On (06/26/14 10:16), Minchan Kim wrote:
> 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.
>
Good catch
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
-ss
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-and-Tested-by: Alexander E. Patrakov <patrakov@xxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
> ---
> 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
>
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html