this comment of ext4_map_blocks()/ext4_ext_map_blocks() need
update after commit c21770573319("ext4: Define a new set of
flags for ext4_get_blocks()").

Signed-off-by: Cheng Nie <niecheng1@uniontech.com>
Link: https://lore.kernel.org/r/20240118062511.28276-1-niecheng1@uniontech.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Since ext4_map_blocks() can recognize a delayed allocated only extent,
make ext4_set_iomap() can also recognize it, and remove the useless
separate check in ext4_iomap_begin_report().

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240127015825.1608160-7-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Add a new map flag EXT4_MAP_DELAYED to indicate the mapping range is a
delayed allocated only (not unwritten) one, and making
ext4_map_blocks() can distinguish it, no longer mixing it with holes.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240127015825.1608160-6-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

In order to cache hole extents in the extent status tree and keep the
hole length as long as possible, re-add a hole entry to the cache just
after punching a hole.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240127015825.1608160-5-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

ext4_da_map_blocks() only hold i_data_sem in shared mode and i_rwsem
when inserting delalloc extents, it could be raced by another querying
path of ext4_map_blocks() without i_rwsem, .e.g buffered read path.
Suppose we buffered read a file containing just a hole, and without any
cached extents tree, then it is raced by another delayed buffered write
to the same area or the near area belongs to the same hole, and the new
delalloc extent could be overwritten to a hole extent.

 pread()                           pwrite()
  filemap_read_folio()
   ext4_mpage_readpages()
    ext4_map_blocks()
     down_read(i_data_sem)
     ext4_ext_determine_hole()
     //find hole
     ext4_ext_put_gap_in_cache()
      ext4_es_find_extent_range()
      //no delalloc extent
                                    ext4_da_map_blocks()
                                     down_read(i_data_sem)
                                     ext4_insert_delayed_block()
                                     //insert delalloc extent
      ext4_es_insert_extent()
      //overwrite delalloc extent to hole

This race could lead to inconsistent delalloc extents tree and
incorrect reserved space counter. Fix this by converting to hold
i_data_sem in exclusive mode when adding a new delalloc extent in
ext4_da_map_blocks().

Cc: stable@vger.kernel.org
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240127015825.1608160-3-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Refactor and cleanup ext4_da_map_blocks(), reduce some unnecessary
parameters and branches, no logic changes.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240127015825.1608160-2-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

The "needed" controls the number of ext4_prealloc_space to discard in
ext4_discard_preallocations. Function ext4_discard_preallocations is
supposed to discard all non-used preallocated blocks when "needed"
is 0 and now ext4_discard_preallocations is always called with "needed"
= 0. Remove unnecessary parameter "needed" and remove all non-used
preallocated spaces in ext4_discard_preallocations to simplify the
code.

Note: If count of non-used preallocated spaces could be more than
UINT_MAX, there was a memory leak as some non-used preallocated
spaces are left ununsed and this commit will fix it. Otherwise,
there is no behavior change.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240105092102.496631-9-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Pull ext4 updates from Ted Ts'o:
 "Various ext4 bug fixes and cleanups. The fixes are mostly in the
  fstrim and mballoc code paths.

  Also enable dioread_nolock in the case where the block size is less
  than the page size (dioread_nolock has been default in the bs == ps
  case for quite some time)"

* tag 'ext4_for_linus-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix inconsistent between segment fstrim and full fstrim
  ext4: fallback to complex scan if aligned scan doesn't work
  ext4: convert ext4_da_do_write_end() to take a folio
  ext4: allow for the last group to be marked as trimmed
  ext4: move ext4_check_bdev_write_error() into nojournal mode
  jbd2: abort journal when detecting metadata writeback error of fs dev
  jbd2: remove unused 'JBD2_CHECKPOINT_IO_ERROR' and 'j_atomic_flags'
  jbd2: replace journal state flag by checking errseq
  jbd2: add errseq to detect client fs's bdev writeback error
  ext4: improving calculation of 'fe_{len|start}' in mb_find_extent()
  ext4: clarify handling of unwritten bh in __ext4_block_zero_page_range()
  ext4: treat end of range as exclusive in ext4_zero_range()
  ext4: enable dioread_nolock as default for bs < ps case
  ext4: delete redundant calculations in ext4_mb_get_buddy_page_lock()
  ext4: reduce unnecessary memory allocation in alloc_flex_gd()
  ext4: avoid online resizing failures due to oversized flex bg
  ext4: remove unnecessary check from alloc_flex_gd()
  ext4: unify the type of flexbg_size to unsigned int

There's nothing page-specific happening in ext4_da_do_write_end();
it's merely used for its refcount & lock, both of which are folio
properties.  Saves four calls to compound_head().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20231214053035.1018876-1-willy@infradead.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Pull MM updates from Andrew Morton:
 "Many singleton patches against the MM code. The patch series which are
  included in this merge do the following:

   - Peng Zhang has done some mapletree maintainance work in the series

	'maple_tree: add mt_free_one() and mt_attr() helpers'
	'Some cleanups of maple tree'

   - In the series 'mm: use memmap_on_memory semantics for dax/kmem'
     Vishal Verma has altered the interworking between memory-hotplug
     and dax/kmem so that newly added 'device memory' can more easily
     have its memmap placed within that newly added memory.

   - Matthew Wilcox continues folio-related work (including a few fixes)
     in the patch series

	'Add folio_zero_tail() and folio_fill_tail()'
	'Make folio_start_writeback return void'
	'Fix fault handler's handling of poisoned tail pages'
	'Convert aops->error_remove_page to ->error_remove_folio'
	'Finish two folio conversions'
	'More swap folio conversions'

   - Kefeng Wang has also contributed folio-related work in the series

	'mm: cleanup and use more folio in page fault'

   - Jim Cromie has improved the kmemleak reporting output in the series
     'tweak kmemleak report format'.

   - In the series 'stackdepot: allow evicting stack traces' Andrey
     Konovalov to permits clients (in this case KASAN) to cause eviction
     of no longer needed stack traces.

   - Charan Teja Kalla has fixed some accounting issues in the page
     allocator's atomic reserve calculations in the series 'mm:
     page_alloc: fixes for high atomic reserve caluculations'.

   - Dmitry Rokosov has added to the samples/ dorectory some sample code
     for a userspace memcg event listener application. See the series
     'samples: introduce cgroup events listeners'.

   - Some mapletree maintanance work from Liam Howlett in the series
     'maple_tree: iterator state changes'.

   - Nhat Pham has improved zswap's approach to writeback in the series
     'workload-specific and memory pressure-driven zswap writeback'.

   - DAMON/DAMOS feature and maintenance work from SeongJae Park in the
     series

	'mm/damon: let users feed and tame/auto-tune DAMOS'
	'selftests/damon: add Python-written DAMON functionality tests'
	'mm/damon: misc updates for 6.8'

   - Yosry Ahmed has improved memcg's stats flushing in the series 'mm:
     memcg: subtree stats flushing and thresholds'.

   - In the series 'Multi-size THP for anonymous memory' Ryan Roberts
     has added a runtime opt-in feature to transparent hugepages which
     improves performance by allocating larger chunks of memory during
     anonymous page faults.

   - Matthew Wilcox has also contributed some cleanup and maintenance
     work against eh buffer_head code int he series 'More buffer_head
     cleanups'.

   - Suren Baghdasaryan has done work on Andrea Arcangeli's series
     'userfaultfd move option'. UFFDIO_MOVE permits userspace heap
     compaction algorithms to move userspace's pages around rather than
     UFFDIO_COPY'a alloc/copy/free.

   - Stefan Roesch has developed a 'KSM Advisor', in the series 'mm/ksm:
     Add ksm advisor'. This is a governor which tunes KSM's scanning
     aggressiveness in response to userspace's current needs.

   - Chengming Zhou has optimized zswap's temporary working memory use
     in the series 'mm/zswap: dstmem reuse optimizations and cleanups'.

   - Matthew Wilcox has performed some maintenance work on the writeback
     code, both code and within filesystems. The series is 'Clean up the
     writeback paths'.

   - Andrey Konovalov has optimized KASAN's handling of alloc and free
     stack traces for secondary-level allocators, in the series 'kasan:
     save mempool stack traces'.

   - Andrey also performed some KASAN maintenance work in the series
     'kasan: assorted clean-ups'.

   - David Hildenbrand has gone to town on the rmap code. Cleanups, more
     pte batching, folio conversions and more. See the series 'mm/rmap:
     interface overhaul'.

   - Kinsey Ho has contributed some maintenance work on the MGLRU code
     in the series 'mm/mglru: Kconfig cleanup'.

   - Matthew Wilcox has contributed lruvec page accounting code cleanups
     in the series 'Remove some lruvec page accounting functions'"

* tag 'mm-stable-2024-01-08-15-31' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (361 commits)
  mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER
  mm, treewide: introduce NR_PAGE_ORDERS
  selftests/mm: add separate UFFDIO_MOVE test for PMD splitting
  selftests/mm: skip test if application doesn't has root privileges
  selftests/mm: conform test to TAP format output
  selftests: mm: hugepage-mmap: conform to TAP format output
  selftests/mm: gup_test: conform test to TAP format output
  mm/selftests: hugepage-mremap: conform test to TAP format output
  mm/vmstat: move pgdemote_* out of CONFIG_NUMA_BALANCING
  mm: zsmalloc: return -ENOSPC rather than -EINVAL in zs_malloc while size is too large
  mm/memcontrol: remove __mod_lruvec_page_state()
  mm/khugepaged: use a folio more in collapse_file()
  slub: use a folio in __kmalloc_large_node
  slub: use folio APIs in free_large_kmalloc()
  slub: use alloc_pages_node() in alloc_slab_page()
  mm: remove inc/dec lruvec page state functions
  mm: ratelimit stat flush from workingset shrinker
  kasan: stop leaking stack trace handles
  mm/mglru: remove CONFIG_TRANSPARENT_HUGEPAGE
  mm/mglru: add dummy pmd_dirty()
  ...