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authorRajesh Ghanekar <Rajesh_Ghanekar@symantec.com>2014-08-02 06:17:30 +0400
committerJ. Bruce Fields <bfields@redhat.com>2014-08-18 23:12:14 +0400
commit18c01ab30288d9d0a7d80b08b659531f37ed379d (patch)
tree327704befb41873e859ae20574f7eda538ac3670 /fs
parentf7b43d0c992c3ec3e8d9285c3fb5e1e0eb0d031a (diff)
downloadlinux-18c01ab30288d9d0a7d80b08b659531f37ed379d.tar.xz
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 <rajesh_ghanekar@symantec.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/nfsd/export.c1
-rw-r--r--fs/nfsd/nfs3proc.c8
2 files changed, 9 insertions, 0 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,