alistair23-linux/drivers/block/zram
Minchan Kim 2e32baea46 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>
2014-07-03 09:21:53 -07:00
..
Kconfig zram: add lz4 algorithm backend 2014-04-07 16:36:01 -07:00
Makefile zram: add lz4 algorithm backend 2014-04-07 16:36:01 -07:00
zcomp.c zram: use scnprintf() in attrs show() methods 2014-04-07 16:36:02 -07:00
zcomp.h zram: propagate error to user 2014-04-07 16:36:02 -07:00
zcomp_lz4.c zram: add lz4 algorithm backend 2014-04-07 16:36:01 -07:00
zcomp_lz4.h zram: add lz4 algorithm backend 2014-04-07 16:36:01 -07:00
zcomp_lzo.c zram: introduce compressing backend abstraction 2014-04-07 16:36:01 -07:00
zcomp_lzo.h zram: introduce compressing backend abstraction 2014-04-07 16:36:01 -07:00
zram_drv.c zram: revalidate disk after capacity change 2014-07-03 09:21:53 -07:00
zram_drv.h zram: make compression algorithm selection possible 2014-04-07 16:36:01 -07:00