[LU-353] write should return written bytes when it's interrupted

• Status: Open
• Project: Lustre
• Affects Version/s: Lustre 2.0.0, Lustre 2.1.0
• Type: Bug
• Priority: Major
• Reporter: Niu Yawei (Inactive)
• Assignee: WC Triage
• Resolution: Unresolved
• Severity: 3

Description

When I was investigating on LU-305, I found that ll_file_write() (master code) always return error to user application where error happened, even if there is data be written, which is not POSIX complied. We should return written bytes if there is any written data.

Comments

[Andreas Dilger]

One difficlty withreturning the bytes written is that they may be sent asynchronously to different stripes, leaving a hole before some of the written bytes. It is easier to return an error to the application and have the VFS truncate the file on write error instead of trying to figure out the largest contiguous range of bytes written.

[Niu Yawei (Inactive)]

Hi, Andreas

As far as I can see, current ll_file_write() write to cache (or synchronously) stripe by stripe sequentially, so there shouldn't be hole problem. Xiong, could you confirm this?