[PATCH] knfsd: Avoid excess stack usage in svc_tcp_recvfrom

..  by allocating the array of 'kvec' in 'struct svc_rqst'.

As we plan to increase RPCSVC_MAXPAGES from 8 upto 256, we can no longer
allocate an array of this size on the stack.  So we allocate it in 'struct
svc_rqst'.

However svc_rqst contains (indirectly) an array of the same type and size
(actually several, but they are in a union).  So rather than waste space, we
move those arrays out of the separately allocated union and into svc_rqst to
share with the kvec moved out of svc_tcp_recvfrom (various arrays are used at
different times, so there is no conflict).

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

11 files changed, 44 insertions, 47 deletions

diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index f61142afea44..0c4fab018791 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -180,7 +180,7 @@ nfsd3_proc_read(struct svc_rqst *rqstp, struct nfsd3_readargs *argp,
         fh_copy(&resp->fh, &argp->fh);
         nfserr = nfsd_read(rqstp, &resp->fh, NULL,
                                   argp->offset,
-                                  argp->vec, argp->vlen,
+                                  rqstp->rq_vec, argp->vlen,
                                   &resp->count);
         if (nfserr == 0) {
                 struct inode    *inode = resp->fh.fh_dentry->d_inode;
@@ -210,7 +210,7 @@ nfsd3_proc_write(struct svc_rqst *rqstp, struct nfsd3_writeargs *argp,
         resp->committed = argp->stable;
         nfserr = nfsd_write(rqstp, &resp->fh, NULL,
                                    argp->offset,
-                                   argp->vec, argp->vlen,
+                                   rqstp->rq_vec, argp->vlen,
                                    argp->len,
                                    &resp->committed);
         resp->count = argp->count;
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 20ba728a4642..4b9aefbcc93c 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -344,9 +344,9 @@ nfs3svc_decode_readargs(struct svc_rqst *rqstp, u32 *p,
         v=0;
         while (len > 0) {
                 pn = rqstp->rq_resused++;
-                args->vec[v].iov_base = page_address(rqstp->rq_respages[pn]);
-                args->vec[v].iov_len = len < PAGE_SIZE? len : PAGE_SIZE;
-                len -= args->vec[v].iov_len;
+                rqstp->rq_vec[v].iov_base = page_address(rqstp->rq_respages[pn]);
+                rqstp->rq_vec[v].iov_len = len < PAGE_SIZE? len : PAGE_SIZE;
+                len -= rqstp->rq_vec[v].iov_len;
                 v++;
         }
         args->vlen = v;
@@ -372,22 +372,22 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, u32 *p,
             rqstp->rq_arg.len - hdr < len)
                 return 0;
 
-        args->vec[0].iov_base = (void*)p;
-        args->vec[0].iov_len = rqstp->rq_arg.head[0].iov_len - hdr;
+        rqstp->rq_vec[0].iov_base = (void*)p;
+        rqstp->rq_vec[0].iov_len = rqstp->rq_arg.head[0].iov_len - hdr;
 
         if (len > NFSSVC_MAXBLKSIZE)
                 len = NFSSVC_MAXBLKSIZE;
         v=  0;
-        while (len > args->vec[v].iov_len) {
-                len -= args->vec[v].iov_len;
+        while (len > rqstp->rq_vec[v].iov_len) {
+                len -= rqstp->rq_vec[v].iov_len;
                 v++;
-                args->vec[v].iov_base = page_address(rqstp->rq_pages[v]);
-                args->vec[v].iov_len = PAGE_SIZE;
+                rqstp->rq_vec[v].iov_base = page_address(rqstp->rq_pages[v]);
+                rqstp->rq_vec[v].iov_len = PAGE_SIZE;
         }
-        args->vec[v].iov_len = len;
+        rqstp->rq_vec[v].iov_len = len;
         args->vlen = v+1;
 
-        return args->count == args->len && args->vec[0].iov_len > 0;
+        return args->count == args->len && rqstp->rq_vec[0].iov_len > 0;
 }
 
 int
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 15ded7a30a72..38b0f91175d0 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -646,7 +646,7 @@ nfsd4_write(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_writ
         *p++ = nfssvc_boot.tv_usec;
 
         status =  nfsd_write(rqstp, current_fh, filp, write->wr_offset,
-                        write->wr_vec, write->wr_vlen, write->wr_buflen,
+                        rqstp->rq_vec, write->wr_vlen, write->wr_buflen,
                         &write->wr_how_written);
         if (filp)
                 fput(filp);
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 9f30c53ac0ed..df341956254e 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -926,26 +926,26 @@ nfsd4_decode_write(struct nfsd4_compoundargs *argp, struct nfsd4_write *write)
                 printk(KERN_NOTICE "xdr error! (%s:%d)\n", __FILE__, __LINE__); 
                 goto xdr_error;
         }
-        write->wr_vec[0].iov_base = p;
-        write->wr_vec[0].iov_len = avail;
+        argp->rqstp->rq_vec[0].iov_base = p;
+        argp->rqstp->rq_vec[0].iov_len = avail;
         v = 0;
         len = write->wr_buflen;
-        while (len > write->wr_vec[v].iov_len) {
-                len -= write->wr_vec[v].iov_len;
+        while (len > argp->rqstp->rq_vec[v].iov_len) {
+                len -= argp->rqstp->rq_vec[v].iov_len;
                 v++;
-                write->wr_vec[v].iov_base = page_address(argp->pagelist[0]);
+                argp->rqstp->rq_vec[v].iov_base = page_address(argp->pagelist[0]);
                 argp->pagelist++;
                 if (argp->pagelen >= PAGE_SIZE) {
-                        write->wr_vec[v].iov_len = PAGE_SIZE;
+                        argp->rqstp->rq_vec[v].iov_len = PAGE_SIZE;
                         argp->pagelen -= PAGE_SIZE;
                 } else {
-                        write->wr_vec[v].iov_len = argp->pagelen;
+                        argp->rqstp->rq_vec[v].iov_len = argp->pagelen;
                         argp->pagelen -= len;
                 }
         }
-        argp->end = (u32*) (write->wr_vec[v].iov_base + write->wr_vec[v].iov_len);
-        argp->p = (u32*)  (write->wr_vec[v].iov_base + (XDR_QUADLEN(len) << 2));
-        write->wr_vec[v].iov_len = len;
+        argp->end = (u32*) (argp->rqstp->rq_vec[v].iov_base + argp->rqstp->rq_vec[v].iov_len);
+        argp->p = (u32*)  (argp->rqstp->rq_vec[v].iov_base + (XDR_QUADLEN(len) << 2));
+        argp->rqstp->rq_vec[v].iov_len = len;
         write->wr_vlen = v+1;
 
         DECODE_TAIL;
@@ -2063,9 +2063,9 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, int nfserr,
         v = 0;
         while (len > 0) {
                 pn = resp->rqstp->rq_resused++;
-                read->rd_iov[v].iov_base =
+                resp->rqstp->rq_vec[v].iov_base =
                         page_address(resp->rqstp->rq_respages[pn]);
-                read->rd_iov[v].iov_len =
+                resp->rqstp->rq_vec[v].iov_len =
                         len < PAGE_SIZE ? len : PAGE_SIZE;
                 v++;
                 len -= PAGE_SIZE;
@@ -2073,7 +2073,7 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, int nfserr,
         read->rd_vlen = v;
 
         nfserr = nfsd_read(read->rd_rqstp, read->rd_fhp, read->rd_filp,
-                        read->rd_offset, read->rd_iov, read->rd_vlen,
+                        read->rd_offset, resp->rqstp->rq_vec, read->rd_vlen,
                         &maxcount);
 
         if (nfserr == nfserr_symlink)
diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index 4e06810b6104..ca4973150218 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -159,7 +159,7 @@ nfsd_proc_read(struct svc_rqst *rqstp, struct nfsd_readargs *argp,
         resp->count = argp->count;
         nfserr = nfsd_read(rqstp, fh_copy(&resp->fh, &argp->fh), NULL,
                                   argp->offset,
-                                  argp->vec, argp->vlen,
+                                  rqstp->rq_vec, argp->vlen,
                                   &resp->count);
 
         if (nfserr) return nfserr;
@@ -185,7 +185,7 @@ nfsd_proc_write(struct svc_rqst *rqstp, struct nfsd_writeargs *argp,
 
         nfserr = nfsd_write(rqstp, fh_copy(&resp->fh, &argp->fh), NULL,
                                    argp->offset,
-                                   argp->vec, argp->vlen,
+                                   rqstp->rq_vec, argp->vlen,
                                    argp->len,
                                    &stable);
         return nfsd_return_attrs(nfserr, resp);
diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index ad2fba3c54f8..ab6745e78d16 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -263,9 +263,9 @@ nfssvc_decode_readargs(struct svc_rqst *rqstp, u32 *p,
         v=0;
         while (len > 0) {
                 pn = rqstp->rq_resused++;
-                args->vec[v].iov_base = page_address(rqstp->rq_respages[pn]);
-                args->vec[v].iov_len = len < PAGE_SIZE?len:PAGE_SIZE;
-                len -= args->vec[v].iov_len;
+                rqstp->rq_vec[v].iov_base = page_address(rqstp->rq_respages[pn]);
+                rqstp->rq_vec[v].iov_len = len < PAGE_SIZE?len:PAGE_SIZE;
+                len -= rqstp->rq_vec[v].iov_len;
                 v++;
         }
         args->vlen = v;
@@ -285,21 +285,21 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, u32 *p,
         args->offset = ntohl(*p++);     /* offset */
         p++;                            /* totalcount */
         len = args->len = ntohl(*p++);
-        args->vec[0].iov_base = (void*)p;
-        args->vec[0].iov_len = rqstp->rq_arg.head[0].iov_len -
+        rqstp->rq_vec[0].iov_base = (void*)p;
+        rqstp->rq_vec[0].iov_len = rqstp->rq_arg.head[0].iov_len -
                                 (((void*)p) - rqstp->rq_arg.head[0].iov_base);
         if (len > NFSSVC_MAXBLKSIZE)
                 len = NFSSVC_MAXBLKSIZE;
         v = 0;
-        while (len > args->vec[v].iov_len) {
-                len -= args->vec[v].iov_len;
+        while (len > rqstp->rq_vec[v].iov_len) {
+                len -= rqstp->rq_vec[v].iov_len;
                 v++;
-                args->vec[v].iov_base = page_address(rqstp->rq_pages[v]);
-                args->vec[v].iov_len = PAGE_SIZE;
+                rqstp->rq_vec[v].iov_base = page_address(rqstp->rq_pages[v]);
+                rqstp->rq_vec[v].iov_len = PAGE_SIZE;
         }
-        args->vec[v].iov_len = len;
+        rqstp->rq_vec[v].iov_len = len;
         args->vlen = v+1;
-        return args->vec[0].iov_len > 0;
+        return rqstp->rq_vec[0].iov_len > 0;
 }
 
 int
diff --git a/include/linux/nfsd/xdr.h b/include/linux/nfsd/xdr.h
index a38f9d776de9..0e53de87d886 100644
--- a/include/linux/nfsd/xdr.h
+++ b/include/linux/nfsd/xdr.h
@@ -30,7 +30,6 @@ struct nfsd_readargs {
         struct svc_fh           fh;
         __u32                   offset;
         __u32                   count;
-        struct kvec             vec[RPCSVC_MAXPAGES];
         int                     vlen;
 };
 
@@ -38,7 +37,6 @@ struct nfsd_writeargs {
         svc_fh                  fh;
         __u32                   offset;
         int                     len;
-        struct kvec             vec[RPCSVC_MAXPAGES];
         int                     vlen;
 };
 
diff --git a/include/linux/nfsd/xdr3.h b/include/linux/nfsd/xdr3.h
index a4322741f8b9..474d882dc2f3 100644
--- a/include/linux/nfsd/xdr3.h
+++ b/include/linux/nfsd/xdr3.h
@@ -33,7 +33,6 @@ struct nfsd3_readargs {
         struct svc_fh           fh;
         __u64                   offset;
         __u32                   count;
-        struct kvec             vec[RPCSVC_MAXPAGES];
         int                     vlen;
 };
 
@@ -43,7 +42,6 @@ struct nfsd3_writeargs {
         __u32                   count;
         int                     stable;
         __u32                   len;
-        struct kvec             vec[RPCSVC_MAXPAGES];
         int                     vlen;
 };
 
diff --git a/include/linux/nfsd/xdr4.h b/include/linux/nfsd/xdr4.h
index 77adba7d2281..66e642762a07 100644
--- a/include/linux/nfsd/xdr4.h
+++ b/include/linux/nfsd/xdr4.h
@@ -241,7 +241,6 @@ struct nfsd4_read {
         stateid_t       rd_stateid;         /* request */
         u64             rd_offset;          /* request */
         u32             rd_length;          /* request */
-        struct kvec     rd_iov[RPCSVC_MAXPAGES];
         int             rd_vlen;
         struct file     *rd_filp;
         
@@ -326,7 +325,6 @@ struct nfsd4_write {
         u64             wr_offset;          /* request */
         u32             wr_stable_how;      /* request */
         u32             wr_buflen;          /* request */
-        struct kvec     wr_vec[RPCSVC_MAXPAGES]; /* request */
         int             wr_vlen;
 
         u32             wr_bytes_written;   /* response */
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 3669e91c43b8..cb0ed9beb227 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -192,6 +192,8 @@ struct svc_rqst {
         struct page *           *rq_respages;   /* points into rq_pages */
         int                     rq_resused;     /* number of pages used for result */
 
+        struct kvec             rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */
+
         __be32                  rq_xid;         /* transmission id */
         u32                     rq_prog;        /* program number */
         u32                     rq_vers;        /* program version */
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 25096d53667a..1d512337ccd9 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -955,7 +955,7 @@ svc_tcp_recvfrom(struct svc_rqst *rqstp)
         struct svc_sock *svsk = rqstp->rq_sock;
         struct svc_serv *serv = svsk->sk_server;
         int             len;
-        struct kvec vec[RPCSVC_MAXPAGES];
+        struct kvec *vec;
         int pnum, vlen;
 
         dprintk("svc: tcp_recv %p data %d conn %d close %d\n",
@@ -1053,6 +1053,7 @@ svc_tcp_recvfrom(struct svc_rqst *rqstp)
         len = svsk->sk_reclen;
         set_bit(SK_DATA, &svsk->sk_flags);
 
+        vec = rqstp->rq_vec;
         vec[0] = rqstp->rq_arg.head[0];
         vlen = PAGE_SIZE;
         pnum = 1;