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net/9p: switch the guts of p9_client_{read,write}() to iov_iter
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... and have get_user_pages_fast() mapping fewer pages than requested
to generate a short read/write.

Signed-off-by: Al Viro <[email protected]>
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Al Viro committed Apr 12, 2015
1 parent 6e242a1 commit 4f3b35c
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Showing 4 changed files with 147 additions and 133 deletions.
2 changes: 1 addition & 1 deletion include/net/9p/transport.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -61,7 +61,7 @@ struct p9_trans_module {
int (*cancel) (struct p9_client *, struct p9_req_t *req);
int (*cancelled)(struct p9_client *, struct p9_req_t *req);
int (*zc_request)(struct p9_client *, struct p9_req_t *,
char *, char *, int , int, int, int);
struct iov_iter *, struct iov_iter *, int , int, int);
};

void v9fs_register_trans(struct p9_trans_module *m);
Expand Down
117 changes: 59 additions & 58 deletions net/9p/client.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include <linux/uio.h>
#include <net/9p/9p.h>
#include <linux/parser.h>
#include <net/9p/client.h>
Expand Down Expand Up @@ -555,7 +556,7 @@ static int p9_check_errors(struct p9_client *c, struct p9_req_t *req)
*/

static int p9_check_zc_errors(struct p9_client *c, struct p9_req_t *req,
char *uidata, int in_hdrlen, int kern_buf)
struct iov_iter *uidata, int in_hdrlen)
{
int err;
int ecode;
Expand Down Expand Up @@ -591,16 +592,11 @@ static int p9_check_zc_errors(struct p9_client *c, struct p9_req_t *req,
ename = &req->rc->sdata[req->rc->offset];
if (len > inline_len) {
/* We have error in external buffer */
if (kern_buf) {
memcpy(ename + inline_len, uidata,
len - inline_len);
} else {
err = copy_from_user(ename + inline_len,
uidata, len - inline_len);
if (err) {
err = -EFAULT;
goto out_err;
}
err = copy_from_iter(ename + inline_len,
len - inline_len, uidata);
if (err != len - inline_len) {
err = -EFAULT;
goto out_err;
}
}
ename = NULL;
Expand Down Expand Up @@ -806,8 +802,8 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
* p9_client_zc_rpc - issue a request and wait for a response
* @c: client session
* @type: type of request
* @uidata: user bffer that should be ued for zero copy read
* @uodata: user buffer that shoud be user for zero copy write
* @uidata: destination for zero copy read
* @uodata: source for zero copy write
* @inlen: read buffer size
* @olen: write buffer size
* @hdrlen: reader header size, This is the size of response protocol data
Expand All @@ -816,9 +812,10 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
* Returns request structure (which client must free using p9_free_req)
*/
static struct p9_req_t *p9_client_zc_rpc(struct p9_client *c, int8_t type,
char *uidata, char *uodata,
struct iov_iter *uidata,
struct iov_iter *uodata,
int inlen, int olen, int in_hdrlen,
int kern_buf, const char *fmt, ...)
const char *fmt, ...)
{
va_list ap;
int sigpending, err;
Expand All @@ -841,12 +838,8 @@ static struct p9_req_t *p9_client_zc_rpc(struct p9_client *c, int8_t type,
} else
sigpending = 0;

/* If we are called with KERNEL_DS force kern_buf */
if (segment_eq(get_fs(), KERNEL_DS))
kern_buf = 1;

err = c->trans_mod->zc_request(c, req, uidata, uodata,
inlen, olen, in_hdrlen, kern_buf);
inlen, olen, in_hdrlen);
if (err < 0) {
if (err == -EIO)
c->status = Disconnected;
Expand Down Expand Up @@ -876,7 +869,7 @@ static struct p9_req_t *p9_client_zc_rpc(struct p9_client *c, int8_t type,
if (err < 0)
goto reterr;

err = p9_check_zc_errors(c, req, uidata, in_hdrlen, kern_buf);
err = p9_check_zc_errors(c, req, uidata, in_hdrlen);
trace_9p_client_res(c, type, req->rc->tag, err);
if (!err)
return req;
Expand Down Expand Up @@ -1545,11 +1538,24 @@ p9_client_read(struct p9_fid *fid, char *data, char __user *udata, u64 offset,
u32 count)
{
char *dataptr;
int kernel_buf = 0;
struct p9_req_t *req;
struct p9_client *clnt;
int err, rsize, non_zc = 0;

struct iov_iter to;
union {
struct kvec kv;
struct iovec iov;
} v;

if (data) {
v.kv.iov_base = data;
v.kv.iov_len = count;
iov_iter_kvec(&to, ITER_KVEC | READ, &v.kv, 1, count);
} else {
v.iov.iov_base = udata;
v.iov.iov_len = count;
iov_iter_init(&to, READ, &v.iov, 1, count);
}

p9_debug(P9_DEBUG_9P, ">>> TREAD fid %d offset %llu %d\n",
fid->fid, (unsigned long long) offset, count);
Expand All @@ -1565,18 +1571,12 @@ p9_client_read(struct p9_fid *fid, char *data, char __user *udata, u64 offset,

/* Don't bother zerocopy for small IO (< 1024) */
if (clnt->trans_mod->zc_request && rsize > 1024) {
char *indata;
if (data) {
kernel_buf = 1;
indata = data;
} else
indata = (__force char *)udata;
/*
* response header len is 11
* PDU Header(7) + IO Size (4)
*/
req = p9_client_zc_rpc(clnt, P9_TREAD, indata, NULL, rsize, 0,
11, kernel_buf, "dqd", fid->fid,
req = p9_client_zc_rpc(clnt, P9_TREAD, &to, NULL, rsize, 0,
11, "dqd", fid->fid,
offset, rsize);
} else {
non_zc = 1;
Expand All @@ -1596,16 +1596,9 @@ p9_client_read(struct p9_fid *fid, char *data, char __user *udata, u64 offset,

p9_debug(P9_DEBUG_9P, "<<< RREAD count %d\n", count);

if (non_zc) {
if (data) {
memmove(data, dataptr, count);
} else {
err = copy_to_user(udata, dataptr, count);
if (err) {
err = -EFAULT;
goto free_and_error;
}
}
if (non_zc && copy_to_iter(dataptr, count, &to) != count) {
err = -EFAULT;
goto free_and_error;
}
p9_free_req(clnt, req);
return count;
Expand All @@ -1622,9 +1615,23 @@ p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,
u64 offset, u32 count)
{
int err, rsize;
int kernel_buf = 0;
struct p9_client *clnt;
struct p9_req_t *req;
struct iov_iter from;
union {
struct kvec kv;
struct iovec iov;
} v;

if (data) {
v.kv.iov_base = data;
v.kv.iov_len = count;
iov_iter_kvec(&from, ITER_KVEC | WRITE, &v.kv, 1, count);
} else {
v.iov.iov_base = udata;
v.iov.iov_len = count;
iov_iter_init(&from, WRITE, &v.iov, 1, count);
}

p9_debug(P9_DEBUG_9P, ">>> TWRITE fid %d offset %llu count %d\n",
fid->fid, (unsigned long long) offset, count);
Expand All @@ -1640,22 +1647,12 @@ p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,

/* Don't bother zerocopy for small IO (< 1024) */
if (clnt->trans_mod->zc_request && rsize > 1024) {
char *odata;
if (data) {
kernel_buf = 1;
odata = data;
} else
odata = (char *)udata;
req = p9_client_zc_rpc(clnt, P9_TWRITE, NULL, odata, 0, rsize,
P9_ZC_HDR_SZ, kernel_buf, "dqd",
req = p9_client_zc_rpc(clnt, P9_TWRITE, NULL, &from, 0, rsize,
P9_ZC_HDR_SZ, "dqd",
fid->fid, offset, rsize);
} else {
if (data)
req = p9_client_rpc(clnt, P9_TWRITE, "dqD", fid->fid,
offset, rsize, data);
else
req = p9_client_rpc(clnt, P9_TWRITE, "dqU", fid->fid,
offset, rsize, udata);
req = p9_client_rpc(clnt, P9_TWRITE, "dqV", fid->fid,
offset, rsize, &from);
}
if (IS_ERR(req)) {
err = PTR_ERR(req);
Expand Down Expand Up @@ -2068,6 +2065,10 @@ int p9_client_readdir(struct p9_fid *fid, char *data, u32 count, u64 offset)
struct p9_client *clnt;
struct p9_req_t *req;
char *dataptr;
struct kvec kv = {.iov_base = data, .iov_len = count};
struct iov_iter to;

iov_iter_kvec(&to, READ | ITER_KVEC, &kv, 1, count);

p9_debug(P9_DEBUG_9P, ">>> TREADDIR fid %d offset %llu count %d\n",
fid->fid, (unsigned long long) offset, count);
Expand All @@ -2088,8 +2089,8 @@ int p9_client_readdir(struct p9_fid *fid, char *data, u32 count, u64 offset)
* response header len is 11
* PDU Header(7) + IO Size (4)
*/
req = p9_client_zc_rpc(clnt, P9_TREADDIR, data, NULL, rsize, 0,
11, 1, "dqd", fid->fid, offset, rsize);
req = p9_client_zc_rpc(clnt, P9_TREADDIR, &to, NULL, rsize, 0,
11, "dqd", fid->fid, offset, rsize);
} else {
non_zc = 1;
req = p9_client_rpc(clnt, P9_TREADDIR, "dqd", fid->fid,
Expand Down
24 changes: 8 additions & 16 deletions net/9p/protocol.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@
#include <linux/sched.h>
#include <linux/stddef.h>
#include <linux/types.h>
#include <linux/uio.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include "protocol.h"
Expand Down Expand Up @@ -69,10 +70,11 @@ static size_t pdu_write(struct p9_fcall *pdu, const void *data, size_t size)
}

static size_t
pdu_write_u(struct p9_fcall *pdu, const char __user *udata, size_t size)
pdu_write_u(struct p9_fcall *pdu, struct iov_iter *from, size_t size)
{
size_t len = min(pdu->capacity - pdu->size, size);
if (copy_from_user(&pdu->sdata[pdu->size], udata, len))
struct iov_iter i = *from;
if (copy_from_iter(&pdu->sdata[pdu->size], len, &i) != len)
len = 0;

pdu->size += len;
Expand Down Expand Up @@ -437,23 +439,13 @@ p9pdu_vwritef(struct p9_fcall *pdu, int proto_version, const char *fmt,
stbuf->extension, stbuf->n_uid,
stbuf->n_gid, stbuf->n_muid);
} break;
case 'D':{
uint32_t count = va_arg(ap, uint32_t);
const void *data = va_arg(ap, const void *);

errcode = p9pdu_writef(pdu, proto_version, "d",
count);
if (!errcode && pdu_write(pdu, data, count))
errcode = -EFAULT;
}
break;
case 'U':{
case 'V':{
int32_t count = va_arg(ap, int32_t);
const char __user *udata =
va_arg(ap, const void __user *);
struct iov_iter *from =
va_arg(ap, struct iov_iter *);
errcode = p9pdu_writef(pdu, proto_version, "d",
count);
if (!errcode && pdu_write_u(pdu, udata, count))
if (!errcode && pdu_write_u(pdu, from, count))
errcode = -EFAULT;
}
break;
Expand Down
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