From: MITSUNARI Shigeo <[email protected]> Subject: fs/block_dev.c: page cache wrongly left invalidated after revalidate_disk()
We found that bdev->bd_invalidated was left set once revalidate_disk() is called, which results in page cache flush every time that device is open. Specifically, we found this problem in MD block device. Once we resize a MD device, mdadm --monitor periodically flush all page cache for that device every 60 or 1000 seconds when it opens the device. This bug lies since at least 3.2.0 till the latest kernel(3.6.2). Patch is attached. The following steps will reproduce the problem. 1. prepair a block device(ex. /dev/sdb). 2. create two partitions. sudo parted /dev/sdb mklabel gpt mkpart primary 0% 50% mkpart primary 50% 100% 3. create a md device. sudo mdadm -C /dev/md/hoge -l 1 -n 2 -e 1.2 --assume-clean --auto=md \ --symlink=no /dev/sdb1 /dev/sdb2 4. create file system and mount it sudo mkfs.ext3 /dev/md/hoge sudo mkdir /mnt/test sudo mount /dev/md/hoge /mnt/test 5. try to resize the device sudo mdadm -G /dev/md/hoge --size=max 6. create a file to fill file cache. sudo dd if=/dev/urandom of=/mnt/test/data bs=1M count=10 and verity the current status of file by free command. 7. mdadm monitor will open the md device every 1000 seconds and you will find all file cache on the device are cleared. The timing can be reduced by the following steps. a) kill mdadm and restart it with --delay option /sbin/mdadm --monitor --delay=30 --pid-file /var/run/mdadm/monitor.pid \ --daemonise --scan --syslog or open the md device directly. sudo dd if=/dev/md/hoge of=/dev/null bs=4096 count=1 Signed-off-by: MITSUNARI Shigeo <[email protected]> Cc: Al Viro <[email protected]> Cc: Jeff Moyer <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> --- fs/block_dev.c | 1 + 1 file changed, 1 insertion(+) diff -puN fs/block_dev.c~fs-block_devc-page-cache-wrongly-left-invalidated-after-revalidate_disk fs/block_dev.c --- a/fs/block_dev.c~fs-block_devc-page-cache-wrongly-left-invalidated-after-revalidate_disk +++ a/fs/block_dev.c @@ -994,6 +994,7 @@ int revalidate_disk(struct gendisk *disk mutex_lock(&bdev->bd_mutex); check_disk_size_change(disk, bdev); + bdev->bd_invalidated = 0; mutex_unlock(&bdev->bd_mutex); bdput(bdev); return ret; _ -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
