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Commit a09759ac authored by Minchan Kim's avatar Minchan Kim Committed by Linus Torvalds
Browse files

zram: remove waitqueue for IO done 

zram_reset_device() waits for ongoing writepage pages to be completed by
zram->refcount logic.  However, it's pointless because before the reset,
we prevent further opening of zram by zram->claim and flush all of
pending IO by fsync_bdev so there should be no pending IO at the
zram_reset_device().

So let's remove that code which is even broken due to the lack of
wake_up elsewhere.

Link: http://lkml.kernel.org/r/1485145031-11661-1-git-send-email-minchan@kernel.org


Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
Reviewed-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3edf41d8

drivers/block/zram/zram_drv.c

+3 −37
Original line number Diff line number Diff line
@@ -391,18 +391,6 @@ static DEVICE_ATTR_RO(io_stat); 
static DEVICE_ATTR_RO(mm_stat);

static DEVICE_ATTR_RO(debug_stat);



static inline bool zram_meta_get(struct zram *zram)

{

	if (atomic_inc_not_zero(&zram->refcount))

		return true;

	return false;

}



static inline void zram_meta_put(struct zram *zram)

{

	atomic_dec(&zram->refcount);

}



static void zram_meta_free(struct zram_meta *meta, u64 disksize)

{

	size_t num_pages = disksize >> PAGE_SHIFT;
@@ -859,22 +847,17 @@ static blk_qc_t zram_make_request(struct request_queue *queue, struct bio *bio) 
{

	struct zram *zram = queue->queuedata;



	if (unlikely(!zram_meta_get(zram)))

		goto error;



	blk_queue_split(queue, &bio, queue->bio_split);



	if (!valid_io_request(zram, bio->bi_iter.bi_sector,

					bio->bi_iter.bi_size)) {

		atomic64_inc(&zram->stats.invalid_io);

		goto put_zram;

		goto error;

	}



	__zram_make_request(zram, bio);

	zram_meta_put(zram);

	return BLK_QC_T_NONE;

put_zram:

	zram_meta_put(zram);



error:

	bio_io_error(bio);

	return BLK_QC_T_NONE;
@@ -904,13 +887,11 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector, 
	struct bio_vec bv;



	zram = bdev->bd_disk->private_data;

	if (unlikely(!zram_meta_get(zram)))

		goto out;



	if (!valid_io_request(zram, sector, PAGE_SIZE)) {

		atomic64_inc(&zram->stats.invalid_io);

		err = -EINVAL;

		goto put_zram;

		goto out;

	}



	index = sector >> SECTORS_PER_PAGE_SHIFT;
@@ -921,8 +902,6 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector, 
	bv.bv_offset = 0;



	err = zram_bvec_rw(zram, &bv, index, offset, is_write);

put_zram:

	zram_meta_put(zram);

out:

	/*

	 * If I/O fails, just return error(ie, non-zero) without
@@ -955,17 +934,6 @@ static void zram_reset_device(struct zram *zram) 
	meta = zram->meta;

	comp = zram->comp;

	disksize = zram->disksize;

	/*

	 * Refcount will go down to 0 eventually and r/w handler

	 * cannot handle further I/O so it will bail out by

	 * check zram_meta_get.

	 */

	zram_meta_put(zram);

	/*

	 * We want to free zram_meta in process context to avoid

	 * deadlock between reclaim path and any other locks.

	 */

	wait_event(zram->io_done, atomic_read(&zram->refcount) == 0);



	/* Reset stats */

	memset(&zram->stats, 0, sizeof(zram->stats));
@@ -1013,8 +981,6 @@ static ssize_t disksize_store(struct device *dev, 
		goto out_destroy_comp;

	}



	init_waitqueue_head(&zram->io_done);

	atomic_set(&zram->refcount, 1);

	zram->meta = meta;

	zram->comp = comp;

	zram->disksize = disksize;

drivers/block/zram/zram_drv.h

+0 −3
Original line number Diff line number Diff line
@@ -106,9 +106,6 @@ struct zram { 
	unsigned long limit_pages;



	struct zram_stats stats;

	atomic_t refcount; /* refcount for zram_meta */

	/* wait all IO under all of cpu are done */

	wait_queue_head_t io_done;

	/*

	 * This is the limit on amount of *uncompressed* worth of data

	 * we can store in a disk.