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BACKPORT: zram: remove waitqueue for IO done

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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: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

(cherry picked from commit a09759acaa)
Signed-off-by: Peter Kalauskas <peskal@google.com>
Bug: 112488418
Change-Id: I97170fb576be7baae63f82334af0dd5e91b16763
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
This commit is contained in:
Minchan Kim
2017-02-24 14:56:47 -08:00
committed by Amit Pundir
parent ff26f4e4a0
commit ea830271ca
2 changed files with 3 additions and 40 deletions
Download Patch File Download Diff File Expand all files Collapse all files

40
drivers/block/zram/zram_drv.c
View File

@@ -390,18 +390,6 @@ 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;
@@ -855,22 +843,17 @@ 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;
@@ -900,13 +883,11 @@ 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;
@@ -917,8 +898,6 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector,
bv.bv_offset = 0;
err = zram_bvec_rw(zram, &bv, index, offset, rw);
put_zram:
zram_meta_put(zram);
out:
/*
* If I/O fails, just return error(ie, non-zero) without
@@ -951,17 +930,6 @@ 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));
@@ -1009,8 +977,6 @@ 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;

3
drivers/block/zram/zram_drv.h
View File

@@ -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.