct drbd_conf *mdev, struct drbd_backing_dev *bdev,
int offset = 0;
struct page *iop = mdev->md_io_page;

D_ASSERT(mutex_is_locked(&mdev->md_io_mutex));
D_ASSERT(atomic_read(&mdev->md_io_in_use) == 1);

BUG_ON(!bdev->md_bdev);

Expand Down Expand Up @@ -326,8 +344,13 @@ w_al_write_transaction(struct drbd_conf *mdev, struct drbd_work *w, int unused)
return 1;
}

mutex_lock(&mdev->md_io_mutex); /* protects md_io_buffer, al_tr_cycle, ... */
buffer = (struct al_transaction *)page_address(mdev->md_io_page);
buffer = drbd_md_get_buffer(mdev); /* protects md_io_buffer, al_tr_cycle, ... */
if (!buffer) {
dev_err(DEV, "disk failed while waiting for md_io buffer\n");
complete(&((struct update_al_work *)w)->event);
put_ldev(mdev);
return 1;
}

buffer->magic = __constant_cpu_to_be32(DRBD_MAGIC);
buffer->tr_number = cpu_to_be32(mdev->al_tr_number);
Expand Down Expand Up @@ -372,7 +395,7 @@ w_al_write_transaction(struct drbd_conf *mdev, struct drbd_work *w, int unused)
D_ASSERT(mdev->al_tr_pos < MD_AL_MAX_SIZE);
mdev->al_tr_number++;

mutex_unlock(&mdev->md_io_mutex);
drbd_md_put_buffer(mdev);

complete(&((struct update_al_work *)w)->event);
put_ldev(mdev);
Expand Down Expand Up @@ -441,16 +464,17 @@ int drbd_al_read_log(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
/* lock out all other meta data io for now,
* and make sure the page is mapped.
*/
mutex_lock(&mdev->md_io_mutex);
buffer = page_address(mdev->md_io_page);
buffer = drbd_md_get_buffer(mdev);
if (!buffer)
return 0;

/* Find the valid transaction in the log */
for (i = 0; i <= mx; i++) {
rv = drbd_al_read_tr(mdev, bdev, buffer, i);
if (rv == 0)
continue;
if (rv == -1) {
mutex_unlock(&mdev->md_io_mutex);
drbd_md_put_buffer(mdev);
return 0;
}
cnr = be32_to_cpu(buffer->tr_number);
Expand All @@ -476,7 +500,7 @@ int drbd_al_read_log(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)

if (!found_valid) {
dev_warn(DEV, "No usable activity log found.\n");
mutex_unlock(&mdev->md_io_mutex);
drbd_md_put_buffer(mdev);
return 1;
}

Expand All @@ -491,7 +515,7 @@ int drbd_al_read_log(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
rv = drbd_al_read_tr(mdev, bdev, buffer, i);
ERR_IF(rv == 0) goto cancel;
if (rv == -1) {
mutex_unlock(&mdev->md_io_mutex);
drbd_md_put_buffer(mdev);
return 0;
}

Expand Down Expand Up @@ -532,7 +556,7 @@ int drbd_al_read_log(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
mdev->al_tr_pos = 0;

/* ok, we are done with it */
mutex_unlock(&mdev->md_io_mutex);
drbd_md_put_buffer(mdev);

dev_info(DEV, "Found %d transactions (%d active extents) in activity log.\n",
transactions, active_extents);
Expand Down
6 changes: 4 additions & 2 deletions drivers/block/drbd/drbd_int.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1095,7 +1095,7 @@ struct drbd_conf {
struct page *md_io_page; /* one page buffer for md_io */
struct page *md_io_tmpp; /* for logical_block_size != 512 */
struct drbd_md_io md_io;
struct mutex md_io_mutex; /* protects the md_io, md_io_page and md_io_tmpp */
atomic_t md_io_in_use; /* protects the md_io, md_io_page and md_io_tmpp */
spinlock_t al_lock;
wait_queue_head_t al_wait;
struct lru_cache *act_log; /* activity log */
Expand Down Expand Up @@ -1537,8 +1537,10 @@ extern void resume_next_sg(struct drbd_conf *mdev);
extern void suspend_other_sg(struct drbd_conf *mdev);
extern int drbd_resync_finished(struct drbd_conf *mdev);
/* maybe rather drbd_main.c ? */
extern void *drbd_md_get_buffer(struct drbd_conf *mdev);
extern void drbd_md_put_buffer(struct drbd_conf *mdev);
extern int drbd_md_sync_page_io(struct drbd_conf *mdev,
struct drbd_backing_dev *bdev, sector_t sector, int rw);
struct drbd_backing_dev *bdev, sector_t sector, int rw);
extern void drbd_ov_oos_found(struct drbd_conf*, sector_t, int);
extern void drbd_rs_controller_reset(struct drbd_conf *mdev);

Expand Down
19 changes: 12 additions & 7 deletions drivers/block/drbd/drbd_main.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3043,8 +3043,8 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
atomic_set(&mdev->rs_sect_in, 0);
atomic_set(&mdev->rs_sect_ev, 0);
atomic_set(&mdev->ap_in_flight, 0);
atomic_set(&mdev->md_io_in_use, 0);

mutex_init(&mdev->md_io_mutex);
mutex_init(&mdev->data.mutex);
mutex_init(&mdev->meta.mutex);
sema_init(&mdev->data.work.s, 0);
Expand Down Expand Up @@ -3722,8 +3722,10 @@ void drbd_md_sync(struct drbd_conf *mdev)
if (!get_ldev_if_state(mdev, D_FAILED))
return;

mutex_lock(&mdev->md_io_mutex);
buffer = (struct meta_data_on_disk *)page_address(mdev->md_io_page);
buffer = drbd_md_get_buffer(mdev);
if (!buffer)
goto out;

memset(buffer, 0, 512);

buffer->la_size = cpu_to_be64(drbd_get_capacity(mdev->this_bdev));
Expand Down Expand Up @@ -3754,7 +3756,8 @@ void drbd_md_sync(struct drbd_conf *mdev)
* since we updated it on metadata. */
mdev->ldev->md.la_size_sect = drbd_get_capacity(mdev->this_bdev);

mutex_unlock(&mdev->md_io_mutex);
drbd_md_put_buffer(mdev);
out:
put_ldev(mdev);
}

Expand All @@ -3774,8 +3777,9 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
if (!get_ldev_if_state(mdev, D_ATTACHING))
return ERR_IO_MD_DISK;

mutex_lock(&mdev->md_io_mutex);
buffer = (struct meta_data_on_disk *)page_address(mdev->md_io_page);
buffer = drbd_md_get_buffer(mdev);
if (!buffer)
goto out;

if (!drbd_md_sync_page_io(mdev, bdev, bdev->md.md_offset, READ)) {
/* NOTE: can't do normal error processing here as this is
Expand Down Expand Up @@ -3836,7 +3840,8 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
mdev->sync_conf.al_extents = 127;

err:
mutex_unlock(&mdev->md_io_mutex);
drbd_md_put_buffer(mdev);
out:
put_ldev(mdev);

return rv;
Expand Down
1 change: 1 addition & 0 deletions drivers/block/drbd/drbd_worker.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,7 @@ void drbd_md_io_complete(struct bio *bio, int error)
md_io->error = error;

complete(&md_io->event);
drbd_md_put_buffer(mdev);
}

/* reads on behalf of the partner,
Expand Down

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