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
