[PATCH 007 of 11] knfsd: Avoid excess stack usage in svc_tcp_recvfrom

NeilBrown
2006-08-24T06:39:52Z

.. 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>

### Diffstat output
./fs/nfsd/nfs3proc.c | 4 ++--
./fs/nfsd/nfs3xdr.c | 22 +++++++++++-----------
./fs/nfsd/nfs4proc.c | 2 +-
./fs/nfsd/nfs4xdr.c | 26 +++++++++++++-------------
./fs/nfsd/nfsproc.c | 4 ++--
./fs/nfsd/nfsxdr.c | 22 +++++++++++-----------
./include/linux/nfsd/xdr.h | 2 --
./include/linux/nfsd/xdr3.h | 2 --
./include/linux/nfsd/xdr4.h | 2 --
./include/linux/sunrpc/svc.h | 2 ++
./net/sunrpc/svcsock.c | 3 ++-
11 files changed, 44 insertions(+), 47 deletions(-)

diff .prev/fs/nfsd/nfs3proc.c ./fs/nfsd/nfs3proc.c
--- .prev/fs/nfsd/nfs3proc.c 2006-08-24 16:25:41.000000000 +1000
+++ ./fs/nfsd/nfs3proc.c 2006-08-24 16:25:41.000000000 +1000
@@ -180,7 +180,7 @@ nfsd3_proc_read(struct svc_rqst *rqstp,
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,
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 .prev/fs/nfsd/nfs3xdr.c ./fs/nfsd/nfs3xdr.c
--- .prev/fs/nfsd/nfs3xdr.c 2006-08-24 16:25:13.000000000 +1000
+++ ./fs/nfsd/nfs3xdr.c 2006-08-24 16:25:41.000000000 +1000
@@ -344,9 +344,9 @@ nfs3svc_decode_readargs(struct svc_rqst
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->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 .prev/fs/nfsd/nfs4proc.c ./fs/nfsd/nfs4proc.c
--- .prev/fs/nfsd/nfs4proc.c 2006-08-24 16:25:41.000000000 +1000
+++ ./fs/nfsd/nfs4proc.c 2006-08-24 16:25:41.000000000 +1000
@@ -646,7 +646,7 @@ nfsd4_write(struct svc_rqst *rqstp, stru
*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 .prev/fs/nfsd/nfs4xdr.c ./fs/nfsd/nfs4xdr.c
--- .prev/fs/nfsd/nfs4xdr.c 2006-08-24 16:25:13.000000000 +1000
+++ ./fs/nfsd/nfs4xdr.c 2006-08-24 16:25:41.000000000 +1000
@@ -927,26 +927,26 @@ nfsd4_decode_write(struct nfsd4_compound
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;
@@ -2064,9 +2064,9 @@ nfsd4_encode_read(struct nfsd4_compoundr
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;
@@ -2074,7 +2074,7 @@ nfsd4_encode_read(struct nfsd4_compoundr
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 .prev/fs/nfsd/nfsproc.c ./fs/nfsd/nfsproc.c
--- .prev/fs/nfsd/nfsproc.c 2006-08-24 16:21:35.000000000 +1000
+++ ./fs/nfsd/nfsproc.c 2006-08-24 16:25:41.000000000 +1000
@@ -159,7 +159,7 @@ nfsd_proc_read(struct svc_rqst *rqstp, s
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,

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 .prev/fs/nfsd/nfsxdr.c ./fs/nfsd/nfsxdr.c
--- .prev/fs/nfsd/nfsxdr.c 2006-08-24 16:25:13.000000000 +1000
+++ ./fs/nfsd/nfsxdr.c 2006-08-24 16:25:41.000000000 +1000
@@ -263,9 +263,9 @@ nfssvc_decode_readargs(struct svc_rqst *
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
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 .prev/include/linux/nfsd/xdr.h ./include/linux/nfsd/xdr.h
--- .prev/include/linux/nfsd/xdr.h 2006-08-24 16:25:41.000000000 +1000
+++ ./include/linux/nfsd/xdr.h 2006-08-24 16:25:41.000000000 +1000
@@ -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 .prev/include/linux/nfsd/xdr3.h ./include/linux/nfsd/xdr3.h
--- .prev/include/linux/nfsd/xdr3.h 2006-08-24 16:25:41.000000000 +1000
+++ ./include/linux/nfsd/xdr3.h 2006-08-24 16:25:41.000000000 +1000
@@ -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 .prev/include/linux/nfsd/xdr4.h ./include/linux/nfsd/xdr4.h
--- .prev/include/linux/nfsd/xdr4.h 2006-08-24 16:25:41.000000000 +1000
+++ ./include/linux/nfsd/xdr4.h 2006-08-24 16:25:41.000000000 +1000
@@ -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 .prev/include/linux/sunrpc/svc.h ./include/linux/sunrpc/svc.h
--- .prev/include/linux/sunrpc/svc.h 2006-08-24 16:25:13.000000000 +1000
+++ ./include/linux/sunrpc/svc.h 2006-08-24 16:25:41.000000000 +1000
@@ -175,6 +175,8 @@ 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.. */
+
u32 rq_xid; /* transmission id */
u32 rq_prog; /* program number */
u32 rq_vers; /* program version */

diff .prev/net/sunrpc/svcsock.c ./net/sunrpc/svcsock.c
--- .prev/net/sunrpc/svcsock.c 2006-08-24 16:25:13.000000000 +1000
+++ ./net/sunrpc/svcsock.c 2006-08-24 16:25:41.000000000 +1000
@@ -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;