| Message ID | 20190302025146.2935-1-longli@linuxonhyperv.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] CIFS: Fix a bug with re-sending wdata when transport returning -EAGAIN | expand |
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 >
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
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; } }