* [PATCH 2/2] CIFS: Fix a bug with re-sending rdata when transport returning -EAGAIN
2019-03-02 2:51 [PATCH 1/2] CIFS: Fix a bug with re-sending wdata when transport returning -EAGAIN Long Li
@ 2019-03-02 2:51 ` Long Li
2019-03-02 5:43 ` [PATCH 1/2] CIFS: Fix a bug with re-sending wdata " Steve French
2019-03-05 19:47 ` Pavel Shilovsky
2 siblings, 0 replies; 4+ messages in thread
From: Long Li @ 2019-03-02 2:51 UTC (permalink / raw)
To: Steve French, linux-cifs, samba-technical, linux-kernel, linux-rdma
Cc: Long Li
From: Long Li <longli@microsoft.com>
When sending a rdata, transport may return -EAGAIN. In this case
we should re-obtain credits because the session may have been
reconnected.
Signed-off-by: Long Li <longli@microsoft.com>
---
fs/cifs/file.c | 51 +++++++++++++++++++++++++-------------------------
1 file changed, 26 insertions(+), 25 deletions(-)
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 08e73759d6ec..c83ca96f883b 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3335,44 +3335,45 @@ static int cifs_resend_rdata(struct cifs_readdata *rdata,
struct TCP_Server_Info *server =
tlink_tcon(rdata->cfile->tlink)->ses->server;
- /*
- * Wait for credits to resend this rdata.
- * Note: we are attempting to resend the whole rdata not in segments
- */
do {
- rc = server->ops->wait_mtu_credits(server, rdata->bytes,
+ /*
+ * Wait for credits to resend this rdata.
+ * Note: we are attempting to resend the whole rdata not in
+ * segments
+ */
+ do {
+ rc = server->ops->wait_mtu_credits(server, rdata->bytes,
&rsize, &credits);
- if (rc)
- goto out;
+ if (rc)
+ goto fail;
- if (rsize < rdata->bytes) {
- add_credits_and_wake_if(server, &credits, 0);
- msleep(1000);
- }
- } while (rsize < rdata->bytes);
+ if (rsize < rdata->bytes) {
+ add_credits_and_wake_if(server, &credits, 0);
+ msleep(1000);
+ }
+ } while (rsize < rdata->bytes);
- rdata->credits = credits;
- rc = -EAGAIN;
- while (rc == -EAGAIN) {
+ rdata->credits = credits;
rc = 0;
if (rdata->cfile->invalidHandle)
rc = cifs_reopen_file(rdata->cfile, true);
if (!rc)
rc = server->ops->async_readv(rdata);
- }
- if (!rc) {
- /* Add to aio pending list */
- list_add_tail(&rdata->list, rdata_list);
- return 0;
- }
+ /* If the read was successfully sent, we are done */
+ if (!rc) {
+ /* Add to aio pending list */
+ list_add_tail(&rdata->list, rdata_list);
+ return 0;
+ }
- add_credits_and_wake_if(server, &rdata->credits, 0);
-out:
- kref_put(&rdata->refcount,
- cifs_uncached_readdata_release);
+ /* Roll back credits and retry if needed */
+ add_credits_and_wake_if(server, &rdata->credits, 0);
+ } while (rc == -EAGAIN);
+fail:
+ kref_put(&rdata->refcount, cifs_uncached_readdata_release);
return rc;
}
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH 1/2] CIFS: Fix a bug with re-sending wdata when transport returning -EAGAIN
2019-03-02 2:51 [PATCH 1/2] CIFS: Fix a bug with re-sending wdata when transport returning -EAGAIN Long Li
2019-03-02 2:51 ` [PATCH 2/2] CIFS: Fix a bug with re-sending rdata " Long Li
@ 2019-03-02 5:43 ` Steve French
2019-03-05 19:47 ` Pavel Shilovsky
2 siblings, 0 replies; 4+ messages in thread
From: Steve French @ 2019-03-02 5:43 UTC (permalink / raw)
To: Long Li; +Cc: Steve French, CIFS, samba-technical, LKML, linux-rdma
I tested this vs. Samba a few minutes ago with test 208 - looks like
it works. Thank you!
Now just need some additional reviews as this can be a complex area of code.
On Fri, Mar 1, 2019 at 9:04 PM Long Li <longli@linuxonhyperv.com> wrote:
>
> From: Long Li <longli@microsoft.com>
>
> When sending a wdata, transport may return -EAGAIN. In this case
> we should re-obtain credits because the session may have been
> reconnected.
>
> Signed-off-by: Long Li <longli@microsoft.com>
> ---
> fs/cifs/file.c | 61 +++++++++++++++++++++++++-------------------------
> 1 file changed, 31 insertions(+), 30 deletions(-)
>
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index 9b53f33137b3..08e73759d6ec 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -2620,43 +2620,44 @@ cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
> struct TCP_Server_Info *server =
> tlink_tcon(wdata->cfile->tlink)->ses->server;
>
> - /*
> - * Wait for credits to resend this wdata.
> - * Note: we are attempting to resend the whole wdata not in segments
> - */
> do {
> - rc = server->ops->wait_mtu_credits(server, wdata->bytes, &wsize,
> - &credits);
> -
> - if (rc)
> - goto out;
> -
> - if (wsize < wdata->bytes) {
> - add_credits_and_wake_if(server, &credits, 0);
> - msleep(1000);
> - }
> - } while (wsize < wdata->bytes);
> + /*
> + * Wait for credits to resend this wdata.
> + * Note: we are attempting to resend the whole wdata not in
> + * segments
> + */
> + do {
> + rc = server->ops->wait_mtu_credits(server, wdata->bytes,
> + &wsize, &credits);
> + if (rc)
> + goto fail;
> +
> + if (wsize < wdata->bytes) {
> + add_credits_and_wake_if(server, &credits, 0);
> + msleep(1000);
> + }
> + } while (wsize < wdata->bytes);
>
> - wdata->credits = credits;
> - rc = -EAGAIN;
> - while (rc == -EAGAIN) {
> + wdata->credits = credits;
> rc = 0;
> if (wdata->cfile->invalidHandle)
> rc = cifs_reopen_file(wdata->cfile, false);
> if (!rc)
> rc = server->ops->async_writev(wdata,
> - cifs_uncached_writedata_release);
> - }
> + cifs_uncached_writedata_release);
>
> - if (!rc) {
> - list_add_tail(&wdata->list, wdata_list);
> - return 0;
> - }
> + /* If the write was successfully sent, we are done */
> + if (!rc) {
> + list_add_tail(&wdata->list, wdata_list);
> + return 0;
> + }
>
> - add_credits_and_wake_if(server, &wdata->credits, 0);
> -out:
> - kref_put(&wdata->refcount, cifs_uncached_writedata_release);
> + /* Roll back credits and retry if needed */
> + add_credits_and_wake_if(server, &wdata->credits, 0);
> + } while (rc == -EAGAIN);
>
> +fail:
> + kref_put(&wdata->refcount, cifs_uncached_writedata_release);
> return rc;
> }
>
> @@ -2884,12 +2885,12 @@ static void collect_uncached_write_data(struct cifs_aio_ctx *ctx)
> wdata->bytes, &tmp_from,
> ctx->cfile, cifs_sb, &tmp_list,
> ctx);
> +
> + kref_put(&wdata->refcount,
> + cifs_uncached_writedata_release);
> }
>
> list_splice(&tmp_list, &ctx->list);
> -
> - kref_put(&wdata->refcount,
> - cifs_uncached_writedata_release);
> goto restart_loop;
> }
> }
> --
> 2.17.1
>
--
Thanks,
Steve
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH 1/2] CIFS: Fix a bug with re-sending wdata when transport returning -EAGAIN
2019-03-02 2:51 [PATCH 1/2] CIFS: Fix a bug with re-sending wdata when transport returning -EAGAIN Long Li
2019-03-02 2:51 ` [PATCH 2/2] CIFS: Fix a bug with re-sending rdata " Long Li
2019-03-02 5:43 ` [PATCH 1/2] CIFS: Fix a bug with re-sending wdata " Steve French
@ 2019-03-05 19:47 ` Pavel Shilovsky
2 siblings, 0 replies; 4+ messages in thread
From: Pavel Shilovsky @ 2019-03-05 19:47 UTC (permalink / raw)
To: Long Li
Cc: Steve French, linux-cifs, samba-technical, Kernel Mailing List,
linux-rdma
пт, 1 мар. 2019 г. в 19:04, Long Li <longli@linuxonhyperv.com>:
>
> From: Long Li <longli@microsoft.com>
>
> When sending a wdata, transport may return -EAGAIN. In this case
> we should re-obtain credits because the session may have been
> reconnected.
>
> Signed-off-by: Long Li <longli@microsoft.com>
> ---
> fs/cifs/file.c | 61 +++++++++++++++++++++++++-------------------------
> 1 file changed, 31 insertions(+), 30 deletions(-)
>
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index 9b53f33137b3..08e73759d6ec 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -2620,43 +2620,44 @@ cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list,
> struct TCP_Server_Info *server =
> tlink_tcon(wdata->cfile->tlink)->ses->server;
>
> - /*
> - * Wait for credits to resend this wdata.
> - * Note: we are attempting to resend the whole wdata not in segments
> - */
> do {
> - rc = server->ops->wait_mtu_credits(server, wdata->bytes, &wsize,
> - &credits);
> -
> - if (rc)
> - goto out;
> -
> - if (wsize < wdata->bytes) {
> - add_credits_and_wake_if(server, &credits, 0);
> - msleep(1000);
> - }
> - } while (wsize < wdata->bytes);
> + /*
> + * Wait for credits to resend this wdata.
> + * Note: we are attempting to resend the whole wdata not in
> + * segments
> + */
> + do {
> + rc = server->ops->wait_mtu_credits(server, wdata->bytes,
> + &wsize, &credits);
The steps in write/read codepaths have been recently re-ordered: now
we need to first check the open handle, re-open it if needed and then
attempt to get credits. This approach avoid a possibility to be stuck
waiting for credits because generally cifs_reopen_file() may need a
lot of credits to complete (up to 2 SMB2_CREATE commands and arbitrary
number of SMB2_LOCK commands).
Please look at this loop as an example:
https://git.samba.org/?p=sfrench/cifs-2.6.git;a=blob;f=fs/cifs/file.c;h=bf864123093162c7ef5cd49ee08d8b40ad7938c8;hb=778d81b65e4d596251943002522d94a7c6fbcf69#l2690
> + if (rc)
> + goto fail;
> +
> + if (wsize < wdata->bytes) {
> + add_credits_and_wake_if(server, &credits, 0);
> + msleep(1000);
> + }
> + } while (wsize < wdata->bytes);
>
> - wdata->credits = credits;
> - rc = -EAGAIN;
> - while (rc == -EAGAIN) {
> + wdata->credits = credits;
let's call adjust_credits before calling async_writev() as in the example above.
> rc = 0;
> if (wdata->cfile->invalidHandle)
> rc = cifs_reopen_file(wdata->cfile, false);
> if (!rc)
> rc = server->ops->async_writev(wdata,
> - cifs_uncached_writedata_release);
> - }
> + cifs_uncached_writedata_release);
>
> - if (!rc) {
> - list_add_tail(&wdata->list, wdata_list);
> - return 0;
> - }
> + /* If the write was successfully sent, we are done */
> + if (!rc) {
> + list_add_tail(&wdata->list, wdata_list);
> + return 0;
> + }
>
> - add_credits_and_wake_if(server, &wdata->credits, 0);
> -out:
> - kref_put(&wdata->refcount, cifs_uncached_writedata_release);
> + /* Roll back credits and retry if needed */
> + add_credits_and_wake_if(server, &wdata->credits, 0);
> + } while (rc == -EAGAIN);
I don't think there is a need for the nested loop here. How about just do:
do {
if (wdata->cfile->invalidHandle) {
rc = cifs_reopen_file(...);
if (rc) break;
}
// get_credits
// if not enough credits - wait and continue the loop.
rc = adjust_credits(...);
if (!rc) {
if (wdata->cfile->invalidHandle)
// set rc, put credits and continue the loop.
else
// send async write
}
// handle write errors
} while(rc == -EAGAIN);
>
> +fail:
> + kref_put(&wdata->refcount, cifs_uncached_writedata_release);
> return rc;
> }
>
> @@ -2884,12 +2885,12 @@ static void collect_uncached_write_data(struct cifs_aio_ctx *ctx)
> wdata->bytes, &tmp_from,
> ctx->cfile, cifs_sb, &tmp_list,
> ctx);
> +
> + kref_put(&wdata->refcount,
> + cifs_uncached_writedata_release);
> }
>
> list_splice(&tmp_list, &ctx->list);
> -
> - kref_put(&wdata->refcount,
> - cifs_uncached_writedata_release);
> goto restart_loop;
> }
> }
> --
> 2.17.1
>
The similar concepts applies for async reads as well.
--
Best regards,
Pavel Shilovsky
^ permalink raw reply [flat|nested] 4+ messages in thread