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Commit ce0c9b53 authored by Sunghan Suh's avatar Sunghan Suh Committed by Olav Haugan
Browse files

zram: prevent data loss in error cases of function zram_bvec_write() 



In function zram_bvec_write(), previous data at the index is
already freed by function zram_free_page().
When failed to compress or zs_malloc, there is no way to restore old data.
Therefore, free previous data when it's about to update.

Also, no need to check whether table is not empty outside of
function zram_free_page(), because the function properly checks inside.

Change-Id: I8cb3daf146a99d3b5999c7a42e5e2a260f4c3a48
Signed-off-by: default avatarSunghan Suh <sunghan.suh@samsung.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit: f40ac2ae1b506484dd9261a24bbf3e86b2206ff8
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: default avatarOlav Haugan <ohaugan@codeaurora.org>
parent 15ff9eda

drivers/staging/zram/zram_drv.c

+9 −8
Original line number Diff line number Diff line
@@ -418,14 +418,6 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, 
			goto out;

	}



	/*

	 * System overwrites unused sectors. Free memory associated

	 * with this sector now.

	 */

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

	    zram_test_flag(meta, index, ZRAM_ZERO))

		zram_free_page(zram, index);



	user_mem = kmap_atomic(page);



	if (is_partial_io(bvec)) {
@@ -439,6 +431,9 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, 


	if (page_zero_filled(uncmem)) {

		kunmap_atomic(user_mem);

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

		zram_free_page(zram, index);



		zram->stats.pages_zero++;

		zram_set_flag(meta, index, ZRAM_ZERO);

		ret = 0;
@@ -486,6 +481,12 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, 


	zs_unmap_object(meta->mem_pool, handle);



	/*

	 * Free memory associated with this sector

	 * before overwriting unused sectors.

	 */

	zram_free_page(zram, index);



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

	meta->table[index].size = clen;