From: Minchan Kim <minchan@xxxxxxxxxx> Subject: zram: write incompressible pages to backing device This patch enables write IO to transfer data to backing device. For that, it implements write_to_bdev function which creates new bio and chaining with parent bio to make the parent bio asynchrnous. For rw_page which don't have parent bio, it submit owned bio and handle IO completion by zram_page_end_io. Also, this patch defines new flag ZRAM_WB to mark written page for later read IO. [xieyisheng1@xxxxxxxxxx: fix typo in comment] Link: http://lkml.kernel.org/r/1502707447-6944-2-git-send-email-xieyisheng1@xxxxxxxxxx Link: http://lkml.kernel.org/r/1498459987-24562-8-git-send-email-minchan@xxxxxxxxxx Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> Signed-off-by: Yisheng Xie <xieyisheng1@xxxxxxxxxx> Cc: Juneho Choi <juno.choi@xxxxxxx> Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/block/zram/zram_drv.c | 113 ++++++++++++++++++++++++++++---- drivers/block/zram/zram_drv.h | 3 2 files changed, 103 insertions(+), 13 deletions(-) diff -puN drivers/block/zram/zram_drv.c~zram-write-incompressible-pages-to-backing-device drivers/block/zram/zram_drv.c --- a/drivers/block/zram/zram_drv.c~zram-write-incompressible-pages-to-backing-device +++ a/drivers/block/zram/zram_drv.c @@ -445,9 +445,76 @@ static void put_entry_bdev(struct zram * WARN_ON_ONCE(!was_set); } +void zram_page_end_io(struct bio *bio) +{ + struct page *page = bio->bi_io_vec[0].bv_page; + + page_endio(page, op_is_write(bio_op(bio)), + blk_status_to_errno(bio->bi_status)); + bio_put(bio); +} + +static int write_to_bdev(struct zram *zram, struct bio_vec *bvec, + u32 index, struct bio *parent, + unsigned long *pentry) +{ + struct bio *bio; + unsigned long entry; + + bio = bio_alloc(GFP_ATOMIC, 1); + if (!bio) + return -ENOMEM; + + entry = get_entry_bdev(zram); + if (!entry) { + bio_put(bio); + return -ENOSPC; + } + + bio->bi_iter.bi_sector = entry * (PAGE_SIZE >> 9); + bio->bi_bdev = zram->bdev; + if (!bio_add_page(bio, bvec->bv_page, bvec->bv_len, + bvec->bv_offset)) { + bio_put(bio); + put_entry_bdev(zram, entry); + return -EIO; + } + + if (!parent) { + bio->bi_opf = REQ_OP_WRITE | REQ_SYNC; + bio->bi_end_io = zram_page_end_io; + } else { + bio->bi_opf = parent->bi_opf; + bio_chain(bio, parent); + } + + submit_bio(bio); + *pentry = entry; + + return 0; +} + +static void zram_wb_clear(struct zram *zram, u32 index) +{ + unsigned long entry; + + zram_clear_flag(zram, index, ZRAM_WB); + entry = zram_get_element(zram, index); + zram_set_element(zram, index, 0); + put_entry_bdev(zram, entry); +} + #else static bool zram_wb_enabled(struct zram *zram) { return false; } static inline void reset_bdev(struct zram *zram) {}; +static int write_to_bdev(struct zram *zram, struct bio_vec *bvec, + u32 index, struct bio *parent, + unsigned long *pentry) + +{ + return -EIO; +} +static void zram_wb_clear(struct zram *zram, u32 index) {} #endif @@ -672,7 +739,13 @@ static bool zram_meta_alloc(struct zram */ static void zram_free_page(struct zram *zram, size_t index) { - unsigned long handle = zram_get_handle(zram, index); + unsigned long handle; + + if (zram_wb_enabled(zram) && zram_test_flag(zram, index, ZRAM_WB)) { + zram_wb_clear(zram, index); + atomic64_dec(&zram->stats.pages_stored); + return; + } /* * No memory is allocated for same element filled pages. @@ -686,6 +759,7 @@ static void zram_free_page(struct zram * return; } + handle = zram_get_handle(zram, index); if (!handle) return; @@ -770,7 +844,8 @@ out: return ret; } -static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index) +static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, + u32 index, struct bio *bio) { int ret = 0; unsigned long alloced_pages; @@ -781,6 +856,7 @@ static int __zram_bvec_write(struct zram struct page *page = bvec->bv_page; unsigned long element = 0; enum zram_pageflags flags = 0; + bool allow_wb = true; mem = kmap_atomic(page); if (page_same_filled(mem, &element)) { @@ -805,8 +881,20 @@ compress_again: return ret; } - if (unlikely(comp_len > max_zpage_size)) + if (unlikely(comp_len > max_zpage_size)) { + if (zram_wb_enabled(zram) && allow_wb) { + zcomp_stream_put(zram->comp); + ret = write_to_bdev(zram, bvec, index, bio, &element); + if (!ret) { + flags = ZRAM_WB; + ret = 1; + goto out; + } + allow_wb = false; + goto compress_again; + } comp_len = PAGE_SIZE; + } /* * handle allocation has 2 paths: @@ -866,10 +954,11 @@ out: */ zram_slot_lock(zram, index); zram_free_page(zram, index); - if (flags == ZRAM_SAME) { - zram_set_flag(zram, index, ZRAM_SAME); + + if (flags) { + zram_set_flag(zram, index, flags); zram_set_element(zram, index, element); - } else { + } else { zram_set_handle(zram, index, handle); zram_set_obj_size(zram, index, comp_len); } @@ -881,7 +970,7 @@ out: } static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, - u32 index, int offset) + u32 index, int offset, struct bio *bio) { int ret; struct page *page = NULL; @@ -914,7 +1003,7 @@ static int zram_bvec_write(struct zram * vec.bv_offset = 0; } - ret = __zram_bvec_write(zram, &vec, index); + ret = __zram_bvec_write(zram, &vec, index, bio); out: if (is_partial_io(bvec)) __free_page(page); @@ -965,7 +1054,7 @@ static void zram_bio_discard(struct zram * Returns 1 if IO request was successfully submitted. */ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index, - int offset, bool is_write) + int offset, bool is_write, struct bio *bio) { unsigned long start_time = jiffies; int rw_acct = is_write ? REQ_OP_WRITE : REQ_OP_READ; @@ -980,7 +1069,7 @@ static int zram_bvec_rw(struct zram *zra flush_dcache_page(bvec->bv_page); } else { atomic64_inc(&zram->stats.num_writes); - ret = zram_bvec_write(zram, bvec, index, offset); + ret = zram_bvec_write(zram, bvec, index, offset, bio); } generic_end_io_acct(rw_acct, &zram->disk->part0, start_time); @@ -1024,7 +1113,7 @@ static void __zram_make_request(struct z bv.bv_len = min_t(unsigned int, PAGE_SIZE - offset, unwritten); if (zram_bvec_rw(zram, &bv, index, offset, - op_is_write(bio_op(bio))) < 0) + op_is_write(bio_op(bio)), bio) < 0) goto out; bv.bv_offset += bv.bv_len; @@ -1098,7 +1187,7 @@ static int zram_rw_page(struct block_dev bv.bv_len = PAGE_SIZE; bv.bv_offset = 0; - ret = zram_bvec_rw(zram, &bv, index, offset, is_write); + ret = zram_bvec_rw(zram, &bv, index, offset, is_write, NULL); out: /* * If I/O fails, just return error(ie, non-zero) without diff -puN drivers/block/zram/zram_drv.h~zram-write-incompressible-pages-to-backing-device drivers/block/zram/zram_drv.h --- a/drivers/block/zram/zram_drv.h~zram-write-incompressible-pages-to-backing-device +++ a/drivers/block/zram/zram_drv.h @@ -60,9 +60,10 @@ static const size_t max_zpage_size = PAG /* Flags for zram pages (table[page_no].value) */ enum zram_pageflags { - /* Page consists entirely of zeros */ + /* Page consists the same element */ ZRAM_SAME = ZRAM_FLAG_SHIFT, ZRAM_ACCESS, /* page is now accessed */ + ZRAM_WB, /* page is stored on backing_device */ __NR_ZRAM_PAGEFLAGS, }; _ -- 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
