[LU-18800] TCU: implement virtual ".Trash" subdirectory for undelete

• Type: Improvement
• Resolution: Unresolved
• Priority: Minor
• Labels: trash_can usability
• Severity: 3
• Assignee: WC Triage
• Reporter: Andreas Dilger

Description

It would be very useful to have a virtual ".Trash" subdirectory accessible in each directory in the filesystem that can be used to browse files/directories in the trash can and access them for recovery.

The FID of the .Trash directory would be derived from the FID of the parent directory (pFID), by looking up the corresponding "stub" directory with the name ".lustre/trash/pFID". Essentially this is just a virtual shortcut to .lustre/trash/pFID that is accessible in each directory if specified by name, though it is not visible in each directory to avoid issues with "rm -r", backups, etc.

It isn't possible that the .Trash directory is a symlink to .lustre/trash/pFID because the .lustre directory is in the root of the filesystem, and may be inaccessible from the mountpoint on the client.

Issue Links

• is related to: LU-18456 TCU: Trash Can/Undelete for Lustre

Comments

[Tim Day]

freedesktop spec for Trash https://specifications.freedesktop.org/trash-spec/latest/

[Andreas Dilger]

Since this feature potentially impacts user workloads, it should be possible to disable the virtual ".Trash" directory lookup on a client, in case users have e.g. accessed the Lustre mountpoint via NFS re-export to a Mac or similar. The ".Trash" directory should be enabled by default, but have a parameter like "llite.*.trash_dir_enable" that enables and disables the virtual directory lookup.

It would be preferable if this could be tuned on a per-client basis with an "llite" parameter, but if that is not practical then an "mdd" parameter would also be Ok.

[Gerrit Updater]

"Qian Yingjin <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/c/fs/lustre-release/+/58571
Subject: LU-18800 trash: forbid to create a file with name ".Trash"
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 7859c752c8cbcb559180f973fbbbb0ede80f9798

[Gerrit Updater]

"Qian Yingjin <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/c/fs/lustre-release/+/58493
Subject: LU-18800 trash: implement virtual ".Trash" subdir for undelete
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 029a4d2f9f7eafb9e1d335bcdc318ca9b353e695