From 18c01ab30288d9d0a7d80b08b659531f37ed379d Mon Sep 17 00:00:00 2001 From: Rajesh Ghanekar Date: Fri, 1 Aug 2014 22:17:30 -0400 Subject: [PATCH] nfsd: allow turning off nfsv3 readdir_plus One of our customer's application only needs file names, not file attributes. With directories having 10K+ inodes (assuming buffer cache has directory blocks cached having file names, but inode cache is limited and hence need eviction of older cached inodes), older inodes are evicted periodically. So if they keep on doing readdir(2) from NSF client on multiple directories, some directory's files are periodically removed from inode cache and hence new readdir(2) on same directory requires disk access to bring back inodes again to inode cache. As READDIRPLUS request fetches attributes also, doing getattr on each file on server, it causes unnecessary disk accesses. If READDIRPLUS on NFS client is returned with -ENOTSUPP, NFS client uses READDIR request which just gets the names of the files in a directory, not attributes, hence avoiding disk accesses on server. There's already a corresponding client-side mount option, but an export option reduces the need for configuration across multiple clients. This flag affects NFSv3 only. If it turns out it's needed for NFSv4 as well then we may have to figure out how to extend the behavior to NFSv4, but it's not currently obvious how to do that. Signed-off-by: Rajesh Ghanekar Signed-off-by: J. Bruce Fields --- fs/nfsd/export.c | 1 + fs/nfsd/nfs3proc.c | 8 ++++++++ include/uapi/linux/nfsd/export.h | 5 +++-- 3 files changed, 12 insertions(+), 2 deletions(-) diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index 72ffd7cce3c3..30a739d896ff 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -1145,6 +1145,7 @@ static struct flags { { NFSEXP_ALLSQUASH, {"all_squash", ""}}, { NFSEXP_ASYNC, {"async", "sync"}}, { NFSEXP_GATHERED_WRITES, {"wdelay", "no_wdelay"}}, + { NFSEXP_NOREADDIRPLUS, {"nordirplus", ""}}, { NFSEXP_NOHIDE, {"nohide", ""}}, { NFSEXP_CROSSMOUNT, {"crossmnt", ""}}, { NFSEXP_NOSUBTREECHECK, {"no_subtree_check", ""}}, diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c index fc51f7f6b36d..12f2aab4f614 100644 --- a/fs/nfsd/nfs3proc.c +++ b/fs/nfsd/nfs3proc.c @@ -466,6 +466,14 @@ nfsd3_proc_readdirplus(struct svc_rqst *rqstp, struct nfsd3_readdirargs *argp, resp->buflen = resp->count; resp->rqstp = rqstp; offset = argp->cookie; + + nfserr = fh_verify(rqstp, &resp->fh, S_IFDIR, NFSD_MAY_NOP); + if (nfserr) + RETURN_STATUS(nfserr); + + if (resp->fh.fh_export->ex_flags & NFSEXP_NOREADDIRPLUS) + RETURN_STATUS(nfserr_notsupp); + nfserr = nfsd_readdir(rqstp, &resp->fh, &offset, &resp->common, diff --git a/include/uapi/linux/nfsd/export.h b/include/uapi/linux/nfsd/export.h index cf47c313794e..584b6ef3a5e8 100644 --- a/include/uapi/linux/nfsd/export.h +++ b/include/uapi/linux/nfsd/export.h @@ -28,7 +28,8 @@ #define NFSEXP_ALLSQUASH 0x0008 #define NFSEXP_ASYNC 0x0010 #define NFSEXP_GATHERED_WRITES 0x0020 -/* 40 80 100 currently unused */ +#define NFSEXP_NOREADDIRPLUS 0x0040 +/* 80 100 currently unused */ #define NFSEXP_NOHIDE 0x0200 #define NFSEXP_NOSUBTREECHECK 0x0400 #define NFSEXP_NOAUTHNLM 0x0800 /* Don't authenticate NLM requests - just trust */ @@ -47,7 +48,7 @@ */ #define NFSEXP_V4ROOT 0x10000 /* All flags that we claim to support. (Note we don't support NOACL.) */ -#define NFSEXP_ALLFLAGS 0x17E3F +#define NFSEXP_ALLFLAGS 0x1FE7F /* The flags that may vary depending on security flavor: */ #define NFSEXP_SECINFO_FLAGS (NFSEXP_READONLY | NFSEXP_ROOTSQUASH \ -- 2.20.1