From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Minchan Kim To: Andrew Morton Cc: linux-kernel@vger.kernel.org, "Alexander E. Patrakov" , Nitin Gupta , Jerome Marchand , Sergey Senozhatsky , Minchan Kim , stable@vger.kernel.org Subject: [PATCH] zram: revalidate disk after capacity change Date: Thu, 26 Jun 2014 10:16:25 +0900 Message-Id: <1403745385-18952-1-git-send-email-minchan@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 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. Cc: stable@vger.kernel.org Reported-and-Tested-by: Alexander E. Patrakov Signed-off-by: Minchan Kim --- 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 48eccb3..089e72c 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; -- 2.0.0