From: Weijie Yang <[email protected]> Subject: zram: correct offset usage in zram_bio_discard
We want to skip the physical block(PAGE_SIZE) which is partially covered by the discard bio, so we check the remaining size and subtract it if there is a need to goto the next physical block. The current offset usage in zram_bio_discard is incorrect, it will cause its upper filesystem breakdown. Consider the following scenario: On some architecture or config, PAGE_SIZE is 64K for example, filesystem is set up on zram disk without PAGE_SIZE aligned, a discard bio leads to a offset = 4K and size=72K, normally, it should not really discard any physical block as it partially cover two physical blocks. However, with the current offset usage, it will discard the second physical block and free its memory, which will cause filesystem breakdown. This patch corrects the offset usage in zram_bio_discard. Signed-off-by: Weijie Yang <[email protected]> Cc: Minchan Kim <[email protected]> Cc: Nitin Gupta <[email protected]> Acked-by: Joonsoo Kim <[email protected]> Cc: Sergey Senozhatsky <[email protected]> Cc: Bob Liu <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> --- drivers/block/zram/zram_drv.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -puN drivers/block/zram/zram_drv.c~zram-correct-offset-usage-in-zram_bio_discard drivers/block/zram/zram_drv.c --- a/drivers/block/zram/zram_drv.c~zram-correct-offset-usage-in-zram_bio_discard +++ a/drivers/block/zram/zram_drv.c @@ -572,10 +572,10 @@ static void zram_bio_discard(struct zram * skipping this logical block is appropriate here. */ if (offset) { - if (n < offset) + if (n <= (PAGE_SIZE - offset)) return; - n -= offset; + n -= (PAGE_SIZE - offset); index++; } _ -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
