[LU-15833] Don't use realpath in llapi_search_fsname.

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.16.0, Lustre 2.15.3
• Assignee: Etienne Aujames
• Reporter: Etienne Aujames

Description

llapi_search_fsname() uses to determine the mountpoint of a path and then return its fsname.

realpath() executes lstat() for each component of the path: this means that the client must have a LDLM read lock on every directory in the path.
These operations can be slow when some clients modify parent directories.

We can use st_dev or llapi_get_name to reduce the number of stats.