mount: check for more requisite mountpoint conditions#5718
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MichaelEischer merged 4 commits intoFeb 19, 2026
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In order to be able to mount a repository over a mountpoint target directory via FUSE, that target directory needs to be both writeable and executable for the UID performing the mount. Without this patch, `restic mount` only checks for the target pathname's existence, which can lead to a lot of data transfer and/or computation for large repos to be performed before eventually croaking with a fatal "fusermount: failed to chdir to mountpoint: Permission denied" (or similar) error. FUSE does allow for mounting over a target path that refers to a regular (writeable) file, but the result is not accessible via chdir(), so we prevent that as well, and accept only directory inodes as the intended target mountpoint path.
MichaelEischer
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Feb 18, 2026
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Please add a small changelog entry, see https://github.com/restic/restic/blob/master/changelog/TEMPLATE for the template.
| // Check the existence of the mount point at the earliest stage to | ||
| // prevent unnecessary computations while opening the repository. | ||
| if _, err := os.Stat(mountpoint); errors.Is(err, os.ErrNotExist) { | ||
| mountpoint_stat, err := os.Stat(mountpoint) |
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| mountpoint_stat, err := os.Stat(mountpoint) | |
| stat, err := os.Stat(mountpoint) |
Or mountpointStat. Go uses camel case.
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Ack, I pushed a change to rectify that :)
I hope the changelog entry is satisfactory!
MichaelEischer
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Feb 19, 2026
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LGTM. Thanks! I've slightly tweaked the changelog summary, we reserve change for breaking changes.
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Thanks very much for merging! Apologies for causing the small bit of extra work - I wasn't aware of the special meaning of these words in the changelog context and mistook "change" for the most neutral/innocent of the three options ;) |
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What does this PR change? What problem does it solve?
Esp. with large repositories,
restic mountmay waste a lot of time and resources on preparing for a fuse mount that ultimately cannot succeed due conditions that are not checked for.In order to be able to mount a repository over a mountpoint target directory via FUSE, that target directory needs to be both writeable and executable for the UID performing the mount, which this patch ensures.
FUSE does allow for mounting over a target path that refers to a regular (writeable) file, but the result is not accessible via chdir(), so we prevent that as well, and accept only directory inodes as the intended target mountpoint path.
Was the change previously discussed in an issue or on the forum?
No.
Checklist
changelog/unreleased/that describes the changes for our users (see template).