Skip fopen on archiver for file change check #2969
Description
Output of restic version
restic 0.10.0 (v0.10.0-37-g5c8a350-dirty) compiled with go1.13.3 on linux/amd64
What should restic do differently? Which functionality do you think we should add?
The archiver module performs an extra fopen check to increase the probability that the file information has not changed from the previous stat. An fopen operation is more expensive that just a stat, and such penalty is magnified when doing the backup of network filesystems.
A WIP pull request #2969 will illustrate the desired behaviour.