[Samba] io_uring cause data corruption
jra at samba.org
Sun Apr 26 17:44:41 UTC 2020
On Sun, Apr 26, 2020 at 11:51:42AM +0200, A L via samba wrote:
> Using Samba 4.12.1 with kernel 5.6.7 on Gentoo Linux, I wanted to test the
> new vfs_io_uring module.
> * Stand-alone Samba server acting as NAS for home setup.
> * /media/usb-backup is a mounted read-only btrfs filesystem.
> * Samba share exported as:
Thanks SO MUCH for testing this !
Can you log this information as a bug
at bugzilla.samba.org so we can properly
track it ?
> ===== smb.conf =====
> log level = 1
> workgroup = WORKGROUP
> netbios name = NAS
> server string = Samba Server
> server role = standalone server
> hosts allow = 192.168.0. 127.
> interfaces = lan
> max protocol = SMB3_11
> log file = /var/log/samba/%I.log
> max log size = 10240
> security = user
> passdb backend = tdbsam
> wins support = yes
> dns proxy = yes
> comment = USB Backup - Media files
> path = /media/usb-backup
> writeable = no
> browseable = yes
> read only = yes
> create mask = 0664
> directory mask = 0775
> guest only = Yes
> guest ok = Yes
> force user = nasuser
> force group = nas
> vfs objects = btrfs, io_uring (also tried without the btrfs module)
> * Connected from a Windows 10 computer over 1G ethernet.
> * Copy data using Windows Explorer and FastCopy(1) from the Samba share to a
> local disk.
> * Verify the sha-256 sum on the files.
> From what I can see there is data corruption on many of the files. Sha-256
> does not match. I copied the same files many times and the data corruption
> occurs within minutes. The total data set is about 800GB.
> When I disable io_uring, no data corruptions occur. I verified this with
> multiple TBs of data transferred and no corruptions were detected.
> Samba log files contain no errors, nor does dmesg. The Windows client detect
> no error when copying the files.
> I'd really like to debug this problem and find the cause. io_uring seems to
> give a massive performance i/o boost.
> * net-fs/samba-4.12.1
> * sys-devel/gcc-9.3.0
> * sys-libs/glibc-2.30-r8
> * sys-kernel/linux-headers-5.6
> * Linux-kernel-5.6.7-gentoo
> Compile info:
> * CFLAGS="-O2 -march=native -pipe"
> * CPU: "AMD Athlon 3000G with Radeon Vega Graphics"
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