CIFS: Fix a bug with re-sending wdata when transport returning -EAGAIN
Subsystems (3)
PATCH 1/2 CIFS: Fix a bug with re-sending wdata when transport returning -EAGAIN
From: Long Li <[email protected]>
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 <[email protected]>
--- fs/cifs/file.c | 61 +++++++++++++++++++++++++------------------------- 1 file changed, 31 insertions(+), 30 deletions(-)
fs/cifs/file.c +31 -30
@@ -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; } }
Signature · 1 line
2.17.1
PATCH 2/2 CIFS: Fix a bug with re-sending rdata when transport returning -EAGAIN
From: Long Li <[email protected]>
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 <[email protected]>
--- fs/cifs/file.c | 51 +++++++++++++++++++++++++------------------------- 1 file changed, 26 insertions(+), 25 deletions(-)
fs/cifs/file.c +26 -25
@@ -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; }
Signature · 1 line
2.17.1
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.
Quoted 107 lines · Long Li
From: Long Li <[email protected]>
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 <[email protected]>--- fs/cifs/file.c | 61 +++++++++++++++++++++++++------------------------- 1 file changed, 31 insertions(+), 30 deletions(-)fs/cifs/file.c +31
-31@@ -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
Signature · 3 lines
Thanks, Steve
пт, 1 мар. 2019 г. в 19:04, Long Li <[email protected]>:
Quoted 34 lines
From: Long Li <[email protected]>
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 <[email protected]>--- fs/cifs/file.c | 61 +++++++++++++++++++++++++------------------------- 1 file changed, 31 insertions(+), 30 deletions(-)fs/cifs/file.c +0
-13@@ -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);
fs/cifs/file.c cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list, · line 2631
Quoted 10 lines
fs/cifs/file.c +8
-2- } - }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
fs/cifs/file.c cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list, · line 2641
Quoted 13 lines
fs/cifs/file.c +9
-3+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.
Quoted 15 lines
fs/cifs/file.c +3
-6rc =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) {
fs/cifs/file.c cifs_resend_wdata(struct cifs_writedata *wdata, struct list_head *wdata_list, · line 2657
Quoted 10 lines
fs/cifs/file.c +6
-3+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);Quoted 23 lines
fs/cifs/file.c +5
-4+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; } } --
Quoted 2 lines
2.17.1
The similar concepts applies for async reads as well.
--
Best regards,
Pavel Shilovsky