提交 1f7319c7 编写于 作者: M Minchan Kim 提交者: Linus Torvalds

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.orgSigned-off-by: NMinchan 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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 e86942c7
......@@ -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;
......@@ -502,169 +546,103 @@ 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,
u32 index, int offset)
u32 index, int offset)
{
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;
page = bvec->bv_page;
if (is_partial_io(bvec)) {
/* Use a temporary buffer to decompress the page */
page = alloc_page(GFP_NOIO|__GFP_HIGHMEM);
if (!page)
return -ENOMEM;
}
bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
if (is_partial_io(bvec))
/* Use a temporary buffer to decompress the page */
uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
ret = zram_decompress_page(zram, page, index);
if (unlikely(ret))
goto out;
user_mem = kmap_atomic(page);
if (!is_partial_io(bvec))
uncmem = user_mem;
if (is_partial_io(bvec)) {
void *dst = kmap_atomic(bvec->bv_page);
void *src = kmap_atomic(page);
if (!uncmem) {
pr_err("Unable to allocate temp memory\n");
ret = -ENOMEM;
goto out_cleanup;
memcpy(dst + bvec->bv_offset, src + offset, bvec->bv_len);
kunmap_atomic(src);
kunmap_atomic(dst);
}
ret = zram_decompress_page(zram, uncmem, index);
/* Should NEVER happen. Return bio error if it does. */
if (unlikely(ret))
goto out_cleanup;
out:
if (is_partial_io(bvec))
memcpy(user_mem + bvec->bv_offset, uncmem + offset,
bvec->bv_len);
__free_page(page);
flush_dcache_page(page);
ret = 0;
out_cleanup:
kunmap_atomic(user_mem);
if (is_partial_io(bvec))
kfree(uncmem);
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 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
* 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 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
if (zram->limit_pages && alloced_pages > zram->limit_pages) {
zs_free(meta->mem_pool, handle);
ret = -ENOMEM;
goto out;
return -ENOMEM;
}
cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
*out_handle = handle;
*out_comp_len = comp_len;
return 0;
}
if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
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;
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 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
*/
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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