From: Minchan Kim <minchan@xxxxxxxxxx> Subject: 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@xxxxxxxxxx Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/block/zram/zram_drv.c | 40 ++------------------------------ drivers/block/zram/zram_drv.h | 3 -- 2 files changed, 3 insertions(+), 40 deletions(-) diff -puN drivers/block/zram/zram_drv.c~zram-remove-waitqueue-for-io-done drivers/block/zram/zram_drv.c --- a/drivers/block/zram/zram_drv.c~zram-remove-waitqueue-for-io-done +++ a/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 { 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_dev 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_dev 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 zra 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 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 -puN drivers/block/zram/zram_drv.h~zram-remove-waitqueue-for-io-done drivers/block/zram/zram_drv.h --- a/drivers/block/zram/zram_drv.h~zram-remove-waitqueue-for-io-done +++ a/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. _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
