<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/drivers/block, branch v5.18-rc2</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>drbd: set QUEUE_FLAG_STABLE_WRITES</title>
<updated>2022-04-06T19:07:53+00:00</updated>
<author>
<name>Christoph Böhmwalder</name>
<email>christoph@boehmwalder.at</email>
</author>
<published>2022-04-06T19:04:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=286901941fd18a52b2138fddbbf589ad3639eb00'/>
<id>286901941fd18a52b2138fddbbf589ad3639eb00</id>
<content type='text'>
We want our pages not to change while they are being written.

Signed-off-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We want our pages not to change while they are being written.

Signed-off-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drbd: fix an invalid memory access caused by incorrect use of list iterator</title>
<updated>2022-04-06T19:07:52+00:00</updated>
<author>
<name>Xiaomeng Tong</name>
<email>xiam0nd.tong@gmail.com</email>
</author>
<published>2022-04-06T19:04:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ae4d37b5df749926891583d42a6801b5da11e3c1'/>
<id>ae4d37b5df749926891583d42a6801b5da11e3c1</id>
<content type='text'>
The bug is here:
	idr_remove(&amp;connection-&gt;peer_devices, vnr);

If the previous for_each_connection() don't exit early (no goto hit
inside the loop), the iterator 'connection' after the loop will be a
bogus pointer to an invalid structure object containing the HEAD
(&amp;resource-&gt;connections). As a result, the use of 'connection' above
will lead to a invalid memory access (including a possible invalid free
as idr_remove could call free_layer).

The original intention should have been to remove all peer_devices,
but the following lines have already done the work. So just remove
this line and the unneeded label, to fix this bug.

Cc: stable@vger.kernel.org
Fixes: c06ece6ba6f1b ("drbd: Turn connection-&gt;volumes into connection-&gt;peer_devices")
Signed-off-by: Xiaomeng Tong &lt;xiam0nd.tong@gmail.com&gt;
Reviewed-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt;
Reviewed-by: Lars Ellenberg &lt;lars.ellenberg@linbit.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The bug is here:
	idr_remove(&amp;connection-&gt;peer_devices, vnr);

If the previous for_each_connection() don't exit early (no goto hit
inside the loop), the iterator 'connection' after the loop will be a
bogus pointer to an invalid structure object containing the HEAD
(&amp;resource-&gt;connections). As a result, the use of 'connection' above
will lead to a invalid memory access (including a possible invalid free
as idr_remove could call free_layer).

The original intention should have been to remove all peer_devices,
but the following lines have already done the work. So just remove
this line and the unneeded label, to fix this bug.

Cc: stable@vger.kernel.org
Fixes: c06ece6ba6f1b ("drbd: Turn connection-&gt;volumes into connection-&gt;peer_devices")
Signed-off-by: Xiaomeng Tong &lt;xiam0nd.tong@gmail.com&gt;
Reviewed-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt;
Reviewed-by: Lars Ellenberg &lt;lars.ellenberg@linbit.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drbd: Fix five use after free bugs in get_initial_state</title>
<updated>2022-04-06T19:07:50+00:00</updated>
<author>
<name>Lv Yunlong</name>
<email>lyl2019@mail.ustc.edu.cn</email>
</author>
<published>2022-04-06T19:04:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=aadb22ba2f656581b2f733deb3a467c48cc618f6'/>
<id>aadb22ba2f656581b2f733deb3a467c48cc618f6</id>
<content type='text'>
In get_initial_state, it calls notify_initial_state_done(skb,..) if
cb-&gt;args[5]==1. If genlmsg_put() failed in notify_initial_state_done(),
the skb will be freed by nlmsg_free(skb).
Then get_initial_state will goto out and the freed skb will be used by
return value skb-&gt;len, which is a uaf bug.

What's worse, the same problem goes even further: skb can also be
freed in the notify_*_state_change -&gt; notify_*_state calls below.
Thus 4 additional uaf bugs happened.

My patch lets the problem callee functions: notify_initial_state_done
and notify_*_state_change return an error code if errors happen.
So that the error codes could be propagated and the uaf bugs can be avoid.

v2 reports a compilation warning. This v3 fixed this warning and built
successfully in my local environment with no additional warnings.
v2: https://lore.kernel.org/patchwork/patch/1435218/

Fixes: a29728463b254 ("drbd: Backport the "events2" command")
Signed-off-by: Lv Yunlong &lt;lyl2019@mail.ustc.edu.cn&gt;
Reviewed-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In get_initial_state, it calls notify_initial_state_done(skb,..) if
cb-&gt;args[5]==1. If genlmsg_put() failed in notify_initial_state_done(),
the skb will be freed by nlmsg_free(skb).
Then get_initial_state will goto out and the freed skb will be used by
return value skb-&gt;len, which is a uaf bug.

What's worse, the same problem goes even further: skb can also be
freed in the notify_*_state_change -&gt; notify_*_state calls below.
Thus 4 additional uaf bugs happened.

My patch lets the problem callee functions: notify_initial_state_done
and notify_*_state_change return an error code if errors happen.
So that the error codes could be propagated and the uaf bugs can be avoid.

v2 reports a compilation warning. This v3 fixed this warning and built
successfully in my local environment with no additional warnings.
v2: https://lore.kernel.org/patchwork/patch/1435218/

Fixes: a29728463b254 ("drbd: Backport the "events2" command")
Signed-off-by: Lv Yunlong &lt;lyl2019@mail.ustc.edu.cn&gt;
Reviewed-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'for-5.18/drivers-2022-04-02' of git://git.kernel.dk/linux-block</title>
<updated>2022-04-02T18:03:03+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-04-02T18:03:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=6f34f8c3d6178527d4c02aa3a53c370cc70cb91e'/>
<id>6f34f8c3d6178527d4c02aa3a53c370cc70cb91e</id>
<content type='text'>
Pull block driver fix from Jens Axboe:
 "Got two reports on nbd spewing warnings on load now, which is a
  regression from a commit that went into your tree yesterday.

  Revert the problematic change for now"

* tag 'for-5.18/drivers-2022-04-02' of git://git.kernel.dk/linux-block:
  Revert "nbd: fix possible overflow on 'first_minor' in nbd_dev_add()"
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull block driver fix from Jens Axboe:
 "Got two reports on nbd spewing warnings on load now, which is a
  regression from a commit that went into your tree yesterday.

  Revert the problematic change for now"

* tag 'for-5.18/drivers-2022-04-02' of git://git.kernel.dk/linux-block:
  Revert "nbd: fix possible overflow on 'first_minor' in nbd_dev_add()"
</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "nbd: fix possible overflow on 'first_minor' in nbd_dev_add()"</title>
<updated>2022-04-02T17:40:23+00:00</updated>
<author>
<name>Jens Axboe</name>
<email>axboe@kernel.dk</email>
</author>
<published>2022-04-02T17:40:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=7198bfc2017644c6b92d2ecef9b8b8e0363bb5fd'/>
<id>7198bfc2017644c6b92d2ecef9b8b8e0363bb5fd</id>
<content type='text'>
This reverts commit 6d35d04a9e18990040e87d2bbf72689252669d54.

Both Gabriel and Borislav report that this commit casues a regression
with nbd:

sysfs: cannot create duplicate filename '/dev/block/43:0'

Revert it before 5.18-rc1 and we'll investigage this separately in
due time.

Link: https://lore.kernel.org/all/YkiJTnFOt9bTv6A2@zn.tnic/
Reported-by: Gabriel L. Somlo &lt;somlo@cmu.edu&gt;
Reported-by: Borislav Petkov &lt;bp@alien8.de&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This reverts commit 6d35d04a9e18990040e87d2bbf72689252669d54.

Both Gabriel and Borislav report that this commit casues a regression
with nbd:

sysfs: cannot create duplicate filename '/dev/block/43:0'

Revert it before 5.18-rc1 and we'll investigage this separately in
due time.

Link: https://lore.kernel.org/all/YkiJTnFOt9bTv6A2@zn.tnic/
Reported-by: Gabriel L. Somlo &lt;somlo@cmu.edu&gt;
Reported-by: Borislav Petkov &lt;bp@alien8.de&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'for-5.18/drivers-2022-04-01' of git://git.kernel.dk/linux-block</title>
<updated>2022-04-01T23:26:57+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-04-01T23:26:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8467b0ed6ce37f7e3f87aa3826627dc9cc55ecb2'/>
<id>8467b0ed6ce37f7e3f87aa3826627dc9cc55ecb2</id>
<content type='text'>
Pull block driver fixes from Jens Axboe:
 "Followup block driver updates and fixes for the 5.18-rc1 merge window.
  In detail:

   - NVMe pull request
       - Fix multipath hang when disk goes live over reconnect (Anton
         Eidelman)
       - fix RCU hole that allowed for endless looping in multipath
         round robin (Chris Leech)
       - remove redundant assignment after left shift (Colin Ian King)
       - add quirks for Samsung X5 SSDs (Monish Kumar R)
       - fix the read-only state for zoned namespaces with unsupposed
         features (Pankaj Raghav)
       - use a private workqueue instead of the system workqueue in
         nvmet (Sagi Grimberg)
       - allow duplicate NSIDs for private namespaces (Sungup Moon)
       - expose use_threaded_interrupts read-only in sysfs (Xin Hao)"

   - nbd minor allocation fix (Zhang)

   - drbd fixes and maintainer addition (Lars, Jakob, Christoph)

   - n64cart build fix (Jackie)

   - loop compat ioctl fix (Carlos)

   - misc fixes (Colin, Dongli)"

* tag 'for-5.18/drivers-2022-04-01' of git://git.kernel.dk/linux-block:
  drbd: remove check of list iterator against head past the loop body
  drbd: remove usage of list iterator variable after loop
  nbd: fix possible overflow on 'first_minor' in nbd_dev_add()
  MAINTAINERS: add drbd co-maintainer
  drbd: fix potential silent data corruption
  loop: fix ioctl calls using compat_loop_info
  nvme-multipath: fix hang when disk goes live over reconnect
  nvme: fix RCU hole that allowed for endless looping in multipath round robin
  nvme: allow duplicate NSIDs for private namespaces
  nvmet: remove redundant assignment after left shift
  nvmet: use a private workqueue instead of the system workqueue
  nvme-pci: add quirks for Samsung X5 SSDs
  nvme-pci: expose use_threaded_interrupts read-only in sysfs
  nvme: fix the read-only state for zoned namespaces with unsupposed features
  n64cart: convert bi_disk to bi_bdev-&gt;bd_disk fix build
  xen/blkfront: fix comment for need_copy
  xen-blkback: remove redundant assignment to variable i
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull block driver fixes from Jens Axboe:
 "Followup block driver updates and fixes for the 5.18-rc1 merge window.
  In detail:

   - NVMe pull request
       - Fix multipath hang when disk goes live over reconnect (Anton
         Eidelman)
       - fix RCU hole that allowed for endless looping in multipath
         round robin (Chris Leech)
       - remove redundant assignment after left shift (Colin Ian King)
       - add quirks for Samsung X5 SSDs (Monish Kumar R)
       - fix the read-only state for zoned namespaces with unsupposed
         features (Pankaj Raghav)
       - use a private workqueue instead of the system workqueue in
         nvmet (Sagi Grimberg)
       - allow duplicate NSIDs for private namespaces (Sungup Moon)
       - expose use_threaded_interrupts read-only in sysfs (Xin Hao)"

   - nbd minor allocation fix (Zhang)

   - drbd fixes and maintainer addition (Lars, Jakob, Christoph)

   - n64cart build fix (Jackie)

   - loop compat ioctl fix (Carlos)

   - misc fixes (Colin, Dongli)"

* tag 'for-5.18/drivers-2022-04-01' of git://git.kernel.dk/linux-block:
  drbd: remove check of list iterator against head past the loop body
  drbd: remove usage of list iterator variable after loop
  nbd: fix possible overflow on 'first_minor' in nbd_dev_add()
  MAINTAINERS: add drbd co-maintainer
  drbd: fix potential silent data corruption
  loop: fix ioctl calls using compat_loop_info
  nvme-multipath: fix hang when disk goes live over reconnect
  nvme: fix RCU hole that allowed for endless looping in multipath round robin
  nvme: allow duplicate NSIDs for private namespaces
  nvmet: remove redundant assignment after left shift
  nvmet: use a private workqueue instead of the system workqueue
  nvme-pci: add quirks for Samsung X5 SSDs
  nvme-pci: expose use_threaded_interrupts read-only in sysfs
  nvme: fix the read-only state for zoned namespaces with unsupposed features
  n64cart: convert bi_disk to bi_bdev-&gt;bd_disk fix build
  xen/blkfront: fix comment for need_copy
  xen-blkback: remove redundant assignment to variable i
</pre>
</div>
</content>
</entry>
<entry>
<title>drbd: remove check of list iterator against head past the loop body</title>
<updated>2022-03-31T23:08:15+00:00</updated>
<author>
<name>Jakob Koschel</name>
<email>jakobkoschel@gmail.com</email>
</author>
<published>2022-03-31T22:03:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=2651ee5ae43241831ca63d7158bb2b151a6a0e1f'/>
<id>2651ee5ae43241831ca63d7158bb2b151a6a0e1f</id>
<content type='text'>
When list_for_each_entry() completes the iteration over the whole list
without breaking the loop, the iterator value will be a bogus pointer
computed based on the head element.

While it is safe to use the pointer to determine if it was computed
based on the head element, either with list_entry_is_head() or
&amp;pos-&gt;member == head, using the iterator variable after the loop should
be avoided.

In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element [1].

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel &lt;jakobkoschel@gmail.com&gt;
Reviewed-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt;
Link: https://lore.kernel.org/r/20220331220349.885126-2-jakobkoschel@gmail.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When list_for_each_entry() completes the iteration over the whole list
without breaking the loop, the iterator value will be a bogus pointer
computed based on the head element.

While it is safe to use the pointer to determine if it was computed
based on the head element, either with list_entry_is_head() or
&amp;pos-&gt;member == head, using the iterator variable after the loop should
be avoided.

In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element [1].

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel &lt;jakobkoschel@gmail.com&gt;
Reviewed-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt;
Link: https://lore.kernel.org/r/20220331220349.885126-2-jakobkoschel@gmail.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drbd: remove usage of list iterator variable after loop</title>
<updated>2022-03-31T23:08:04+00:00</updated>
<author>
<name>Jakob Koschel</name>
<email>jakobkoschel@gmail.com</email>
</author>
<published>2022-03-31T22:03:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=901aeda62efa21f2eae937bccb71b49ae531be06'/>
<id>901aeda62efa21f2eae937bccb71b49ae531be06</id>
<content type='text'>
In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to iterate through the list [1].

Since that variable should not be used past the loop iteration, a
separate variable is used to 'remember the current location within the
loop'.

To either continue iterating from that position or skip the iteration
(if the previous iteration was complete) list_prepare_entry() is used.

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel &lt;jakobkoschel@gmail.com&gt;
Link: https://lore.kernel.org/r/20220331220349.885126-1-jakobkoschel@gmail.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to iterate through the list [1].

Since that variable should not be used past the loop iteration, a
separate variable is used to 'remember the current location within the
loop'.

To either continue iterating from that position or skip the iteration
(if the previous iteration was complete) list_prepare_entry() is used.

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel &lt;jakobkoschel@gmail.com&gt;
Link: https://lore.kernel.org/r/20220331220349.885126-1-jakobkoschel@gmail.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>nbd: fix possible overflow on 'first_minor' in nbd_dev_add()</title>
<updated>2022-03-31T14:30:21+00:00</updated>
<author>
<name>Zhang Wensheng</name>
<email>zhangwensheng5@huawei.com</email>
</author>
<published>2022-03-10T09:32:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=6d35d04a9e18990040e87d2bbf72689252669d54'/>
<id>6d35d04a9e18990040e87d2bbf72689252669d54</id>
<content type='text'>
When 'index' is a big numbers, it may become negative which forced
to 'int'. then 'index &lt;&lt; part_shift' might overflow to a positive
value that is not greater than '0xfffff', then sysfs might complains
about duplicate creation. Because of this, move the 'index' judgment
to the front will fix it and be better.

Fixes: b0d9111a2d53 ("nbd: use an idr to keep track of nbd devices")
Fixes: 940c264984fd ("nbd: fix possible overflow for 'first_minor' in nbd_dev_add()")
Signed-off-by: Zhang Wensheng &lt;zhangwensheng5@huawei.com&gt;
Reviewed-by: Josef Bacik &lt;josef@toxicpanda.com&gt;
Link: https://lore.kernel.org/r/20220310093224.4002895-1-zhangwensheng5@huawei.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When 'index' is a big numbers, it may become negative which forced
to 'int'. then 'index &lt;&lt; part_shift' might overflow to a positive
value that is not greater than '0xfffff', then sysfs might complains
about duplicate creation. Because of this, move the 'index' judgment
to the front will fix it and be better.

Fixes: b0d9111a2d53 ("nbd: use an idr to keep track of nbd devices")
Fixes: 940c264984fd ("nbd: fix possible overflow for 'first_minor' in nbd_dev_add()")
Signed-off-by: Zhang Wensheng &lt;zhangwensheng5@huawei.com&gt;
Reviewed-by: Josef Bacik &lt;josef@toxicpanda.com&gt;
Link: https://lore.kernel.org/r/20220310093224.4002895-1-zhangwensheng5@huawei.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drbd: fix potential silent data corruption</title>
<updated>2022-03-30T18:58:56+00:00</updated>
<author>
<name>Lars Ellenberg</name>
<email>lars.ellenberg@linbit.com</email>
</author>
<published>2022-03-30T18:55:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=f4329d1f848ac35757d9cc5487669d19dfc5979c'/>
<id>f4329d1f848ac35757d9cc5487669d19dfc5979c</id>
<content type='text'>
Scenario:
---------

bio chain generated by blk_queue_split().
Some split bio fails and propagates its error status to the "parent" bio.
But then the (last part of the) parent bio itself completes without error.

We would clobber the already recorded error status with BLK_STS_OK,
causing silent data corruption.

Reproducer:
-----------

How to trigger this in the real world within seconds:

DRBD on top of degraded parity raid,
small stripe_cache_size, large read_ahead setting.
Drop page cache (sysctl vm.drop_caches=1, fadvise "DONTNEED",
umount and mount again, "reboot").

Cause significant read ahead.

Large read ahead request is split by blk_queue_split().
Parts of the read ahead that are already in the stripe cache,
or find an available stripe cache to use, can be serviced.
Parts of the read ahead that would need "too much work",
would need to wait for a "stripe_head" to become available,
are rejected immediately.

For larger read ahead requests that are split in many pieces, it is very
likely that some "splits" will be serviced, but then the stripe cache is
exhausted/busy, and the remaining ones will be rejected.

Signed-off-by: Lars Ellenberg &lt;lars.ellenberg@linbit.com&gt;
Signed-off-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt;
Cc: &lt;stable@vger.kernel.org&gt; # 4.13.x
Link: https://lore.kernel.org/r/20220330185551.3553196-1-christoph.boehmwalder@linbit.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
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<pre>
Scenario:
---------

bio chain generated by blk_queue_split().
Some split bio fails and propagates its error status to the "parent" bio.
But then the (last part of the) parent bio itself completes without error.

We would clobber the already recorded error status with BLK_STS_OK,
causing silent data corruption.

Reproducer:
-----------

How to trigger this in the real world within seconds:

DRBD on top of degraded parity raid,
small stripe_cache_size, large read_ahead setting.
Drop page cache (sysctl vm.drop_caches=1, fadvise "DONTNEED",
umount and mount again, "reboot").

Cause significant read ahead.

Large read ahead request is split by blk_queue_split().
Parts of the read ahead that are already in the stripe cache,
or find an available stripe cache to use, can be serviced.
Parts of the read ahead that would need "too much work",
would need to wait for a "stripe_head" to become available,
are rejected immediately.

For larger read ahead requests that are split in many pieces, it is very
likely that some "splits" will be serviced, but then the stripe cache is
exhausted/busy, and the remaining ones will be rejected.

Signed-off-by: Lars Ellenberg &lt;lars.ellenberg@linbit.com&gt;
Signed-off-by: Christoph Böhmwalder &lt;christoph.boehmwalder@linbit.com&gt;
Cc: &lt;stable@vger.kernel.org&gt; # 4.13.x
Link: https://lore.kernel.org/r/20220330185551.3553196-1-christoph.boehmwalder@linbit.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
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