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authorMichal Kubecek <mkubecek@suse.cz>2018-12-05 22:36:16 +0100
committerMichal Kubecek <mkubecek@suse.cz>2018-12-05 22:36:16 +0100
commit8970eff1d1b9561524368917e3249971bd2ca320 (patch)
treed68c45e086d1e209df8431725c5d42591922cc85
parentc4b3c9024afa761b1279bb1c1c7688d270ccff59 (diff)
blk-mq: fix corruption with direct issue (bko#201685).
-rw-r--r--patches.suse/blk-mq-fix-corruption-with-direct-issue.patch55
-rw-r--r--series.conf1
2 files changed, 56 insertions, 0 deletions
diff --git a/patches.suse/blk-mq-fix-corruption-with-direct-issue.patch b/patches.suse/blk-mq-fix-corruption-with-direct-issue.patch
new file mode 100644
index 0000000000..c318517c3a
--- /dev/null
+++ b/patches.suse/blk-mq-fix-corruption-with-direct-issue.patch
@@ -0,0 +1,55 @@
+From: Jens Axboe <axboe@kernel.dk>
+Date: Tue, 4 Dec 2018 15:47:46 -0700
+Subject: blk-mq: fix corruption with direct issue
+Patch-mainline: Submitted, 2018-12-05
+References: bko#201685
+
+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+merge with this request, then the old tables are no longer valid.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
+
+Fixes: 6ce3dd6eec1 ("blk-mq: issue directly if hw queue isn't busy in case of 'none'")
+Signed-off-by: Jens Axboe <axboe@kernel.dk>
+Acked-by: Michal Kubecek <mkubecek@suse.cz>
+---
+ block/blk-mq.c | 9 +++++++++
+ 1 file changed, 9 insertions(+)
+
+--- 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;
diff --git a/series.conf b/series.conf
index 2ba3ba5534..7fdc48b6a7 100644
--- a/series.conf
+++ b/series.conf
@@ -292,6 +292,7 @@
patches.suse/scsi-retry-alua-transition-in-progress
patches.suse/megaraid-mbox-fix-SG_IO
+ patches.suse/blk-mq-fix-corruption-with-direct-issue.patch
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# DRM/Video