[ 147/221] staging: zram: factor-out zram_decompress_page() function

Greg Kroah-Hartman
2013-01-15T22:33:10Z

From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>

commit 37b51fdddf64e7ba0971d070428655f8d6f36578 upstream.

zram_bvec_read() shared decompress functionality with zram_read_before_write() function.
Factor-out and make commonly used zram_decompress_page() function, which also simplified
error handling in zram_bvec_read().

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/staging/zram/zram_drv.c | 113 ++++++++++++++++------------------------
1 file changed, 48 insertions(+), 65 deletions(-)

--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -183,62 +183,25 @@ static inline int is_partial_io(struct b
return bvec->bv_len != PAGE_SIZE;
}

-static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
- u32 index, int offset, struct bio *bio)
+static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
{
- int ret;
- size_t clen;
- struct page *page;
- unsigned char *user_mem, *cmem, *uncmem = NULL;
-
- page = bvec->bv_page;
-
- if (zram_test_flag(zram, index, ZRAM_ZERO)) {
- handle_zero_page(bvec);
- return 0;
- }
+ int ret = LZO_E_OK;
+ size_t clen = PAGE_SIZE;
+ unsigned char *cmem;
+ unsigned long handle = zram->table[index].handle;

- /* Requested page is not present in compressed area */
- if (unlikely(!zram->table[index].handle)) {
- pr_debug("Read before write: sector=%lu, size=%u",
- (ulong)(bio->bi_sector), bio->bi_size);
- handle_zero_page(bvec);
+ if (!handle || zram_test_flag(zram, index, ZRAM_ZERO)) {
+ memset(mem, 0, PAGE_SIZE);
return 0;
}

- if (is_partial_io(bvec)) {
- /* Use a temporary buffer to decompress the page */
- uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
- if (!uncmem) {
- pr_info("Error allocating temp memory!\n");
- return -ENOMEM;
- }
- }
-
- user_mem = kmap_atomic(page);
- if (!is_partial_io(bvec))
- uncmem = user_mem;
- clen = PAGE_SIZE;
-
- cmem = zs_map_object(zram->mem_pool, zram->table[index].handle,
- ZS_MM_RO);
-
- if (zram->table[index].size == PAGE_SIZE) {
- memcpy(uncmem, cmem, PAGE_SIZE);
- ret = LZO_E_OK;
- } else {
+ cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
+ if (zram->table[index].size == PAGE_SIZE)
+ memcpy(mem, cmem, PAGE_SIZE);
+ else
ret = lzo1x_decompress_safe(cmem, zram->table[index].size,
- uncmem, &clen);
- }
-
- if (is_partial_io(bvec)) {
- memcpy(user_mem + bvec->bv_offset, uncmem + offset,
- bvec->bv_len);
- kfree(uncmem);
- }
-
- zs_unmap_object(zram->mem_pool, zram->table[index].handle);
- kunmap_atomic(user_mem);
+ mem, &clen);
+ zs_unmap_object(zram->mem_pool, handle);

/* Should NEVER happen. Return bio error if it does. */
if (unlikely(ret != LZO_E_OK)) {
@@ -247,36 +210,56 @@ static int zram_bvec_read(struct zram *z
return ret;
}

- flush_dcache_page(page);
-
return 0;
}

-static int zram_read_before_write(struct zram *zram, char *mem, u32 index)
+static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
+ u32 index, int offset, struct bio *bio)
{
int ret;
- size_t clen = PAGE_SIZE;
- unsigned char *cmem;
- unsigned long handle = zram->table[index].handle;
+ struct page *page;
+ unsigned char *user_mem, *uncmem = NULL;

- if (zram_test_flag(zram, index, ZRAM_ZERO) || !handle) {
- memset(mem, 0, PAGE_SIZE);
+ page = bvec->bv_page;
+
+ if (unlikely(!zram->table[index].handle) ||
+ zram_test_flag(zram, index, ZRAM_ZERO)) {
+ handle_zero_page(bvec);
return 0;
}

- cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
- ret = lzo1x_decompress_safe(cmem, zram->table[index].size,
- mem, &clen);
- zs_unmap_object(zram->mem_pool, handle);
+ user_mem = kmap_atomic(page);
+ if (is_partial_io(bvec))
+ /* Use a temporary buffer to decompress the page */
+ uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ else
+ uncmem = user_mem;
+
+ if (!uncmem) {
+ pr_info("Unable to allocate temp memory\n");
+ ret = -ENOMEM;
+ goto out_cleanup;
+ }

+ ret = zram_decompress_page(zram, uncmem, index);
/* Should NEVER happen. Return bio error if it does. */
if (unlikely(ret != LZO_E_OK)) {
pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
zram_stat64_inc(zram, &zram->stats.failed_reads);
- return ret;
+ goto out_cleanup;
}

- return 0;
+ if (is_partial_io(bvec))
+ memcpy(user_mem + bvec->bv_offset, uncmem + offset,
+ bvec->bv_len);
+
+ 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,
@@ -302,7 +285,7 @@ static int zram_bvec_write(struct zram *
ret = -ENOMEM;
goto out;
}
- ret = zram_read_before_write(zram, uncmem, index);
+ ret = zram_decompress_page(zram, uncmem, index);
if (ret) {
kfree(uncmem);
goto out;