We'll reference it directly in xlog_recover_attri_commit_pass2, so move
it up a bit.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

Consolidate the xfs_attr_defer_* helpers into a single xfs_attr_defer_add
one that picks the right dela_state based on the passed in operation.
Also move to a single trace point as the actual operation is visible
through the flags in the delta_state passed to the trace point.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

Merge tag 'fix-growfsrt-failures-6.8_2023-12-13' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.8-mergeB

xfs: fix growfsrt failure during rt volume attach

One more series to fix a transaction reservation overrun while
trying to attach a very large rt volume to a filesystem.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

* tag 'fix-growfsrt-failures-6.8_2023-12-13' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: recompute growfsrtfree transaction reservation while growing rt volume

While playing with growfs to create a 20TB realtime section on a
filesystem that didn't previously have an rt section, I noticed that
growfs would occasionally shut down the log due to a transaction
reservation overflow.

xfs_calc_growrtfree_reservation uses the current size of the realtime
summary file (m_rsumsize) to compute the transaction reservation for a
growrtfree transaction.  The reservations are computed at mount time,
which means that m_rsumsize is zero when growfs starts "freeing" the new
realtime extents into the rt volume.  As a result, the transaction is
undersized and fails.

Fix this by recomputing the transaction reservations every time we
change m_rsumsize.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Move xfs_ondisk.h to libxfs so that we can do the struct sanity checks
in userspace libxfs as well.  This should allow us to retire the
somewhat fragile xfs/122 test on xfstests.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

Use the compiler-provided static_assert built-in from C11 instead of
the kernel-specific BUILD_BUG_ON_MSG for the structure size and offset
checks in xfs_ondisk.  This not only gives slightly nicer error messages
in case things go south, but can also be trivially used as-is in
userspace.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

This patch does not modify logic.

xfs_da_buf_copy() will copy one block from src xfs_buf to
dst xfs_buf, and update the block metadata in dst directly.
Signed-off-by: Zhang Tianci <zhangtianci.1997@bytedance.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

xfs_da3_swap_lastblock() copy the last block content to the dead block,
but do not update the metadata in it. We need update some metadata
for some kinds of type block, such as dir3 leafn block records its
blkno, we shall update it to the dead block blkno. Otherwise,
before write the xfs_buf to disk, the verify_write() will fail in
blk_hdr->blkno != xfs_buf->b_bn, then xfs will be shutdown.

We will get this warning:

  XFS (dm-0): Metadata corruption detected at xfs_dir3_leaf_verify+0xa8/0xe0 [xfs], xfs_dir3_leafn block 0x178
  XFS (dm-0): Unmount and run xfs_repair
  XFS (dm-0): First 128 bytes of corrupted metadata buffer:
  00000000e80f1917: 00 80 00 0b 00 80 00 07 3d ff 00 00 00 00 00 00  ........=.......
  000000009604c005: 00 00 00 00 00 00 01 a0 00 00 00 00 00 00 00 00  ................
  000000006b6fb2bf: e4 44 e3 97 b5 64 44 41 8b 84 60 0e 50 43 d9 bf  .D...dDA..`.PC..
  00000000678978a2: 00 00 00 00 00 00 00 83 01 73 00 93 00 00 00 00  .........s......
  00000000b28b247c: 99 29 1d 38 00 00 00 00 99 29 1d 40 00 00 00 00  .).8.....).@....
  000000002b2a662c: 99 29 1d 48 00 00 00 00 99 49 11 00 00 00 00 00  .).H.....I......
  00000000ea2ffbb8: 99 49 11 08 00 00 45 25 99 49 11 10 00 00 48 fe  .I....E%.I....H.
  0000000069e86440: 99 49 11 18 00 00 4c 6b 99 49 11 20 00 00 4d 97  .I....Lk.I. ..M.
  XFS (dm-0): xfs_do_force_shutdown(0x8) called from line 1423 of file fs/xfs/xfs_buf.c.  Return address = 00000000c0ff63c1
  XFS (dm-0): Corruption of in-memory data detected.  Shutting down filesystem
  XFS (dm-0): Please umount the filesystem and rectify the problem(s)

>From the log above, we know xfs_buf->b_no is 0x178, but the block's hdr record
its blkno is 0x1a0.

Fixes: 24df33b4 ("xfs: add CRC checking to dir2 leaf blocks")
Signed-off-by: Zhang Tianci <zhangtianci.1997@bytedance.com>
Suggested-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

In the case of returning -ENOSPC, ensure logflagsp is initialized by 0.
Otherwise the caller __xfs_bunmapi will set uninitialized illegal
tmp_logflags value into xfs log, which might cause unpredictable error
in the log recovery procedure.

Also, remove the flags variable and set the *logflagsp directly, so that
the code should be more robust in the long run.

Fixes: 1b24b633 ("xfs: move some more code into xfs_bmap_del_extent_real")
Signed-off-by: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

Use struct types instead of typedefs so that the header can be included
with pulling in the headers that define the typedefs, and remove the
pointless externs.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

xfs_reserve_blocks has a very odd interface that can only be explained
by it directly deriving from the IRIX fcntl handler back in the day.

Split reporting out the reserved blocks out of xfs_reserve_blocks into
the only caller that cares.  This means that the value reported from
XFS_IOC_SET_RESBLKS isn't atomically sampled in the same critical
section as when it was set anymore, but as the values could change
right after setting them anyway that does not matter.  It does
provide atomic sampling of both values for XFS_IOC_GET_RESBLKS now,
though.

Also pass a normal scalar integer value for the requested value instead
of the pointless pointer.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

Split XFS_IOC_FSCOUNTS out of the main xfs_file_ioctl function, and
merge the xfs_fs_counts helper into the ioctl handler.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

The XFS_IOC_GET_RESBLKS and XFS_IOC_SET_RESBLKS already share a fair
amount of code, and will share even more soon.  Move the logic for both
of them out of the main xfs_file_ioctl function into a
xfs_ioctl_getset_resblocks helper to share the code and prepare for
additional changes.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

XFS docs are currently in upper-level Documentation/filesystems.
Although these are currently 4 docs, they are already outstanding as
a group and can be moved to its own subdirectory.

Consolidate them into Documentation/filesystems/xfs/.
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Bill O'Donnell <bodonnel@redhat.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

Now, if we suddenly remove a PMEM device(by calling unbind) which
contains FSDAX while programs are still accessing data in this device,
e.g.:
```
 $FSSTRESS_PROG -d $SCRATCH_MNT -n 99999 -p 4 &
 # $FSX_PROG -N 1000000 -o 8192 -l 500000 $SCRATCH_MNT/t001 &
 echo "pfn1.1" > /sys/bus/nd/drivers/nd_pmem/unbind
```
it could come into an unacceptable state:
  1. device has gone but mount point still exists, and umount will fail
       with "target is busy"
  2. programs will hang and cannot be killed
  3. may crash with NULL pointer dereference

To fix this, we introduce a MF_MEM_PRE_REMOVE flag to let it know that we
are going to remove the whole device, and make sure all related processes
could be notified so that they could end up gracefully.

This patch is inspired by Dan's "mm, dax, pmem: Introduce
dev_pagemap_failure()"[1].  With the help of dax_holder and
->notify_failure() mechanism, the pmem driver is able to ask filesystem
on it to unmap all files in use, and notify processes who are using
those files.

Call trace:
trigger unbind
 -> unbind_store()
  -> ... (skip)
   -> devres_release_all()
    -> kill_dax()
     -> dax_holder_notify_failure(dax_dev, 0, U64_MAX, MF_MEM_PRE_REMOVE)
      -> xfs_dax_notify_failure()
      `-> freeze_super()             // freeze (kernel call)
      `-> do xfs rmap
      ` -> mf_dax_kill_procs()
      `  -> collect_procs_fsdax()    // all associated processes
      `  -> unmap_and_kill()
      ` -> invalidate_inode_pages2_range() // drop file's cache
      `-> thaw_super()               // thaw (both kernel & user call)

Introduce MF_MEM_PRE_REMOVE to let filesystem know this is a remove
event.  Use the exclusive freeze/thaw[2] to lock the filesystem to prevent
new dax mapping from being created.  Do not shutdown filesystem directly
if configuration is not supported, or if failure range includes metadata
area.  Make sure all files and processes(not only the current progress)
are handled correctly.  Also drop the cache of associated files before
pmem is removed.

[1]: https://lore.kernel.org/linux-mm/161604050314.1463742.14151665140035795571.stgit@dwillia2-desk3.amr.corp.intel.com/
[2]: https://lore.kernel.org/linux-xfs/169116275623.3187159.16862410128731457358.stg-ugh@frogsfrogsfrogs/Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

Merge tag 'repair-auto-reap-space-reservations-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.8-mergeA

xfs: reserve disk space for online repairs

Online repair fixes metadata structures by writing a new copy out to
disk and atomically committing the new structure into the filesystem.
For this to work, we need to reserve all the space we're going to need
ahead of time so that the atomic commit transaction is as small as
possible.  We also require the reserved space to be freed if the system
goes down, or if we decide not to commit the repair, or if we reserve
too much space.

To keep the atomic commit transaction as small as possible, we would
like to allocate some space and simultaneously schedule automatic
reaping of the reserved space, even on log recovery.  EFIs are the
mechanism to get us there, but we need to use them in a novel manner.
Once we allocate the space, we want to hold on to the EFI (relogging as
necessary) until we can commit or cancel the repair.  EFIs for written
committed blocks need to go away, but unwritten or uncommitted blocks
can be freed like normal.

Earlier versions of this patchset directly manipulated the log items,
but Dave thought that to be a layering violation.  For v27, I've
modified the defer ops handling code to be capable of pausing a deferred
work item.  Log intent items are created as they always have been, but
paused items are pushed onto a side list when finishing deferred work
items, and pushed back onto the transaction after that.  Log intent done
item are not created for paused work.

The second part adds a "stale" flag to the EFI so that the repair
reservation code can dispose of an EFI the normal way, but without the
space actually being freed.

This has been lightly tested with fstests.  Enjoy!
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

* tag 'repair-auto-reap-space-reservations-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: force small EFIs for reaping btree extents
  xfs: log EFIs for all btree blocks being used to stage a btree
  xfs: implement block reservation accounting for btrees we're staging
  xfs: remove unused fields from struct xbtree_ifakeroot
  xfs: automatic freeing of freshly allocated unwritten space
  xfs: remove __xfs_free_extent_later
  xfs: allow pausing of pending deferred work items
  xfs: don't append work items to logged xfs_defer_pending objects

Merge tag 'scrub-livelock-prevention-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.8-mergeA

xfs: prevent livelocks in xchk_iget

Prevent scrub from live locking in xchk_iget if there's a cycle in the
inobt by allocating an empty transaction.

This has been lightly tested with fstests.  Enjoy!
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

* tag 'scrub-livelock-prevention-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: make xchk_iget safer in the presence of corrupt inode btrees

Merge tag 'defer-elide-create-done-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.8-mergeA

xfs: elide defer work ->create_done if no intent

Christoph pointed out that the defer ops machinery doesn't need to call
->create_done if the deferred work item didn't generate a log intent
item in the first place.  Let's clean that up and save an indirect call
in the non-logged xattr update call path.

This has been lightly tested with fstests.  Enjoy!
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

* tag 'defer-elide-create-done-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: elide ->create_done calls for unlogged deferred work
  xfs: document what LARP means

Merge tag 'fix-rtmount-overflows-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.8-mergeA

xfs: fix realtime geometry integer overflows

While reading through the realtime geometry support code in xfsprogs, I
noticed a discrepancy between the sb_rextslog computation used when
writing out the superblock during mkfs and the validation code used in
xfs_repair.  This discrepancy would lead to system failure for a runt rt
volume having more than 1 rt block but zero rt extents in length.  Most
people aren't going to configure a 1M extent size for their 360k rt
floppy disk volume, but I did!

In the process of studying that code, it occurred to me that there is a
second bug in the computation -- the use of highbit32 for a 64-bit
value means that the upper 32 bits are not considered in the search for
a high bit.  This causes the creation of a realtime summary file that is
the wrong length.  If rextents is a multiple of U32_MAX then this will
appear to work fine because highbit32 returns -1 for an input of 0; but
for all other cases the rt summary is undersized, leading to failures.

Fix the first problem by standardizing the computation with a helper in
libxfs; and the second problem by correcting the computation.  This will
cause any existing rt volumes larger than 2^32 blocks to fail validation
but they probably were already crashing anyway.

This has been lightly tested with fstests.  Enjoy!
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

* tag 'fix-rtmount-overflows-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: don't allow overly small or large realtime volumes
  xfs: fix 32-bit truncation in xfs_compute_rextslog
  xfs: make rextslog computation consistent with mkfs

Merge tag 'reconstruct-defer-cleanups-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.8-mergeA

xfs: continue removing defer item boilerplate

Now that we've restructured log intent item recovery to reconstruct the
incore deferred work state, apply further cleanups to that code to
remove boilerplate that is duplicated across all the _item.c files.
Having done that, collapse a bunch of trivial helpers to reduce the
overall call chain.  That enables us to refactor the relog code so that
the ->relog_item implementations only have to know how to format the
implementation-specific data encoded in an intent item and don't
themselves have to handle the log item juggling.

This has been lightly tested with fstests.  Enjoy!
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

* tag 'reconstruct-defer-cleanups-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: move ->iop_relog to struct xfs_defer_op_type
  xfs: collapse the ->create_done functions
  xfs: hoist xfs_trans_add_item calls to defer ops functions
  xfs: clean out XFS_LI_DIRTY setting boilerplate from ->iop_relog
  xfs: use xfs_defer_create_done for the relogging operation
  xfs: hoist ->create_intent boilerplate to its callsite
  xfs: collapse the ->finish_item helpers
  xfs: hoist intent done flag setting to ->finish_item callsite
  xfs: don't set XFS_TRANS_HAS_INTENT_DONE when there's no ATTRD log item

Merge tag 'reconstruct-defer-work-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.8-mergeA

xfs: log intent item recovery should reconstruct defer work state

Long Li reported a KASAN report from a UAF when intent recovery fails:

 ==================================================================
 BUG: KASAN: slab-use-after-free in xfs_cui_release+0xb7/0xc0
 Read of size 4 at addr ffff888012575e60 by task kworker/u8:3/103
 CPU: 3 PID: 103 Comm: kworker/u8:3 Not tainted 6.4.0-rc7-next-20230619-00003-g94543a53f9a4-dirty #166
 Workqueue: xfs-cil/sda xlog_cil_push_work
 Call Trace:
  <TASK>
  dump_stack_lvl+0x50/0x70
  print_report+0xc2/0x600
  kasan_report+0xb6/0xe0
  xfs_cui_release+0xb7/0xc0
  xfs_cud_item_release+0x3c/0x90
  xfs_trans_committed_bulk+0x2d5/0x7f0
  xlog_cil_committed+0xaba/0xf20
  xlog_cil_push_work+0x1a60/0x2360
  process_one_work+0x78e/0x1140
  worker_thread+0x58b/0xf60
  kthread+0x2cd/0x3c0
  ret_from_fork+0x1f/0x30
  </TASK>

 Allocated by task 531:
  kasan_save_stack+0x22/0x40
  kasan_set_track+0x25/0x30
  __kasan_slab_alloc+0x55/0x60
  kmem_cache_alloc+0x195/0x5f0
  xfs_cui_init+0x198/0x1d0
  xlog_recover_cui_commit_pass2+0x133/0x5f0
  xlog_recover_items_pass2+0x107/0x230
  xlog_recover_commit_trans+0x3e7/0x9c0
  xlog_recovery_process_trans+0x140/0x1d0
  xlog_recover_process_ophdr+0x1a0/0x3d0
  xlog_recover_process_data+0x108/0x2d0
  xlog_recover_process+0x1f6/0x280
  xlog_do_recovery_pass+0x609/0xdb0
  xlog_do_log_recovery+0x84/0xe0
  xlog_do_recover+0x7d/0x470
  xlog_recover+0x25f/0x490
  xfs_log_mount+0x2dd/0x6f0
  xfs_mountfs+0x11ce/0x1e70
  xfs_fs_fill_super+0x10ec/0x1b20
  get_tree_bdev+0x3c8/0x730
  vfs_get_tree+0x89/0x2c0
  path_mount+0xecf/0x1800
  do_mount+0xf3/0x110
  __x64_sys_mount+0x154/0x1f0
  do_syscall_64+0x39/0x80
  entry_SYSCALL_64_after_hwframe+0x63/0xcd

 Freed by task 531:
  kasan_save_stack+0x22/0x40
  kasan_set_track+0x25/0x30
  kasan_save_free_info+0x2b/0x40
  __kasan_slab_free+0x114/0x1b0
  kmem_cache_free+0xf8/0x510
  xfs_cui_item_free+0x95/0xb0
  xfs_cui_release+0x86/0xc0
  xlog_recover_cancel_intents.isra.0+0xf8/0x210
  xlog_recover_finish+0x7e7/0x980
  xfs_log_mount_finish+0x2bb/0x4a0
  xfs_mountfs+0x14bf/0x1e70
  xfs_fs_fill_super+0x10ec/0x1b20
  get_tree_bdev+0x3c8/0x730
  vfs_get_tree+0x89/0x2c0
  path_mount+0xecf/0x1800
  do_mount+0xf3/0x110
  __x64_sys_mount+0x154/0x1f0
  do_syscall_64+0x39/0x80
  entry_SYSCALL_64_after_hwframe+0x63/0xcd

 The buggy address belongs to the object at ffff888012575dc8
  which belongs to the cache xfs_cui_item of size 432
 The buggy address is located 152 bytes inside of
  freed 432-byte region [ffff888012575dc8, ffff888012575f78)

 The buggy address belongs to the physical page:
 page:ffffea0000495d00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888012576208 pfn:0x12574
 head:ffffea0000495d00 order:2 entire_mapcount:0 nr_pages_mapped:0 pincount:0
 flags: 0x1fffff80010200(slab|head|node=0|zone=1|lastcpupid=0x1fffff)
 page_type: 0xffffffff()
 raw: 001fffff80010200 ffff888012092f40 ffff888014570150 ffff888014570150
 raw: ffff888012576208 00000000001e0010 00000001ffffffff 0000000000000000
 page dumped because: kasan: bad access detected

 Memory state around the buggy address:
  ffff888012575d00: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc
  ffff888012575d80: fc fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb
 >ffff888012575e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                        ^
  ffff888012575e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff888012575f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc
 ==================================================================

"If process intents fails, intent items left in AIL will be delete
from AIL and freed in error handling, even intent items that have been
recovered and created done items. After this, uaf will be triggered when
done item committed, because at this point the released intent item will
be accessed.

xlog_recover_finish                     xlog_cil_push_work
----------------------------            ---------------------------
xlog_recover_process_intents
  xfs_cui_item_recover//cui_refcount == 1
    xfs_trans_get_cud
    xfs_trans_commit
      <add cud item to cil>
  xfs_cui_item_recover
    <error occurred and return>
xlog_recover_cancel_intents
  xfs_cui_release     //cui_refcount == 0
    xfs_cui_item_free //free cui
  <release other intent items>
xlog_force_shutdown   //shutdown
                               <...>
                                        <push items in cil>
                                        xlog_cil_committed
                                          xfs_cud_item_release
                                            xfs_cui_release // UAF

"Intent log items are created with a reference count of 2, one for the
creator, and one for the intent done object. Log recovery explicitly
drops the creator reference after it is inserted into the AIL, but it
then processes the log item as if it also owns the intent-done reference.

"The code in ->iop_recovery should assume that it passes the reference
to the done intent, we can remove the intent item from the AIL after
creating the done-intent, but if that code fails before creating the
done-intent then it needs to release the intent reference by log recovery
itself.

"That way when we go to cancel the intent, the only intents we find in
the AIL are the ones we know have not been processed yet and hence we
can safely drop both the creator and the intent done reference from
xlog_recover_cancel_intents().

"Hence if we remove the intent from the list of intents that need to
be recovered after we have done the initial recovery, we acheive two
things:

"1. the tail of the log can be moved forward with the commit of the
done intent or new intent to continue the operation, and

"2. We avoid the problem of trying to determine how many reference
counts we need to drop from intent recovery cancelling because we
never come across intents we've actually attempted recovery on."

Restated: The cause of the UAF is that xlog_recover_cancel_intents
thinks that it owns the refcount on any intent item in the AIL, and that
it's always safe to release these intent items.  This is not true after
the recovery function creates an log intent done item and points it at
the log intent item because releasing the done item always releases the
intent item.

The runtime defer ops code avoids all this by tracking both the log
intent and the intent done items, and releasing only the intent done
item if both have been created.  Long Li proposed fixing this by adding
state flags, but I have a more comprehensive fix.

First, observe that the latter half of the intent _recover functions are
nearly open-coded versions of the corresponding _finish_one function
that uses an onstack deferred work item to single-step through the item.

Second, notice that the recover function is not an exact match because
of the odd behavior that unfinished recovered work items are relogged
with separate log intent items instead of a single new log intent item,
which is what the defer ops machinery does.

Dave and I have long suspected that recovery should be reconstructing
the defer work state from what's in the recovered intent item.  Now we
finally have an excuse to refactor the code to do that.

This series starts by fixing a resource leak in LARP recovery.  We fix
the bug that Long Li reported by switching the intent recovery code to
construct chains of xfs_defer_pending objects and then using the defer
pending objects to track the intent/done item ownership.  Finally, we
clean up the code to reconstruct the exact incore state, which means we
can remove all the opencoded _recover code, which makes maintaining log
items much easier.

v2: minor changes per review comments
v3: pick up more rvb tags, fix build errors

This has been lightly tested with fstests.  Enjoy!
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

* tag 'reconstruct-defer-work-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: move ->iop_recover to xfs_defer_op_type
  xfs: use xfs_defer_finish_one to finish recovered work items
  xfs: dump the recovered xattri log item if corruption happens
  xfs: recreate work items when recovering intent items
  xfs: transfer recovered intent item ownership in ->iop_recover
  xfs: pass the xfs_defer_pending object to iop_recover
  xfs: use xfs_defer_pending objects to recover intent items
  xfs: don't leak recovered attri intent items

Introduce the concept of a defer ops barrier to separate consecutively
queued pending work items of the same type.  With a barrier in place,
the two work items will be tracked separately, and receive separate log
intent items.  The goal here is to prevent reaping of old metadata
blocks from creating unnecessarily huge EFIs that could then run the
risk of overflowing the scrub transaction.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

We need to log EFIs for every extent that we allocate for the purpose of
staging a new btree so that if we fail then the blocks will be freed
during log recovery.  Use the autoreaping mechanism provided by the
previous patch to attach paused freeing work to the scrub transaction.
We can then mark the EFIs stale if we decide to commit the new btree, or
we can unpause the EFIs if we decide to abort the repair.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Create a new xrep_newbt structure to encapsulate a fake root for
creating a staged btree cursor as well as to track all the blocks that
we need to reserve in order to build that btree.

As for the particular choice of lowspace thresholds and btree block
slack factors -- at this point one could say that the thresholds in
online repair come from bulkload_estimate_ag_slack in xfs_repair[1].
But that's not the entire story, since the offline btree rebuilding
code in xfs_repair was merged as a retroport of the online btree code
in this patchset!

Before xfs_btree_staging.[ch] came along, xfs_repair determined the
slack factor (aka the number of slots to leave unfilled in each new
btree block) via open-coded logic in repair/phase5.c[2].  At that point
the slack factors were arbitrary quantities per btree.  The rmapbt
automatically left 10 slots free; everything else left zero.

That had a noticeable effect on performance straight after mounting
because adding records to /any/ btree would result in splits.  A few
years ago when this patch was first written, Dave and I decided that
repair should generate btree blocks that were 75% full unless space was
tight, in which case it should try to fill the blocks to nearly full.
We defined tight as ~10% free to avoid repair failures but settled on
3/32 (~9%) to avoid div64.

IOWs, we mostly pulled the thresholds out of thin air.  We've been
QAing with those geometry numbers ever since. ;)

Link: https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git/tree/repair/bulkload.c?h=v6.5.0#n114
Link: https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git/tree/repair/phase5.c?h=v4.19.0#n1349Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Remove these unused fields since nobody uses them.  They should have
been removed years ago in a different cleanup series from Christoph
Hellwig.

Fixes: daf83964 ("xfs: move the per-fork nextents fields into struct xfs_ifork")
Fixes: f7e67b20 ("xfs: move the fork format fields into struct xfs_ifork")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

As mentioned in the previous commit, online repair wants to allocate
space to write out a new metadata structure, and it also wants to hedge
against system crashes during repairs by logging (and later cancelling)
EFIs to free the space if we crash before committing the new data
structure.

Therefore, create a trio of functions to schedule automatic reaping of
freshly allocated unwritten space.  xfs_alloc_schedule_autoreap creates
a paused EFI representing the space we just allocated.  Once the
allocations are made and the autoreaps scheduled, we can start writing
to disk.

If the writes succeed, xfs_alloc_cancel_autoreap marks the EFI work
items as stale and unpauses the pending deferred work item.  Assuming
that's done in the same transaction that commits the new structure into
the filesystem, we guarantee that either the new object is fully
visible, or that all the space gets reclaimed.

If the writes succeed but only part of an extent was used, repair must
call the same _cancel_autoreap function to kill the first EFI and then
log a new EFI to free the unused space.  The first EFI is already
committed, so it cannot be changed.

For full extents that aren't used, xfs_alloc_commit_autoreap will
unpause the EFI, which results in the space being freed during the next
_defer_finish cycle.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

xfs_free_extent_later is a trivial helper, so remove it to reduce the
amount of thinking required to understand the deferred freeing
interface.  This will make it easier to introduce automatic reaping of
speculative allocations in the next patch.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Traditionally, all pending deferred work attached to a transaction is
finished when one of the xfs_defer_finish* functions is called.
However, online repair wants to be able to allocate space for a new data
structure, format a new metadata structure into the allocated space, and
commit that into the filesystem.

As a hedge against system crashes during repairs, we also want to log
some EFI items for the allocated space speculatively, and cancel them if
we elect to commit the new data structure.

Therefore, introduce the idea of pausing a pending deferred work item.
Log intent items are still created for paused items and relogged as
necessary.  However, paused items are pushed onto a side list before we
start calling ->finish_item, and the whole list is reattach to the
transaction afterwards.  New work items are never attached to paused
pending items.

Modify xfs_defer_cancel to clean up pending deferred work items holding
a log intent item but not a log intent done item, since that is now
possible.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

When someone tries to add a deferred work item to xfs_defer_add, it will
try to attach the work item to the most recently added xfs_defer_pending
object attached to the transaction.  However, it doesn't check if the
pending object has a log intent item attached to it.  This is incorrect
behavior because we cannot add more work to an object that has already
been committed to the ondisk log.

Therefore, change the behavior not to append to pending items with a non
null dfp_intent.  In practice this has not been an issue because the
only way xfs_defer_add gets called after log intent items have been
committed is from the defer ops ->finish_item functions themselves, and
the @dop_pending isolation in xfs_defer_finish_noroll protects the
pending items that have already been logged.

However, the next patch will add the ability to pause a deferred extent
free object during online btree rebuilding, and any new extfree work
items need to have their own pending event.

While we're at it, hoist the predicate to its own static inline function
for readability.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

When scrub is trying to iget an inode, ensure that it won't end up
deadlocked on a cycle in the inode btree by using an empty transaction
to store all the buffers.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Extended attribute updates use the deferred work machinery to manage
state across a chain of smaller transactions.  All previous deferred
work users have employed log intent items and log done items to manage
restarting of interrupted operations, which means that ->create_intent
sets dfp_intent to a log intent item and ->create_done uses that item to
create a log intent done item.

However, xattrs have used the INCOMPLETE flag to deal with the lack of
recovery support for an interrupted transaction chain.  Log items are
optional if the xattr update caller didn't set XFS_DA_OP_LOGGED to
require a restartable sequence.

In other words, ->create_intent can return NULL to say that there's no
log intent item.  If that's the case, no log intent done item should be
created.  Clean up xfs_defer_create_done not to do this, so that the
->create_done functions don't have to check for non-null dfp_intent
themselves.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Don't allow realtime volumes that are less than one rt extent long.
This has been broken across 4 LTS kernels with nobody noticing, so let's
just disable it.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

The only log items that need relogging are the ones created for deferred
work operations, and the only part of the code base that relogs log
items is the deferred work machinery.  Move the function pointers.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Christoph requested a blurb somewhere explaining exactly what LARP
means.  I don't know of a good place other than the source code (debug
knobs aren't covered in Documentation/), so here it is.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

It's quite reasonable that some customer somewhere will want to
configure a realtime volume with more than 2^32 extents.  If they try to
do this, the highbit32() call will truncate the upper bits of the
xfs_rtbxlen_t and produce the wrong value for rextslog.  This in turn
causes the rsumlevels to be wrong, which results in a realtime summary
file that is the wrong length.  Fix that.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

There's a weird discrepancy in xfsprogs dating back to the creation of
the Linux port -- if there are zero rt extents, mkfs will set
sb_rextents and sb_rextslog both to zero:

	sbp->sb_rextslog =
		(uint8_t)(rtextents ?
			libxfs_highbit32((unsigned int)rtextents) : 0);

However, that's not the check that xfs_repair uses for nonzero rtblocks:

	if (sb->sb_rextslog !=
			libxfs_highbit32((unsigned int)sb->sb_rextents))

The difference here is that xfs_highbit32 returns -1 if its argument is
zero.  Unfortunately, this means that in the weird corner case of a
realtime volume shorter than 1 rt extent, xfs_repair will immediately
flag a freshly formatted filesystem as corrupt.  Because mkfs has been
writing ondisk artifacts like this for decades, we have to accept that
as "correct".  TBH, zero rextslog for zero rtextents makes more sense to
me anyway.

Regrettably, the superblock verifier checks created in commit copied
xfs_repair even though mkfs has been writing out such filesystems for
ages.  Fix the superblock verifier to accept what mkfs spits out; the
userspace version of this patch will have to fix xfs_repair as well.

Note that the new helper leaves the zeroday bug where the upper 32 bits
of sb_rextents is ripped off and fed to highbit32.  This leads to a
seriously undersized rt summary file, which immediately breaks mkfs:

$ hugedisk.sh foo /dev/sdc $(( 0x100000080 * 4096))B
$ /sbin/mkfs.xfs -f /dev/sda -m rmapbt=0,reflink=0 -r rtdev=/dev/mapper/foo
meta-data=/dev/sda               isize=512    agcount=4, agsize=1298176 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=1, sparse=1, rmapbt=0
         =                       reflink=0    bigtime=1 inobtcount=1 nrext64=1
data     =                       bsize=4096   blocks=5192704, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0, ftype=1
log      =internal log           bsize=4096   blocks=16384, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =/dev/mapper/foo        extsz=4096   blocks=4294967424, rtextents=4294967424
Discarding blocks...Done.
mkfs.xfs: Error initializing the realtime space [117 - Structure needs cleaning]

The next patch will drop support for rt volumes with fewer than 1 or
more than 2^32-1 rt extents, since they've clearly been broken forever.

Fixes: f8e566c0 ("xfs: validate the realtime geometry in xfs_validate_sb_common")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Move the meat of the ->create_done function helpers into ->create_done
to reduce the amount of boilerplate.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Remove even more repeated boilerplate.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Hoist this dirty flag setting to the ->iop_relog callsite to reduce
boilerplate.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Now that we have a helper to handle creating a log intent done item and
updating all the necessary state flags, use it to reduce boilerplate in
the ->iop_relog implementations.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>