| commit 4017afe28d640c535109576bd149bc7e0345f075 |
| Author: Rajesh Ghanekar <rajesh_ghanekar@symantec.com> |
| Date: Wed Aug 20 14:00:59 2014 -0400 |
| |
| nfs-utils: 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: Steve Dickson <steved@redhat.com> |
| |
| diff --git a/support/include/nfs/export.h b/support/include/nfs/export.h |
| index 1547a87..2f59e6a 100644 |
| --- a/support/include/nfs/export.h |
| +++ b/support/include/nfs/export.h |
| @@ -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 --git a/support/nfs/exports.c b/support/nfs/exports.c |
| index 819d6c4..eb782b9 100644 |
| --- a/support/nfs/exports.c |
| +++ b/support/nfs/exports.c |
| @@ -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, int warn, int *had_subtree_opt_ptr) |
| 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 --git a/utils/exportfs/exports.man b/utils/exportfs/exports.man |
| index e8b29df..3d974d9 100644 |
| --- a/utils/exportfs/exports.man |
| +++ b/utils/exportfs/exports.man |
| @@ -360,6 +360,11 @@ supported so the same configuration can be made to work on old and new |
| 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. |
