Re: SMB Partial Send Causes CIFS VFS Reconnection and File Copy Failure

[Pavel Shilovsky <piastryyy@gmail.com>]

Hi David,

Some issues with partial sends were fixed in the 5.1 kernel. I don't
think the patches were backported to 4.9.

In particular the following patches are needed:

https://www.spinics.net/lists/linux-cifs/msg16569.html
https://www.spinics.net/lists/linux-cifs/msg20496.html

The errors may occur if an application accessing a share uses signals
that may be triggered during system calls. Such errors should be
handled by retrying in the userspace if getting -EINTR.

--
Best regards,
Pavel Shilovsky

вт, 22 июн. 2021 г. в 20:42, David Manpearl <david@gnarbox.com>:

>
> During file copy operations from our local file system to a Synology Samba server file system from within our app, we are seeing numerous partial data sends which appear to cause CIFS reconnections, which in turn cause the copies to fail.
> We see these errors logged by our Golang application on the following operations:
> os.Create
> - tbd|ERROR [tbd/daemon] (tbd_copy_file.go:333#openWriters) Failed create file [open /media/smb_192_168_86_40_GBXShare/SHAREBOX/100MEDIA/DJI_0114.JPG: no such file or directory]
> write
> - tbd|ERROR [tbd/daemon] (tbd_copy_file.go:440#finishFile) writer [write /media/smb_192_168_86_40_GBXShare/SHAREBOX2/100MEDIA_01/DJI_0002.JPG: bad file descriptor]
> - tbd|ERROR [tbd/daemon] (tbd_copy_file.go:294#openWriters) Failed create file [open /media/smb_192_168_86_40_GBXShare/SHAREBOX2/100MEDIA_01/DJI_0073.JPG: resource temporarily unavailable]
> - tbd|ERROR [tbd/daemon] (tbd_copy_file.go:393#finishFile) writer [write /media/smb_192_168_86_40_GBXShare/SHAREBOX2/100MEDIA_01/DJI_0072.JPG: broken pipe]
> file.Sync
> - tbd|ERROR [tbd/daemon] (tbd_copy_file.go:395#finishFile) sync [sync /media/smb_192_168_86_40_GBXShare/SMBSHARE/100MEDIA_02/DJI_0014(1).JPG: input/output error]
> file.Close
> - tbd|WARN  [tbd/daemon] (tbd_copy_file.go:435#finishFile) close [close /media/smb_192_168_86_40_GBXShare/SHAREBOX2/100MEDIA_02/DJI_0097.JPG: input/output error]
>
> Partial send log example:
> [196361.832049] /usr/src/kernel/fs/cifs/transport.c: partial send (wanted=65652 sent=116): terminating session
>
> Usually followed by:
> [196361.868197] CIFS VFS: Free previous auth_key.response = ffff88011748b000
>
> - What are the scenarios in which a partial send will occur, because this does not appear to be a network issue on our side?
>
> - If this is expected behavior, how are we supposed to be handling the partial sends in userspace?
>
> - Are there other errors you see in the attached logs?
>
> Linux Kernel version: 4.9.115-yocto-standard
> We are using the "fs/cifs/" directory from the "linux-4.9-full-backports" branch from this repo: https://github.com/smfrench/smb3-cifs-linux-stable-backports
>
> Mount.cifs version: 6.7
> Samba version:
> http://192.168.86.40:5000
> Control Panel > File Services > Max SMB3, Min SMB2.
> Appliance: Synology:
> Model name: DS1618
> CPU: INTEL Atom C3538
>
> DebugData:
> # cat /proc/fs/cifs/DebugData
> Display Internal CIFS Data Structures for Debugging
> ---------------------------------------------------
> CIFS Version 2.11
> Features: posix xattr
> Active VFS Requests: 0
> Servers:
> Number of credits: 512 Dialect 0x202
> 1) Name: 192.168.86.40 Uses: 1 Capability: 0x300001 Session Status: 1 TCP status: 1
> Local Users To Server: 1 SecMode: 0x1 Req On Wire: 0
> Shares:
> 0) IPC: \\192.168.86.40\IPC$ Mounts: 1 DevInfo: 0x0 Attributes: 0x0
> PathComponentMax: 0 Status: 1 type: 0
> 1) \\192.168.86.40\GBXShare Mounts: 4 DevInfo: 0x20 Attributes: 0x5006f
> PathComponentMax: 255 Status: 1 type: DISK
> MIDs:
> Number of credits: 528 Dialect 0x302
> 2) Name: 192.168.86.40 Uses: 1 Capability: 0x300005 Session Status: 1 TCP status: 1
> Local Users To Server: 1 SecMode: 0x1 Req On Wire: 0
> Shares:
> 0) IPC: \\192.168.86.40\IPC$ Mounts: 1 DevInfo: 0x0 Attributes: 0x0
> PathComponentMax: 0 Status: 1 type: 0
> Share Capabilities: None Share Flags: 0x0
>
> 1) \\192.168.86.40\GBXShare Mounts: 1 DevInfo: 0x20 Attributes: 0x5006f
> PathComponentMax: 255 Status: 1 type: DISK
> Share Capabilities: None Aligned, Partition Aligned, Share Flags: 0x0 Optimal sector size: 0x200
> MIDs:
>
> Logs: dmesgCIFS-h.log: https://drive.google.com/file/d/1_fWpvSs5zeOFaV-YlGfW2ej3LGwFZSns/view?usp=sharing
>
> - Thank you, David
>
>