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raid5-cache: add trim support for log 

Since superblock is updated infrequently, we do a simple trim of log
disk (a synchronous trim)

Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
This commit is contained in:
Shaohua Li 2015-10-08 21:54:06 -07:00 committed by NeilBrown
parent 9efdca16e0
commit 4b482044d2
1 changed files with 62 additions and 1 deletions
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63
drivers/md/raid5-cache.c
View File

@ -85,6 +85,7 @@ struct r5l_log {
spinlock_t no_space_stripes_lock;
bool need_cache_flush;
bool in_teardown;
};
/*
@ -644,6 +645,60 @@ void r5l_flush_stripe_to_raid(struct r5l_log *log)
}
static void r5l_write_super(struct r5l_log *log, sector_t cp);
static void r5l_write_super_and_discard_space(struct r5l_log *log,
sector_t end)
{
struct block_device *bdev = log->rdev->bdev;
struct mddev *mddev;
r5l_write_super(log, end);
if (!blk_queue_discard(bdev_get_queue(bdev)))
return;
mddev = log->rdev->mddev;
/*
* This is to avoid a deadlock. r5l_quiesce holds reconfig_mutex and
* wait for this thread to finish. This thread waits for
* MD_CHANGE_PENDING clear, which is supposed to be done in
* md_check_recovery(). md_check_recovery() tries to get
* reconfig_mutex. Since r5l_quiesce already holds the mutex,
* md_check_recovery() fails, so the PENDING never get cleared. The
* in_teardown check workaround this issue.
*/
if (!log->in_teardown) {
set_bit(MD_CHANGE_DEVS, &mddev->flags);
set_bit(MD_CHANGE_PENDING, &mddev->flags);
md_wakeup_thread(mddev->thread);
wait_event(mddev->sb_wait,
!test_bit(MD_CHANGE_PENDING, &mddev->flags) ||
log->in_teardown);
/*
* r5l_quiesce could run after in_teardown check and hold
* mutex first. Superblock might get updated twice.
*/
if (log->in_teardown)
md_update_sb(mddev, 1);
} else {
WARN_ON(!mddev_is_locked(mddev));
md_update_sb(mddev, 1);
}
if (log->last_checkpoint < end) {
blkdev_issue_discard(bdev,
log->last_checkpoint + log->rdev->data_offset,
end - log->last_checkpoint, GFP_NOIO, 0);
} else {
blkdev_issue_discard(bdev,
log->last_checkpoint + log->rdev->data_offset,
log->device_size - log->last_checkpoint,
GFP_NOIO, 0);
blkdev_issue_discard(bdev, log->rdev->data_offset, end,
GFP_NOIO, 0);
}
}
static void r5l_do_reclaim(struct r5l_log *log)
{
sector_t reclaim_target = xchg(&log->reclaim_target, 0);
@ -685,7 +740,7 @@ static void r5l_do_reclaim(struct r5l_log *log)
* here, because the log area might be reused soon and we don't want to
* confuse recovery
*/
r5l_write_super(log, next_checkpoint);
r5l_write_super_and_discard_space(log, next_checkpoint);
mutex_lock(&log->io_mutex);
log->last_checkpoint = next_checkpoint;
@ -721,9 +776,11 @@ static void r5l_wake_reclaim(struct r5l_log *log, sector_t space)
void r5l_quiesce(struct r5l_log *log, int state)
{
struct mddev *mddev;
if (!log || state == 2)
return;
if (state == 0) {
log->in_teardown = 0;
log->reclaim_thread = md_register_thread(r5l_reclaim_thread,
log->rdev->mddev, "reclaim");
} else if (state == 1) {
@ -731,6 +788,10 @@ void r5l_quiesce(struct r5l_log *log, int state)
* at this point all stripes are finished, so io_unit is at
* least in STRIPE_END state
*/
log->in_teardown = 1;
/* make sure r5l_write_super_and_discard_space exits */
mddev = log->rdev->mddev;
wake_up(&mddev->sb_wait);
r5l_wake_reclaim(log, -1L);
md_unregister_thread(&log->reclaim_thread);
r5l_do_reclaim(log);