From 38515c73398a4c58059ecf1087e844561b58ee0f Mon Sep 17 00:00:00 2001 From: Weijie Yang Date: Wed, 4 Jun 2014 16:11:06 -0700 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 Cc: Minchan Kim Cc: Nitin Gupta Acked-by: Joonsoo Kim Cc: Sergey Senozhatsky Cc: Bob Liu Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/block/zram/zram_drv.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/block/zram/zram_drv.c') diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 9849b5233bf4..48eccb350180 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -572,10 +572,10 @@ static void zram_bio_discard(struct zram *zram, u32 index, * 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++; } -- cgit v1.2.3 From 2e32baea46ce542c561a519414c840295b229c8f Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Wed, 2 Jul 2014 15:22:36 -0700 Subject: zram: revalidate disk after capacity change Alexander reported mkswap on /dev/zram0 is failed if other process is opening the block device file. Step is as follows, 0. Reset the unused zram device. 1. Use a program that opens /dev/zram0 with O_RDWR and sleeps until killed. 2. While that program sleeps, echo the correct value to /sys/block/zram0/disksize. 3. Verify (e.g. in /proc/partitions) that the disk size is applied correctly. It is. 4. While that program still sleeps, attempt to mkswap /dev/zram0. This fails: mkswap: error: swap area needs to be at least 40 KiB When I investigated, the size get by ioctl(fd, BLKGETSIZE64, xxx) on mkswap to get a size of blockdev was zero although zram0 has right size by 2. The reason is zram didn't revalidate disk after changing capacity so that size of blockdev's inode is not uptodate until all of file is close. This patch should fix the BUG. Signed-off-by: Minchan Kim Reported-by: Alexander E. Patrakov Tested-by: Alexander E. Patrakov Reviewed-by: Sergey Senozhatsky Cc: Nitin Gupta Acked-by: Jerome Marchand Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/block/zram/zram_drv.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'drivers/block/zram/zram_drv.c') diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 48eccb350180..089e72cd37be 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -622,8 +622,10 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity) memset(&zram->stats, 0, sizeof(zram->stats)); zram->disksize = 0; - if (reset_capacity) + if (reset_capacity) { set_capacity(zram->disk, 0); + revalidate_disk(zram->disk); + } up_write(&zram->init_lock); } @@ -664,6 +666,7 @@ static ssize_t disksize_store(struct device *dev, zram->comp = comp; zram->disksize = disksize; set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT); + revalidate_disk(zram->disk); up_write(&zram->init_lock); return len; -- cgit v1.2.3