#Snapshot folder of Synology NAS & Watchers

p_xatzi · January 11, 2024, 10:11pm

Hi to all,

I have setup a two way folder sync between two synology NASes with same folder structure and have added the following ignore patterns:

/#snapshot
/#recycle
/.sync
!PC1 (John)/1. PROJECTS
!PC2 (Thanos)/1-CONSULTANCY/1-Μ Ε Λ Ε Τ Ε Σ
*

I also increased inotify watchers to 204800 which as a result stopped error: ΓΡΑΦΕΙΟ failed to setup inotify handler. Please increase inotify limits, see FAQ — Syncthing documentation

However now I get another error: "For the following folders an error occurred while starting to watch for changes. It will be retried every minute, so the errors might go away soon. If they persist, try to fix the underlying issue and ask for help if you can’t. Support

ΓΡΑΦΕΙΟ error while traversing /volume1/ΓΡΑΦΕΙΟ/#snapshot/GMT+02-2024.01.11-22.45.16/#recycle: permission denied"

What does actually this error mean and how to troubleshoot it? Of course I don’t want any of #snapshot folder to be edited.

Thank you!

p_xatzi · January 12, 2024, 6:54pm

I guess I understand the fault.

With the previous post’s exception rules (for including files) apparently syncthing found the same structure inside #snapshot folder so it was giving that error.

Just to mention that root folder is /volume1/ΓΡΑΦΕΙΟ and then “PC1 (John)” and “PC2 (Thanos)” are first in hierarchy.

So, I tried to declare these rules explicitly: !/PC1 (John)/1. PROJECTS !/PC2 (Thanos)/1-CONSULTANCY/1-Μ Ε Λ Ε Τ Ε Σ * These are not top level include patterns as documentation says, and they did work as exception for files but not as exception for watchers.

I also tried putting the above rules first and last (does really order of rules have any value?)

I finally tried the following rules: /!PC1 (John)/1. PROJECTS /!PC2 (Thanos)/1-CONSULTANCY/1-Μ Ε Λ Ε Τ Ε Σ but of course they wasn’t read at all.

So, if I get it right, explicit exception rules are valid for files but watchers do not take them into account. Could that be a bug?

acolomb · January 12, 2024, 9:05pm

You could call it a bug or rather an unfortunate property of the current implementation. Any negated pattern will cause the whole tree to be watched, even though large parts of it will be ignored later on. There is work underway to change that, see here:

github.com/syncthing/syncthing

Optimise ignoring directories for filesystem watcher (fixes #9339)

syncthing:main ← calmh:ignoptim

opened 08:21AM - 12 Jan 24 UTC

calmh

+237 -164

This improves the ignore handling so that directories can be fully ignored (skip…ped in the watcher) in more cases. Specifically, where the previous rule was that any complex `!`-pattern would disable skipping directories, the new rule is that only matches on patterns *after* such a `!`-pattern disable skipping. That is, the following now does the intuitive thing: ``` /foo /bar !whatever * ``` - `/foo/**` and `/bar/**` are completely skipped, since there is no chance anything underneath them could ever be not-ignored - `!whatever` toggles the "can't skip directories any more" flag - Anything that matches `*` can't skip directories, because it's possible we can have `whatever` match something deeper. To enable this, some refactoring was necessary: - The "can skip dirs" flag is now a property of the match result, not of the pattern set as a whole. - That meant returning a boolean is not good enough, we need to actually return the entire `Result` (or, like, two booleans but that seemed uglier and more annoying to use) - `ShouldIgnore(string) boolean` went away with `Match(string).IsIgnored()` being the obvious replacement (API simplification!) - The watcher then needed to import the `ignore` package (for the `Result` type), but `fs` imports the watcher and `ignore` imports `fs`. That's a cycle, so I broke out `Result` into a package of its own so that it can be safely imported everywhere in things like `type Matcher interface { Match(string) result.Result }`. There's a fair amount of stuttering in `result.Result` and maybe we should go with something like `ignoreresult.R` or so, leaving this open for discussion. Tests refactored to suit, I think this change is in fact quite well covered by the existing ones... Also some noise because a few of the changed files were quite old and got the `gofumpt` treatment by my editor. Sorry not sorry.

And yes, the order of ignore patterns does matter. They are interpreted top to bottom, first match wins. See the documentation at Ignoring Files — Syncthing documentation

system · February 11, 2024, 9:05pm

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