<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/fs, branch v4.4.232</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>xfs: set format back to extents if xfs_bmap_extents_to_btree</title>
<updated>2020-07-31T14:43:16+00:00</updated>
<author>
<name>Eric Sandeen</name>
<email>sandeen@redhat.com</email>
</author>
<published>2018-04-17T06:07:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f88efa4d6cb1fcacb9591979bacc6c57ec9d7c53'/>
<id>f88efa4d6cb1fcacb9591979bacc6c57ec9d7c53</id>
<content type='text'>
commit 2c4306f719b083d17df2963bc761777576b8ad1b upstream.

If xfs_bmap_extents_to_btree fails in a mode where we call
xfs_iroot_realloc(-1) to de-allocate the root, set the
format back to extents.

Otherwise we can assume we can dereference ifp-&gt;if_broot
based on the XFS_DINODE_FMT_BTREE format, and crash.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199423
Signed-off-by: Eric Sandeen &lt;sandeen@redhat.com&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
Signed-off-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
[iwamatsu: backported to 4.4.y]
Signed-off-by: Nobuhiro Iwamatsu (CIP) &lt;nobuhiro1.iwamatsu@toshiba.co.jp&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 2c4306f719b083d17df2963bc761777576b8ad1b upstream.

If xfs_bmap_extents_to_btree fails in a mode where we call
xfs_iroot_realloc(-1) to de-allocate the root, set the
format back to extents.

Otherwise we can assume we can dereference ifp-&gt;if_broot
based on the XFS_DINODE_FMT_BTREE format, and crash.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199423
Signed-off-by: Eric Sandeen &lt;sandeen@redhat.com&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
Signed-off-by: Darrick J. Wong &lt;darrick.wong@oracle.com&gt;
[iwamatsu: backported to 4.4.y]
Signed-off-by: Nobuhiro Iwamatsu (CIP) &lt;nobuhiro1.iwamatsu@toshiba.co.jp&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "cifs: Fix the target file was deleted when rename failed."</title>
<updated>2020-07-31T14:43:14+00:00</updated>
<author>
<name>Steve French</name>
<email>stfrench@microsoft.com</email>
</author>
<published>2020-07-23T19:41:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=39c6ea8661bd21979fee2a7d4078d9277e42ffa9'/>
<id>39c6ea8661bd21979fee2a7d4078d9277e42ffa9</id>
<content type='text'>
commit 0e6705182d4e1b77248a93470d6d7b3013d59b30 upstream.

This reverts commit 9ffad9263b467efd8f8dc7ae1941a0a655a2bab2.

Upon additional testing with older servers, it was found that
the original commit introduced a regression when using the old SMB1
dialect and rsyncing over an existing file.

The patch will need to be respun to address this, likely including
a larger refactoring of the SMB1 and SMB3 rename code paths to make
it less confusing and also to address some additional rename error
cases that SMB3 may be able to workaround.

Signed-off-by: Steve French &lt;stfrench@microsoft.com&gt;
Reported-by: Patrick Fernie &lt;patrick.fernie@gmail.com&gt;
CC: Stable &lt;stable@vger.kernel.org&gt;
Acked-by: Ronnie Sahlberg &lt;lsahlber@redhat.com&gt;
Acked-by: Pavel Shilovsky &lt;pshilov@microsoft.com&gt;
Acked-by: Zhang Xiaoxu &lt;zhangxiaoxu5@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 0e6705182d4e1b77248a93470d6d7b3013d59b30 upstream.

This reverts commit 9ffad9263b467efd8f8dc7ae1941a0a655a2bab2.

Upon additional testing with older servers, it was found that
the original commit introduced a regression when using the old SMB1
dialect and rsyncing over an existing file.

The patch will need to be respun to address this, likely including
a larger refactoring of the SMB1 and SMB3 rename code paths to make
it less confusing and also to address some additional rename error
cases that SMB3 may be able to workaround.

Signed-off-by: Steve French &lt;stfrench@microsoft.com&gt;
Reported-by: Patrick Fernie &lt;patrick.fernie@gmail.com&gt;
CC: Stable &lt;stable@vger.kernel.org&gt;
Acked-by: Ronnie Sahlberg &lt;lsahlber@redhat.com&gt;
Acked-by: Pavel Shilovsky &lt;pshilov@microsoft.com&gt;
Acked-by: Zhang Xiaoxu &lt;zhangxiaoxu5@huawei.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>btrfs: fix mount failure caused by race with umount</title>
<updated>2020-07-31T14:43:13+00:00</updated>
<author>
<name>Boris Burkov</name>
<email>boris@bur.io</email>
</author>
<published>2020-07-16T20:29:46+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=78684ada0d0e32714784b5d57106d95cb0e853b0'/>
<id>78684ada0d0e32714784b5d57106d95cb0e853b0</id>
<content type='text'>
[ Upstream commit 48cfa61b58a1fee0bc49eef04f8ccf31493b7cdd ]

It is possible to cause a btrfs mount to fail by racing it with a slow
umount. The crux of the sequence is generic_shutdown_super not yet
calling sop-&gt;put_super before btrfs_mount_root calls btrfs_open_devices.
If that occurs, btrfs_open_devices will decide the opened counter is
non-zero, increment it, and skip resetting fs_devices-&gt;total_rw_bytes to
0. From here, mount will call sget which will result in grab_super
trying to take the super block umount semaphore. That semaphore will be
held by the slow umount, so mount will block. Before up-ing the
semaphore, umount will delete the super block, resulting in mount's sget
reliably allocating a new one, which causes the mount path to dutifully
fill it out, and increment total_rw_bytes a second time, which causes
the mount to fail, as we see double the expected bytes.

Here is the sequence laid out in greater detail:

CPU0                                                    CPU1
down_write sb-&gt;s_umount
btrfs_kill_super
  kill_anon_super(sb)
    generic_shutdown_super(sb);
      shrink_dcache_for_umount(sb);
      sync_filesystem(sb);
      evict_inodes(sb); // SLOW

                                              btrfs_mount_root
                                                btrfs_scan_one_device
                                                fs_devices = device-&gt;fs_devices
                                                fs_info-&gt;fs_devices = fs_devices
                                                // fs_devices-opened makes this a no-op
                                                btrfs_open_devices(fs_devices, mode, fs_type)
                                                s = sget(fs_type, test, set, flags, fs_info);
                                                  find sb in s_instances
                                                  grab_super(sb);
                                                    down_write(&amp;s-&gt;s_umount); // blocks

      sop-&gt;put_super(sb)
        // sb-&gt;fs_devices-&gt;opened == 2; no-op
      spin_lock(&amp;sb_lock);
      hlist_del_init(&amp;sb-&gt;s_instances);
      spin_unlock(&amp;sb_lock);
      up_write(&amp;sb-&gt;s_umount);
                                                    return 0;
                                                  retry lookup
                                                  don't find sb in s_instances (deleted by CPU0)
                                                  s = alloc_super
                                                  return s;
                                                btrfs_fill_super(s, fs_devices, data)
                                                  open_ctree // fs_devices total_rw_bytes improperly set!
                                                    btrfs_read_chunk_tree
                                                      read_one_dev // increment total_rw_bytes again!!
                                                      super_total_bytes &lt; fs_devices-&gt;total_rw_bytes // ERROR!!!

To fix this, we clear total_rw_bytes from within btrfs_read_chunk_tree
before the calls to read_one_dev, while holding the sb umount semaphore
and the uuid mutex.

To reproduce, it is sufficient to dirty a decent number of inodes, then
quickly umount and mount.

  for i in $(seq 0 500)
  do
    dd if=/dev/zero of="/mnt/foo/$i" bs=1M count=1
  done
  umount /mnt/foo&amp;
  mount /mnt/foo

does the trick for me.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Boris Burkov &lt;boris@bur.io&gt;
Reviewed-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 48cfa61b58a1fee0bc49eef04f8ccf31493b7cdd ]

It is possible to cause a btrfs mount to fail by racing it with a slow
umount. The crux of the sequence is generic_shutdown_super not yet
calling sop-&gt;put_super before btrfs_mount_root calls btrfs_open_devices.
If that occurs, btrfs_open_devices will decide the opened counter is
non-zero, increment it, and skip resetting fs_devices-&gt;total_rw_bytes to
0. From here, mount will call sget which will result in grab_super
trying to take the super block umount semaphore. That semaphore will be
held by the slow umount, so mount will block. Before up-ing the
semaphore, umount will delete the super block, resulting in mount's sget
reliably allocating a new one, which causes the mount path to dutifully
fill it out, and increment total_rw_bytes a second time, which causes
the mount to fail, as we see double the expected bytes.

Here is the sequence laid out in greater detail:

CPU0                                                    CPU1
down_write sb-&gt;s_umount
btrfs_kill_super
  kill_anon_super(sb)
    generic_shutdown_super(sb);
      shrink_dcache_for_umount(sb);
      sync_filesystem(sb);
      evict_inodes(sb); // SLOW

                                              btrfs_mount_root
                                                btrfs_scan_one_device
                                                fs_devices = device-&gt;fs_devices
                                                fs_info-&gt;fs_devices = fs_devices
                                                // fs_devices-opened makes this a no-op
                                                btrfs_open_devices(fs_devices, mode, fs_type)
                                                s = sget(fs_type, test, set, flags, fs_info);
                                                  find sb in s_instances
                                                  grab_super(sb);
                                                    down_write(&amp;s-&gt;s_umount); // blocks

      sop-&gt;put_super(sb)
        // sb-&gt;fs_devices-&gt;opened == 2; no-op
      spin_lock(&amp;sb_lock);
      hlist_del_init(&amp;sb-&gt;s_instances);
      spin_unlock(&amp;sb_lock);
      up_write(&amp;sb-&gt;s_umount);
                                                    return 0;
                                                  retry lookup
                                                  don't find sb in s_instances (deleted by CPU0)
                                                  s = alloc_super
                                                  return s;
                                                btrfs_fill_super(s, fs_devices, data)
                                                  open_ctree // fs_devices total_rw_bytes improperly set!
                                                    btrfs_read_chunk_tree
                                                      read_one_dev // increment total_rw_bytes again!!
                                                      super_total_bytes &lt; fs_devices-&gt;total_rw_bytes // ERROR!!!

To fix this, we clear total_rw_bytes from within btrfs_read_chunk_tree
before the calls to read_one_dev, while holding the sb umount semaphore
and the uuid mutex.

To reproduce, it is sufficient to dirty a decent number of inodes, then
quickly umount and mount.

  for i in $(seq 0 500)
  do
    dd if=/dev/zero of="/mnt/foo/$i" bs=1M count=1
  done
  umount /mnt/foo&amp;
  mount /mnt/foo

does the trick for me.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Boris Burkov &lt;boris@bur.io&gt;
Reviewed-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>btrfs: fix double free on ulist after backref resolution failure</title>
<updated>2020-07-31T14:43:13+00:00</updated>
<author>
<name>Filipe Manana</name>
<email>fdmanana@suse.com</email>
</author>
<published>2020-07-13T14:11:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=fb83a0980843fc5ab397b675edd47998875ec618'/>
<id>fb83a0980843fc5ab397b675edd47998875ec618</id>
<content type='text'>
commit 580c079b5766ac706f56eec5c79aee4bf929fef6 upstream.

At btrfs_find_all_roots_safe() we allocate a ulist and set the **roots
argument to point to it. However if later we fail due to an error returned
by find_parent_nodes(), we free that ulist but leave a dangling pointer in
the **roots argument. Upon receiving the error, a caller of this function
can attempt to free the same ulist again, resulting in an invalid memory
access.

One such scenario is during qgroup accounting:

btrfs_qgroup_account_extents()

 --&gt; calls btrfs_find_all_roots() passes &amp;new_roots (a stack allocated
     pointer) to btrfs_find_all_roots()

   --&gt; btrfs_find_all_roots() just calls btrfs_find_all_roots_safe()
       passing &amp;new_roots to it

     --&gt; allocates ulist and assigns its address to **roots (which
         points to new_roots from btrfs_qgroup_account_extents())

     --&gt; find_parent_nodes() returns an error, so we free the ulist
         and leave **roots pointing to it after returning

 --&gt; btrfs_qgroup_account_extents() sees btrfs_find_all_roots() returned
     an error and jumps to the label 'cleanup', which just tries to
     free again the same ulist

Stack trace example:

 ------------[ cut here ]------------
 BTRFS: tree first key check failed
 WARNING: CPU: 1 PID: 1763215 at fs/btrfs/disk-io.c:422 btrfs_verify_level_key+0xe0/0x180 [btrfs]
 Modules linked in: dm_snapshot dm_thin_pool (...)
 CPU: 1 PID: 1763215 Comm: fsstress Tainted: G        W         5.8.0-rc3-btrfs-next-64 #1
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
 RIP: 0010:btrfs_verify_level_key+0xe0/0x180 [btrfs]
 Code: 28 5b 5d (...)
 RSP: 0018:ffffb89b473779a0 EFLAGS: 00010286
 RAX: 0000000000000000 RBX: ffff90397759bf08 RCX: 0000000000000000
 RDX: 0000000000000001 RSI: 0000000000000027 RDI: 00000000ffffffff
 RBP: ffff9039a419c000 R08: 0000000000000000 R09: 0000000000000000
 R10: 0000000000000000 R11: ffffb89b43301000 R12: 000000000000005e
 R13: ffffb89b47377a2e R14: ffffb89b473779af R15: 0000000000000000
 FS:  00007fc47e1e1000(0000) GS:ffff9039ac200000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007fc47e1df000 CR3: 00000003d9e4e001 CR4: 00000000003606e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  read_block_for_search+0xf6/0x350 [btrfs]
  btrfs_next_old_leaf+0x242/0x650 [btrfs]
  resolve_indirect_refs+0x7cf/0x9e0 [btrfs]
  find_parent_nodes+0x4ea/0x12c0 [btrfs]
  btrfs_find_all_roots_safe+0xbf/0x130 [btrfs]
  btrfs_qgroup_account_extents+0x9d/0x390 [btrfs]
  btrfs_commit_transaction+0x4f7/0xb20 [btrfs]
  btrfs_sync_file+0x3d4/0x4d0 [btrfs]
  do_fsync+0x38/0x70
  __x64_sys_fdatasync+0x13/0x20
  do_syscall_64+0x5c/0xe0
  entry_SYSCALL_64_after_hwframe+0x44/0xa9
 RIP: 0033:0x7fc47e2d72e3
 Code: Bad RIP value.
 RSP: 002b:00007fffa32098c8 EFLAGS: 00000246 ORIG_RAX: 000000000000004b
 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fc47e2d72e3
 RDX: 00007fffa3209830 RSI: 00007fffa3209830 RDI: 0000000000000003
 RBP: 000000000000072e R08: 0000000000000001 R09: 0000000000000003
 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000003e8
 R13: 0000000051eb851f R14: 00007fffa3209970 R15: 00005607c4ac8b50
 irq event stamp: 0
 hardirqs last  enabled at (0): [&lt;0000000000000000&gt;] 0x0
 hardirqs last disabled at (0): [&lt;ffffffffb8eb5e85&gt;] copy_process+0x755/0x1eb0
 softirqs last  enabled at (0): [&lt;ffffffffb8eb5e85&gt;] copy_process+0x755/0x1eb0
 softirqs last disabled at (0): [&lt;0000000000000000&gt;] 0x0
 ---[ end trace 8639237550317b48 ]---
 BTRFS error (device sdc): tree first key mismatch detected, bytenr=62324736 parent_transid=94 key expected=(262,108,1351680) has=(259,108,1921024)
 general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI
 CPU: 2 PID: 1763215 Comm: fsstress Tainted: G        W         5.8.0-rc3-btrfs-next-64 #1
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
 RIP: 0010:ulist_release+0x14/0x60 [btrfs]
 Code: c7 07 00 (...)
 RSP: 0018:ffffb89b47377d60 EFLAGS: 00010282
 RAX: 6b6b6b6b6b6b6b6b RBX: ffff903959b56b90 RCX: 0000000000000000
 RDX: 0000000000000001 RSI: 0000000000270024 RDI: ffff9036e2adc840
 RBP: ffff9036e2adc848 R08: 0000000000000000 R09: 0000000000000000
 R10: 0000000000000000 R11: 0000000000000000 R12: ffff9036e2adc840
 R13: 0000000000000015 R14: ffff9039a419ccf8 R15: ffff90395d605840
 FS:  00007fc47e1e1000(0000) GS:ffff9039ac600000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007f8c1c0a51c8 CR3: 00000003d9e4e004 CR4: 00000000003606e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  ulist_free+0x13/0x20 [btrfs]
  btrfs_qgroup_account_extents+0xf3/0x390 [btrfs]
  btrfs_commit_transaction+0x4f7/0xb20 [btrfs]
  btrfs_sync_file+0x3d4/0x4d0 [btrfs]
  do_fsync+0x38/0x70
  __x64_sys_fdatasync+0x13/0x20
  do_syscall_64+0x5c/0xe0
  entry_SYSCALL_64_after_hwframe+0x44/0xa9
 RIP: 0033:0x7fc47e2d72e3
 Code: Bad RIP value.
 RSP: 002b:00007fffa32098c8 EFLAGS: 00000246 ORIG_RAX: 000000000000004b
 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fc47e2d72e3
 RDX: 00007fffa3209830 RSI: 00007fffa3209830 RDI: 0000000000000003
 RBP: 000000000000072e R08: 0000000000000001 R09: 0000000000000003
 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000003e8
 R13: 0000000051eb851f R14: 00007fffa3209970 R15: 00005607c4ac8b50
 Modules linked in: dm_snapshot dm_thin_pool (...)
 ---[ end trace 8639237550317b49 ]---
 RIP: 0010:ulist_release+0x14/0x60 [btrfs]
 Code: c7 07 00 (...)
 RSP: 0018:ffffb89b47377d60 EFLAGS: 00010282
 RAX: 6b6b6b6b6b6b6b6b RBX: ffff903959b56b90 RCX: 0000000000000000
 RDX: 0000000000000001 RSI: 0000000000270024 RDI: ffff9036e2adc840
 RBP: ffff9036e2adc848 R08: 0000000000000000 R09: 0000000000000000
 R10: 0000000000000000 R11: 0000000000000000 R12: ffff9036e2adc840
 R13: 0000000000000015 R14: ffff9039a419ccf8 R15: ffff90395d605840
 FS:  00007fc47e1e1000(0000) GS:ffff9039ad200000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007f6a776f7d40 CR3: 00000003d9e4e002 CR4: 00000000003606e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Fix this by making btrfs_find_all_roots_safe() set *roots to NULL after
it frees the ulist.

Fixes: 8da6d5815c592b ("Btrfs: added btrfs_find_all_roots()")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik &lt;josef@toxicpanda.com&gt;
Signed-off-by: Filipe Manana &lt;fdmanana@suse.com&gt;
Reviewed-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 580c079b5766ac706f56eec5c79aee4bf929fef6 upstream.

At btrfs_find_all_roots_safe() we allocate a ulist and set the **roots
argument to point to it. However if later we fail due to an error returned
by find_parent_nodes(), we free that ulist but leave a dangling pointer in
the **roots argument. Upon receiving the error, a caller of this function
can attempt to free the same ulist again, resulting in an invalid memory
access.

One such scenario is during qgroup accounting:

btrfs_qgroup_account_extents()

 --&gt; calls btrfs_find_all_roots() passes &amp;new_roots (a stack allocated
     pointer) to btrfs_find_all_roots()

   --&gt; btrfs_find_all_roots() just calls btrfs_find_all_roots_safe()
       passing &amp;new_roots to it

     --&gt; allocates ulist and assigns its address to **roots (which
         points to new_roots from btrfs_qgroup_account_extents())

     --&gt; find_parent_nodes() returns an error, so we free the ulist
         and leave **roots pointing to it after returning

 --&gt; btrfs_qgroup_account_extents() sees btrfs_find_all_roots() returned
     an error and jumps to the label 'cleanup', which just tries to
     free again the same ulist

Stack trace example:

 ------------[ cut here ]------------
 BTRFS: tree first key check failed
 WARNING: CPU: 1 PID: 1763215 at fs/btrfs/disk-io.c:422 btrfs_verify_level_key+0xe0/0x180 [btrfs]
 Modules linked in: dm_snapshot dm_thin_pool (...)
 CPU: 1 PID: 1763215 Comm: fsstress Tainted: G        W         5.8.0-rc3-btrfs-next-64 #1
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
 RIP: 0010:btrfs_verify_level_key+0xe0/0x180 [btrfs]
 Code: 28 5b 5d (...)
 RSP: 0018:ffffb89b473779a0 EFLAGS: 00010286
 RAX: 0000000000000000 RBX: ffff90397759bf08 RCX: 0000000000000000
 RDX: 0000000000000001 RSI: 0000000000000027 RDI: 00000000ffffffff
 RBP: ffff9039a419c000 R08: 0000000000000000 R09: 0000000000000000
 R10: 0000000000000000 R11: ffffb89b43301000 R12: 000000000000005e
 R13: ffffb89b47377a2e R14: ffffb89b473779af R15: 0000000000000000
 FS:  00007fc47e1e1000(0000) GS:ffff9039ac200000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007fc47e1df000 CR3: 00000003d9e4e001 CR4: 00000000003606e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  read_block_for_search+0xf6/0x350 [btrfs]
  btrfs_next_old_leaf+0x242/0x650 [btrfs]
  resolve_indirect_refs+0x7cf/0x9e0 [btrfs]
  find_parent_nodes+0x4ea/0x12c0 [btrfs]
  btrfs_find_all_roots_safe+0xbf/0x130 [btrfs]
  btrfs_qgroup_account_extents+0x9d/0x390 [btrfs]
  btrfs_commit_transaction+0x4f7/0xb20 [btrfs]
  btrfs_sync_file+0x3d4/0x4d0 [btrfs]
  do_fsync+0x38/0x70
  __x64_sys_fdatasync+0x13/0x20
  do_syscall_64+0x5c/0xe0
  entry_SYSCALL_64_after_hwframe+0x44/0xa9
 RIP: 0033:0x7fc47e2d72e3
 Code: Bad RIP value.
 RSP: 002b:00007fffa32098c8 EFLAGS: 00000246 ORIG_RAX: 000000000000004b
 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fc47e2d72e3
 RDX: 00007fffa3209830 RSI: 00007fffa3209830 RDI: 0000000000000003
 RBP: 000000000000072e R08: 0000000000000001 R09: 0000000000000003
 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000003e8
 R13: 0000000051eb851f R14: 00007fffa3209970 R15: 00005607c4ac8b50
 irq event stamp: 0
 hardirqs last  enabled at (0): [&lt;0000000000000000&gt;] 0x0
 hardirqs last disabled at (0): [&lt;ffffffffb8eb5e85&gt;] copy_process+0x755/0x1eb0
 softirqs last  enabled at (0): [&lt;ffffffffb8eb5e85&gt;] copy_process+0x755/0x1eb0
 softirqs last disabled at (0): [&lt;0000000000000000&gt;] 0x0
 ---[ end trace 8639237550317b48 ]---
 BTRFS error (device sdc): tree first key mismatch detected, bytenr=62324736 parent_transid=94 key expected=(262,108,1351680) has=(259,108,1921024)
 general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI
 CPU: 2 PID: 1763215 Comm: fsstress Tainted: G        W         5.8.0-rc3-btrfs-next-64 #1
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
 RIP: 0010:ulist_release+0x14/0x60 [btrfs]
 Code: c7 07 00 (...)
 RSP: 0018:ffffb89b47377d60 EFLAGS: 00010282
 RAX: 6b6b6b6b6b6b6b6b RBX: ffff903959b56b90 RCX: 0000000000000000
 RDX: 0000000000000001 RSI: 0000000000270024 RDI: ffff9036e2adc840
 RBP: ffff9036e2adc848 R08: 0000000000000000 R09: 0000000000000000
 R10: 0000000000000000 R11: 0000000000000000 R12: ffff9036e2adc840
 R13: 0000000000000015 R14: ffff9039a419ccf8 R15: ffff90395d605840
 FS:  00007fc47e1e1000(0000) GS:ffff9039ac600000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007f8c1c0a51c8 CR3: 00000003d9e4e004 CR4: 00000000003606e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  ulist_free+0x13/0x20 [btrfs]
  btrfs_qgroup_account_extents+0xf3/0x390 [btrfs]
  btrfs_commit_transaction+0x4f7/0xb20 [btrfs]
  btrfs_sync_file+0x3d4/0x4d0 [btrfs]
  do_fsync+0x38/0x70
  __x64_sys_fdatasync+0x13/0x20
  do_syscall_64+0x5c/0xe0
  entry_SYSCALL_64_after_hwframe+0x44/0xa9
 RIP: 0033:0x7fc47e2d72e3
 Code: Bad RIP value.
 RSP: 002b:00007fffa32098c8 EFLAGS: 00000246 ORIG_RAX: 000000000000004b
 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fc47e2d72e3
 RDX: 00007fffa3209830 RSI: 00007fffa3209830 RDI: 0000000000000003
 RBP: 000000000000072e R08: 0000000000000001 R09: 0000000000000003
 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000003e8
 R13: 0000000051eb851f R14: 00007fffa3209970 R15: 00005607c4ac8b50
 Modules linked in: dm_snapshot dm_thin_pool (...)
 ---[ end trace 8639237550317b49 ]---
 RIP: 0010:ulist_release+0x14/0x60 [btrfs]
 Code: c7 07 00 (...)
 RSP: 0018:ffffb89b47377d60 EFLAGS: 00010282
 RAX: 6b6b6b6b6b6b6b6b RBX: ffff903959b56b90 RCX: 0000000000000000
 RDX: 0000000000000001 RSI: 0000000000270024 RDI: ffff9036e2adc840
 RBP: ffff9036e2adc848 R08: 0000000000000000 R09: 0000000000000000
 R10: 0000000000000000 R11: 0000000000000000 R12: ffff9036e2adc840
 R13: 0000000000000015 R14: ffff9039a419ccf8 R15: ffff90395d605840
 FS:  00007fc47e1e1000(0000) GS:ffff9039ad200000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007f6a776f7d40 CR3: 00000003d9e4e002 CR4: 00000000003606e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Fix this by making btrfs_find_all_roots_safe() set *roots to NULL after
it frees the ulist.

Fixes: 8da6d5815c592b ("Btrfs: added btrfs_find_all_roots()")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik &lt;josef@toxicpanda.com&gt;
Signed-off-by: Filipe Manana &lt;fdmanana@suse.com&gt;
Reviewed-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>SUNRPC reverting d03727b248d0 ("NFSv4 fix CLOSE not waiting for direct IO compeletion")</title>
<updated>2020-07-31T14:43:12+00:00</updated>
<author>
<name>Olga Kornievskaia</name>
<email>kolga@netapp.com</email>
</author>
<published>2020-07-15T17:04:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=81475c5dbd61ceb2af63b4b3a1a82851082c2768'/>
<id>81475c5dbd61ceb2af63b4b3a1a82851082c2768</id>
<content type='text'>
commit 65caafd0d2145d1dd02072c4ced540624daeab40 upstream.

Reverting commit d03727b248d0 "NFSv4 fix CLOSE not waiting for
direct IO compeletion". This patch made it so that fput() by calling
inode_dio_done() in nfs_file_release() would wait uninterruptably
for any outstanding directIO to the file (but that wait on IO should
be killable).

The problem the patch was also trying to address was REMOVE returning
ERR_ACCESS because the file is still opened, is supposed to be resolved
by server returning ERR_FILE_OPEN and not ERR_ACCESS.

Signed-off-by: Olga Kornievskaia &lt;kolga@netapp.com&gt;
Signed-off-by: Anna Schumaker &lt;Anna.Schumaker@Netapp.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 65caafd0d2145d1dd02072c4ced540624daeab40 upstream.

Reverting commit d03727b248d0 "NFSv4 fix CLOSE not waiting for
direct IO compeletion". This patch made it so that fput() by calling
inode_dio_done() in nfs_file_release() would wait uninterruptably
for any outstanding directIO to the file (but that wait on IO should
be killable).

The problem the patch was also trying to address was REMOVE returning
ERR_ACCESS because the file is still opened, is supposed to be resolved
by server returning ERR_FILE_OPEN and not ERR_ACCESS.

Signed-off-by: Olga Kornievskaia &lt;kolga@netapp.com&gt;
Signed-off-by: Anna Schumaker &lt;Anna.Schumaker@Netapp.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>fuse: Fix parameter for FS_IOC_{GET,SET}FLAGS</title>
<updated>2020-07-22T07:10:06+00:00</updated>
<author>
<name>Chirantan Ekbote</name>
<email>chirantan@chromium.org</email>
</author>
<published>2020-07-14T10:26:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=1e93bd075fca377ad26789bcc809107401e2cf5b'/>
<id>1e93bd075fca377ad26789bcc809107401e2cf5b</id>
<content type='text'>
commit 31070f6ccec09f3bd4f1e28cd1e592fa4f3ba0b6 upstream.

The ioctl encoding for this parameter is a long but the documentation says
it should be an int and the kernel drivers expect it to be an int.  If the
fuse driver treats this as a long it might end up scribbling over the stack
of a userspace process that only allocated enough space for an int.

This was previously discussed in [1] and a patch for fuse was proposed in
[2].  From what I can tell the patch in [2] was nacked in favor of adding
new, "fixed" ioctls and using those from userspace.  However there is still
no "fixed" version of these ioctls and the fact is that it's sometimes
infeasible to change all userspace to use the new one.

Handling the ioctls specially in the fuse driver seems like the most
pragmatic way for fuse servers to support them without causing crashes in
userspace applications that call them.

[1]: https://lore.kernel.org/linux-fsdevel/20131126200559.GH20559@hall.aurel32.net/T/
[2]: https://sourceforge.net/p/fuse/mailman/message/31771759/

Signed-off-by: Chirantan Ekbote &lt;chirantan@chromium.org&gt;
Fixes: 59efec7b9039 ("fuse: implement ioctl support")
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Miklos Szeredi &lt;mszeredi@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 31070f6ccec09f3bd4f1e28cd1e592fa4f3ba0b6 upstream.

The ioctl encoding for this parameter is a long but the documentation says
it should be an int and the kernel drivers expect it to be an int.  If the
fuse driver treats this as a long it might end up scribbling over the stack
of a userspace process that only allocated enough space for an int.

This was previously discussed in [1] and a patch for fuse was proposed in
[2].  From what I can tell the patch in [2] was nacked in favor of adding
new, "fixed" ioctls and using those from userspace.  However there is still
no "fixed" version of these ioctls and the fact is that it's sometimes
infeasible to change all userspace to use the new one.

Handling the ioctls specially in the fuse driver seems like the most
pragmatic way for fuse servers to support them without causing crashes in
userspace applications that call them.

[1]: https://lore.kernel.org/linux-fsdevel/20131126200559.GH20559@hall.aurel32.net/T/
[2]: https://sourceforge.net/p/fuse/mailman/message/31771759/

Signed-off-by: Chirantan Ekbote &lt;chirantan@chromium.org&gt;
Fixes: 59efec7b9039 ("fuse: implement ioctl support")
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Miklos Szeredi &lt;mszeredi@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>btrfs: fix fatal extent_buffer readahead vs releasepage race</title>
<updated>2020-07-22T07:10:02+00:00</updated>
<author>
<name>Boris Burkov</name>
<email>boris@bur.io</email>
</author>
<published>2020-06-17T18:35:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d707433ab97557ed885a4676c5027f458e9f7f6d'/>
<id>d707433ab97557ed885a4676c5027f458e9f7f6d</id>
<content type='text'>
commit 6bf9cd2eed9aee6d742bb9296c994a91f5316949 upstream.

Under somewhat convoluted conditions, it is possible to attempt to
release an extent_buffer that is under io, which triggers a BUG_ON in
btrfs_release_extent_buffer_pages.

This relies on a few different factors. First, extent_buffer reads done
as readahead for searching use WAIT_NONE, so they free the local extent
buffer reference while the io is outstanding. However, they should still
be protected by TREE_REF. However, if the system is doing signficant
reclaim, and simultaneously heavily accessing the extent_buffers, it is
possible for releasepage to race with two concurrent readahead attempts
in a way that leaves TREE_REF unset when the readahead extent buffer is
released.

Essentially, if two tasks race to allocate a new extent_buffer, but the
winner who attempts the first io is rebuffed by a page being locked
(likely by the reclaim itself) then the loser will still go ahead with
issuing the readahead. The loser's call to find_extent_buffer must also
race with the reclaim task reading the extent_buffer's refcount as 1 in
a way that allows the reclaim to re-clear the TREE_REF checked by
find_extent_buffer.

The following represents an example execution demonstrating the race:

            CPU0                                                         CPU1                                           CPU2
reada_for_search                                            reada_for_search
  readahead_tree_block                                        readahead_tree_block
    find_create_tree_block                                      find_create_tree_block
      alloc_extent_buffer                                         alloc_extent_buffer
                                                                  find_extent_buffer // not found
                                                                  allocates eb
                                                                  lock pages
                                                                  associate pages to eb
                                                                  insert eb into radix tree
                                                                  set TREE_REF, refs == 2
                                                                  unlock pages
                                                              read_extent_buffer_pages // WAIT_NONE
                                                                not uptodate (brand new eb)
                                                                                                            lock_page
                                                                if !trylock_page
                                                                  goto unlock_exit // not an error
                                                              free_extent_buffer
                                                                release_extent_buffer
                                                                  atomic_dec_and_test refs to 1
        find_extent_buffer // found
                                                                                                            try_release_extent_buffer
                                                                                                              take refs_lock
                                                                                                              reads refs == 1; no io
          atomic_inc_not_zero refs to 2
          mark_buffer_accessed
            check_buffer_tree_ref
              // not STALE, won't take refs_lock
              refs == 2; TREE_REF set // no action
    read_extent_buffer_pages // WAIT_NONE
                                                                                                              clear TREE_REF
                                                                                                              release_extent_buffer
                                                                                                                atomic_dec_and_test refs to 1
                                                                                                                unlock_page
      still not uptodate (CPU1 read failed on trylock_page)
      locks pages
      set io_pages &gt; 0
      submit io
      return
    free_extent_buffer
      release_extent_buffer
        dec refs to 0
        delete from radix tree
        btrfs_release_extent_buffer_pages
          BUG_ON(io_pages &gt; 0)!!!

We observe this at a very low rate in production and were also able to
reproduce it in a test environment by introducing some spurious delays
and by introducing probabilistic trylock_page failures.

To fix it, we apply check_tree_ref at a point where it could not
possibly be unset by a competing task: after io_pages has been
incremented. All the codepaths that clear TREE_REF check for io, so they
would not be able to clear it after this point until the io is done.

Stack trace, for reference:
[1417839.424739] ------------[ cut here ]------------
[1417839.435328] kernel BUG at fs/btrfs/extent_io.c:4841!
[1417839.447024] invalid opcode: 0000 [#1] SMP
[1417839.502972] RIP: 0010:btrfs_release_extent_buffer_pages+0x20/0x1f0
[1417839.517008] Code: ed e9 ...
[1417839.558895] RSP: 0018:ffffc90020bcf798 EFLAGS: 00010202
[1417839.570816] RAX: 0000000000000002 RBX: ffff888102d6def0 RCX: 0000000000000028
[1417839.586962] RDX: 0000000000000002 RSI: ffff8887f0296482 RDI: ffff888102d6def0
[1417839.603108] RBP: ffff88885664a000 R08: 0000000000000046 R09: 0000000000000238
[1417839.619255] R10: 0000000000000028 R11: ffff88885664af68 R12: 0000000000000000
[1417839.635402] R13: 0000000000000000 R14: ffff88875f573ad0 R15: ffff888797aafd90
[1417839.651549] FS:  00007f5a844fa700(0000) GS:ffff88885f680000(0000) knlGS:0000000000000000
[1417839.669810] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[1417839.682887] CR2: 00007f7884541fe0 CR3: 000000049f609002 CR4: 00000000003606e0
[1417839.699037] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[1417839.715187] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[1417839.731320] Call Trace:
[1417839.737103]  release_extent_buffer+0x39/0x90
[1417839.746913]  read_block_for_search.isra.38+0x2a3/0x370
[1417839.758645]  btrfs_search_slot+0x260/0x9b0
[1417839.768054]  btrfs_lookup_file_extent+0x4a/0x70
[1417839.778427]  btrfs_get_extent+0x15f/0x830
[1417839.787665]  ? submit_extent_page+0xc4/0x1c0
[1417839.797474]  ? __do_readpage+0x299/0x7a0
[1417839.806515]  __do_readpage+0x33b/0x7a0
[1417839.815171]  ? btrfs_releasepage+0x70/0x70
[1417839.824597]  extent_readpages+0x28f/0x400
[1417839.833836]  read_pages+0x6a/0x1c0
[1417839.841729]  ? startup_64+0x2/0x30
[1417839.849624]  __do_page_cache_readahead+0x13c/0x1a0
[1417839.860590]  filemap_fault+0x6c7/0x990
[1417839.869252]  ? xas_load+0x8/0x80
[1417839.876756]  ? xas_find+0x150/0x190
[1417839.884839]  ? filemap_map_pages+0x295/0x3b0
[1417839.894652]  __do_fault+0x32/0x110
[1417839.902540]  __handle_mm_fault+0xacd/0x1000
[1417839.912156]  handle_mm_fault+0xaa/0x1c0
[1417839.921004]  __do_page_fault+0x242/0x4b0
[1417839.930044]  ? page_fault+0x8/0x30
[1417839.937933]  page_fault+0x1e/0x30
[1417839.945631] RIP: 0033:0x33c4bae
[1417839.952927] Code: Bad RIP value.
[1417839.960411] RSP: 002b:00007f5a844f7350 EFLAGS: 00010206
[1417839.972331] RAX: 000000000000006e RBX: 1614b3ff6a50398a RCX: 0000000000000000
[1417839.988477] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
[1417840.004626] RBP: 00007f5a844f7420 R08: 000000000000006e R09: 00007f5a94aeccb8
[1417840.020784] R10: 00007f5a844f7350 R11: 0000000000000000 R12: 00007f5a94aecc79
[1417840.036932] R13: 00007f5a94aecc78 R14: 00007f5a94aecc90 R15: 00007f5a94aecc40

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana &lt;fdmanana@suse.com&gt;
Signed-off-by: Boris Burkov &lt;boris@bur.io&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 6bf9cd2eed9aee6d742bb9296c994a91f5316949 upstream.

Under somewhat convoluted conditions, it is possible to attempt to
release an extent_buffer that is under io, which triggers a BUG_ON in
btrfs_release_extent_buffer_pages.

This relies on a few different factors. First, extent_buffer reads done
as readahead for searching use WAIT_NONE, so they free the local extent
buffer reference while the io is outstanding. However, they should still
be protected by TREE_REF. However, if the system is doing signficant
reclaim, and simultaneously heavily accessing the extent_buffers, it is
possible for releasepage to race with two concurrent readahead attempts
in a way that leaves TREE_REF unset when the readahead extent buffer is
released.

Essentially, if two tasks race to allocate a new extent_buffer, but the
winner who attempts the first io is rebuffed by a page being locked
(likely by the reclaim itself) then the loser will still go ahead with
issuing the readahead. The loser's call to find_extent_buffer must also
race with the reclaim task reading the extent_buffer's refcount as 1 in
a way that allows the reclaim to re-clear the TREE_REF checked by
find_extent_buffer.

The following represents an example execution demonstrating the race:

            CPU0                                                         CPU1                                           CPU2
reada_for_search                                            reada_for_search
  readahead_tree_block                                        readahead_tree_block
    find_create_tree_block                                      find_create_tree_block
      alloc_extent_buffer                                         alloc_extent_buffer
                                                                  find_extent_buffer // not found
                                                                  allocates eb
                                                                  lock pages
                                                                  associate pages to eb
                                                                  insert eb into radix tree
                                                                  set TREE_REF, refs == 2
                                                                  unlock pages
                                                              read_extent_buffer_pages // WAIT_NONE
                                                                not uptodate (brand new eb)
                                                                                                            lock_page
                                                                if !trylock_page
                                                                  goto unlock_exit // not an error
                                                              free_extent_buffer
                                                                release_extent_buffer
                                                                  atomic_dec_and_test refs to 1
        find_extent_buffer // found
                                                                                                            try_release_extent_buffer
                                                                                                              take refs_lock
                                                                                                              reads refs == 1; no io
          atomic_inc_not_zero refs to 2
          mark_buffer_accessed
            check_buffer_tree_ref
              // not STALE, won't take refs_lock
              refs == 2; TREE_REF set // no action
    read_extent_buffer_pages // WAIT_NONE
                                                                                                              clear TREE_REF
                                                                                                              release_extent_buffer
                                                                                                                atomic_dec_and_test refs to 1
                                                                                                                unlock_page
      still not uptodate (CPU1 read failed on trylock_page)
      locks pages
      set io_pages &gt; 0
      submit io
      return
    free_extent_buffer
      release_extent_buffer
        dec refs to 0
        delete from radix tree
        btrfs_release_extent_buffer_pages
          BUG_ON(io_pages &gt; 0)!!!

We observe this at a very low rate in production and were also able to
reproduce it in a test environment by introducing some spurious delays
and by introducing probabilistic trylock_page failures.

To fix it, we apply check_tree_ref at a point where it could not
possibly be unset by a competing task: after io_pages has been
incremented. All the codepaths that clear TREE_REF check for io, so they
would not be able to clear it after this point until the io is done.

Stack trace, for reference:
[1417839.424739] ------------[ cut here ]------------
[1417839.435328] kernel BUG at fs/btrfs/extent_io.c:4841!
[1417839.447024] invalid opcode: 0000 [#1] SMP
[1417839.502972] RIP: 0010:btrfs_release_extent_buffer_pages+0x20/0x1f0
[1417839.517008] Code: ed e9 ...
[1417839.558895] RSP: 0018:ffffc90020bcf798 EFLAGS: 00010202
[1417839.570816] RAX: 0000000000000002 RBX: ffff888102d6def0 RCX: 0000000000000028
[1417839.586962] RDX: 0000000000000002 RSI: ffff8887f0296482 RDI: ffff888102d6def0
[1417839.603108] RBP: ffff88885664a000 R08: 0000000000000046 R09: 0000000000000238
[1417839.619255] R10: 0000000000000028 R11: ffff88885664af68 R12: 0000000000000000
[1417839.635402] R13: 0000000000000000 R14: ffff88875f573ad0 R15: ffff888797aafd90
[1417839.651549] FS:  00007f5a844fa700(0000) GS:ffff88885f680000(0000) knlGS:0000000000000000
[1417839.669810] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[1417839.682887] CR2: 00007f7884541fe0 CR3: 000000049f609002 CR4: 00000000003606e0
[1417839.699037] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[1417839.715187] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[1417839.731320] Call Trace:
[1417839.737103]  release_extent_buffer+0x39/0x90
[1417839.746913]  read_block_for_search.isra.38+0x2a3/0x370
[1417839.758645]  btrfs_search_slot+0x260/0x9b0
[1417839.768054]  btrfs_lookup_file_extent+0x4a/0x70
[1417839.778427]  btrfs_get_extent+0x15f/0x830
[1417839.787665]  ? submit_extent_page+0xc4/0x1c0
[1417839.797474]  ? __do_readpage+0x299/0x7a0
[1417839.806515]  __do_readpage+0x33b/0x7a0
[1417839.815171]  ? btrfs_releasepage+0x70/0x70
[1417839.824597]  extent_readpages+0x28f/0x400
[1417839.833836]  read_pages+0x6a/0x1c0
[1417839.841729]  ? startup_64+0x2/0x30
[1417839.849624]  __do_page_cache_readahead+0x13c/0x1a0
[1417839.860590]  filemap_fault+0x6c7/0x990
[1417839.869252]  ? xas_load+0x8/0x80
[1417839.876756]  ? xas_find+0x150/0x190
[1417839.884839]  ? filemap_map_pages+0x295/0x3b0
[1417839.894652]  __do_fault+0x32/0x110
[1417839.902540]  __handle_mm_fault+0xacd/0x1000
[1417839.912156]  handle_mm_fault+0xaa/0x1c0
[1417839.921004]  __do_page_fault+0x242/0x4b0
[1417839.930044]  ? page_fault+0x8/0x30
[1417839.937933]  page_fault+0x1e/0x30
[1417839.945631] RIP: 0033:0x33c4bae
[1417839.952927] Code: Bad RIP value.
[1417839.960411] RSP: 002b:00007f5a844f7350 EFLAGS: 00010206
[1417839.972331] RAX: 000000000000006e RBX: 1614b3ff6a50398a RCX: 0000000000000000
[1417839.988477] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
[1417840.004626] RBP: 00007f5a844f7420 R08: 000000000000006e R09: 00007f5a94aeccb8
[1417840.020784] R10: 00007f5a844f7350 R11: 0000000000000000 R12: 00007f5a94aecc79
[1417840.036932] R13: 00007f5a94aecc78 R14: 00007f5a94aecc90 R15: 00007f5a94aecc40

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana &lt;fdmanana@suse.com&gt;
Signed-off-by: Boris Burkov &lt;boris@bur.io&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>cifs: Fix the target file was deleted when rename failed.</title>
<updated>2020-07-09T07:35:09+00:00</updated>
<author>
<name>Zhang Xiaoxu</name>
<email>zhangxiaoxu5@huawei.com</email>
</author>
<published>2020-06-29T01:06:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=3fe62ca7096cd9ae74b07282e79b9568d4a129a3'/>
<id>3fe62ca7096cd9ae74b07282e79b9568d4a129a3</id>
<content type='text'>
commit 9ffad9263b467efd8f8dc7ae1941a0a655a2bab2 upstream.

When xfstest generic/035, we found the target file was deleted
if the rename return -EACESS.

In cifs_rename2, we unlink the positive target dentry if rename
failed with EACESS or EEXIST, even if the target dentry is positived
before rename. Then the existing file was deleted.

We should just delete the target file which created during the
rename.

Reported-by: Hulk Robot &lt;hulkci@huawei.com&gt;
Signed-off-by: Zhang Xiaoxu &lt;zhangxiaoxu5@huawei.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Steve French &lt;stfrench@microsoft.com&gt;
Reviewed-by: Aurelien Aptel &lt;aaptel@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 9ffad9263b467efd8f8dc7ae1941a0a655a2bab2 upstream.

When xfstest generic/035, we found the target file was deleted
if the rename return -EACESS.

In cifs_rename2, we unlink the positive target dentry if rename
failed with EACESS or EEXIST, even if the target dentry is positived
before rename. Then the existing file was deleted.

We should just delete the target file which created during the
rename.

Reported-by: Hulk Robot &lt;hulkci@huawei.com&gt;
Signed-off-by: Zhang Xiaoxu &lt;zhangxiaoxu5@huawei.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Steve French &lt;stfrench@microsoft.com&gt;
Reviewed-by: Aurelien Aptel &lt;aaptel@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>SMB3: Honor persistent/resilient handle flags for multiuser mounts</title>
<updated>2020-07-09T07:35:09+00:00</updated>
<author>
<name>Paul Aurich</name>
<email>paul@darkrain42.org</email>
</author>
<published>2020-06-26T19:58:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=45999d78c5051cee0399fec398d6e1b7b26a8a60'/>
<id>45999d78c5051cee0399fec398d6e1b7b26a8a60</id>
<content type='text'>
commit 00dfbc2f9c61185a2e662f27c45a0bb29b2a134f upstream.

Without this:

- persistent handles will only be enabled for per-user tcons if the
  server advertises the 'Continuous Availabity' capability
- resilient handles would never be enabled for per-user tcons

Signed-off-by: Paul Aurich &lt;paul@darkrain42.org&gt;
CC: Stable &lt;stable@vger.kernel.org&gt;
Signed-off-by: Steve French &lt;stfrench@microsoft.com&gt;
Reviewed-by: Aurelien Aptel &lt;aaptel@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 00dfbc2f9c61185a2e662f27c45a0bb29b2a134f upstream.

Without this:

- persistent handles will only be enabled for per-user tcons if the
  server advertises the 'Continuous Availabity' capability
- resilient handles would never be enabled for per-user tcons

Signed-off-by: Paul Aurich &lt;paul@darkrain42.org&gt;
CC: Stable &lt;stable@vger.kernel.org&gt;
Signed-off-by: Steve French &lt;stfrench@microsoft.com&gt;
Reviewed-by: Aurelien Aptel &lt;aaptel@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>SMB3: Honor 'seal' flag for multiuser mounts</title>
<updated>2020-07-09T07:35:09+00:00</updated>
<author>
<name>Paul Aurich</name>
<email>paul@darkrain42.org</email>
</author>
<published>2020-06-26T19:58:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b2ae3accb5f0928d874aef7cf627c7b4fd038403'/>
<id>b2ae3accb5f0928d874aef7cf627c7b4fd038403</id>
<content type='text'>
commit cc15461c73d7d044d56c47e869a215e49bd429c8 upstream.

Ensure multiuser SMB3 mounts use encryption for all users' tcons if the
mount options are configured to require encryption. Without this, only
the primary tcon and IPC tcons are guaranteed to be encrypted. Per-user
tcons would only be encrypted if the server was configured to require
encryption.

Signed-off-by: Paul Aurich &lt;paul@darkrain42.org&gt;
CC: Stable &lt;stable@vger.kernel.org&gt;
Signed-off-by: Steve French &lt;stfrench@microsoft.com&gt;
Reviewed-by: Aurelien Aptel &lt;aaptel@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit cc15461c73d7d044d56c47e869a215e49bd429c8 upstream.

Ensure multiuser SMB3 mounts use encryption for all users' tcons if the
mount options are configured to require encryption. Without this, only
the primary tcon and IPC tcons are guaranteed to be encrypted. Per-user
tcons would only be encrypted if the server was configured to require
encryption.

Signed-off-by: Paul Aurich &lt;paul@darkrain42.org&gt;
CC: Stable &lt;stable@vger.kernel.org&gt;
Signed-off-by: Steve French &lt;stfrench@microsoft.com&gt;
Reviewed-by: Aurelien Aptel &lt;aaptel@suse.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
</feed>
