Re: [NFS] [PATCH] knfsd: Correct reserved reply space for read requests.

[Marc Eshel <eshel@almaden.ibm.com>]

Hi Neil
Can we use this opportunity to change NFSSVC_MAXBLKSIZE from 32K to 64K to 
match RPCSVC_MAXPAYLOAD. It makes real difference in I/O performance (we 
will still be saving half the space we used to allocate :).
Thanks, Marc. 

NeilBrown wrote on 03/29/2006 09:53:50 PM:

> Single patch for nfsd in 2.6.16.  As the comment say, it is sensible
> for this to sit in -mm for a while just in case.
> 
> ### Comments for Changeset
> 
> NFSd makes sure there is enough space to hold the maximum possible
> reply before accepting a request.  The units for this maximum is
> (4byte) words.  However in three places, particularly for read
> request, the number given is a number of bytes.
> 
> This means too much space is reserved which is slightly wasteful.
> 
> This is the sort of patch that could uncover a deeper bug, and it is
> not critical, so it would be best for it to spend a while in -mm 
> before going in to mainline.
> 
> Discovered-by: "Eivind  Sarto" <ivan@kasenna.com>
> 
> Cc: "Eivind  Sarto" <ivan@kasenna.com>
> 
> Signed-off-by: Neil Brown <neilb@suse.de>
> 
> ### Diffstat output
>  ./fs/nfsd/nfs3proc.c |    2 +-
>  ./fs/nfsd/nfs4proc.c |    2 +-
>  ./fs/nfsd/nfsproc.c  |    2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff ./fs/nfsd/nfs3proc.c~current~ ./fs/nfsd/nfs3proc.c
> --- ./fs/nfsd/nfs3proc.c~current~   2006-03-30 16:48:30.000000000 +1100
> +++ ./fs/nfsd/nfs3proc.c   2006-03-30 16:48:58.000000000 +1100
> @@ -682,7 +682,7 @@ static struct svc_procedure      nfsd_proced
>    PROC(lookup,    dirop,      dirop,      fhandle2, RC_NOCACHE, 
> ST+FH+pAT+pAT),
>    PROC(access,    access,   access,      fhandle,  RC_NOCACHE, 
ST+pAT+1),
>    PROC(readlink, readlink,   readlink,   fhandle,  RC_NOCACHE, 
> ST+pAT+1+NFS3_MAXPATHLEN/4),
> -  PROC(read,    read,      read,      fhandle,  RC_NOCACHE, 
> ST+pAT+4+NFSSVC_MAXBLKSIZE),
> +  PROC(read,    read,      read,      fhandle,  RC_NOCACHE, 
> ST+pAT+4+NFSSVC_MAXBLKSIZE/4),
>    PROC(write,    write,      write,      fhandle,  RC_REPLBUFF, 
ST+WC+4),
>    PROC(create,    create,   create,      fhandle2, RC_REPLBUFF, 
> ST+(1+FH+pAT)+WC),
>    PROC(mkdir,    mkdir,      create,      fhandle2, RC_REPLBUFF, 
> ST+(1+FH+pAT)+WC),
> 
> diff ./fs/nfsd/nfs4proc.c~current~ ./fs/nfsd/nfs4proc.c
> --- ./fs/nfsd/nfs4proc.c~current~   2006-03-30 16:48:30.000000000 +1100
> +++ ./fs/nfsd/nfs4proc.c   2006-03-30 16:48:58.000000000 +1100
> @@ -973,7 +973,7 @@ struct nfsd4_voidargs { int dummy; };
>   */
>  static struct svc_procedure      nfsd_procedures4[2] = {
>    PROC(null,    void,      void,      void,     RC_NOCACHE, 1),
> -  PROC(compound, compound,   compound,   compound, RC_NOCACHE, 
NFSD_BUFSIZE)
> +  PROC(compound, compound,   compound,   compound, RC_NOCACHE, 
> NFSD_BUFSIZE/4)
>  };
> 
>  struct svc_version   nfsd_version4 = {
> 
> diff ./fs/nfsd/nfsproc.c~current~ ./fs/nfsd/nfsproc.c
> --- ./fs/nfsd/nfsproc.c~current~   2006-03-30 16:48:30.000000000 +1100
> +++ ./fs/nfsd/nfsproc.c   2006-03-30 16:48:58.000000000 +1100
> @@ -553,7 +553,7 @@ static struct svc_procedure      nfsd_proced
>    PROC(none,    void,      void,      none,      RC_NOCACHE, ST),
>    PROC(lookup,    diropargs,   diropres,   fhandle,   RC_NOCACHE, 
ST+FH+AT),
>    PROC(readlink, readlinkargs,   readlinkres,   none, 
> RC_NOCACHE, ST+1+NFS_MAXPATHLEN/4),
> -  PROC(read,    readargs,   readres,   fhandle,   RC_NOCACHE, 
> ST+AT+1+NFSSVC_MAXBLKSIZE),
> +  PROC(read,    readargs,   readres,   fhandle,   RC_NOCACHE, 
> ST+AT+1+NFSSVC_MAXBLKSIZE/4),
>    PROC(none,    void,      void,      none,      RC_NOCACHE, ST),
>    PROC(write,    writeargs,   attrstat,   fhandle,   RC_REPLBUFF, 
ST+AT),
>    PROC(create,    createargs,   diropres,   fhandle, 
RC_REPLBUFF,ST+FH+AT),
> 
> 
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