[LU-12125] Allow parallel rename of regular files

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.15.0
• Assignee: Andreas Dilger
• Reporter: Andreas Dilger

Description

In theory it should be possible to relax renaming rules and allow parallel renaming of regular (or non-directory) files.

• the easiest and most common case would be rename of files within the same parent directory, like "mv foo foo.old" where we would only need to lock the DLM resources of the source and target name hashes
• the next case would be to allow rename of files between directories

Probably the easiest is to order such locks by DLM resource (FID+hash) to avoid deadlocks between multiple threads doing renames. For directory renames, they still need to be serialized by the BFL and also take the name hash locks in the source and target dirs to avoid conflict with regular file renames. In theory it would also be possible to allow concurrent rename of directories within the same parent, but that could be done in a separate step.

For renames across shards within a single DNE striped directory they would be treated as renames across directories.

Issue Links

• is related to: LU-15913 rename stress test leads to REMOTE_PARENT_DIR corruption
• is related to: LU-15285 same dir rename deadlock
• is related to: LU-17426 parallel cross-directory rename of regular files on single MDT
• is related to: LU-12037 Possible DNE issue leading to hung filesystem
• is related to: LU-6864 DNE3: Support multiple modify RPCs in flight for MDT-MDT connection