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authorMinchan Kim <minchan@kernel.org>2014-07-02 15:22:36 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-07-03 09:21:53 -0700
commit2e32baea46ce542c561a519414c840295b229c8f (patch)
tree1d260e3d42b7bac729de43168cbce143996c0c65 /Documentation
parente98f776224301141f79b2b1e8d01633429a5dbfe (diff)
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 <minchan@kernel.org> Reported-by: Alexander E. Patrakov <patrakov@gmail.com> Tested-by: Alexander E. Patrakov <patrakov@gmail.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Nitin Gupta <ngupta@vflare.org> Acked-by: Jerome Marchand <jmarchan@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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