Bug 1051350

Bug 995415 for qemu-kvm-rhev is moved to RHEL7.2.

set bz 995415 to needinfo and ask if any updates happened in that bg.
And this testonly bg shows the readonly works but with small problem. 

My env
Host Versions:
libvirt-1.2.17-7.el7.x86_64
qemu-kvm-rhev-2.3.0-22.el7.x86_64
kernel-3.10.0-304.el7.x86_64

Guest OS versions:
kernel-3.10.0-313.el7.x86_64

Steps:
Prepare a iscsi lun 
# lsscsi
...      
[15:0:0:1]   disk    IET      VIRTUAL-DISK     0001  /dev/sdi 


In Host:
1. add following xml seg in to vm's xml
# virsh edit rhel7_Sep4
...
    <hostdev mode='subsystem' type='scsi' managed='no'>
      <source>
        <adapter name='scsi_host15'/>
        <address bus='0' target='0' unit='1'/>
      </source>
      <readonly/>
    </hostdev>
2. start the guest
#virsh start rhel7_Sep4

3. check the qemu cmd
#ps -ef | grep qemu-kvm
/usr/libexec/qemu-kvm -name rhel7_Sep4 -S -machine pc-i440fx-rhel7.2.0,accel=kvm,usb=off,vmport=off -cpu SandyBridge -m 1024 -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -uuid d6caff70-2e88-4973-816c-997290ea1b1a -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-rhel7_Sep4/monitor.sock,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc,driftfix=slew -global kvm-pit.lost_tick_policy=discard -no-hpet -no-shutdown -global PIIX4_PM.disable_s3=1 -global PIIX4_PM.disable_s4=1 -boot strict=on -device ich9-usb-ehci1,id=usb,bus=pci.0,addr=0x6.0x7 -device ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x6 -device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.0,addr=0x6.0x1 -device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,addr=0x6.0x2 -device virtio-scsi-pci,id=scsi0,bus=pci.0,addr=0x9 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x5 -drive file=/home/pool/rhel7_Sep4.qcow2,if=none,id=drive-virtio-disk0,format=qcow2 -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x7,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -netdev tap,fd=26,id=hostnet0,vhost=on,vhostfd=27 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:64:b8:97,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev socket,id=charchannel0,path=/var/lib/libvirt/qemu/channel/target/domain-rhel7_Sep4/org.qemu.guest_agent.0,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0 -chardev spicevmc,id=charchannel1,name=vdagent -device virtserialport,bus=virtio-serial0.0,nr=2,chardev=charchannel1,id=channel1,name=com.redhat.spice.0 -device usb-tablet,id=input0 -spice port=5901,addr=127.0.0.1,disable-ticketing,image-compression=off,seamless-migration=on -device qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,vgamem_mb=16,bus=pci.0,addr=0x2 -device intel-hda,id=sound0,bus=pci.0,addr=0x4 -device hda-duplex,id=sound0-codec0,bus=sound0.0,cad=0 -chardev spicevmc,id=charredir0,name=usbredir -device usb-redir,chardev=charredir0,id=redir0 -chardev spicevmc,id=charredir1,name=usbredir -device usb-redir,chardev=charredir1,id=redir1 -drive file=/dev/sg11,if=none,id=drive-hostdev0,readonly=on -device scsi-generic,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-hostdev0,id=hostdev0 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x8 -msg timestamp=on

In Guest:
(sda is already mkfs.ext4'd previously)
1. # mount /dev/sda /mnt
2. ll /mnt    <==== there are some existing files. 
total 20
-rw-r--r--. 1 root root     5 Sep  7 14:20 1
-rw-r--r--. 1 root root     0 Sep  7 14:18 21
drwx------. 2 root root 16384 Sep  7 14:17 lost+found

3. write to sda <=== sda seems still can be written
[root@localhost ~]# echo "test" > /mnt/3
[root@localhost ~]# cat /mnt/3 
test

4. in a few seconds, there are following errors produced in /var/log/messages
#tailf /var/log/messages
...
Sep  7 15:33:24 localhost kernel: sd 2:0:0:0: [sda] FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Sep  7 15:33:24 localhost kernel: sd 2:0:0:0: [sda] Sense Key : Aborted Command [current] 
Sep  7 15:33:24 localhost kernel: sd 2:0:0:0: [sda] Add. Sense: I/O process terminated
Sep  7 15:33:24 localhost kernel: sd 2:0:0:0: [sda] CDB: Write(10) 2a 00 00 10 00 00 00 00 08 00
Sep  7 15:33:24 localhost kernel: blk_update_request: I/O error, dev sda, sector 1048576
Sep  7 15:33:24 localhost kernel: Buffer I/O error on device sda, logical block 131072
Sep  7 15:33:24 localhost kernel: lost page write due to I/O error on sda
Sep  7 15:33:24 localhost kernel: JBD2: Error -5 detected when updating journal superblock for sda-8.
Sep  7 15:33:24 localhost kernel: sd 2:0:0:0: [sda] FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Sep  7 15:33:24 localhost kernel: sd 2:0:0:0: [sda] Sense Key : Aborted Command [current] 
Sep  7 15:33:24 localhost kernel: sd 2:0:0:0: [sda] Add. Sense: I/O process terminated
Sep  7 15:33:24 localhost kernel: sd 2:0:0:0: [sda] CDB: Write(10) 2a 00 00 10 00 08 00 00 30 00
Sep  7 15:33:24 localhost kernel: blk_update_request: I/O error, dev sda, sector 1048584
Sep  7 15:33:24 localhost kernel: Aborting journal on device sda-8.
Sep  7 15:33:24 localhost kernel: sd 2:0:0:0: [sda] FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Sep  7 15:33:24 localhost kernel: sd 2:0:0:0: [sda] Sense Key : Aborted Command [current] 
Sep  7 15:33:24 localhost kernel: sd 2:0:0:0: [sda] Add. Sense: I/O process terminated
Sep  7 15:33:24 localhost kernel: sd 2:0:0:0: [sda] CDB: Write(10) 2a 00 00 10 00 00 00 00 08 00
Sep  7 15:33:24 localhost kernel: blk_update_request: I/O error, dev sda, sector 1048576
Sep  7 15:33:24 localhost kernel: Buffer I/O error on device sda, logical block 131072
Sep  7 15:33:24 localhost kernel: lost page write due to I/O error on sda
Sep  7 15:33:24 localhost kernel: JBD2: Error -5 detected when updating journal superblock for sda-8.

5. after errors logged in /var/log/messages, the sda cannot be written anymore with explicit error in terminal, as follow:

# echo "test" > /mnt/4
-bash: /mnt/4: Read-only file system



In guest step 3, the write option should be failed and error should be popped up to terminal. And actually, if I remount the /dev/sda, the data generated in step 3 is lost.

Verified on:
libvirt-1.3.5-1.el7.x86_64
qemu-kvm-rhev-2.6.0-5.el7.x86_64


On HOST:
# lsscsi
[0:0:0:0]    disk    ATA      WDC WD5000AAKX-6 1H18  /dev/sda 
[2:0:0:0]    cd/dvd  hp       CDDVDW SH-216BB  HE50  /dev/sr0 
[6:0:0:0]    storage IET      Controller       0001  -        
[6:0:0:1]    disk    IET      VIRTUAL-DISK     0001  /dev/sdb 
[6:0:0:2]    disk    IET      VIRTUAL-DISK     0001  /dev/sdc 
[6:0:0:3]    disk    IET      VIRTUAL-DISK     0001  /dev/sdd 

# mkfs.ext4 /dev/sdb
mke2fs 1.42.9 (28-Dec-2013)
/dev/sdb is entire device, not just one partition!
Proceed anyway? (y,n) y
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
65536 inodes, 262144 blocks
13107 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=268435456
8 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks: 
	32768, 98304, 163840, 229376

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done

# virsh list
 Id    Name                           State
----------------------------------------------------
 8     virtlab_test                   running

# virsh dumpxml  virtlab_test  | grep hostdev -A10
    <hostdev mode='subsystem' type='scsi' managed='no'>
      <source>
        <adapter name='scsi_host6'/>
        <address bus='0' target='0' unit='1'/>
      </source>
      <readonly/>
      <alias name='hostdev0'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </hostdev>
...


On GUEST:
# mkfs.ext4 /dev/sda 
mke2fs 1.42.12 (29-Aug-2014)
/dev/sda contains a ext4 file system
	created on Tue Jun 14 02:47:19 2016
Proceed anyway? (y,n) y
/dev/sda: Read-only file system while setting up superblock


# mount /dev/sda /mnt/
mount: /dev/sda is write-protected, mounting read-only

# echo "hahha" > /mnt/1.txt
-bash: /mnt/1.txt: Read-only file system

# ll /mnt
total 16
drwx------ 2 root root 16384 Jun 14 02:47 lost+found

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHSA-2016-2577.html