It is possible for i_disksize can exceed i_size, triggering a warning.

generic_perform_write
 copied = iov_iter_copy_from_user_atomic(len) // copied < len
 ext4_da_write_end
 | ext4_update_i_disksize
 |  new_i_size = pos + copied;
 |  WRITE_ONCE(EXT4_I(inode)->i_disksize, newsize) // update i_disksize
 | generic_write_end
 |  copied = block_write_end(copied, len) // copied = 0
 |   if (unlikely(copied < len))
 |    if (!PageUptodate(page))
 |     copied = 0;
 |  if (pos + copied > inode->i_size) // return false
 if (unlikely(copied == 0))
  goto again;
 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
  status = -EFAULT;
  break;
 }

We get i_disksize greater than i_size here, which could trigger WARNING
check 'i_size_read(inode) < EXT4_I(inode)->i_disksize' while doing dio:

ext4_dio_write_iter
 iomap_dio_rw
  __iomap_dio_rw // return err, length is not aligned to 512
 ext4_handle_inode_extension
  WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize) // Oops

 WARNING: CPU: 2 PID: 2609 at fs/ext4/file.c:319
 CPU: 2 PID: 2609 Comm: aa Not tainted 6.3.0-rc2
 RIP: 0010:ext4_file_write_iter+0xbc7
 Call Trace:
  vfs_write+0x3b1
  ksys_write+0x77
  do_syscall_64+0x39

Fix it by updating 'copied' value before updating i_disksize just like
ext4_write_inline_data_end() does.

A reproducer can be found in the buganizer link below.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=217209
Fixes: 64769240 ("ext4: Add delayed allocation support in data=writeback mode")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230321013721.89818-1-chengzhihao1@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Create a uapi header include/uapi/linux/ext4.h, move the ioctls and
associated data structures to the uapi header, and include it from
fs/ext4/ext4.h.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Link: https://lore.kernel.org/r/680175260970d977d16b5cc7e7606483ec99eb63.1680402881.git.josh@joshtriplett.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

It's ok because the code will be optimized by the compiler, just
try to simple the code.
Signed-off-by: wuchi <wuchi.zero@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230401075303.45206-1-wuchi.zero@gmail.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

cppcheck reports
fs/ext4/page-io.c:516:51: style:
  Condition 'nr_to_submit' is always true [knownConditionTrueFalse]
 if (fscrypt_inode_uses_fs_layer_crypto(inode) && nr_to_submit) {
                                                  ^
This earlier check to bail, makes this check unncessary
	/* Nothing to submit? Just unlock the page... */
	if (!nr_to_submit)
		return 0;
Signed-off-by: Tom Rix <trix@redhat.com>
Fixes: dff4ac75 ("ext4: move keep_towrite handling to ext4_bio_write_page()")
Reviewed-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20230316204831.2472537-1-trix@redhat.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

These checkings are also related with feature compatibility checkings.
So move them into ext4_check_feature_compatibility(). No functional
change.
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20230323140517.1070239-9-yanaijie@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Factor out ext4_block_group_meta_init(). No functional change.
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20230323140517.1070239-8-yanaijie@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

These two checkings are more suitable to be put into
ext4_check_geometry() rather than spreading outside.
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20230323140517.1070239-7-yanaijie@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

The naming styles are different for some functions with 'check' in their
names. Some of them are like:

ext4_check_quota_consistency
ext4_check_test_dummy_encryption
ext4_check_opt_consistency
ext4_check_descriptors
ext4_check_feature_compatibility

While the others looks like below:

ext4_geometry_check
ext4_journal_data_mode_check

This is not a big deal and boils down to personal preference. But I'd
like to make them consistent.
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20230323140517.1070239-6-yanaijie@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Factor out ext4_flex_groups_free() and it can be used both in
__ext4_fill_super() and ext4_put_super().
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20230323140517.1070239-5-yanaijie@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

The only difference here is that ->s_group_desc and ->s_flex_groups share
the same rcu read lock here but it is not necessary. In other places they
do not share the lock at all.
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20230323140517.1070239-4-yanaijie@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Factor out ext4_percpu_param_init() and ext4_percpu_param_destroy(). And
also use ext4_percpu_param_destroy() in ext4_put_super() to avoid
duplicated code. No functional change.
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20230323140517.1070239-3-yanaijie@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Factor out ext4_hash_info_init() to simplify __ext4_fill_super(). No
functional change.
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20230323140517.1070239-2-yanaijie@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

After making ext4_writepages() properly clean all pages there is no need
for special treatment of filesystem freezing. Revert commit
e6c28a26.
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-13-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Since filemap_write_and_wait() is now enough to get journalled data to
final location update the comment in mpage_prepare_extent_to_map().
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-12-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Now that ext4_writepages() gets journalled data into its final location
we just use filemap_write_and_wait() instead of special handling of
journalled data in ext4_bmap(). We can also drop EXT4_STATE_JDATA flag
as it is not used anymore.
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-11-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Now that ext4_writepages() makes sure all journalled data is committed
and checkpointed, sync_filesystem() call done by dquot_quota_on() is
enough for quota IO to see uptodate data. So drop special handling of
journalled data from ext4_quota_on().
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-10-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Now that ext4_writepages() makes sure journalled data is on stable
storage, write_inode_now() call in iput_final() is enough to make
pagecache pages with journalled data really clean (data committed and
checkpointed). So we can drop special handling of journalled data in
ext4_evict_inode().
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-9-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

The handling of journalled data in ext4_zero_range() is incomplete. We
do not need to commit running transaction but we rather need to
checkpoint pages with journalled data. If we don't, journal tail can be
advanced beyond transaction containing the journalled data and if we
then crash before committing the transaction doing the zeroing we will
have inconsistent (too old) data in the file. Make sure file pages with
journalled data are properly checkpointed before removing them from the
page cache.
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-8-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Now that filemap_write_and_wait() makes sure pages with journalled data
are safely on disk, ext4_collapse_range() and ext4_insert_range() do
not need special handling of journalled data.
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-7-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Now that ext4_writepages() make sure all pages with journalled data are
stable on disk, we don't need special handling of journalled data in
ext4_sync_file().
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-6-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

When journalling data we currently just walk over pages, journal those
that are marked for delayed dirtying (only pinned pages dirtied behing
our back these days) and checkpoint other dirty pages. Because some
pages may be part of running transaction the result is that after
filemap_write_and_wait() we are not guaranteed pages are stable on disk.
Thus places that want to flush current pagecache content need to jump
through hoops to make sure journalled data is not lost. This is
manageable in cases completely controlled by ext4 (such as extent
shifting operations or inode eviction) but it gets ugly for stuff like
fsverity. Furthermore it is rather error prone as people often do not
realize journalled data needs special handling.

So change ext4_writepages() to commit transaction with inode's data
before going through the writeback loop in WB_SYNC_ALL mode. As a result
filemap_write_and_wait() is now really getting pages to stable storage
and makes pagecache pages safe to reclaim. Consequently we can remove
the special handling of journalled data from several places in follow up
patches.

Note that this will make fsync(2) for journalled data more expensive as
we will end up not only committing the transaction we need but also
checkpointing the data (which we may have previously skipped if the data
was part of the running transaction). If we really cared, we would need
to introduce special VFS function for writing out & invalidating page
cache for a range, use ->launder_page callback to perform checkpointing,
and use it from all the places that need this functionality. But at this
point I'm not convinced the complexity is worth it.
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-5-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

With journalled data it can happen that checkpointing code will write
out page contents without clearing the page dirty bit. The logic in
ext4_page_nomap_can_writeout() then results in us never calling
mpage_submit_page() and thus clearing the dirty bit. Drop the
optimization with ext4_page_nomap_can_writeout() and just always call to
mpage_submit_page(). ext4_bio_write_page() knows when to redirty the
page and the additional clearing & setting of page dirty bit for ordered
mode writeout is not that expensive to jump through the hoops for it.
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-4-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Currently we clear page dirty bit when we checkpoint some buffers from a
page with journalled data or when we perform delayed dirtying of a page
in ext4_writepages(). In a quest to simplify handling of journalled data
we want to keep page dirty as long as it has either buffers to
checkpoint or journalled dirty data. So make sure to keep page dirty in
ext4_writepages() if it still has journalled data attached to it.
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-3-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Currently pages with journalled data written by write(2) or modified by
block zeroing during truncate(2) are not marked as dirty. They are
dirtied only once the transaction commits. This however makes writeback
code think inode has no pages to write and so ext4_writepages() is not
called to make pages with journalled data persistent. Mark pages with
journalled data dirty (similarly as it happens for writes through mmap)
so that writeback code knows about them and ext4_writepages() can do
what it needs to to the inode.
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-2-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

When invalidating buffers under the partial tail page,
jbd2_journal_invalidate_folio() returns -EBUSY if the buffer is part of
the committing transaction as we cannot safely modify buffer state.
However if the buffer is already invalidated (due to previous
invalidation attempts from ext4_wait_for_tail_page_commit()), there's
nothing to do and there's no point in returning -EBUSY. This fixes
occasional warnings from ext4_journalled_invalidate_folio() triggered by
generic/051 fstest when blocksize < pagesize.

Fixes: 53e87268 ("ext4: fix deadlock in journal_unmap_buffer()")
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230329154950.19720-1-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

This is an implementation of fsverity_operations read_merkle_tree_page,
so it must still return the precise page asked for, but we can use the
folio API to reduce the number of conversions between folios & pages.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-30-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Use the folio API and support folios of arbitrary sizes.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-29-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Use a folio throughout.  Does not support large folios due to
an array sized for MAX_BUF_PER_PAGE, but it does remove a few
calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-28-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Iterate once per folio, not once per page.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-27-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Convert to the folio API, saving a few calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-26-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

All the callers now have a folio, so pass that in and operate on folios.
Removes four calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230324180129.1220691-25-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

This definitely doesn't include support for large folios; there
are all kinds of assumptions about the number of buffers attached
to a folio.  But it does remove several calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-24-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Remove a few calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-23-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Its one caller already uses a folio.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20230324180129.1220691-22-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Use folio APIs throughout.  Saves many calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230324180129.1220691-21-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Remove a call to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-20-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Convert the incoming page to a folio to remove a few calls to
compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20230324180129.1220691-19-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Convert the incoming struct page to a folio.  Replaces two implicit
calls to compound_head() with one explicit call.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20230324180129.1220691-18-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Remove a lot of calls to compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20230324180129.1220691-17-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Convert the incoming page to a folio so that we call compound_head()
only once instead of seven times.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20230324180129.1220691-16-willy@infradead.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>