2011/12/07 0:20, Christoph Hellwig wrote:
On Thu, Dec 01, 2011 at 04:51:07PM +0900, Kazuya Mio wrote:
dd slept infinitely when fsfeeze failed because of EIO.
To fix this problem, if ->freeze_fs fails, freeze_super() wakes up
the tasks waiting for the filesystem to become unfrozen.
When s_frozen isn't SB_UNFROZEN in __generic_file_aio_write(),
the function sleeps until FITHAW ioctl wakes up s_wait_unfrozen.
However, if ->freeze_fs fails, s_frozen is set to SB_UNFROZEN and then
freeze_super() returns an error number. In this case, FITHAW ioctl returns
EINVAL because s_frozen is already SB_UNFROZEN. There is no way to wake up
s_wait_unfrozen, so __generic_file_aio_write() sleeps infinitely.
Looks good,
Reviewed-by: Christoph Hellwig<hch@xxxxxx>
You don't happen to have testcase (e.g. by using dm-fauly or XFS error
injection) that we could add to xfstests for this?
The problem can be reproduced by the following steps:
1. make faulty md device with mdadm
# mdadm -B /dev/md1000 -l faulty -n 1 -R <device>
2. mkfs and mount filesystem
# mkfs.ext4 /dev/md1000
# mount /dev/md1000 <mount point>
3. run 1000 dd commands in the background to create one 10MB file
# for NO in {1..1000} ; do dd if=/dev/zero of=<mount point>/testfile \
bs=1M count=10 ;done
4. sleep three seconds for the adjustment with the time of fault injection
# sleep 3
5. inject the md device with fault in the background
# mdadm -G /dev/md1000 -l faulty -p wp1 &
6. freeze filesystem with fsfreeze (and it fails because of EIO)
# freeze -f <mount point>
As a result, dd executed in step 3 sleeps forever.
Regards,
Kazuya Mio
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