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Date: Mon, 23 Jan 2017 13:17:11 +0900
From: Minchan Kim <minchan@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
linux-kernel@...r.kernel.org, Minchan Kim <minchan@...nel.org>
Subject: [PATCH] zram: remove waitqueue for IO done
zram_reset_device waits ongoing writepage pages 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 lacking
of wake_up elsewhere.
Signed-off-by: Minchan Kim <minchan@...nel.org>
---
drivers/block/zram/zram_drv.c | 40 +++-------------------------------------
drivers/block/zram/zram_drv.h | 3 ---
2 files changed, 3 insertions(+), 40 deletions(-)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 85737b6474ac..eaeff0696420 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -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;
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 74fcf10da374..2692554b7737 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -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.
--
2.7.4
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