A user doesn't necessarily want to wait for all the requested data to
be available, since the waiting time is unbounded.
Signed-off-by: Sergey Alirzaev <[email protected]>
---
include/net/9p/client.h | 2 +
net/9p/client.c | 133 ++++++++++++++++++++++------------------
2 files changed, 76 insertions(+), 59 deletions(-)
diff --git a/include/net/9p/client.h b/include/net/9p/client.h
index acc60d8a3b3b..f6c890e94f87 100644
--- a/include/net/9p/client.h
+++ b/include/net/9p/client.h
@@ -200,6 +200,8 @@ int p9_client_fsync(struct p9_fid *fid, int datasync);
int p9_client_remove(struct p9_fid *fid);
int p9_client_unlinkat(struct p9_fid *dfid, const char *name, int flags);
int p9_client_read(struct p9_fid *fid, u64 offset, struct iov_iter *to, int *err);
+int p9_client_read_once(struct p9_fid *fid, u64 offset, struct iov_iter *to,
+ int *err);
int p9_client_write(struct p9_fid *fid, u64 offset, struct iov_iter *from, int *err);
int p9_client_readdir(struct p9_fid *fid, char *data, u32 count, u64 offset);
int p9dirent_read(struct p9_client *clnt, char *buf, int len,
diff --git a/net/9p/client.c b/net/9p/client.c
index 1d48afc7033c..186f5b44aa01 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -1548,83 +1548,98 @@ EXPORT_SYMBOL(p9_client_unlinkat);
int
p9_client_read(struct p9_fid *fid, u64 offset, struct iov_iter *to, int *err)
+{
+ int total = 0;
+ *err = 0;
+
+ while (iov_iter_count(to)) {
+ int count;
+
+ count = p9_client_read_once(fid, offset, to, err);
+ if (!count || *err)
+ break;
+ offset += count;
+ total += count;
+ }
+ return total;
+}
+EXPORT_SYMBOL(p9_client_read);
+
+int
+p9_client_read_once(struct p9_fid *fid, u64 offset, struct iov_iter *to,
+ int *err)
{
struct p9_client *clnt = fid->clnt;
struct p9_req_t *req;
int total = 0;
- *err = 0;
+ int count = iov_iter_count(to);
+ int rsize, non_zc = 0;
+ char *dataptr;
+ *err = 0;
p9_debug(P9_DEBUG_9P, ">>> TREAD fid %d offset %llu %d\n",
fid->fid, (unsigned long long) offset, (int)iov_iter_count(to));
- while (iov_iter_count(to)) {
- int count = iov_iter_count(to);
- int rsize, non_zc = 0;
- char *dataptr;
+ rsize = fid->iounit;
+ if (!rsize || rsize > clnt->msize - P9_IOHDRSZ)
+ rsize = clnt->msize - P9_IOHDRSZ;
- rsize = fid->iounit;
- if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
- rsize = clnt->msize - P9_IOHDRSZ;
+ if (count < rsize)
+ rsize = count;
- if (count < rsize)
- rsize = count;
+ /* Don't bother zerocopy for small IO (< 1024) */
+ if (clnt->trans_mod->zc_request && rsize > 1024) {
+ /* response header len is 11
+ * PDU Header(7) + IO Size (4)
+ */
+ req = p9_client_zc_rpc(clnt, P9_TREAD, to, NULL, rsize,
+ 0, 11, "dqd", fid->fid,
+ offset, rsize);
+ } else {
+ non_zc = 1;
+ req = p9_client_rpc(clnt, P9_TREAD, "dqd", fid->fid, offset,
+ rsize);
+ }
+ if (IS_ERR(req)) {
+ *err = PTR_ERR(req);
+ return total;
+ }
- /* Don't bother zerocopy for small IO (< 1024) */
- if (clnt->trans_mod->zc_request && rsize > 1024) {
- /*
- * response header len is 11
- * PDU Header(7) + IO Size (4)
- */
- req = p9_client_zc_rpc(clnt, P9_TREAD, to, NULL, rsize,
- 0, 11, "dqd", fid->fid,
- offset, rsize);
- } else {
- non_zc = 1;
- req = p9_client_rpc(clnt, P9_TREAD, "dqd", fid->fid, offset,
- rsize);
- }
- if (IS_ERR(req)) {
- *err = PTR_ERR(req);
- break;
- }
+ *err = p9pdu_readf(&req->rc, clnt->proto_version,
+ "D", &count, &dataptr);
+ if (*err) {
+ trace_9p_protocol_dump(clnt, &req->rc);
+ p9_tag_remove(clnt, req);
+ return total;
+ }
+ if (rsize < count) {
+ pr_err("bogus RREAD count (%d > %d)\n", count, rsize);
+ count = rsize;
+ }
- *err = p9pdu_readf(&req->rc, clnt->proto_version,
- "D", &count, &dataptr);
- if (*err) {
- trace_9p_protocol_dump(clnt, &req->rc);
- p9_tag_remove(clnt, req);
- break;
- }
- if (rsize < count) {
- pr_err("bogus RREAD count (%d > %d)\n", count, rsize);
- count = rsize;
- }
+ p9_debug(P9_DEBUG_9P, "<<< RREAD count %d\n", count);
+ if (!count) {
+ p9_tag_remove(clnt, req);
+ return total;
+ }
- p9_debug(P9_DEBUG_9P, "<<< RREAD count %d\n", count);
- if (!count) {
- p9_tag_remove(clnt, req);
- break;
- }
+ if (non_zc) {
+ int n = copy_to_iter(dataptr, count, to);
- if (non_zc) {
- int n = copy_to_iter(dataptr, count, to);
- total += n;
- offset += n;
- if (n != count) {
- *err = -EFAULT;
- p9_tag_remove(clnt, req);
- break;
- }
- } else {
- iov_iter_advance(to, count);
- total += count;
- offset += count;
+ total += n;
+ if (n != count) {
+ *err = -EFAULT;
+ p9_tag_remove(clnt, req);
+ return total;
}
- p9_tag_remove(clnt, req);
+ } else {
+ iov_iter_advance(to, count);
+ total += count;
}
+ p9_tag_remove(clnt, req);
return total;
}
-EXPORT_SYMBOL(p9_client_read);
+EXPORT_SYMBOL(p9_client_read_once);
int
p9_client_write(struct p9_fid *fid, u64 offset, struct iov_iter *from, int *err)
--
2.25.0
Sergey Alirzaev wrote on Wed, Feb 05, 2020:
> A user doesn't necessarily want to wait for all the requested data to
> be available, since the waiting time is unbounded.
I'm not sure I agree on the argument there: the waiting time is
unbounded for a single request as well. What's your use case?
I think it would be better to describe what you really do with
O_NONBLOCK that requires this, and not just false theoritical
arguments.
> Signed-off-by: Sergey Alirzaev <[email protected]>
Code-wise looks mostly good, just a nitpick about keeping the total
variable in p9_client_read_once inline.
> ---
> include/net/9p/client.h | 2 +
> net/9p/client.c | 133 ++++++++++++++++++++++------------------
> 2 files changed, 76 insertions(+), 59 deletions(-)
>
> --- a/net/9p/client.c
> +++ b/net/9p/client.c
> @@ -1548,83 +1548,98 @@ EXPORT_SYMBOL(p9_client_unlinkat);
>
> int
> p9_client_read(struct p9_fid *fid, u64 offset, struct iov_iter *to, int *err)
> +{
> + int total = 0;
> + *err = 0;
> +
> + while (iov_iter_count(to)) {
> + int count;
> +
> + count = p9_client_read_once(fid, offset, to, err);
> + if (!count || *err)
> + break;
> + offset += count;
> + total += count;
> + }
> + return total;
> +}
> +EXPORT_SYMBOL(p9_client_read);
> +
> +int
> +p9_client_read_once(struct p9_fid *fid, u64 offset, struct iov_iter *to,
> + int *err)
> {
> struct p9_client *clnt = fid->clnt;
> struct p9_req_t *req;
> int total = 0;
total only makes sense in an iterating p9_client_read, I think it makes
code harder to read here (can basically use count or 0 directly now)
> - *err = 0;
> + int count = iov_iter_count(to);
> + int rsize, non_zc = 0;
> + char *dataptr;
>
> + *err = 0;
> p9_debug(P9_DEBUG_9P, ">>> TREAD fid %d offset %llu %d\n",
> fid->fid, (unsigned long long) offset, (int)iov_iter_count(to));
>
> - while (iov_iter_count(to)) {
> - int count = iov_iter_count(to);
> - int rsize, non_zc = 0;
> - char *dataptr;
> + rsize = fid->iounit;
> + if (!rsize || rsize > clnt->msize - P9_IOHDRSZ)
> + rsize = clnt->msize - P9_IOHDRSZ;
>
> - rsize = fid->iounit;
> - if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
> - rsize = clnt->msize - P9_IOHDRSZ;
> + if (count < rsize)
> + rsize = count;
>
> - if (count < rsize)
> - rsize = count;
> + /* Don't bother zerocopy for small IO (< 1024) */
> + if (clnt->trans_mod->zc_request && rsize > 1024) {
> + /* response header len is 11
> + * PDU Header(7) + IO Size (4)
> + */
> + req = p9_client_zc_rpc(clnt, P9_TREAD, to, NULL, rsize,
> + 0, 11, "dqd", fid->fid,
> + offset, rsize);
> + } else {
> + non_zc = 1;
> + req = p9_client_rpc(clnt, P9_TREAD, "dqd", fid->fid, offset,
> + rsize);
> + }
> + if (IS_ERR(req)) {
> + *err = PTR_ERR(req);
> + return total;
> + }
>
> - /* Don't bother zerocopy for small IO (< 1024) */
> - if (clnt->trans_mod->zc_request && rsize > 1024) {
> - /*
> - * response header len is 11
> - * PDU Header(7) + IO Size (4)
> - */
> - req = p9_client_zc_rpc(clnt, P9_TREAD, to, NULL, rsize,
> - 0, 11, "dqd", fid->fid,
> - offset, rsize);
> - } else {
> - non_zc = 1;
> - req = p9_client_rpc(clnt, P9_TREAD, "dqd", fid->fid, offset,
> - rsize);
> - }
> - if (IS_ERR(req)) {
> - *err = PTR_ERR(req);
> - break;
> - }
> + *err = p9pdu_readf(&req->rc, clnt->proto_version,
> + "D", &count, &dataptr);
> + if (*err) {
> + trace_9p_protocol_dump(clnt, &req->rc);
> + p9_tag_remove(clnt, req);
> + return total;
> + }
> + if (rsize < count) {
> + pr_err("bogus RREAD count (%d > %d)\n", count, rsize);
> + count = rsize;
> + }
>
> - *err = p9pdu_readf(&req->rc, clnt->proto_version,
> - "D", &count, &dataptr);
> - if (*err) {
> - trace_9p_protocol_dump(clnt, &req->rc);
> - p9_tag_remove(clnt, req);
> - break;
> - }
> - if (rsize < count) {
> - pr_err("bogus RREAD count (%d > %d)\n", count, rsize);
> - count = rsize;
> - }
> + p9_debug(P9_DEBUG_9P, "<<< RREAD count %d\n", count);
> + if (!count) {
> + p9_tag_remove(clnt, req);
> + return total;
> + }
>
> - p9_debug(P9_DEBUG_9P, "<<< RREAD count %d\n", count);
> - if (!count) {
> - p9_tag_remove(clnt, req);
> - break;
> - }
> + if (non_zc) {
> + int n = copy_to_iter(dataptr, count, to);
>
> - if (non_zc) {
> - int n = copy_to_iter(dataptr, count, to);
> - total += n;
> - offset += n;
> - if (n != count) {
> - *err = -EFAULT;
> - p9_tag_remove(clnt, req);
> - break;
> - }
> - } else {
> - iov_iter_advance(to, count);
> - total += count;
> - offset += count;
> + total += n;
> + if (n != count) {
> + *err = -EFAULT;
> + p9_tag_remove(clnt, req);
> + return total;
> }
> - p9_tag_remove(clnt, req);
> + } else {
> + iov_iter_advance(to, count);
> + total += count;
> }
> + p9_tag_remove(clnt, req);
> return total;
> }
> -EXPORT_SYMBOL(p9_client_read);
> +EXPORT_SYMBOL(p9_client_read_once);
>
> int
> p9_client_write(struct p9_fid *fid, u64 offset, struct iov_iter *from, int *err)
--
Dominique
On Wed, Feb 05, 2020 at 08:35:04AM +0100, Dominique Martinet wrote:
> Sergey Alirzaev wrote on Wed, Feb 05, 2020:
> > A user doesn't necessarily want to wait for all the requested data to
> > be available, since the waiting time is unbounded.
>
> I'm not sure I agree on the argument there: the waiting time is
> unbounded for a single request as well. What's your use case?
I want to interface with synthetic file systems that represent arbitrary data streams.
The one where i've hit the problem is reading the log of a XMPP chat client that blocks if there's no new data available.
--
() ascii ribbon campaign - against html mail
/\ http://arc.pasp.de/ - against proprietary attachments
[email protected] wrote on Wed, Feb 05, 2020:
> On Wed, Feb 05, 2020 at 08:35:04AM +0100, Dominique Martinet wrote:
> > I'm not sure I agree on the argument there: the waiting time is
> > unbounded for a single request as well. What's your use case?
>
> I want to interface with synthetic file systems that represent
> arbitrary data streams.
> The one where i've hit the problem is reading the log of a XMPP chat
> client that blocks if there's no new data available.
Definitely a valid use case for 9p, please rephrase your commit message
to describe the problem a bit better.
I'll wait for a v2 removing the 'total' variable from
p9_client_read_once anyway, unless you disagree.
Thanks,
--
Dominique