The patch titled
Subject: fs/block_dev.c: page cache wrongly left invalidated after revalidate_disk()
has been added to the -mm tree. Its filename is
fs-block_devc-page-cache-wrongly-left-invalidated-after-revalidate_disk.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: MITSUNARI Shigeo <herumi@xxxxxxxxx>
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 <herumi@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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
@@ -1073,6 +1073,7 @@ 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;
_
Patches currently in -mm which might be from herumi@xxxxxxxxx are
fs-block_devc-page-cache-wrongly-left-invalidated-after-revalidate_disk.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
