1) Description of problem:

Trying to unmount an XFS filesystem on an offlined drive hangs with the message "metadata I/O error: block 0x0 ("xfs_buf_iodone_callbacks") error 19 numblks 1"

2) Version-Release number of selected component (if applicable):

kernel 3.10.0-121.el7.x86_64
xfsprogs-3.2.0-0.10.alpha2.el7.x86_64


3) How reproducible:

Always

4) Steps to Reproduce:

The following script helps to reproduce the problem easily.

~~~
#!/bin/bash

DISK=/dev/sdc1
SCSI=`ls /sys/block/${DISK:5:3}/device/scsi_device/`

mkdir -p /mnt/xfs

while true; do

    echo "mkfs on $DISK"
    mkfs.xfs -f $DISK
    sleep 1;
    echo "mount and IO on $DISK"
    mount $DISK /mnt/xfs
    dd if=/dev/zero of=/mnt/xfs/file1 bs=1M count=500
    sync
    sleep 1
    echo "offline $DISK"
    echo 1 > /sys/block/${DISK:5:3}/device/delete
    echo "umount..."
    while ( ! umount /mnt/xfs ) && [ -n "`cat /proc/mounts | egrep -e \"/mnt/xfs\"`" ] ; do echo "retrying in 5 sec."; sleep 5; done
    echo "done"
    sleep 3;
    echo "online $SCSI"
    echo "- - -" > /sys/class/scsi_host/host${SCSI:0:1}/scan
    sleep 5
    DISK=/dev/`ls /sys/class/scsi_device/$SCSI/device/block`1
    echo "new disk name: $DISK"
done
~~~

5) Actual results:

The unmount hangs at the terminal, and the logs fills up /var/log/messages. The logs are as following:

~~~
May 26 22:50:51 localhost kernel: XFS (sda1): Mounting Filesystem
May 26 22:50:51 localhost kernel: XFS (sda1): Ending clean mount
May 26 22:50:58 localhost kernel: sd 2:0:0:1: [sda] Synchronizing SCSI cache
May 26 22:50:58 localhost kernel: XFS (sda1): metadata I/O error: block 0x0 ("xfs_buf_iodone_callbacks") error 19 numblks 1
May 26 22:50:58 localhost kernel: XFS (sda1): Detected failing async write on buffer block 0x10. Retrying async write.
May 26 22:50:58 localhost kernel: XFS (sda1): Detected failing async write on buffer block 0x8. Retrying async write.
May 26 22:50:58 localhost kernel: XFS (sda1): Detected failing async write on buffer block 0x1. Retrying async write.
May 26 22:50:58 localhost kernel: XFS (sda1): Detected failing async write on buffer block 0x0. Retrying async write.
May 26 22:50:58 localhost kernel: XFS (sda1): Detected failing async write on buffer block 0x18. Retrying async write.
May 26 22:50:58 localhost kernel: XFS (sda1): Detected failing async write on buffer block 0x2. Retrying async write.
May 26 22:50:58 localhost kernel: XFS (sda1): Detected failing async write on buffer block 0x10. Retrying async write.
May 26 22:50:58 localhost kernel: XFS (sda1): Detected failing async write on buffer block 0x8. Retrying async write.
May 26 22:50:58 localhost kernel: XFS (sda1): Detected failing async write on buffer block 0x1. Retrying async write.
May 26 22:50:58 localhost kernel: XFS (sda1): Detected failing async write on buffer block 0x0. Retrying async write.
May 26 22:51:03 localhost kernel: XFS (sda1): metadata I/O error: block 0x0 ("xfs_buf_iodone_callbacks") error 19 numblks 1
May 26 22:51:08 localhost kernel: XFS (sda1): metadata I/O error: block 0x0 ("xfs_buf_iodone_callbacks") error 19 numblks 1
May 26 22:51:13 localhost kernel: XFS (sda1): metadata I/O error: block 0x0 ("xfs_buf_iodone_callbacks") error 19 numblks 1
May 26 22:51:18 localhost kernel: XFS (sda1): metadata I/O error: block 0x0 ("xfs_buf_iodone_callbacks") error 19 numblks 1
May 26 22:51:23 localhost kernel: XFS (sda1): metadata I/O error: block 0x0 ("xfs_buf_iodone_callbacks") error 19 numblks 1
May 26 22:51:28 localhost kernel: XFS:: 3590 callbacks suppressed
~~~

6) Expected results:

The umount should either fail or finish properly.