[v6,00/13] Readdir improvements

Message

Trond Myklebust Feb. 21, 2022, 4:08 p.m. UTC

From: Trond Myklebust <[e-mail]>

The current NFS readdir code will always try to maximise the amount of
readahead it performs on the assumption that we can cache anything that
isn't immediately read by the process.
There are several cases where this assumption breaks down, including
when the 'ls -l' heuristic kicks in to try to force use of readdirplus
as a batch replacement for lookup/getattr.

--
v2: Remove reset of dtsize when NFS_INO_FORCE_READDIR is set
v3: Avoid excessive window shrinking in uncached_readdir case
v4: Track 'ls -l' cache hit/miss statistics
    Improved algorithm for falling back to uncached readdir
    Skip readdirplus when files are being written to
v5: bugfixes
    Skip readdirplus when the acdirmax/acregmax values are low
    Request a full XDR buffer when doing READDIRPLUS
v6: Add tracing
    Don't have lookup request readdirplus when it won't help

Trond Myklebust (13):
  NFS: constify nfs_server_capable() and nfs_have_writebacks()
  NFS: Trace lookup revalidation failure
  NFS: Adjust the amount of readahead performed by NFS readdir
  NFS: Simplify nfs_readdir_xdr_to_array()
  NFS: Improve algorithm for falling back to uncached readdir
  NFS: Improve heuristic for readdirplus
  NFS: Don't ask for readdirplus unless it can help nfs_getattr()
  NFSv4: Ask for a full XDR buffer of readdir goodness
  NFS: Readdirplus can't help lookup for case insensitive filesystems
  NFS: Don't request readdirplus when revaldation was forced
  NFS: Add basic readdir tracing
  NFS: Trace effects of readdirplus on the dcache
  NFS: Trace effects of the readdirplus heuristic

 fs/nfs/dir.c           | 275 +++++++++++++++++++++++++++--------------
 fs/nfs/inode.c         |  37 +++---
 fs/nfs/internal.h      |   4 +-
 fs/nfs/nfs3xdr.c       |   7 +-
 fs/nfs/nfs4xdr.c       |   6 +-
 fs/nfs/nfstrace.h      | 122 +++++++++++++++++-
 include/linux/nfs_fs.h |  14 ++-
 7 files changed, 339 insertions(+), 126 deletions(-)