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: Minchan 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Minchan Kim
Linus Torvalds
parent
e86942c7b6
commit
1f7319c742
@ -45,6 +45,8 @@ static const char *default_compressor = "lzo";
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/* Module params (documentation at end) */
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static unsigned int num_devices = 1;
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static void zram_free_page(struct zram *zram, size_t index);
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static inline bool init_done(struct zram *zram)
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{
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return zram->disksize;
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@ -98,10 +100,17 @@ static void zram_set_obj_size(struct zram_meta *meta,
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meta->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size;
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}
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#if PAGE_SIZE != 4096
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static inline bool is_partial_io(struct bio_vec *bvec)
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{
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return bvec->bv_len != PAGE_SIZE;
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}
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#else
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static inline bool is_partial_io(struct bio_vec *bvec)
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{
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return false;
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}
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#endif
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static void zram_revalidate_disk(struct zram *zram)
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{
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@ -189,18 +198,6 @@ static bool page_same_filled(void *ptr, unsigned long *element)
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return true;
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}
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static void handle_same_page(struct bio_vec *bvec, unsigned long element)
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{
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struct page *page = bvec->bv_page;
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void *user_mem;
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user_mem = kmap_atomic(page);
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zram_fill_page(user_mem + bvec->bv_offset, bvec->bv_len, element);
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kunmap_atomic(user_mem);
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flush_dcache_page(page);
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}
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static ssize_t initstate_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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@ -416,6 +413,53 @@ static DEVICE_ATTR_RO(io_stat);
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static DEVICE_ATTR_RO(mm_stat);
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static DEVICE_ATTR_RO(debug_stat);
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static bool zram_same_page_read(struct zram *zram, u32 index,
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struct page *page,
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unsigned int offset, unsigned int len)
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{
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struct zram_meta *meta = zram->meta;
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bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
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if (unlikely(!meta->table[index].handle) ||
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zram_test_flag(meta, index, ZRAM_SAME)) {
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void *mem;
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bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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mem = kmap_atomic(page);
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zram_fill_page(mem + offset, len, meta->table[index].element);
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kunmap_atomic(mem);
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return true;
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}
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bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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return false;
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}
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static bool zram_same_page_write(struct zram *zram, u32 index,
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struct page *page)
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{
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unsigned long element;
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void *mem = kmap_atomic(page);
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if (page_same_filled(mem, &element)) {
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struct zram_meta *meta = zram->meta;
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kunmap_atomic(mem);
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/* Free memory associated with this sector now. */
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bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
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zram_free_page(zram, index);
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zram_set_flag(meta, index, ZRAM_SAME);
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zram_set_element(meta, index, element);
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bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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atomic64_inc(&zram->stats.same_pages);
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return true;
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}
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kunmap_atomic(mem);
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return false;
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}
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static void zram_meta_free(struct zram_meta *meta, u64 disksize)
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{
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size_t num_pages = disksize >> PAGE_SHIFT;
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@ -502,169 +546,103 @@ static void zram_free_page(struct zram *zram, size_t index)
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zram_set_obj_size(meta, index, 0);
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}
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static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
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static int zram_decompress_page(struct zram *zram, struct page *page, u32 index)
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{
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int ret = 0;
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unsigned char *cmem;
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struct zram_meta *meta = zram->meta;
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int ret;
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unsigned long handle;
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unsigned int size;
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void *src, *dst;
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struct zram_meta *meta = zram->meta;
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if (zram_same_page_read(zram, index, page, 0, PAGE_SIZE))
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return 0;
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bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
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handle = meta->table[index].handle;
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size = zram_get_obj_size(meta, index);
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if (!handle || zram_test_flag(meta, index, ZRAM_SAME)) {
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bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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zram_fill_page(mem, PAGE_SIZE, meta->table[index].element);
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return 0;
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}
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cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
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src = zs_map_object(meta->mem_pool, handle, ZS_MM_RO);
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if (size == PAGE_SIZE) {
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memcpy(mem, cmem, PAGE_SIZE);
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dst = kmap_atomic(page);
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memcpy(dst, src, PAGE_SIZE);
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kunmap_atomic(dst);
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ret = 0;
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} else {
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struct zcomp_strm *zstrm = zcomp_stream_get(zram->comp);
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ret = zcomp_decompress(zstrm, cmem, size, mem);
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dst = kmap_atomic(page);
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ret = zcomp_decompress(zstrm, src, size, dst);
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kunmap_atomic(dst);
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zcomp_stream_put(zram->comp);
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}
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zs_unmap_object(meta->mem_pool, handle);
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bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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/* Should NEVER happen. Return bio error if it does. */
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if (unlikely(ret)) {
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pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
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return ret;
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}
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return 0;
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}
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static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
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u32 index, int offset)
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{
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int ret;
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struct page *page;
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unsigned char *user_mem, *uncmem = NULL;
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struct zram_meta *meta = zram->meta;
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page = bvec->bv_page;
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bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
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if (unlikely(!meta->table[index].handle) ||
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zram_test_flag(meta, index, ZRAM_SAME)) {
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bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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handle_same_page(bvec, meta->table[index].element);
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return 0;
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}
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bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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if (is_partial_io(bvec))
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/* Use a temporary buffer to decompress the page */
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uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
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user_mem = kmap_atomic(page);
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if (!is_partial_io(bvec))
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uncmem = user_mem;
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if (!uncmem) {
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pr_err("Unable to allocate temp memory\n");
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ret = -ENOMEM;
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goto out_cleanup;
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}
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ret = zram_decompress_page(zram, uncmem, index);
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/* Should NEVER happen. Return bio error if it does. */
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if (unlikely(ret))
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goto out_cleanup;
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pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
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if (is_partial_io(bvec))
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memcpy(user_mem + bvec->bv_offset, uncmem + offset,
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bvec->bv_len);
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flush_dcache_page(page);
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ret = 0;
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out_cleanup:
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kunmap_atomic(user_mem);
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if (is_partial_io(bvec))
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kfree(uncmem);
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return ret;
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}
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static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
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int offset)
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static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
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u32 index, int offset)
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{
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int ret = 0;
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unsigned int clen;
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unsigned long handle = 0;
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int ret;
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struct page *page;
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unsigned char *user_mem, *cmem, *src, *uncmem = NULL;
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struct zram_meta *meta = zram->meta;
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struct zcomp_strm *zstrm = NULL;
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unsigned long alloced_pages;
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unsigned long element;
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page = bvec->bv_page;
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if (is_partial_io(bvec)) {
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/*
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* This is a partial IO. We need to read the full page
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* before to write the changes.
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*/
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uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
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if (!uncmem) {
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ret = -ENOMEM;
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goto out;
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}
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ret = zram_decompress_page(zram, uncmem, index);
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if (ret)
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goto out;
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/* Use a temporary buffer to decompress the page */
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page = alloc_page(GFP_NOIO|__GFP_HIGHMEM);
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if (!page)
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return -ENOMEM;
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}
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ret = zram_decompress_page(zram, page, index);
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if (unlikely(ret))
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goto out;
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if (is_partial_io(bvec)) {
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void *dst = kmap_atomic(bvec->bv_page);
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void *src = kmap_atomic(page);
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memcpy(dst + bvec->bv_offset, src + offset, bvec->bv_len);
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kunmap_atomic(src);
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kunmap_atomic(dst);
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}
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out:
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if (is_partial_io(bvec))
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__free_page(page);
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return ret;
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}
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static int zram_compress(struct zram *zram, struct zcomp_strm **zstrm,
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struct page *page,
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unsigned long *out_handle, unsigned int *out_comp_len)
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{
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int ret;
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unsigned int comp_len;
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void *src;
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unsigned long alloced_pages;
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unsigned long handle = 0;
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struct zram_meta *meta = zram->meta;
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compress_again:
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user_mem = kmap_atomic(page);
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if (is_partial_io(bvec)) {
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memcpy(uncmem + offset, user_mem + bvec->bv_offset,
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bvec->bv_len);
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kunmap_atomic(user_mem);
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user_mem = NULL;
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} else {
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uncmem = user_mem;
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}
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if (page_same_filled(uncmem, &element)) {
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if (user_mem)
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kunmap_atomic(user_mem);
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/* Free memory associated with this sector now. */
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bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
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zram_free_page(zram, index);
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zram_set_flag(meta, index, ZRAM_SAME);
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zram_set_element(meta, index, element);
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bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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atomic64_inc(&zram->stats.same_pages);
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ret = 0;
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goto out;
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}
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zstrm = zcomp_stream_get(zram->comp);
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ret = zcomp_compress(zstrm, uncmem, &clen);
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if (!is_partial_io(bvec)) {
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kunmap_atomic(user_mem);
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user_mem = NULL;
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uncmem = NULL;
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}
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src = kmap_atomic(page);
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ret = zcomp_compress(*zstrm, src, &comp_len);
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kunmap_atomic(src);
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if (unlikely(ret)) {
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pr_err("Compression failed! err=%d\n", ret);
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goto out;
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if (handle)
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zs_free(meta->mem_pool, handle);
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return ret;
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}
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src = zstrm->buffer;
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if (unlikely(clen > max_zpage_size)) {
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clen = PAGE_SIZE;
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if (is_partial_io(bvec))
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src = uncmem;
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}
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if (unlikely(comp_len > max_zpage_size))
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comp_len = PAGE_SIZE;
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/*
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* handle allocation has 2 paths:
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@ -680,27 +658,21 @@ compress_again:
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* from the slow path and handle has already been allocated.
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*/
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if (!handle)
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handle = zs_malloc(meta->mem_pool, clen,
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handle = zs_malloc(meta->mem_pool, comp_len,
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__GFP_KSWAPD_RECLAIM |
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__GFP_NOWARN |
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__GFP_HIGHMEM |
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__GFP_MOVABLE);
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if (!handle) {
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zcomp_stream_put(zram->comp);
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zstrm = NULL;
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atomic64_inc(&zram->stats.writestall);
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handle = zs_malloc(meta->mem_pool, clen,
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handle = zs_malloc(meta->mem_pool, comp_len,
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GFP_NOIO | __GFP_HIGHMEM |
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__GFP_MOVABLE);
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*zstrm = zcomp_stream_get(zram->comp);
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if (handle)
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goto compress_again;
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pr_err("Error allocating memory for compressed page: %u, size=%u\n",
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index, clen);
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ret = -ENOMEM;
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goto out;
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return -ENOMEM;
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}
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alloced_pages = zs_get_total_pages(meta->mem_pool);
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@ -708,22 +680,45 @@ compress_again:
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if (zram->limit_pages && alloced_pages > zram->limit_pages) {
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zs_free(meta->mem_pool, handle);
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ret = -ENOMEM;
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goto out;
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return -ENOMEM;
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}
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cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
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*out_handle = handle;
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*out_comp_len = comp_len;
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return 0;
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}
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if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
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static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index)
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{
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int ret;
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unsigned long handle;
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unsigned int comp_len;
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void *src, *dst;
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struct zcomp_strm *zstrm;
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struct zram_meta *meta = zram->meta;
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struct page *page = bvec->bv_page;
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if (zram_same_page_write(zram, index, page))
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return 0;
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zstrm = zcomp_stream_get(zram->comp);
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ret = zram_compress(zram, &zstrm, page, &handle, &comp_len);
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if (ret) {
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zcomp_stream_put(zram->comp);
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return ret;
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}
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dst = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
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src = zstrm->buffer;
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if (comp_len == PAGE_SIZE)
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src = kmap_atomic(page);
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memcpy(cmem, src, PAGE_SIZE);
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memcpy(dst, src, comp_len);
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if (comp_len == PAGE_SIZE)
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kunmap_atomic(src);
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} else {
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memcpy(cmem, src, clen);
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}
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zcomp_stream_put(zram->comp);
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zstrm = NULL;
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zs_unmap_object(meta->mem_pool, handle);
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/*
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@ -732,19 +727,54 @@ compress_again:
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*/
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bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
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zram_free_page(zram, index);
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meta->table[index].handle = handle;
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zram_set_obj_size(meta, index, clen);
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zram_set_obj_size(meta, index, comp_len);
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bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
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/* Update stats */
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atomic64_add(clen, &zram->stats.compr_data_size);
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atomic64_add(comp_len, &zram->stats.compr_data_size);
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atomic64_inc(&zram->stats.pages_stored);
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return 0;
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}
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static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
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u32 index, int offset)
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{
|
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int ret;
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struct page *page = NULL;
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void *src;
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struct bio_vec vec;
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|
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vec = *bvec;
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if (is_partial_io(bvec)) {
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void *dst;
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/*
|
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* This is a partial IO. We need to read the full page
|
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* before to write the changes.
|
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*/
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page = alloc_page(GFP_NOIO|__GFP_HIGHMEM);
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if (!page)
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return -ENOMEM;
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ret = zram_decompress_page(zram, page, index);
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if (ret)
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goto out;
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src = kmap_atomic(bvec->bv_page);
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dst = kmap_atomic(page);
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||||
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);
|
||||
|
||||
Loading…
Reference in New Issue
Block a user