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https://github.com/torvalds/linux.git
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Staging: zram: Refactor zram_read/write() functions
This patch refactor the code of zram_read/write() functions. It does not removes a lot of duplicate code alone, but is mostly a helper for the third patch of this series (Staging: zram: allow partial page operations). Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Jerome Marchand
Greg Kroah-Hartman
parent
6a587e835e
commit
8c921b2b43
@ -203,196 +203,199 @@ static void handle_uncompressed_page(struct zram *zram,
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flush_dcache_page(page);
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}
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static void zram_read(struct zram *zram, struct bio *bio)
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static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
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u32 index, struct bio *bio)
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{
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int ret;
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size_t clen;
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struct page *page;
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struct zobj_header *zheader;
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unsigned char *user_mem, *cmem;
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int i;
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u32 index;
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struct bio_vec *bvec;
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page = bvec->bv_page;
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zram_stat64_inc(zram, &zram->stats.num_reads);
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index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
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bio_for_each_segment(bvec, bio, i) {
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int ret;
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size_t clen;
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struct page *page;
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struct zobj_header *zheader;
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unsigned char *user_mem, *cmem;
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page = bvec->bv_page;
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if (zram_test_flag(zram, index, ZRAM_ZERO)) {
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handle_zero_page(page);
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index++;
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continue;
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}
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/* Requested page is not present in compressed area */
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if (unlikely(!zram->table[index].page)) {
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pr_debug("Read before write: sector=%lu, size=%u",
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(ulong)(bio->bi_sector), bio->bi_size);
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handle_zero_page(page);
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index++;
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continue;
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}
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/* Page is stored uncompressed since it's incompressible */
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if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
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handle_uncompressed_page(zram, page, index);
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index++;
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continue;
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}
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user_mem = kmap_atomic(page, KM_USER0);
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clen = PAGE_SIZE;
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cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
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zram->table[index].offset;
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ret = lzo1x_decompress_safe(
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cmem + sizeof(*zheader),
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xv_get_object_size(cmem) - sizeof(*zheader),
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user_mem, &clen);
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kunmap_atomic(user_mem, KM_USER0);
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kunmap_atomic(cmem, KM_USER1);
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/* Should NEVER happen. Return bio error if it does. */
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if (unlikely(ret != LZO_E_OK)) {
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pr_err("Decompression failed! err=%d, page=%u\n",
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ret, index);
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zram_stat64_inc(zram, &zram->stats.failed_reads);
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goto out;
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}
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flush_dcache_page(page);
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index++;
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if (zram_test_flag(zram, index, ZRAM_ZERO)) {
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handle_zero_page(page);
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return 0;
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}
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set_bit(BIO_UPTODATE, &bio->bi_flags);
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bio_endio(bio, 0);
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return;
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/* Requested page is not present in compressed area */
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if (unlikely(!zram->table[index].page)) {
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pr_debug("Read before write: sector=%lu, size=%u",
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(ulong)(bio->bi_sector), bio->bi_size);
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handle_zero_page(page);
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return 0;
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}
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out:
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bio_io_error(bio);
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/* Page is stored uncompressed since it's incompressible */
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if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED))) {
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handle_uncompressed_page(zram, page, index);
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return 0;
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}
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user_mem = kmap_atomic(page, KM_USER0);
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clen = PAGE_SIZE;
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cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
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zram->table[index].offset;
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ret = lzo1x_decompress_safe(cmem + sizeof(*zheader),
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xv_get_object_size(cmem) - sizeof(*zheader),
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user_mem, &clen);
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kunmap_atomic(user_mem, KM_USER0);
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kunmap_atomic(cmem, KM_USER1);
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/* Should NEVER happen. Return bio error if it does. */
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if (unlikely(ret != LZO_E_OK)) {
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pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
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zram_stat64_inc(zram, &zram->stats.failed_reads);
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return ret;
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}
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flush_dcache_page(page);
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return 0;
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}
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static void zram_write(struct zram *zram, struct bio *bio)
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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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u32 offset;
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size_t clen;
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struct zobj_header *zheader;
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struct page *page, *page_store;
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unsigned char *user_mem, *cmem, *src;
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page = bvec->bv_page;
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src = zram->compress_buffer;
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/*
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* System overwrites unused sectors. Free memory associated
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* with this sector now.
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*/
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if (zram->table[index].page ||
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zram_test_flag(zram, index, ZRAM_ZERO))
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zram_free_page(zram, index);
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mutex_lock(&zram->lock);
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user_mem = kmap_atomic(page, KM_USER0);
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if (page_zero_filled(user_mem)) {
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kunmap_atomic(user_mem, KM_USER0);
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mutex_unlock(&zram->lock);
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zram_stat_inc(&zram->stats.pages_zero);
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zram_set_flag(zram, index, ZRAM_ZERO);
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return 0;
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}
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ret = lzo1x_1_compress(user_mem, PAGE_SIZE, src, &clen,
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zram->compress_workmem);
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kunmap_atomic(user_mem, KM_USER0);
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if (unlikely(ret != LZO_E_OK)) {
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mutex_unlock(&zram->lock);
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pr_err("Compression failed! err=%d\n", ret);
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zram_stat64_inc(zram, &zram->stats.failed_writes);
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return ret;
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}
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/*
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* Page is incompressible. Store it as-is (uncompressed)
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* since we do not want to return too many disk write
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* errors which has side effect of hanging the system.
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*/
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if (unlikely(clen > max_zpage_size)) {
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clen = PAGE_SIZE;
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page_store = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
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if (unlikely(!page_store)) {
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mutex_unlock(&zram->lock);
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pr_info("Error allocating memory for "
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"incompressible page: %u\n", index);
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zram_stat64_inc(zram, &zram->stats.failed_writes);
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return -ENOMEM;
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}
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offset = 0;
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zram_set_flag(zram, index, ZRAM_UNCOMPRESSED);
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zram_stat_inc(&zram->stats.pages_expand);
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zram->table[index].page = page_store;
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src = kmap_atomic(page, KM_USER0);
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goto memstore;
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}
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if (xv_malloc(zram->mem_pool, clen + sizeof(*zheader),
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&zram->table[index].page, &offset,
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GFP_NOIO | __GFP_HIGHMEM)) {
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mutex_unlock(&zram->lock);
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pr_info("Error allocating memory for compressed "
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"page: %u, size=%zu\n", index, clen);
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zram_stat64_inc(zram, &zram->stats.failed_writes);
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return -ENOMEM;
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}
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memstore:
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zram->table[index].offset = offset;
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cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
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zram->table[index].offset;
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#if 0
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/* Back-reference needed for memory defragmentation */
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if (!zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)) {
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zheader = (struct zobj_header *)cmem;
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zheader->table_idx = index;
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cmem += sizeof(*zheader);
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}
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#endif
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memcpy(cmem, src, clen);
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kunmap_atomic(cmem, KM_USER1);
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if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)))
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kunmap_atomic(src, KM_USER0);
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/* Update stats */
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zram_stat64_add(zram, &zram->stats.compr_size, clen);
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zram_stat_inc(&zram->stats.pages_stored);
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if (clen <= PAGE_SIZE / 2)
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zram_stat_inc(&zram->stats.good_compress);
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mutex_unlock(&zram->lock);
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return 0;
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}
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static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
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struct bio *bio, int rw)
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{
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if (rw == READ)
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return zram_bvec_read(zram, bvec, index, bio);
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return zram_bvec_write(zram, bvec, index);
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}
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static void __zram_make_request(struct zram *zram, struct bio *bio, int rw)
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{
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int i;
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u32 index;
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struct bio_vec *bvec;
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zram_stat64_inc(zram, &zram->stats.num_writes);
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switch (rw) {
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case READ:
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zram_stat64_inc(zram, &zram->stats.num_reads);
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break;
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case WRITE:
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zram_stat64_inc(zram, &zram->stats.num_writes);
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break;
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}
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index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
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bio_for_each_segment(bvec, bio, i) {
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int ret;
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u32 offset;
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size_t clen;
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struct zobj_header *zheader;
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struct page *page, *page_store;
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unsigned char *user_mem, *cmem, *src;
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page = bvec->bv_page;
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src = zram->compress_buffer;
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/*
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* System overwrites unused sectors. Free memory associated
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* with this sector now.
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*/
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if (zram->table[index].page ||
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zram_test_flag(zram, index, ZRAM_ZERO))
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zram_free_page(zram, index);
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mutex_lock(&zram->lock);
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user_mem = kmap_atomic(page, KM_USER0);
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if (page_zero_filled(user_mem)) {
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kunmap_atomic(user_mem, KM_USER0);
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mutex_unlock(&zram->lock);
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zram_stat_inc(&zram->stats.pages_zero);
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zram_set_flag(zram, index, ZRAM_ZERO);
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index++;
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continue;
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}
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ret = lzo1x_1_compress(user_mem, PAGE_SIZE, src, &clen,
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zram->compress_workmem);
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kunmap_atomic(user_mem, KM_USER0);
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if (unlikely(ret != LZO_E_OK)) {
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mutex_unlock(&zram->lock);
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pr_err("Compression failed! err=%d\n", ret);
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zram_stat64_inc(zram, &zram->stats.failed_writes);
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if (zram_bvec_rw(zram, bvec, index, bio, rw) < 0)
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goto out;
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}
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/*
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* Page is incompressible. Store it as-is (uncompressed)
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* since we do not want to return too many disk write
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* errors which has side effect of hanging the system.
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*/
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if (unlikely(clen > max_zpage_size)) {
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clen = PAGE_SIZE;
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page_store = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
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if (unlikely(!page_store)) {
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mutex_unlock(&zram->lock);
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pr_info("Error allocating memory for "
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"incompressible page: %u\n", index);
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zram_stat64_inc(zram,
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&zram->stats.failed_writes);
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goto out;
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}
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offset = 0;
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zram_set_flag(zram, index, ZRAM_UNCOMPRESSED);
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zram_stat_inc(&zram->stats.pages_expand);
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zram->table[index].page = page_store;
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src = kmap_atomic(page, KM_USER0);
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goto memstore;
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}
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if (xv_malloc(zram->mem_pool, clen + sizeof(*zheader),
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&zram->table[index].page, &offset,
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GFP_NOIO | __GFP_HIGHMEM)) {
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mutex_unlock(&zram->lock);
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pr_info("Error allocating memory for compressed "
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"page: %u, size=%zu\n", index, clen);
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zram_stat64_inc(zram, &zram->stats.failed_writes);
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goto out;
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}
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memstore:
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zram->table[index].offset = offset;
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cmem = kmap_atomic(zram->table[index].page, KM_USER1) +
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zram->table[index].offset;
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#if 0
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/* Back-reference needed for memory defragmentation */
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if (!zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)) {
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zheader = (struct zobj_header *)cmem;
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zheader->table_idx = index;
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cmem += sizeof(*zheader);
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}
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#endif
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memcpy(cmem, src, clen);
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kunmap_atomic(cmem, KM_USER1);
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if (unlikely(zram_test_flag(zram, index, ZRAM_UNCOMPRESSED)))
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kunmap_atomic(src, KM_USER0);
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/* Update stats */
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zram_stat64_add(zram, &zram->stats.compr_size, clen);
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zram_stat_inc(&zram->stats.pages_stored);
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if (clen <= PAGE_SIZE / 2)
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zram_stat_inc(&zram->stats.good_compress);
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mutex_unlock(&zram->lock);
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index++;
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}
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@ -439,15 +442,7 @@ static int zram_make_request(struct request_queue *queue, struct bio *bio)
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return 0;
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}
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switch (bio_data_dir(bio)) {
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case READ:
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zram_read(zram, bio);
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break;
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case WRITE:
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zram_write(zram, bio);
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break;
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}
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__zram_make_request(zram, bio, bio_data_dir(bio));
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return 0;
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}
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