From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx>
Reported-by: Alexander E. Patrakov <patrakov@xxxxxxxxx>
Tested-by: Alexander E. Patrakov <patrakov@xxxxxxxxx>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Acked-by: Jerome Marchand <jmarchan@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff -puN drivers/block/zram/zram_drv.c~zram-revalidate-disk-after-capacity-change drivers/block/zram/zram_drv.c
--- a/drivers/block/zram/zram_drv.c~zram-revalidate-disk-after-capacity-change
+++ a/drivers/block/zram/zram_drv.c
@@ -622,8 +622,10 @@ static void zram_reset_device(struct zra
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 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;
_
--
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