[Bug-tar] spurious "file changed as we read it" error

[Egmont Koblinger]

Hi,

Tar checks the file's ctime before and after archiving it, and fails if it
not the same. However, under Linux, in some special circumstances ctime of a
file changes when the kernel syncs that file to the disk, despite that its
contents or meta-data is not modified by any processes.

Please read this mail I posted to the linux kernel mailing list yesterday
for a detailed discussion. (No answer yet, but it may change; you might even
want to join this thread.)

http://marc.info/?l=linux-kernel&m=118599089926466

I don't know if the kernel's behavior is okay or it is a kernel bug.
Anyway, I suggest that tar could probably watch for mtime instead of ctime.
It seems to me more logical since I guess tar tries to protect against
archiving inconsistent files, which means that we should protect against
changing content, and not changing meta-info during archiving.



thanks,

Egmont