Fix corruption bug in direct dispatch for blk-mq
This commit is contained in:
Jeremy Cline
parent
4d43220d69
commit
c0dbaa3cc5
99
blk-mq-fix-corruption-with-direct-issue.patch
Normal file
99
blk-mq-fix-corruption-with-direct-issue.patch
Normal file
@ -0,0 +1,99 @@
|
||||
From ffe81d45322cc3cb140f0db080a4727ea284661e Mon Sep 17 00:00:00 2001
|
||||
From: Jens Axboe <axboe@kernel.dk>
|
||||
Date: Tue, 4 Dec 2018 20:06:48 -0700
|
||||
Subject: [PATCH] blk-mq: fix corruption with direct issue
|
||||
|
||||
If we attempt a direct issue to a SCSI device, and it returns BUSY, then
|
||||
we queue the request up normally. However, the SCSI layer may have
|
||||
already setup SG tables etc for this particular command. If we later
|
||||
merge with this request, then the old tables are no longer valid. Once
|
||||
we issue the IO, we only read/write the original part of the request,
|
||||
not the new state of it.
|
||||
|
||||
This causes data corruption, and is most often noticed with the file
|
||||
system complaining about the just read data being invalid:
|
||||
|
||||
[ 235.934465] EXT4-fs error (device sda1): ext4_iget:4831: inode #7142: comm dpkg-query: bad extra_isize 24937 (inode size 256)
|
||||
|
||||
because most of it is garbage...
|
||||
|
||||
This doesn't happen from the normal issue path, as we will simply defer
|
||||
the request to the hardware queue dispatch list if we fail. Once it's on
|
||||
the dispatch list, we never merge with it.
|
||||
|
||||
Fix this from the direct issue path by flagging the request as
|
||||
REQ_NOMERGE so we don't change the size of it before issue.
|
||||
|
||||
See also:
|
||||
https://bugzilla.kernel.org/show_bug.cgi?id=201685
|
||||
|
||||
Tested-by: Guenter Roeck <linux@roeck-us.net>
|
||||
Fixes: 6ce3dd6eec1 ("blk-mq: issue directly if hw queue isn't busy in case of 'none'")
|
||||
Cc: stable@vger.kernel.org
|
||||
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
||||
Signed-off-by: Jeremy Cline <jcline@redhat.com>
|
||||
---
|
||||
block/blk-mq.c | 26 +++++++++++++++++++++++++-
|
||||
1 file changed, 25 insertions(+), 1 deletion(-)
|
||||
|
||||
diff --git a/block/blk-mq.c b/block/blk-mq.c
|
||||
index 3f91c6e5b17a..3262d83b9e07 100644
|
||||
--- a/block/blk-mq.c
|
||||
+++ b/block/blk-mq.c
|
||||
@@ -1715,6 +1715,15 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
|
||||
break;
|
||||
case BLK_STS_RESOURCE:
|
||||
case BLK_STS_DEV_RESOURCE:
|
||||
+ /*
|
||||
+ * If direct dispatch fails, we cannot allow any merging on
|
||||
+ * this IO. Drivers (like SCSI) may have set up permanent state
|
||||
+ * for this request, like SG tables and mappings, and if we
|
||||
+ * merge to it later on then we'll still only do IO to the
|
||||
+ * original part.
|
||||
+ */
|
||||
+ rq->cmd_flags |= REQ_NOMERGE;
|
||||
+
|
||||
blk_mq_update_dispatch_busy(hctx, true);
|
||||
__blk_mq_requeue_request(rq);
|
||||
break;
|
||||
@@ -1727,6 +1736,18 @@ static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
|
||||
return ret;
|
||||
}
|
||||
|
||||
+/*
|
||||
+ * Don't allow direct dispatch of anything but regular reads/writes,
|
||||
+ * as some of the other commands can potentially share request space
|
||||
+ * with data we need for the IO scheduler. If we attempt a direct dispatch
|
||||
+ * on those and fail, we can't safely add it to the scheduler afterwards
|
||||
+ * without potentially overwriting data that the driver has already written.
|
||||
+ */
|
||||
+static bool blk_rq_can_direct_dispatch(struct request *rq)
|
||||
+{
|
||||
+ return req_op(rq) == REQ_OP_READ || req_op(rq) == REQ_OP_WRITE;
|
||||
+}
|
||||
+
|
||||
static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
|
||||
struct request *rq,
|
||||
blk_qc_t *cookie,
|
||||
@@ -1748,7 +1769,7 @@ static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
|
||||
goto insert;
|
||||
}
|
||||
|
||||
- if (q->elevator && !bypass_insert)
|
||||
+ if (!blk_rq_can_direct_dispatch(rq) || (q->elevator && !bypass_insert))
|
||||
goto insert;
|
||||
|
||||
if (!blk_mq_get_dispatch_budget(hctx))
|
||||
@@ -1810,6 +1831,9 @@ void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
|
||||
struct request *rq = list_first_entry(list, struct request,
|
||||
queuelist);
|
||||
|
||||
+ if (!blk_rq_can_direct_dispatch(rq))
|
||||
+ break;
|
||||
+
|
||||
list_del_init(&rq->queuelist);
|
||||
ret = blk_mq_request_issue_directly(rq);
|
||||
if (ret != BLK_STS_OK) {
|
||||
--
|
||||
2.19.2
|
||||
|
||||
@ -609,6 +609,9 @@ Patch504: iio-accel-kxcjk1013-Add-more-hardware-ids.patch
|
||||
# rhbz 1645070 patch queued upstream for merging into 4.21
|
||||
Patch505: asus-fx503-keyb.patch
|
||||
|
||||
# https://bugzilla.kernel.org/show_bug.cgi?id=201685
|
||||
Patch506: blk-mq-fix-corruption-with-direct-issue.patch
|
||||
|
||||
# END OF PATCH DEFINITIONS
|
||||
|
||||
%endif
|
||||
@ -1881,6 +1884,9 @@ fi
|
||||
#
|
||||
#
|
||||
%changelog
|
||||
* Wed Dec 05 2018 Jeremy Cline <jeremy@jcline.org>
|
||||
- Fix corruption bug in direct dispatch for blk-mq
|
||||
|
||||
* Tue Dec 04 2018 Justin M. Forbes <jforbes@fedoraproject.org> - 4.20.0-0.rc5.git1.1
|
||||
- Linux v4.20-rc5-21-g0072a0c14d5b
|
||||
- Reenable debugging options.
|
||||
|
||||
Loading…
Reference in New Issue
Block a user