[PATCH 1/2] dm-log-writes: don't use all the cpu

[PATCH 1/2] dm-log-writes: don't use all the cpu

[josef]

From: Josef Bacik <jbacik@fb.com>

The check to see if the logging kthread needs to go to sleep is wrong,
it checks lc->pending_blocks, which will be non-0 if there are any
blocks that are pending, whether they are ready to be logged or not.
What we really want is to go to sleep until it's time to log blocks, so
change this check so we do actually go to sleep in between flushes.

Signed-off-by: Josef Bacik <jbacik@fb.com>
---
 drivers/md/dm-log-writes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index a1da0eb..9aab510 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -399,7 +399,7 @@ static int log_writes_kthread(void *arg)
 		if (!try_to_freeze()) {
 			set_current_state(TASK_INTERRUPTIBLE);
 			if (!kthread_should_stop() &&
-			    !atomic_read(&lc->pending_blocks))
+			    list_empty(&lc->logging_blocks))
 				schedule();
 			__set_current_state(TASK_RUNNING);
 		}
-- 
2.7.4

[PATCH 2/2] dm-log-writes: fix >512b sectorsize support

[josef]

From: Josef Bacik <jbacik@fb.com>

I screwed up the initial >512b support, I was storing the bio sectors
which are 512b sectors in the log metadata which expects them to be in
sectorsize units of sectors.  I also was assuming device sectors when
assigning the bi_sector for the blocks I was logging in some places.

Fix this up by adding two helpers to convert between bio and dev
sectors, and use these in the appropriate places to fix the problem and
make it clear which units go where.  With this patch I could now
properly use dm-log-writes with 4k devices.

Signed-off-by: Josef Bacik <jbacik@fb.com>
---
 drivers/md/dm-log-writes.c | 43 ++++++++++++++++++++++++++++++++-----------
 1 file changed, 32 insertions(+), 11 deletions(-)

diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index 9aab510..6f1b954 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -100,6 +100,7 @@ struct log_writes_c {
 	struct dm_dev *logdev;
 	u64 logged_entries;
 	u32 sectorsize;
+	u32 sectorshift;
 	atomic_t io_blocks;
 	atomic_t pending_blocks;
 	sector_t next_sector;
@@ -128,6 +129,18 @@ struct per_bio_data {
 	struct pending_block *block;
 };
 
+static inline sector_t bio_to_dev_sectors(struct log_writes_c *lc,
+					  sector_t sectors)
+{
+	return sectors >> (lc->sectorshift - SECTOR_SHIFT);
+}
+
+static inline sector_t dev_to_bio_sectors(struct log_writes_c *lc,
+					  sector_t sectors)
+{
+	return sectors << (lc->sectorshift - SECTOR_SHIFT);
+}
+
 static void put_pending_block(struct log_writes_c *lc)
 {
 	if (atomic_dec_and_test(&lc->pending_blocks)) {
@@ -253,7 +266,7 @@ static int log_one_block(struct log_writes_c *lc,
 
 	if (!block->vec_cnt)
 		goto out;
-	sector++;
+	sector += dev_to_bio_sectors(lc, 1);
 
 	atomic_inc(&lc->io_blocks);
 	bio = bio_alloc(GFP_KERNEL, min(block->vec_cnt, BIO_MAX_PAGES));
@@ -354,10 +367,10 @@ static int log_writes_kthread(void *arg)
 				goto next;
 
 			sector = lc->next_sector;
-			if (block->flags & LOG_DISCARD_FLAG)
-				lc->next_sector++;
-			else
-				lc->next_sector += block->nr_sectors + 1;
+			if (!(block->flags & LOG_DISCARD_FLAG))
+				lc->next_sector +=
+					dev_to_bio_sectors(lc, block->nr_sectors);
+			lc->next_sector += dev_to_bio_sectors(lc, 1);
 
 			/*
 			 * Apparently the size of the device may not be known
@@ -435,7 +448,6 @@ static int log_writes_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	INIT_LIST_HEAD(&lc->unflushed_blocks);
 	INIT_LIST_HEAD(&lc->logging_blocks);
 	init_waitqueue_head(&lc->wait);
-	lc->sectorsize = 1 << SECTOR_SHIFT;
 	atomic_set(&lc->io_blocks, 0);
 	atomic_set(&lc->pending_blocks, 0);
 
@@ -455,6 +467,8 @@ static int log_writes_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		goto bad;
 	}
 
+	lc->sectorsize = bdev_logical_block_size(lc->dev->bdev);
+	lc->sectorshift = ilog2(lc->sectorsize);
 	lc->log_kthread = kthread_run(log_writes_kthread, lc, "log-write");
 	if (IS_ERR(lc->log_kthread)) {
 		ret = PTR_ERR(lc->log_kthread);
@@ -464,8 +478,12 @@ static int log_writes_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		goto bad;
 	}
 
-	/* We put the super at sector 0, start logging at sector 1 */
-	lc->next_sector = 1;
+	/*
+	 * next_sector is in 512 sectors to correspond to what bi_sector expects
+	 * to be.  The super starts at sector 0, and the next_sector is the next
+	 * logical one based on the sectorsize of the device.
+	 */
+	lc->next_sector = lc->sectorsize >> SECTOR_SHIFT;
 	lc->logging_enabled = true;
 	lc->end_sector = logdev_last_sector(lc);
 	lc->device_supports_discard = true;
@@ -599,8 +617,8 @@ static int log_writes_map(struct dm_target *ti, struct bio *bio)
 	if (discard_bio)
 		block->flags |= LOG_DISCARD_FLAG;
 
-	block->sector = bio->bi_iter.bi_sector;
-	block->nr_sectors = bio_sectors(bio);
+	block->sector = bio_to_dev_sectors(lc, bio->bi_iter.bi_sector);
+	block->nr_sectors = bio_to_dev_sectors(lc, bio_sectors(bio));
 
 	/* We don't need the data, just submit */
 	if (discard_bio) {
@@ -767,9 +785,12 @@ static void log_writes_io_hints(struct dm_target *ti, struct queue_limits *limit
 
 	if (!q || !blk_queue_discard(q)) {
 		lc->device_supports_discard = false;
-		limits->discard_granularity = 1 << SECTOR_SHIFT;
+		limits->discard_granularity = lc->sectorsize;
 		limits->max_discard_sectors = (UINT_MAX >> SECTOR_SHIFT);
 	}
+	limits->logical_block_size = bdev_logical_block_size(lc->dev->bdev);
+	limits->physical_block_size = bdev_physical_block_size(lc->dev->bdev);
+	limits->io_min = limits->physical_block_size;
 }
 
 static struct target_type log_writes_target = {
-- 
2.7.4