Delete some xarray-based buffer wangling functions that are intended for
use with bounce buffering, but aren't used because bounce-buffering got
deferred to a later patch series.  Now, however, the intention is to use
something other than an xarray to do this.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20240620173137.610345-9-dhowells@redhat.com


Signed-off-by: Christian Brauner <brauner@kernel.org>

During the writeback procedure, at the end of netfs_write_folio(), pending
write operations are flushed if the amount of write-streaming data stored
in a page is less than the size of the folio because if we haven't modified
a folio to the end, it cannot be contiguous with the following folio...
except if the dirty region of the folio is right at the end of the folio
space.

Fix the test to take the offset into the folio into account as well, such
that if the dirty region runs right up to the end of the folio, we leave
the flushing for later.

Fixes: 288ace2f

 ("netfs: New writeback implementation")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Eric Van Hensbergen <ericvh@kernel.org>
cc: Latchesar Ionkov <lucho@ionkov.net>
cc: Dominique Martinet <asmadeus@codewreck.org>
cc: Christian Schoenebeck <linux_oss@crudebyte.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Steve French <sfrench@samba.org>
cc: Paulo Alcantara <pc@manguebit.com> (DFS, global name space)
cc: v9fs@lists.linux.dev
cc: linux-afs@lists.infradead.org
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20240620173137.610345-4-dhowells@redhat.com


Signed-off-by: Christian Brauner <brauner@kernel.org>

[This was included in v2 of 9b038d00, but
v1 got pushed instead]

Fix netfs_unbuffered_write_iter_locked() to set the total request length in
the netfs_io_request struct rather than leaving it as zero.

Fixes: 288ace2f

 ("netfs: New writeback implementation")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Steve French <stfrench@microsoft.com>
cc: Enzo Matsumiya <ematsumiya@suse.de>
cc: Christian Brauner <brauner@kernel.org>
cc: netfs@lists.linux.dev
cc: v9fs@lists.linux.dev
cc: linux-afs@lists.infradead.org
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20240620173137.610345-2-dhowells@redhat.com


Signed-off-by: Christian Brauner <brauner@kernel.org>

When a file is opened and created with open(..., O_CREAT) we get
both the CREATE and OPEN fsnotify events and would expect them in that
order.   For most filesystems we get them in that order because
open_last_lookups() calls fsnofify_create() and then do_open() (from
path_openat()) calls vfs_open()->do_dentry_open() which calls
fsnotify_open().

However when ->atomic_open is used, the
   do_dentry_open() -> fsnotify_open()
call happens from finish_open() which is called from the ->atomic_open
handler in lookup_open() which is called *before* open_last_lookups()
calls fsnotify_create.  So we get the "open" notification before
"create" - which is backwards.  ltp testcase inotify02 tests this and
reports the inconsistency.

This patch lifts the fsnotify_open() call out of do_dentry_open() and
places it higher up the call stack.  There are three callers of
do_dentry_open().

For vfs_open() and kernel_file_open() the fsnotify_open() is placed
directly in that caller so there should be no behavioural change.

For finish_open() there are two cases:
 - finish_open is used in ->atomic_open handlers.  For these we add a
   call to fsnotify_open() at open_last_lookups() if FMODE_OPENED is
   set - which means do_dentry_open() has been called.
 - finish_open is used in ->tmpfile() handlers.  For these a similar
   call to fsnotify_open() is added to vfs_tmpfile()

With this patch NFSv3 is restored to its previous behaviour (before
->atomic_open support was added) of generating CREATE notifications
before OPEN, and NFSv4 now has that same correct ordering that is has
not had before.  I haven't tested other filesystems.

Fixes: 7c6c5249

 ("NFS: add atomic_open for NFSv3 to handle O_TRUNC correctly.")
Reported-by: James Clark <james.clark@arm.com>
Closes: https://lore.kernel.org/all/01c3bf2e-eb1f-4b7f-a54f-d2a05dd3d8c8@arm.com


Signed-off-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/171817619547.14261.975798725161704336@noble.neil.brown.name
Fixes: 7b8c9d7b

 ("fsnotify: move fsnotify_open() hook into do_dentry_open()")
Tested-by: James Clark <james.clark@arm.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240617162303.1596-2-jack@suse.cz


Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

The block device may have been frozen before it was claimed by a
filesystem. Concurrently another process might try to mount that
frozen block device and has temporarily claimed the block device for
that purpose causing a concurrent fs_bdev_thaw() to end up here. The
mounter is already about to abort mounting because they still saw an
elevanted bdev->bd_fsfreeze_count so get_bdev_super() will return
NULL in that case.

For example, P1 calls dm_suspend() which calls into bdev_freeze() before
the block device has been claimed by the filesystem. This brings
bdev->bd_fsfreeze_count to 1 and no call into fs_bdev_freeze() is
required.

Now P2 tries to mount that frozen block device. It claims it and checks
bdev->bd_fsfreeze_count. As it's elevated it aborts mounting.

In the meantime P3 called dm_resume(). P3 sees that the block device is
already claimed by a filesystem and calls into fs_bdev_thaw().

P3 takes a passive reference and realizes that the filesystem isn't
ready yet. P3 puts itself to sleep to wait for the filesystem to become
ready.

P2 now puts the last active reference to the filesystem and marks it as
dying. P3 gets woken, sees that the filesystem is dying and
get_bdev_super() fails.

Fixes: 49ef8832

 ("bdev: implement freeze and thaw holder operations")
Cc: <stable@vger.kernel.org>
Reported-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20240611085210.GA1838544@mit.edu
Link: https://lore.kernel.org/r/20240613-lackmantel-einsehen-90f0d727358d@brauner


Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

There's now no need to make sure subreq->io_iter is advanced to match
subreq->transferred before calling one of the netfs subrequest termination
functions as the check has been removed netfslib and the iterator is reset
prior to retrying a subreq.

Fixes: 3ee1a1fc

 ("cifs: Cut over to using netfslib")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <sfrench@samba.org>
cc: Paulo Alcantara <pc@manguebit.com>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: Rohith Surabattula <rohiths.msft@gmail.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
Signed-off-by: Steve French <stfrench@microsoft.com>

Unlock cifs_tcp_ses_lock before calling cifs_put_smb_ses() to avoid such
deadlock.

Cc: stable@vger.kernel.org
Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

[BUG]
Since v6.8 there are rare kernel crashes reported by various people,
the common factor is bad page status error messages like this:

  BUG: Bad page state in process kswapd0  pfn:d6e840
  page: refcount:0 mapcount:0 mapping:000000007512f4f2 index:0x2796c2c7c
  pfn:0xd6e840
  aops:btree_aops ino:1
  flags: 0x17ffffe0000008(uptodate|node=0|zone=2|lastcpupid=0x3fffff)
  page_type: 0xffffffff()
  raw: 0017ffffe0000008 dead000000000100 dead000000000122 ffff88826d0be4c0
  raw: 00000002796c2c7c 0000000000000000 00000000ffffffff 0000000000000000
  page dumped because: non-NULL mapping

[CAUSE]
Commit 09e6cef1 ("btrfs: refactor alloc_extent_buffer() to
allocate-then-attach method") changes the sequence when allocating a new
extent buffer.

Previously we always called grab_extent_buffer() under
mapping->i_private_lock, to ensure the safety on modification on
folio::private (which is a pointer to extent buffer for regular
sectorsize).

This can lead to the following race:

Thread A is trying to allocate an extent buffer at bytenr X, with 4
4K pages, meanwhile thread B is trying to release the page at X + 4K
(the second page of the extent buffer at X).

           Thread A                |                 Thread B
-----------------------------------+-------------------------------------
                                   | btree_release_folio()
				   | | This is for the page at X + 4K,
				   | | Not page X.
				   | |
alloc_extent_buffer()              | |- release_extent_buffer()
|- filemap_add_folio() for the     | |  |- atomic_dec_and_test(eb->refs)
|  page at bytenr X (the first     | |  |
|  page).                          | |  |
|  Which returned -EEXIST.         | |  |
|                                  | |  |
|- filemap_lock_folio()            | |  |
|  Returned the first page locked. | |  |
|                                  | |  |
|- grab_extent_buffer()            | |  |
|  |- atomic_inc_not_zero()        | |  |
|  |  Returned false               | |  |
|  |- folio_detach_private()       | |  |- folio_detach_private() for X
|     |- folio_test_private()      | |     |- folio_test_private()
      |  Returned true             | |     |  Returned true
      |- folio_put()               |       |- folio_put()

Now there are two puts on the same folio at folio X, leading to refcount
underflow of the folio X, and eventually causing the BUG_ON() on the
page->mapping.

The condition is not that easy to hit:

- The release must be triggered for the middle page of an eb
  If the release is on the same first page of an eb, page lock would kick
  in and prevent the race.

- folio_detach_private() has a very small race window
  It's only between folio_test_private() and folio_clear_private().

That's exactly when mapping->i_private_lock is used to prevent such race,
and commit 09e6cef1

 ("btrfs: refactor alloc_extent_buffer() to
allocate-then-attach method") screwed that up.

At that time, I thought the page lock would kick in as
filemap_release_folio() also requires the page to be locked, but forgot
the filemap_release_folio() only locks one page, not all pages of an
extent buffer.

[FIX]
Move all the code requiring i_private_lock into
attach_eb_folio_to_filemap(), so that everything is done with proper
lock protection.

Furthermore to prevent future problems, add an extra
lockdep_assert_locked() to ensure we're holding the proper lock.

To reproducer that is able to hit the race (takes a few minutes with
instrumented code inserting delays to alloc_extent_buffer()):

  #!/bin/sh
  drop_caches () {
	  while(true); do
		  echo 3 > /proc/sys/vm/drop_caches
		  echo 1 > /proc/sys/vm/compact_memory
	  done
  }

  run_tar () {
	  while(true); do
		  for x in `seq 1 80` ; do
			  tar cf /dev/zero /mnt > /dev/null &
		  done
		  wait
	  done
  }

  mkfs.btrfs -f -d single -m single /dev/vda
  mount -o noatime /dev/vda /mnt
  # create 200,000 files, 1K each
  ./simoop -n 200000 -E -f 1k /mnt
  drop_caches &
  (run_tar)

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/linux-btrfs/CAHk-=wgt362nGfScVOOii8cgKn2LVVHeOvOA7OBwg1OwbuJQcw@mail.gmail.com/


Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Link: https://lore.kernel.org/lkml/CABXGCsPktcHQOvKTbPaTwegMExije=Gpgci5NW=hqORo-s7diA@mail.gmail.com/


Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Link: https://lore.kernel.org/linux-btrfs/e8b3311c-9a75-4903-907f-fc0f7a3fe423@gmx.de/


Reported-by:  <syzbot+f80b066392366b4af85e@syzkaller.appspotmail.com>
Fixes: 09e6cef1

 ("btrfs: refactor alloc_extent_buffer() to allocate-then-attach method")
CC: stable@vger.kernel.org # 6.8+
CC: Chris Mason <clm@fb.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

The error handling in nilfs_empty_dir() when a directory folio/page read
fails is incorrect, as in the old ext2 implementation, and if the
folio/page cannot be read or nilfs_check_folio() fails, it will falsely
determine the directory as empty and corrupt the file system.

In addition, since nilfs_empty_dir() does not immediately return on a
failed folio/page read, but continues to loop, this can cause a long loop
with I/O if i_size of the directory's inode is also corrupted, causing the
log writer thread to wait and hang, as reported by syzbot.

Fix these issues by making nilfs_empty_dir() immediately return a false
value (0) if it fails to get a directory folio/page.

Link: https://lkml.kernel.org/r/20240604134255.7165-1-konishi.ryusuke@gmail.com


Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by:  <syzbot+c8166c541d3971bf6c87@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=c8166c541d3971bf6c87
Fixes: 2ba466d7

 ("nilfs2: directory entry operations")
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

We normally ksm_zero_pages++ in ksmd when page is merged with zero page,
but ksm_zero_pages-- is done from page tables side, where there is no any
accessing protection of ksm_zero_pages.

So we can read very exceptional value of ksm_zero_pages in rare cases,
such as -1, which is very confusing to users.

Fix it by changing to use atomic_long_t, and the same case with the
mm->ksm_zero_pages.

Link: https://lkml.kernel.org/r/20240528-b4-ksm-counters-v3-2-34bb358fdc13@linux.dev
Fixes: e2942062 ("ksm: count all zero pages placed by KSM")
Fixes: 6080d19f

 ("ksm: add ksm zero pages for each process")
Signed-off-by: Chengming Zhou <chengming.zhou@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Cc: Stefan Roesch <shr@devkernel.io>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Destructive writes to a block device on which nilfs2 is mounted can cause
a kernel bug in the folio/page writeback start routine or writeback end
routine (__folio_start_writeback in the log below):

 kernel BUG at mm/page-writeback.c:3070!
 Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
 ...
 RIP: 0010:__folio_start_writeback+0xbaa/0x10e0
 Code: 25 ff 0f 00 00 0f 84 18 01 00 00 e8 40 ca c6 ff e9 17 f6 ff ff
  e8 36 ca c6 ff 4c 89 f7 48 c7 c6 80 c0 12 84 e8 e7 b3 0f 00 90 <0f>
  0b e8 1f ca c6 ff 4c 89 f7 48 c7 c6 a0 c6 12 84 e8 d0 b3 0f 00
 ...
 Call Trace:
  <TASK>
  nilfs_segctor_do_construct+0x4654/0x69d0 [nilfs2]
  nilfs_segctor_construct+0x181/0x6b0 [nilfs2]
  nilfs_segctor_thread+0x548/0x11c0 [nilfs2]
  kthread+0x2f0/0x390
  ret_from_fork+0x4b/0x80
  ret_from_fork_asm+0x1a/0x30
  </TASK>

This is because when the log writer starts a writeback for segment summary
blocks or a super root block that use the backing device's page cache, it
does not wait for the ongoing folio/page writeback, resulting in an
inconsistent writeback state.

Fix this issue by waiting for ongoing writebacks when putting
folios/pages on the backing device into writeback state.

Link: https://lkml.kernel.org/r/20240530141556.4411-1-konishi.ryusuke@gmail.com
Fixes: 9ff05123

 ("nilfs2: segment constructor")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Qgroup extent records are created when delayed ref heads are created and
then released after accounting extents at btrfs_qgroup_account_extents(),
called during the transaction commit path.

If a transaction is aborted we free the qgroup records by calling
btrfs_qgroup_destroy_extent_records() at btrfs_destroy_delayed_refs(),
unless we don't have delayed references. We are incorrectly assuming
that no delayed references means we don't have qgroup extents records.

We can currently have no delayed references because we ran them all
during a transaction commit and the transaction was aborted after that
due to some error in the commit path.

So fix this by ensuring we btrfs_qgroup_destroy_extent_records() at
btrfs_destroy_delayed_refs() even if we don't have any delayed references.

Reported-by:  <syzbot+0fecc032fa134afd49df@syzkaller.appspotmail.com>
Link: https://lore.kernel.org/linux-btrfs/0000000000004e7f980619f91835@google.com/
Fixes: 81f7eb00

 ("btrfs: destroy qgroup extent records on transaction abort")
CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

We have been seeing crashes on duplicate keys in
btrfs_set_item_key_safe():

  BTRFS critical (device vdb): slot 4 key (450 108 8192) new key (450 108 8192)
  ------------[ cut here ]------------
  kernel BUG at fs/btrfs/ctree.c:2620!
  invalid opcode: 0000 [#1] PREEMPT SMP PTI
  CPU: 0 PID: 3139 Comm: xfs_io Kdump: loaded Not tainted 6.9.0 #6
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014
  RIP: 0010:btrfs_set_item_key_safe+0x11f/0x290 [btrfs]

With the following stack trace:

  #0  btrfs_set_item_key_safe (fs/btrfs/ctree.c:2620:4)
  #1  btrfs_drop_extents (fs/btrfs/file.c:411:4)
  #2  log_one_extent (fs/btrfs/tree-log.c:4732:9)
  #3  btrfs_log_changed_extents (fs/btrfs/tree-log.c:4955:9)
  #4  btrfs_log_inode (fs/btrfs/tree-log.c:6626:9)
  #5  btrfs_log_inode_parent (fs/btrfs/tree-log.c:7070:8)
  #6  btrfs_log_dentry_safe (fs/btrfs/tree-log.c:7171:8)
  #7  btrfs_sync_file (fs/btrfs/file.c:1933:8)
  #8  vfs_fsync_range (fs/sync.c:188:9)
  #9  vfs_fsync (fs/sync.c:202:9)
  #10 do_fsync (fs/sync.c:212:9)
  #11 __do_sys_fdatasync (fs/sync.c:225:9)
  #12 __se_sys_fdatasync (fs/sync.c:223:1)
  #13 __x64_sys_fdatasync (fs/sync.c:223:1)
  #14 do_syscall_x64 (arch/x86/entry/common.c:52:14)
  #15 do_syscall_64 (arch/x86/entry/common.c:83:7)
  #16 entry_SYSCALL_64+0xaf/0x14c (arch/x86/entry/entry_64.S:121)

So we're logging a changed extent from fsync, which is splitting an
extent in the log tree. But this split part already exists in the tree,
triggering the BUG().

This is the state of the log tree at the time of the crash, dumped with
drgn (https://github.com/osandov/drgn/blob/main/contrib/btrfs_tree.py

)
to get more details than btrfs_print_leaf() gives us:

  >>> print_extent_buffer(prog.crashed_thread().stack_trace()[0]["eb"])
  leaf 33439744 level 0 items 72 generation 9 owner 18446744073709551610
  leaf 33439744 flags 0x100000000000000
  fs uuid e5bd3946-400c-4223-8923-190ef1f18677
  chunk uuid d58cb17e-6d02-494a-829a-18b7d8a399da
          item 0 key (450 INODE_ITEM 0) itemoff 16123 itemsize 160
                  generation 7 transid 9 size 8192 nbytes 8473563889606862198
                  block group 0 mode 100600 links 1 uid 0 gid 0 rdev 0
                  sequence 204 flags 0x10(PREALLOC)
                  atime 1716417703.220000000 (2024-05-22 15:41:43)
                  ctime 1716417704.983333333 (2024-05-22 15:41:44)
                  mtime 1716417704.983333333 (2024-05-22 15:41:44)
                  otime 17592186044416.000000000 (559444-03-08 01:40:16)
          item 1 key (450 INODE_REF 256) itemoff 16110 itemsize 13
                  index 195 namelen 3 name: 193
          item 2 key (450 XATTR_ITEM 1640047104) itemoff 16073 itemsize 37
                  location key (0 UNKNOWN.0 0) type XATTR
                  transid 7 data_len 1 name_len 6
                  name: user.a
                  data a
          item 3 key (450 EXTENT_DATA 0) itemoff 16020 itemsize 53
                  generation 9 type 1 (regular)
                  extent data disk byte 303144960 nr 12288
                  extent data offset 0 nr 4096 ram 12288
                  extent compression 0 (none)
          item 4 key (450 EXTENT_DATA 4096) itemoff 15967 itemsize 53
                  generation 9 type 2 (prealloc)
                  prealloc data disk byte 303144960 nr 12288
                  prealloc data offset 4096 nr 8192
          item 5 key (450 EXTENT_DATA 8192) itemoff 15914 itemsize 53
                  generation 9 type 2 (prealloc)
                  prealloc data disk byte 303144960 nr 12288
                  prealloc data offset 8192 nr 4096
  ...

So the real problem happened earlier: notice that items 4 (4k-12k) and 5
(8k-12k) overlap. Both are prealloc extents. Item 4 straddles i_size and
item 5 starts at i_size.

Here is the state of the filesystem tree at the time of the crash:

  >>> root = prog.crashed_thread().stack_trace()[2]["inode"].root
  >>> ret, nodes, slots = btrfs_search_slot(root, BtrfsKey(450, 0, 0))
  >>> print_extent_buffer(nodes[0])
  leaf 30425088 level 0 items 184 generation 9 owner 5
  leaf 30425088 flags 0x100000000000000
  fs uuid e5bd3946-400c-4223-8923-190ef1f18677
  chunk uuid d58cb17e-6d02-494a-829a-18b7d8a399da
  	...
          item 179 key (450 INODE_ITEM 0) itemoff 4907 itemsize 160
                  generation 7 transid 7 size 4096 nbytes 12288
                  block group 0 mode 100600 links 1 uid 0 gid 0 rdev 0
                  sequence 6 flags 0x10(PREALLOC)
                  atime 1716417703.220000000 (2024-05-22 15:41:43)
                  ctime 1716417703.220000000 (2024-05-22 15:41:43)
                  mtime 1716417703.220000000 (2024-05-22 15:41:43)
                  otime 1716417703.220000000 (2024-05-22 15:41:43)
          item 180 key (450 INODE_REF 256) itemoff 4894 itemsize 13
                  index 195 namelen 3 name: 193
          item 181 key (450 XATTR_ITEM 1640047104) itemoff 4857 itemsize 37
                  location key (0 UNKNOWN.0 0) type XATTR
                  transid 7 data_len 1 name_len 6
                  name: user.a
                  data a
          item 182 key (450 EXTENT_DATA 0) itemoff 4804 itemsize 53
                  generation 9 type 1 (regular)
                  extent data disk byte 303144960 nr 12288
                  extent data offset 0 nr 8192 ram 12288
                  extent compression 0 (none)
          item 183 key (450 EXTENT_DATA 8192) itemoff 4751 itemsize 53
                  generation 9 type 2 (prealloc)
                  prealloc data disk byte 303144960 nr 12288
                  prealloc data offset 8192 nr 4096

Item 5 in the log tree corresponds to item 183 in the filesystem tree,
but nothing matches item 4. Furthermore, item 183 is the last item in
the leaf.

btrfs_log_prealloc_extents() is responsible for logging prealloc extents
beyond i_size. It first truncates any previously logged prealloc extents
that start beyond i_size. Then, it walks the filesystem tree and copies
the prealloc extent items to the log tree.

If it hits the end of a leaf, then it calls btrfs_next_leaf(), which
unlocks the tree and does another search. However, while the filesystem
tree is unlocked, an ordered extent completion may modify the tree. In
particular, it may insert an extent item that overlaps with an extent
item that was already copied to the log tree.

This may manifest in several ways depending on the exact scenario,
including an EEXIST error that is silently translated to a full sync,
overlapping items in the log tree, or this crash. This particular crash
is triggered by the following sequence of events:

- Initially, the file has i_size=4k, a regular extent from 0-4k, and a
  prealloc extent beyond i_size from 4k-12k. The prealloc extent item is
  the last item in its B-tree leaf.
- The file is fsync'd, which copies its inode item and both extent items
  to the log tree.
- An xattr is set on the file, which sets the
  BTRFS_INODE_COPY_EVERYTHING flag.
- The range 4k-8k in the file is written using direct I/O. i_size is
  extended to 8k, but the ordered extent is still in flight.
- The file is fsync'd. Since BTRFS_INODE_COPY_EVERYTHING is set, this
  calls copy_inode_items_to_log(), which calls
  btrfs_log_prealloc_extents().
- btrfs_log_prealloc_extents() finds the 4k-12k prealloc extent in the
  filesystem tree. Since it starts before i_size, it skips it. Since it
  is the last item in its B-tree leaf, it calls btrfs_next_leaf().
- btrfs_next_leaf() unlocks the path.
- The ordered extent completion runs, which converts the 4k-8k part of
  the prealloc extent to written and inserts the remaining prealloc part
  from 8k-12k.
- btrfs_next_leaf() does a search and finds the new prealloc extent
  8k-12k.
- btrfs_log_prealloc_extents() copies the 8k-12k prealloc extent into
  the log tree. Note that it overlaps with the 4k-12k prealloc extent
  that was copied to the log tree by the first fsync.
- fsync calls btrfs_log_changed_extents(), which tries to log the 4k-8k
  extent that was written.
- This tries to drop the range 4k-8k in the log tree, which requires
  adjusting the start of the 4k-12k prealloc extent in the log tree to
  8k.
- btrfs_set_item_key_safe() sees that there is already an extent
  starting at 8k in the log tree and calls BUG().

Fix this by detecting when we're about to insert an overlapping file
extent item in the log tree and truncating the part that would overlap.

CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

in bch2_move_data_btree, we might start with the trans unlocked from a
previous loop iteration - we need a trans_begin() before iter_init().

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

This fixes an issue where setting a device to durability=0 after it's
been used makes it impossible to remove.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

When running fstest generic/423 with sfu mount option, it
was being skipped due to inability to create sockets:

  generic/423  [not run] cifs does not support mknod/mkfifo

which can also be easily reproduced with their af_unix tool:

  ./src/af_unix /mnt1/socket-two bind: Operation not permitted

Fix sfu mount option to allow creating and reporting sockets.

Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

This was reported as an error when running coreutils shred.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

This reverts commit 681ce862.

We gave it a try, but it turns out the kernel test robot did in fact
find performance regressions for it, so we'll have to look at the more
involved alternative fixes for Yafang Shao's Elasticsearch load issue.

There were several alternatives discussed, they just weren't as simple
as this first attempt.

The report is of a -7.4% regression of filebench.sum_operations/s, which
appears significant enough to trigger my "this patch may get reverted if
somebody finds a performance regression on some other load" rule.

So it's still the case that we should end up deleting dentries more
aggressively - or just be better at pruning them later - but it needs a
bit more finesse than this simple thing.

Link: https://lore.kernel.org/all/202405291318.4dfbb352-oliver.sang@intel.com/


Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We were accidentally returning -EROFS during recovery on filesystem
inconsistency - since this is what the journal returns on emergency
shutdown.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Can't actually be used uninitialized, but gcc was being silly.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Compatibility fix - we no longer have a separate table for which order
gc walks btrees in, and special case the stripes btree directly.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Fix the 'make W=1' warning:
WARNING: modpost: missing MODULE_DESCRIPTION() in fs/bcachefs/mean_and_variance_test.o

Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

bch2_check_version_downgrade() was setting c->sb.version, which
bch2_sb_set_downgrade() expects to be at the previous version; and it
shouldn't even have been set directly because c->sb.version is updated
by write_super().

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

delete_dead_snapshots now runs before the main fsck.c passes which check
for keys for invalid snapshots; thus, it needs those checks as well.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Consolidate per-key work into delete_dead_snapshots_process_key(), so we
now walk all keys once, not twice.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

We now track whether a transaction is locked, and verify that we don't
have nodes locked when the transaction isn't locked; reorder relocks to
not pop the new assert.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

This function is used for finding the hash seed (which is the same in
all versions of an inode in different snapshots): ff an inode has been
deleted in a child snapshot we need to iterate until we find a live
version.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

It can be useful to know the exact byte offset within a btree node where
an error occured.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

If a write path in COW mode fails, either before submitting a bio for the
new extents or an actual IO error happens, we can end up allowing a fast
fsync to log file extent items that point to unwritten extents.

This is because dropping the extent maps happens when completing ordered
extents, at btrfs_finish_one_ordered(), and the completion of an ordered
extent is executed in a work queue.

This can result in a fast fsync to start logging file extent items based
on existing extent maps before the ordered extents complete, therefore
resulting in a log that has file extent items that point to unwritten
extents, resulting in a corrupt file if a crash happens after and the log
tree is replayed the next time the fs is mounted.

This can happen for both direct IO writes and buffered writes.

For example consider a direct IO write, in COW mode, that fails at
btrfs_dio_submit_io() because btrfs_extract_ordered_extent() returned an
error:

1) We call btrfs_finish_ordered_extent() with the 'uptodate' parameter
   set to false, meaning an error happened;

2) That results in marking the ordered extent with the BTRFS_ORDERED_IOERR
   flag;

3) btrfs_finish_ordered_extent() queues the completion of the ordered
   extent - so that btrfs_finish_one_ordered() will be executed later in
   a work queue. That function will drop extent maps in the range when
   it's executed, since the extent maps point to unwritten locations
   (signaled by the BTRFS_ORDERED_IOERR flag);

4) After calling btrfs_finish_ordered_extent() we keep going down the
   write path and unlock the inode;

5) After that a fast fsync starts and locks the inode;

6) Before the work queue executes btrfs_finish_one_ordered(), the fsync
   task sees the extent maps that point to the unwritten locations and
   logs file extent items based on them - it does not know they are
   unwritten, and the fast fsync path does not wait for ordered extents
   to complete, which is an intentional behaviour in order to reduce
   latency.

For the buffered write case, here's one example:

1) A fast fsync begins, and it starts by flushing delalloc and waiting for
   the writeback to complete by calling filemap_fdatawait_range();

2) Flushing the dellaloc created a new extent map X;

3) During the writeback some IO error happened, and at the end io callback
   (end_bbio_data_write()) we call btrfs_finish_ordered_extent(), which
   sets the BTRFS_ORDERED_IOERR flag in the ordered extent and queues its
   completion;

4) After queuing the ordered extent completion, the end io callback clears
   the writeback flag from all pages (or folios), and from that moment the
   fast fsync can proceed;

5) The fast fsync proceeds sees extent map X and logs a file extent item
   based on extent map X, resulting in a log that points to an unwritten
   data extent - because the ordered extent completion hasn't run yet, it
   happens only after the logging.

To fix this make btrfs_finish_ordered_extent() set the inode flag
BTRFS_INODE_NEEDS_FULL_SYNC in case an error happened for a COW write,
so that a fast fsync will wait for ordered extent completion.

Note that this issues of using extent maps that point to unwritten
locations can not happen for reads, because in read paths we start by
locking the extent range and wait for any ordered extents in the range
to complete before looking for extent maps.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

An async dio write to a sparse file can generate a lot of extents
and when we unlink this file (using rm), the kernel can be busy in umapping
and freeing those extents as part of transaction processing.

Similarly xfs reflink remapping path can also iterate over a million
extent entries in xfs_reflink_remap_blocks().

Since we can busy loop in these two functions, so let's add cond_resched()
to avoid softlockup messages like these.

watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [kworker/1:0:82435]
CPU: 1 PID: 82435 Comm: kworker/1:0 Tainted: G S  L   6.9.0-rc5-0-default #1
Workqueue: xfs-inodegc/sda2 xfs_inodegc_worker
NIP [c000000000beea10] xfs_extent_busy_trim+0x100/0x290
LR [c000000000bee958] xfs_extent_busy_trim+0x48/0x290
Call Trace:
  xfs_alloc_get_rec+0x54/0x1b0 (unreliable)
  xfs_alloc_compute_aligned+0x5c/0x144
  xfs_alloc_ag_vextent_size+0x238/0x8d4
  xfs_alloc_fix_freelist+0x540/0x694
  xfs_free_extent_fix_freelist+0x84/0xe0
  __xfs_free_extent+0x74/0x1ec
  xfs_extent_free_finish_item+0xcc/0x214
  xfs_defer_finish_one+0x194/0x388
  xfs_defer_finish_noroll+0x1b4/0x5c8
  xfs_defer_finish+0x2c/0xc4
  xfs_bunmapi_range+0xa4/0x100
  xfs_itruncate_extents_flags+0x1b8/0x2f4
  xfs_inactive_truncate+0xe0/0x124
  xfs_inactive+0x30c/0x3e0
  xfs_inodegc_worker+0x140/0x234
  process_scheduled_works+0x240/0x57c
  worker_thread+0x198/0x468
  kthread+0x138/0x140
  start_kernel_thread+0x14/0x18

run fstests generic/175 at 2024-02-02 04:40:21
[   C17] watchdog: BUG: soft lockup - CPU#17 stuck for 23s! [xfs_io:7679]
 watchdog: BUG: soft lockup - CPU#17 stuck for 23s! [xfs_io:7679]
 CPU: 17 PID: 7679 Comm: xfs_io Kdump: loaded Tainted: G X 6.4.0
 NIP [c008000005e3ec94] xfs_rmapbt_diff_two_keys+0x54/0xe0 [xfs]
 LR [c008000005e08798] xfs_btree_get_leaf_keys+0x110/0x1e0 [xfs]
 Call Trace:
  0xc000000014107c00 (unreliable)
  __xfs_btree_updkeys+0x8c/0x2c0 [xfs]
  xfs_btree_update_keys+0x150/0x170 [xfs]
  xfs_btree_lshift+0x534/0x660 [xfs]
  xfs_btree_make_block_unfull+0x19c/0x240 [xfs]
  xfs_btree_insrec+0x4e4/0x630 [xfs]
  xfs_btree_insert+0x104/0x2d0 [xfs]
  xfs_rmap_insert+0xc4/0x260 [xfs]
  xfs_rmap_map_shared+0x228/0x630 [xfs]
  xfs_rmap_finish_one+0x2d4/0x350 [xfs]
  xfs_rmap_update_finish_item+0x44/0xc0 [xfs]
  xfs_defer_finish_noroll+0x2e4/0x740 [xfs]
  __xfs_trans_commit+0x1f4/0x400 [xfs]
  xfs_reflink_remap_extent+0x2d8/0x650 [xfs]
  xfs_reflink_remap_blocks+0x154/0x320 [xfs]
  xfs_file_remap_range+0x138/0x3a0 [xfs]
  do_clone_file_range+0x11c/0x2f0
  vfs_clone_file_range+0x60/0x1c0
  ioctl_file_clone+0x78/0x140
  sys_ioctl+0x934/0x1270
  system_call_exception+0x158/0x320
  system_call_vectored_common+0x15c/0x2ec

Cc: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Tested-by: Disha <Goel&lt;disgoel@linux.ibm.com>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

There's a problem in 9p's interaction with netfslib whereby a crash occurs
because the 9p_fid structs get forcibly destroyed during client teardown
(without paying attention to their refcounts) before netfslib has finished
with them.  However, it's not a simple case of deferring the clunking that
p9_fid_put() does as that requires the p9_client record to still be
present.

The problem is that netfslib has to unlock pages and clear the IN_PROGRESS
flag before destroying the objects involved - including the fid - and, in
any case, nothing checks to see if writeback completed barring looking at
the page flags.

Fix this by keeping a count of outstanding I/O requests (of any type) and
waiting for it to quiesce during inode eviction.

Reported-by:  <syzbot+df038d463cca332e8414@syzkaller.appspotmail.com>
Link: https://lore.kernel.org/all/0000000000005be0aa061846f8d6@google.com/


Reported-by:  <syzbot+d7c7a495a5e466c031b6@syzkaller.appspotmail.com>
Link: h...

Don't open-code what the kernel already provides.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>