Commit 1f7319c7 authored by Minchan Kim's avatar Minchan Kim Committed by Linus Torvalds
Browse files

zram: partial IO refactoring 

For architecture(PAGE_SIZE > 4K), zram have supported partial IO.
However, the mixed code for handling normal/partial IO is too mess,
error-prone to modify IO handler functions with upcoming feature so this
patch aims for cleaning up zram's IO handling functions.

Link: http://lkml.kernel.org/r/1492052365-16169-3-git-send-email-minchan@kernel.org


Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e86942c7

drivers/block/zram/zram_drv.c

+184 −153
Original line number Diff line number Diff line
@@ -45,6 +45,8 @@ static const char *default_compressor = "lzo"; 
/* Module params (documentation at end) */

static unsigned int num_devices = 1;



static void zram_free_page(struct zram *zram, size_t index);



static inline bool init_done(struct zram *zram)

{

	return zram->disksize;
@@ -98,10 +100,17 @@ static void zram_set_obj_size(struct zram_meta *meta, 
	meta->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size;

}



#if PAGE_SIZE != 4096

static inline bool is_partial_io(struct bio_vec *bvec)

{

	return bvec->bv_len != PAGE_SIZE;

}

#else

static inline bool is_partial_io(struct bio_vec *bvec)

{

	return false;

}

#endif



static void zram_revalidate_disk(struct zram *zram)

{
@@ -189,18 +198,6 @@ static bool page_same_filled(void *ptr, unsigned long *element) 
	return true;

}



static void handle_same_page(struct bio_vec *bvec, unsigned long element)

{

	struct page *page = bvec->bv_page;

	void *user_mem;



	user_mem = kmap_atomic(page);

	zram_fill_page(user_mem + bvec->bv_offset, bvec->bv_len, element);

	kunmap_atomic(user_mem);



	flush_dcache_page(page);

}



static ssize_t initstate_show(struct device *dev,

		struct device_attribute *attr, char *buf)

{
@@ -416,6 +413,53 @@ static DEVICE_ATTR_RO(io_stat); 
static DEVICE_ATTR_RO(mm_stat);

static DEVICE_ATTR_RO(debug_stat);



static bool zram_same_page_read(struct zram *zram, u32 index,

				struct page *page,

				unsigned int offset, unsigned int len)

{

	struct zram_meta *meta = zram->meta;



	bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);

	if (unlikely(!meta->table[index].handle) ||

			zram_test_flag(meta, index, ZRAM_SAME)) {

		void *mem;



		bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);

		mem = kmap_atomic(page);

		zram_fill_page(mem + offset, len, meta->table[index].element);

		kunmap_atomic(mem);

		return true;

	}

	bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);



	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)) {

		struct zram_meta *meta = zram->meta;



		kunmap_atomic(mem);

		/* Free memory associated with this sector now. */

		bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);

		zram_free_page(zram, index);

		zram_set_flag(meta, index, ZRAM_SAME);

		zram_set_element(meta, index, element);

		bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);



		atomic64_inc(&zram->stats.same_pages);

		return true;

	}

	kunmap_atomic(mem);



	return false;

}



static void zram_meta_free(struct zram_meta *meta, u64 disksize)

{

	size_t num_pages = disksize >> PAGE_SHIFT;
@@ -502,43 +546,43 @@ static void zram_free_page(struct zram *zram, size_t index) 
	zram_set_obj_size(meta, index, 0);

}



static int zram_decompress_page(struct zram *zram, char *mem, u32 index)

static int zram_decompress_page(struct zram *zram, struct page *page, u32 index)

{

	int ret = 0;

	unsigned char *cmem;

	struct zram_meta *meta = zram->meta;

	int ret;

	unsigned long handle;

	unsigned int size;

	void *src, *dst;

	struct zram_meta *meta = zram->meta;



	if (zram_same_page_read(zram, index, page, 0, PAGE_SIZE))

		return 0;



	bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);

	handle = meta->table[index].handle;

	size = zram_get_obj_size(meta, index);



	if (!handle || zram_test_flag(meta, index, ZRAM_SAME)) {

		bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);

		zram_fill_page(mem, PAGE_SIZE, meta->table[index].element);

		return 0;

	}



	cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);

	src = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);

	if (size == PAGE_SIZE) {

		memcpy(mem, cmem, PAGE_SIZE);

		dst = kmap_atomic(page);

		memcpy(dst, src, PAGE_SIZE);

		kunmap_atomic(dst);

		ret = 0;

	} else {

		struct zcomp_strm *zstrm = zcomp_stream_get(zram->comp);



		ret = zcomp_decompress(zstrm, cmem, size, mem);

		dst = kmap_atomic(page);

		ret = zcomp_decompress(zstrm, src, size, dst);

		kunmap_atomic(dst);

		zcomp_stream_put(zram->comp);

	}

	zs_unmap_object(meta->mem_pool, handle);

	bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);



	/* Should NEVER happen. Return bio error if it does. */

	if (unlikely(ret)) {

	if (unlikely(ret))

		pr_err("Decompression failed! err=%d, page=%u\n", ret, index);

		return ret;

	}



	return 0;

	return ret;

}



static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
@@ -546,125 +590,59 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec, 
{

	int ret;

	struct page *page;

	unsigned char *user_mem, *uncmem = NULL;

	struct zram_meta *meta = zram->meta;

	page = bvec->bv_page;



	bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);

	if (unlikely(!meta->table[index].handle) ||

			zram_test_flag(meta, index, ZRAM_SAME)) {

		bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);

		handle_same_page(bvec, meta->table[index].element);

		return 0;

	}

	bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);



	if (is_partial_io(bvec))

	page = bvec->bv_page;

	if (is_partial_io(bvec)) {

		/* Use a temporary buffer to decompress the page */

		uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);



	user_mem = kmap_atomic(page);

	if (!is_partial_io(bvec))

		uncmem = user_mem;



	if (!uncmem) {

		pr_err("Unable to allocate temp memory\n");

		ret = -ENOMEM;

		goto out_cleanup;

		page = alloc_page(GFP_NOIO|__GFP_HIGHMEM);

		if (!page)

			return -ENOMEM;

	}



	ret = zram_decompress_page(zram, uncmem, index);

	/* Should NEVER happen. Return bio error if it does. */

	ret = zram_decompress_page(zram, page, index);

	if (unlikely(ret))

		goto out_cleanup;

		goto out;



	if (is_partial_io(bvec))

		memcpy(user_mem + bvec->bv_offset, uncmem + offset,

				bvec->bv_len);

	if (is_partial_io(bvec)) {

		void *dst = kmap_atomic(bvec->bv_page);

		void *src = kmap_atomic(page);



	flush_dcache_page(page);

	ret = 0;

out_cleanup:

	kunmap_atomic(user_mem);

		memcpy(dst + bvec->bv_offset, src + offset, bvec->bv_len);

		kunmap_atomic(src);

		kunmap_atomic(dst);

	}

out:

	if (is_partial_io(bvec))

		kfree(uncmem);

		__free_page(page);



	return ret;

}



static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,

			   int offset)

static int zram_compress(struct zram *zram, struct zcomp_strm **zstrm,

			struct page *page,

			unsigned long *out_handle, unsigned int *out_comp_len)

{

	int ret = 0;

	unsigned int clen;

	int ret;

	unsigned int comp_len;

	void *src;

	unsigned long alloced_pages;

	unsigned long handle = 0;

	struct page *page;

	unsigned char *user_mem, *cmem, *src, *uncmem = NULL;

	struct zram_meta *meta = zram->meta;

	struct zcomp_strm *zstrm = NULL;

	unsigned long alloced_pages;

	unsigned long element;



	page = bvec->bv_page;

	if (is_partial_io(bvec)) {

		/*

		 * This is a partial IO. We need to read the full page

		 * before to write the changes.

		 */

		uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);

		if (!uncmem) {

			ret = -ENOMEM;

			goto out;

		}

		ret = zram_decompress_page(zram, uncmem, index);

		if (ret)

			goto out;

	}



compress_again:

	user_mem = kmap_atomic(page);

	if (is_partial_io(bvec)) {

		memcpy(uncmem + offset, user_mem + bvec->bv_offset,

		       bvec->bv_len);

		kunmap_atomic(user_mem);

		user_mem = NULL;

	} else {

		uncmem = user_mem;

	}



	if (page_same_filled(uncmem, &element)) {

		if (user_mem)

			kunmap_atomic(user_mem);

		/* Free memory associated with this sector now. */

		bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);

		zram_free_page(zram, index);

		zram_set_flag(meta, index, ZRAM_SAME);

		zram_set_element(meta, index, element);

		bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);



		atomic64_inc(&zram->stats.same_pages);

		ret = 0;

		goto out;

	}



	zstrm = zcomp_stream_get(zram->comp);

	ret = zcomp_compress(zstrm, uncmem, &clen);

	if (!is_partial_io(bvec)) {

		kunmap_atomic(user_mem);

		user_mem = NULL;

		uncmem = NULL;

	}

	src = kmap_atomic(page);

	ret = zcomp_compress(*zstrm, src, &comp_len);

	kunmap_atomic(src);



	if (unlikely(ret)) {

		pr_err("Compression failed! err=%d\n", ret);

		goto out;

		if (handle)

			zs_free(meta->mem_pool, handle);

		return ret;

	}



	src = zstrm->buffer;

	if (unlikely(clen > max_zpage_size)) {

		clen = PAGE_SIZE;

		if (is_partial_io(bvec))

			src = uncmem;

	}

	if (unlikely(comp_len > max_zpage_size))

		comp_len = PAGE_SIZE;



	/*

	 * handle allocation has 2 paths:
@@ -680,27 +658,21 @@ compress_again: 
	 * from the slow path and handle has already been allocated.

	 */

	if (!handle)

		handle = zs_malloc(meta->mem_pool, clen,

		handle = zs_malloc(meta->mem_pool, comp_len,

				__GFP_KSWAPD_RECLAIM |

				__GFP_NOWARN |

				__GFP_HIGHMEM |

				__GFP_MOVABLE);

	if (!handle) {

		zcomp_stream_put(zram->comp);

		zstrm = NULL;



		atomic64_inc(&zram->stats.writestall);



		handle = zs_malloc(meta->mem_pool, clen,

		handle = zs_malloc(meta->mem_pool, comp_len,

				GFP_NOIO | __GFP_HIGHMEM |

				__GFP_MOVABLE);

		*zstrm = zcomp_stream_get(zram->comp);

		if (handle)

			goto compress_again;



		pr_err("Error allocating memory for compressed page: %u, size=%u\n",

			index, clen);

		ret = -ENOMEM;

		goto out;

		return -ENOMEM;

	}



	alloced_pages = zs_get_total_pages(meta->mem_pool);
@@ -708,22 +680,45 @@ compress_again: 


	if (zram->limit_pages && alloced_pages > zram->limit_pages) {

		zs_free(meta->mem_pool, handle);

		ret = -ENOMEM;

		goto out;

		return -ENOMEM;

	}



	*out_handle = handle;

	*out_comp_len = comp_len;

	return 0;

}



	cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);

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;

	struct zcomp_strm *zstrm;

	struct zram_meta *meta = zram->meta;

	struct page *page = bvec->bv_page;



	if (zram_same_page_write(zram, index, page))

		return 0;



	if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {

	zstrm = zcomp_stream_get(zram->comp);

	ret = zram_compress(zram, &zstrm, page, &handle, &comp_len);

	if (ret) {

		zcomp_stream_put(zram->comp);

		return ret;

	}





	dst = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);



	src = zstrm->buffer;

	if (comp_len == PAGE_SIZE)

		src = kmap_atomic(page);

		memcpy(cmem, src, PAGE_SIZE);

	memcpy(dst, src, comp_len);

	if (comp_len == PAGE_SIZE)

		kunmap_atomic(src);

	} else {

		memcpy(cmem, src, clen);

	}



	zcomp_stream_put(zram->comp);

	zstrm = NULL;

	zs_unmap_object(meta->mem_pool, handle);



	/*
@@ -732,19 +727,54 @@ compress_again: 
	 */

	bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);

	zram_free_page(zram, index);



	meta->table[index].handle = handle;

	zram_set_obj_size(meta, index, clen);

	zram_set_obj_size(meta, index, comp_len);

	bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);



	/* Update stats */

	atomic64_add(clen, &zram->stats.compr_data_size);

	atomic64_add(comp_len, &zram->stats.compr_data_size);

	atomic64_inc(&zram->stats.pages_stored);

	return 0;

}



static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec,

				u32 index, int offset)

{

	int ret;

	struct page *page = NULL;

	void *src;

	struct bio_vec vec;



	vec = *bvec;

	if (is_partial_io(bvec)) {

		void *dst;

		/*

		 * This is a partial IO. We need to read the full page

		 * before to write the changes.

		 */

		page = alloc_page(GFP_NOIO|__GFP_HIGHMEM);

		if (!page)

			return -ENOMEM;



		ret = zram_decompress_page(zram, page, index);

		if (ret)

			goto out;



		src = kmap_atomic(bvec->bv_page);

		dst = kmap_atomic(page);

		memcpy(dst + offset, src + bvec->bv_offset, bvec->bv_len);

		kunmap_atomic(dst);

		kunmap_atomic(src);



		vec.bv_page = page;

		vec.bv_len = PAGE_SIZE;

		vec.bv_offset = 0;

	}



	ret = __zram_bvec_write(zram, &vec, index);

out:

	if (zstrm)

		zcomp_stream_put(zram->comp);

	if (is_partial_io(bvec))

		kfree(uncmem);

		__free_page(page);

	return ret;

}
@@ -800,6 +830,7 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index, 
	if (!is_write) {

		atomic64_inc(&zram->stats.num_reads);

		ret = zram_bvec_read(zram, bvec, index, offset);

		flush_dcache_page(bvec->bv_page);

	} else {

		atomic64_inc(&zram->stats.num_writes);

		ret = zram_bvec_write(zram, bvec, index, offset);

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