[Gluster-devel] IO errors when booting VM images on gluster volume via FUSE mount

[Bharata B Rao]

Hi,

With latest QEMU and latest gluster git, I observe guest root
filesystem corruption when the VM boots.

QEMU command line I am using is this:
qemu-system-x86_64 --enable-kvm --nographic -m 1024 -smp 4 -drive
file=/mnt/F17,if=virtio -net nic,model=virtio -net user -redir
tcp:2000::22

Gluster volume is mounted in this manner:
glusterfs -s bharata --volfile-id=test -L DEBUG -l glusterfs.log /mnt

I see IO errors like this when VM boots:
[    1.698583] end_request: I/O error, dev vda, sector 9680896
[    1.699328] Buffer I/O error on device vda3, logical block 1081344
[    1.699328] lost page write due to I/O error on vda3
[    1.706644] end_request: I/O error, dev vda, sector 1030144
[    1.707630] Buffer I/O error on device vda3, logical block 0
[    1.707630] lost page write due to I/O error on vda3
[    1.718671] dracut:
/dev/disk/by-uuid/d29b972f-3568-4db6-bf96-d2702ec83ab6: clean,
21999/623392 files, 796916/2492672 blocks
[    1.723455] dracut: Remounting
/dev/disk/by-uuid/d29b972f-3568-4db6-bf96-d2702ec83ab6 with -o ro

VM eventually comes up with RO rootfs. Shutdown path sees these kinds of error:

[   16.034271] EXT4-fs (vda3): previous I/O error to superblock detected
[   16.041699] end_request: I/O error, dev vda, sector 1030144
[   16.042679] EXT4-fs error (device vda3): ext4_remount:4418: Abort
forced by user
[   16.046465] EXT4-fs (vda3): re-mounted. Opts: (null)

Full glusterfs log is too big to go with this mail. I can see this
kind of errors:

[2012-08-07 05:56:29.598636] T [io-cache.c:128:ioc_inode_flush]
0-test-io-cache: locked inode(0xd2d2c0)
[2012-08-07 05:56:29.598642] T [io-cache.c:132:ioc_inode_flush]
0-test-io-cache: unlocked inode(0xd2d2c0)
[2012-08-07 05:56:29.598651] T [fuse-bridge.c:2113:fuse_writev_cbk]
0-glusterfs-fuse: 319: WRITE => 4096/4096,4956618752/10737418240
[2012-08-07 05:56:29.598749] T [fuse-bridge.c:2293:fuse_fsync_resume]
0-glusterfs-fuse: 320: FSYNC 0xd6f060
[2012-08-07 05:56:29.598845] W [write-behind.c:2809:wb_fsync]
0-test-write-behind: write behind wb_inode pointer is not stored in
context of inode(0x7f9cb1eab0c0), returning EBADFD
[2012-08-07 05:56:29.598858] W [fuse-bridge.c:1063:fuse_err_cbk]
0-glusterfs-fuse: 320: FSYNC() ERR => -1 (File descriptor in bad
state)
[2012-08-07 05:56:29.605831] T [fuse-bridge.c:2154:fuse_write_resume]
0-glusterfs-fuse: 322: WRITE (0xd6f060, size=4096, offset=527433728)

Just to clarify, I am not using GlusterFS block backend in QEMU (via
libgfapi) here but instead using it with normal FUSE mount.

Regards,
Bharata.
-- 
http://bharata.sulekha.com/blog/posts.htm, http://raobharata.wordpress.com/