[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>

4 files changed, 2 insertions, 6 deletions

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 */