On 08/20/2014 03:12 AM, Rajesh Ghanekar wrote:
> Hi Steve,
> Please see the nfs-utils patch for making readdir_plus
> configurable for NFSv3. I already sent it in
> "[PATCH] nfsd: allow turning off nfsv3 readdir_plus", so
> apologies for resending, but I thought to make its own subject.
> Let me know if you think any changes are required.
>
> From: Rajesh Ghanekar <Rajesh_Ghanekar@xxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxx>
committed...
steved
>
> diff -uprN nfs-utils-1.3.0.old/support/include/nfs/export.h nfs-utils-1.3.0/support/include/nfs/export.h
> --- nfs-utils-1.3.0.old/support/include/nfs/export.h 2014-03-25 20:42:07.000000000 +0530
> +++ nfs-utils-1.3.0/support/include/nfs/export.h 2014-08-18 22:28:24.420262810 +0530
> @@ -17,7 +17,8 @@
> #define NFSEXP_ALLSQUASH 0x0008
> #define NFSEXP_ASYNC 0x0010
> #define NFSEXP_GATHERED_WRITES 0x0020
> -/* 40, 80, 100 unused */
> +#define NFSEXP_NOREADDIRPLUS 0x0040
> +/* 80, 100 unused */
> #define NFSEXP_NOHIDE 0x0200
> #define NFSEXP_NOSUBTREECHECK 0x0400
> #define NFSEXP_NOAUTHNLM 0x0800
> diff -uprN nfs-utils-1.3.0.old/support/nfs/exports.c nfs-utils-1.3.0/support/nfs/exports.c
> --- nfs-utils-1.3.0.old/support/nfs/exports.c 2014-03-25 20:42:07.000000000 +0530
> +++ nfs-utils-1.3.0/support/nfs/exports.c 2014-08-18 22:28:24.600262814 +0530
> @@ -273,6 +273,8 @@ putexportent(struct exportent *ep)
> "in" : "");
> fprintf(fp, "%sacl,", (ep->e_flags & NFSEXP_NOACL)?
> "no_" : "");
> + if (ep->e_flags & NFSEXP_NOREADDIRPLUS)
> + fprintf(fp, "nordirplus,");
> if (ep->e_flags & NFSEXP_FSID) {
> fprintf(fp, "fsid=%d,", ep->e_fsid);
> }
> @@ -539,6 +541,8 @@ parseopts(char *cp, struct exportent *ep
> clearflags(NFSEXP_ASYNC, active, ep);
> else if (!strcmp(opt, "async"))
> setflags(NFSEXP_ASYNC, active, ep);
> + else if (!strcmp(opt, "nordirplus"))
> + setflags(NFSEXP_NOREADDIRPLUS, active, ep);
> else if (!strcmp(opt, "nohide"))
> setflags(NFSEXP_NOHIDE, active, ep);
> else if (!strcmp(opt, "hide"))
> diff -uprN nfs-utils-1.3.0.old/utils/exportfs/exports.man nfs-utils-1.3.0/utils/exportfs/exports.man
> --- nfs-utils-1.3.0.old/utils/exportfs/exports.man 2014-03-25 20:42:07.000000000 +0530
> +++ nfs-utils-1.3.0/utils/exportfs/exports.man 2014-08-19 12:32:30.498780854 +0530
> @@ -360,6 +360,11 @@ supported so the same configuration can
> kernels alike.
>
> .TP
> +.IR nordirplus
> +This option will disable READDIRPLUS request handling. When set,
> +READDIRPLUS requests from NFS clients return NFS3ERR_NOTSUPP, and
> +clients fall back on READDIR. This option affects only NFSv3 clients.
> +.TP
> .IR refer= path@host[+host][:path@host[+host]]
> A client referencing the export point will be directed to choose from
> the given list an alternative location for the filesystem.
>
> -----
>
> Thanks,
> Rajesh
>
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