From 2e32baea46ce542c561a519414c840295b229c8f Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Wed, 2 Jul 2014 15:22:36 -0700 Subject: [PATCH] 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(-) 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; -- 2.20.1