From: Minchan Kim <minchan@xxxxxxxxxx> Subject: zram: clean up duplicated codes in __zram_bvec_write Patch series "writeback incompressible pages to storage", v1. zRam is useful for memory saving with compressible pages but sometime, workload can be changed and system has lots of incompressible pages which is very harmful for zram. This patch supports writeback feature of zram so admin can set up a block device and with it, zram can save the memory via writing out the incompressile pages once it found it's incompressible pages (1/4 comp ratio) instead of keeping the page in memory. [1-3] is just clean up and [4-8] is step by step feature enablement. [4-8] is logically not bisectable(ie, logical unit separation) although I tried to compiled out without breaking but I think it would be better to review. This patch (of 9): __zram_bvec_write has some of duplicated logic for zram meta data handling of same_page|compressed_page. This patch aims to clean it up without behavior change. [xieyisheng1@xxxxxxxxxx: fix compr_data_size stat] Link: http://lkml.kernel.org/r/1502707447-6944-1-git-send-email-xieyisheng1@xxxxxxxxxx Link: http://lkml.kernel.org/r/1496019048-27016-1-git-send-email-minchan@xxxxxxxxxx Link: http://lkml.kernel.org/r/1498459987-24562-2-git-send-email-minchan@xxxxxxxxxx Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> Signed-off-by: Yisheng Xie <xieyisheng1@xxxxxxxxxx> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Cc: Juneho Choi <juno.choi@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/block/zram/zram_drv.c | 56 +++++++++++++------------------- 1 file changed, 23 insertions(+), 33 deletions(-) diff -puN drivers/block/zram/zram_drv.c~zram-clean-up-duplicated-codes-in-__zram_bvec_write drivers/block/zram/zram_drv.c --- a/drivers/block/zram/zram_drv.c~zram-clean-up-duplicated-codes-in-__zram_bvec_write +++ a/drivers/block/zram/zram_drv.c @@ -453,30 +453,6 @@ static bool zram_same_page_read(struct z return false; } -static bool zram_same_page_write(struct zram *zram, u32 index, - struct page *page) -{ - unsigned long element; - void *mem = kmap_atomic(page); - - if (page_same_filled(mem, &element)) { - kunmap_atomic(mem); - /* Free memory associated with this sector now. */ - zram_slot_lock(zram, index); - zram_free_page(zram, index); - zram_set_flag(zram, index, ZRAM_SAME); - zram_set_element(zram, index, element); - zram_slot_unlock(zram, index); - - atomic64_inc(&zram->stats.same_pages); - atomic64_inc(&zram->stats.pages_stored); - return true; - } - kunmap_atomic(mem); - - return false; -} - static void zram_meta_free(struct zram *zram, u64 disksize) { size_t num_pages = disksize >> PAGE_SHIFT; @@ -685,14 +661,23 @@ compress_again: static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index) { int ret; - unsigned long handle; - unsigned int comp_len; - void *src, *dst; + unsigned long handle = 0; + unsigned int comp_len = 0; + void *src, *dst, *mem; struct zcomp_strm *zstrm; struct page *page = bvec->bv_page; + unsigned long element = 0; + enum zram_pageflags flags = 0; - if (zram_same_page_write(zram, index, page)) - return 0; + mem = kmap_atomic(page); + if (page_same_filled(mem, &element)) { + kunmap_atomic(mem); + /* Free memory associated with this sector now */ + atomic64_inc(&zram->stats.same_pages); + flags = ZRAM_SAME; + goto out; + } + kunmap_atomic(mem); zstrm = zcomp_stream_get(zram->comp); ret = zram_compress(zram, &zstrm, page, &handle, &comp_len); @@ -712,19 +697,24 @@ static int __zram_bvec_write(struct zram zcomp_stream_put(zram->comp); zs_unmap_object(zram->mem_pool, handle); - + atomic64_add(comp_len, &zram->stats.compr_data_size); +out: /* * Free memory associated with this sector * before overwriting unused sectors. */ zram_slot_lock(zram, index); zram_free_page(zram, index); - zram_set_handle(zram, index, handle); - zram_set_obj_size(zram, index, comp_len); + if (flags == ZRAM_SAME) { + zram_set_flag(zram, index, ZRAM_SAME); + zram_set_element(zram, index, element); + } else { + zram_set_handle(zram, index, handle); + zram_set_obj_size(zram, index, comp_len); + } zram_slot_unlock(zram, index); /* Update stats */ - atomic64_add(comp_len, &zram->stats.compr_data_size); atomic64_inc(&zram->stats.pages_stored); return 0; } _ -- 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
