btrfs: stop setting PageError in the data I/O path

PageError is not used by the VFS/MM and deprecated because it uses up a
page bit and has no coherent rules. Instead read errors are usually
propag

btrfs: stop setting PageError in the data I/O path

PageError is not used by the VFS/MM and deprecated because it uses up a
page bit and has no coherent rules. Instead read errors are usually
propagated by not setting or clearing the uptodate bit, and write errors
are propagated through the address_space. Btrfs now only sets the flag
and never clears it for data pages, so just remove all places setting it,
and the subpage error bit.

Note that the error propagation for superblock writes that work on the
block device mapping still uses PageError for now, but that will be
addressed in a separate series.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: subpage: dump extra subpage bitmaps for debug

There is a bug report that assert_eb_page_uptodate() gets triggered for
free space tree metadata.

Without proper dump for the subpage bitmaps it

btrfs: subpage: dump extra subpage bitmaps for debug

There is a bug report that assert_eb_page_uptodate() gets triggered for
free space tree metadata.

Without proper dump for the subpage bitmaps it's much harder to debug.

Thus this patch would dump all the subpage bitmaps (split them into
their own bitmaps) for a easier debugging.

The output would look like this:
(Dumped after a tree block got read from disk)

page:000000006e34bf49 refcount:4 mapcount:0 mapping:0000000067661ac4 index:0x1d1 pfn:0x110e9
memcg:ffff0000d7d62000
aops:btree_aops [btrfs] ino:1
flags: 0x8000000000002002(referenced|private|zone=2)
page_type: 0xffffffff()
raw: 8000000000002002 0000000000000000 dead000000000122 ffff00000188bed0
raw: 00000000000001d1 ffff0000c7992700 00000004ffffffff ffff0000d7d62000
page dumped because: btrfs subpage dump
BTRFS warning (device dm-1): start=30490624 len=16384 page=30474240 bitmaps: uptodate=4-7 error= dirty= writeback= ordered= checked=

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: export bitmap_test_range_all_{set,zero}

bitmap_test_range_all_{set,zero} defined in subpage.c are useful for other
components. Move them to misc.h and use them in zoned.c. Also, as
find_next{

btrfs: export bitmap_test_range_all_{set,zero}

bitmap_test_range_all_{set,zero} defined in subpage.c are useful for other
components. Move them to misc.h and use them in zoned.c. Also, as
find_next{,_zero}_bit take/return "unsigned long" instead of "unsigned
int", convert the type to "unsigned long".

While at it, also rewrite the "if (...) return true; else return false;"
pattern and add const to the input bitmap.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: move the printk helpers out of ctree.h

We have a bunch of printk helpers that are in ctree.h. These have
nothing to do with ctree.c, so move them into their own header.
Subsequent patches wi

btrfs: move the printk helpers out of ctree.h

We have a bunch of printk helpers that are in ctree.h. These have
nothing to do with ctree.c, so move them into their own header.
Subsequent patches will cleanup the printk helpers.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: convert process_page_range() to use filemap_get_folios_contig()

Converted function to use folios throughout. This is in preparation for
the removal of find_get_pages_contig(). Now also supp

btrfs: convert process_page_range() to use filemap_get_folios_contig()

Converted function to use folios throughout. This is in preparation for
the removal of find_get_pages_contig(). Now also supports large folios.

Since we may receive more than nr_pages pages, nr_pages may underflow.
Since nr_pages > 0 is equivalent to index <= end_index, we replaced it
with this check instead.

Also minor comment renaming for consistency in subpage.

Link: https://lkml.kernel.org/r/20220824004023.77310-5-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: David Sterba <dsterb@suse.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

show more ...

btrfs: remove extent writepage address space operation

Same as in commit 21b4ee7029c9 ("xfs: drop ->writepage completely"): we
can remove the callback as it's only used in one place - single page
wr

btrfs: remove extent writepage address space operation

Same as in commit 21b4ee7029c9 ("xfs: drop ->writepage completely"): we
can remove the callback as it's only used in one place - single page
writeback from memory reclaim and is not called for cgroup writeback at
all.

We only allow such writeback from kswapd, not from direct memory
reclaim, and so it is rarely used. When it comes from kswapd, it is
effectively random dirty page shoot-down, which is horrible for IO
patterns. We can rely on background writeback to clean all dirty pages
in an efficient way and not let it be interrupted by kswapd.

Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: fix typos in comments

Codespell has found a few typos.

Signed-off-by: David Sterba <dsterba@suse.com>

btrfs: remove unnecessary type casts

Explicit type casts are not necessary when it's void* to another pointer
type.

Signed-off-by: Yu Zhe <yuzhe@nfschina.com>
Reviewed-by: David Sterba <dsterba@sus

btrfs: remove unnecessary type casts

Explicit type casts are not necessary when it's void* to another pointer
type.

Signed-off-by: Yu Zhe <yuzhe@nfschina.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: make nodesize >= PAGE_SIZE case to reuse the non-subpage routine

The reason why we only support 64K page size for subpage is, for 64K
page size we can ensure no matter what the nodesize is, w

btrfs: make nodesize >= PAGE_SIZE case to reuse the non-subpage routine

The reason why we only support 64K page size for subpage is, for 64K
page size we can ensure no matter what the nodesize is, we can fit it
into one page.

When other page size come, especially like 16K, the limitation is a bit
limiting.

To remove such limitation, we allow nodesize >= PAGE_SIZE case to go the
non-subpage routine. By this, we can allow 4K sectorsize on 16K page
size.

Although this introduces another smaller limitation, the metadata can
not cross page boundary, which is already met by most recent mkfs.

Another small improvement is, we can avoid the overhead for metadata if
nodesize >= PAGE_SIZE.
For 4K sector size and 64K page size/node size, or 4K sector size and
16K page size/node size, we don't need to allocate extra memory for the
metadata pages.

Please note that, this patch will not yet enable other page size support
yet.

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

show more ...

btrfs: subpage: fix a wrong check on subpage->writers

[BUG]
When looping btrfs/074 with 64K page size and 4K sectorsize, there is a
low chance (1/50~1/100) to crash with the following ASSERT() trigg

btrfs: subpage: fix a wrong check on subpage->writers

[BUG]
When looping btrfs/074 with 64K page size and 4K sectorsize, there is a
low chance (1/50~1/100) to crash with the following ASSERT() triggered
in btrfs_subpage_start_writer():

ret = atomic_add_return(nbits, &subpage->writers);
ASSERT(ret == nbits); <<< This one <<<

[CAUSE]
With more debugging output on the parameters of
btrfs_subpage_start_writer(), it shows a very concerning error:

ret=29 nbits=13 start=393216 len=53248

For @nbits it's correct, but @ret which is the returned value from
atomic_add_return(), it's not only larger than nbits, but also larger
than max sectors per page value (for 64K page size and 4K sector size,
it's 16).

This indicates that some call sites are not properly decreasing the value.

And that's exactly the case, in btrfs_page_unlock_writer(), due to the
fact that we can have page locked either by lock_page() or
process_one_page(), we have to check if the subpage has any writer.

If no writers, it's locked by lock_page() and we only need to unlock it.

But unfortunately the check for the writers are completely opposite:

if (atomic_read(&subpage->writers))
/* No writers, locked by plain lock_page() */
return unlock_page(page);

We directly unlock the page if it has writers, which is the completely
opposite what we want.

Thankfully the affected call site is only limited to
extent_write_locked_range(), so it's mostly affecting compressed write.

[FIX]
Just fix the wrong check condition to fix the bug.

Fixes: e55a0de18572 ("btrfs: rework page locking in __extent_writepage()")
CC: stable@vger.kernel.org # 5.16
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: handle page locking in btrfs_page_end_writer_lock with no writers

There are several call sites of extent_clear_unlock_delalloc() which get
@locked_page = NULL.
So that extent_clear_unlock_del

btrfs: handle page locking in btrfs_page_end_writer_lock with no writers

There are several call sites of extent_clear_unlock_delalloc() which get
@locked_page = NULL.
So that extent_clear_unlock_delalloc() will try to call
process_one_page() to unlock every page even the first page is not
locked by btrfs_page_start_writer_lock().

This will trigger an ASSERT() in btrfs_subpage_end_and_test_writer() as
previously we require every page passed to
btrfs_subpage_end_and_test_writer() to be locked by
btrfs_page_start_writer_lock().

But compression path doesn't go that way.

Thankfully it's not hard to distinguish page locked by lock_page() and
btrfs_page_start_writer_lock().

So do the check in btrfs_subpage_end_and_test_writer() so now it can
handle both cases well.

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

show more ...

btrfs: rework page locking in __extent_writepage()

Pages passed to __extent_writepage() are always locked, but they may be
locked by different functions.

There are two types of locked page for __ex

btrfs: rework page locking in __extent_writepage()

Pages passed to __extent_writepage() are always locked, but they may be
locked by different functions.

There are two types of locked page for __extent_writepage():

- Page locked by plain lock_page()
It should not have any subpage::writers count.
Can be unlocked by unlock_page().
This is the most common locked page for __extent_writepage() called
inside extent_write_cache_pages() or extent_write_full_page().
Rarer cases include the @locked_page from extent_write_locked_range().

- Page locked by lock_delalloc_pages()
There is only one caller, all pages except @locked_page for
extent_write_locked_range().
In this case, we have to call subpage helper to handle the case.

So here we introduce a helper, btrfs_page_unlock_writer(), to allow
__extent_writepage() to unlock different locked pages.

And since for all other callers of __extent_writepage() their pages are
ensured to be locked by lock_page(), also add an extra check for
epd::extent_locked to unlock such pages directly.

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

show more ...

btrfs: subpage: add bitmap for PageChecked flag

Although in btrfs we have very limited usage of PageChecked flag, it's
still some page flag not yet subpage compatible.

Fix it by introducing btrfs_s

btrfs: subpage: add bitmap for PageChecked flag

Although in btrfs we have very limited usage of PageChecked flag, it's
still some page flag not yet subpage compatible.

Fix it by introducing btrfs_subpage::checked_offset to do the convert.

For most call sites, especially for free-space cache, COW fixup and
btrfs_invalidatepage(), they all work in full page mode anyway.

For other call sites, they work as subpage compatible mode.

Some call sites need extra modification:

- btrfs_drop_pages()
Needs extra parameter to get the real range we need to clear checked
flag.

Also since btrfs_drop_pages() will accept pages beyond the dirtied
range, update btrfs_subpage_clamp_range() to handle such case
by setting @len to 0 if the page is beyond target range.

- btrfs_invalidatepage()
We need to call subpage helper before calling __btrfs_releasepage(),
or it will trigger ASSERT() as page->private will be cleared.

- btrfs_verify_data_csum()
In theory we don't need the io_bio->csum check anymore, but it's
won't hurt. Just change the comment.

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

show more ...

btrfs: subpage: pack all subpage bitmaps into a larger bitmap

Currently we use u16 bitmap to make 4k sectorsize work for 64K page
size.

But this u16 bitmap is not large enough to contain larger pag

btrfs: subpage: pack all subpage bitmaps into a larger bitmap

Currently we use u16 bitmap to make 4k sectorsize work for 64K page
size.

But this u16 bitmap is not large enough to contain larger page size like
128K, nor is space efficient for 16K page size.

To handle both cases, here we pack all subpage bitmaps into a larger
bitmap, now btrfs_subpage::bitmaps[] will be the ultimate bitmap for
subpage usage.

Each sub-bitmap will has its start bit number recorded in
btrfs_subpage_info::*_start, and its bitmap length will be recorded in
btrfs_subpage_info::bitmap_nr_bits.

All subpage bitmap operations will be converted from using direct u16
operations to bitmap operations, with above *_start calculated.

For 64K page size with 4K sectorsize, this should not cause much
difference.

While for 16K page size, we will only need 1 unsigned long (u32) to
store all the bitmaps, which saves quite some space.

Furthermore, this allows us to support larger page size like 128K and
258K.

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

show more ...

btrfs: subpage: introduce btrfs_subpage_bitmap_info

Currently we use fixed size u16 bitmap for subpage bitmap. This is fine
for 4K sectorsize with 64K page size.

But for 4K sectorsize and larger p

btrfs: subpage: introduce btrfs_subpage_bitmap_info

Currently we use fixed size u16 bitmap for subpage bitmap. This is fine
for 4K sectorsize with 64K page size.

But for 4K sectorsize and larger page size, the bitmap is too small,
while for smaller page size like 16K, u16 bitmaps waste too much space.

Here we introduce a new helper structure, btrfs_subpage_bitmap_info, to
record the proper bitmap size, and where each bitmap should start at.

By this, we can later compact all subpage bitmaps into one u32 bitmap.
This patch is the first step.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: subpage: make btrfs_alloc_subpage() return btrfs_subpage directly

The existing calling convention of btrfs_alloc_subpage() is pretty
awful. Change it to a more common pattern by returning st

btrfs: subpage: make btrfs_alloc_subpage() return btrfs_subpage directly

The existing calling convention of btrfs_alloc_subpage() is pretty
awful. Change it to a more common pattern by returning struct
btrfs_subpage directly and let the caller to determine if the call
succeeded.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: subpage: only call btrfs_alloc_subpage() when sectorsize is smaller than PAGE_SIZE

There are two call sites of btrfs_alloc_subpage():

- btrfs_attach_subpage()
We have ensured sectorsize is

btrfs: subpage: only call btrfs_alloc_subpage() when sectorsize is smaller than PAGE_SIZE

There are two call sites of btrfs_alloc_subpage():

- btrfs_attach_subpage()
We have ensured sectorsize is smaller than PAGE_SIZE

- alloc_extent_buffer()
We call btrfs_alloc_subpage() unconditionally.

The alloc_extent_buffer() forces us to check the sectorsize size against
page size inside btrfs_alloc_subpage().

Since the function name, btrfs_alloc_subpage(), already indicates it
should only get called for subpage cases, do the check in
alloc_extent_buffer() and add an ASSERT() in btrfs_alloc_subpage().

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: subpage: fix a potential use-after-free in writeback helper

[BUG]
There is a possible use-after-free bug when running generic/095.

BUG: Unable to handle kernel data access on write at 0x6b6

btrfs: subpage: fix a potential use-after-free in writeback helper

[BUG]
There is a possible use-after-free bug when running generic/095.

BUG: Unable to handle kernel data access on write at 0x6b6b6b6b6b6b725b
Faulting instruction address: 0xc000000000283654
c000000000283078 do_raw_spin_unlock+0x88/0x230
c0000000012b1e14 _raw_spin_unlock_irqrestore+0x44/0x90
c000000000a918dc btrfs_subpage_clear_writeback+0xac/0xe0
c0000000009e0458 end_bio_extent_writepage+0x158/0x270
c000000000b6fd14 bio_endio+0x254/0x270
c0000000009fc0f0 btrfs_end_bio+0x1a0/0x200
c000000000b6fd14 bio_endio+0x254/0x270
c000000000b781fc blk_update_request+0x46c/0x670
c000000000b8b394 blk_mq_end_request+0x34/0x1d0
c000000000d82d1c lo_complete_rq+0x11c/0x140
c000000000b880a4 blk_complete_reqs+0x84/0xb0
c0000000012b2ca4 __do_softirq+0x334/0x680
c0000000001dd878 irq_exit+0x148/0x1d0
c000000000016f4c do_IRQ+0x20c/0x240
c000000000009240 hardware_interrupt_common_virt+0x1b0/0x1c0

[CAUSE]
There is very small race window like the following in generic/095.

Thread 1 | Thread 2
--------------------------------+------------------------------------
end_bio_extent_writepage() | btrfs_releasepage()
|- spin_lock_irqsave() | |
|- end_page_writeback() | |
| | |- if (PageWriteback() ||...)
| | |- clear_page_extent_mapped()
| | |- kfree(subpage);
|- spin_unlock_irqrestore().

The race can also happen between writeback and btrfs_invalidatepage(),
although that would be much harder as btrfs_invalidatepage() has much
more work to do before the clear_page_extent_mapped() call.

[FIX]
Here we "wait" for the subapge spinlock to be released before we detach
subpage structure.
So this patch will introduce a new function, wait_subpage_spinlock(), to
do the "wait" by acquiring the spinlock and release it.

Since the caller has ensured the page is not dirty nor writeback, and
page is already locked, the only way to hold the subpage spinlock is
from endio function.
Thus we only need to acquire the spinlock to wait for any existing
holder.

Reported-by: Ritesh Harjani <riteshh@linux.ibm.com>
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

btrfs: subpage: fix writeback which does not have ordered extent

[BUG]
When running fsstress with subpage RW support, there are random
BUG_ON()s triggered with the following trace:

kernel BUG at f

btrfs: subpage: fix writeback which does not have ordered extent

[BUG]
When running fsstress with subpage RW support, there are random
BUG_ON()s triggered with the following trace:

kernel BUG at fs/btrfs/file-item.c:667!
Internal error: Oops - BUG: 0 [#1] SMP
CPU: 1 PID: 3486 Comm: kworker/u13:2 5.11.0-rc4-custom+ #43
Hardware name: Radxa ROCK Pi 4B (DT)
Workqueue: btrfs-worker-high btrfs_work_helper [btrfs]
pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
pc : btrfs_csum_one_bio+0x420/0x4e0 [btrfs]
lr : btrfs_csum_one_bio+0x400/0x4e0 [btrfs]
Call trace:
btrfs_csum_one_bio+0x420/0x4e0 [btrfs]
btrfs_submit_bio_start+0x20/0x30 [btrfs]
run_one_async_start+0x28/0x44 [btrfs]
btrfs_work_helper+0x128/0x1b4 [btrfs]
process_one_work+0x22c/0x430
worker_thread+0x70/0x3a0
kthread+0x13c/0x140
ret_from_fork+0x10/0x30

[CAUSE]
Above BUG_ON() means there is some bio range which doesn't have ordered
extent, which indeed is worth a BUG_ON().

Unlike regular sectorsize == PAGE_SIZE case, in subpage we have extra
subpage dirty bitmap to record which range is dirty and should be
written back.

This means, if we submit bio for a subpage range, we do not only need to
clear page dirty, but also need to clear subpage dirty bits.

In __extent_writepage_io(), we will call btrfs_page_clear_dirty() for
any range we submit a bio.

But there is loophole, if we hit a range which is beyond i_size, we just
call btrfs_writepage_endio_finish_ordered() to finish the ordered io,
then break out, without clearing the subpage dirty.

This means, if we hit above branch, the subpage dirty bits are still
there, if other range of the page get dirtied and we need to writeback
that page again, we will submit bio for the old range, leaving a wild
bio range which doesn't have ordered extent.

[FIX]
Fix it by always calling btrfs_page_clear_dirty() in
__extent_writepage_io().

Also to avoid such problem from happening again, add a new assert,
btrfs_page_assert_not_dirty(), to make sure both page dirty and subpage
dirty bits are cleared before exiting __extent_writepage_io().

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

show more ...

btrfs: subpage: fix a rare race between metadata endio and eb freeing

[BUG]
There is a very rare ASSERT() triggering during full fstests run for
subpage rw support.

No other reproducer so far.

The

btrfs: subpage: fix a rare race between metadata endio and eb freeing

[BUG]
There is a very rare ASSERT() triggering during full fstests run for
subpage rw support.

No other reproducer so far.

The ASSERT() gets triggered for metadata read in
btrfs_page_set_uptodate() inside end_page_read().

[CAUSE]
There is still a small race window for metadata only, the race could
happen like this:

T1 | T2
------------------------------------+-----------------------------
end_bio_extent_readpage() |
|- btrfs_validate_metadata_buffer() |
| |- free_extent_buffer() |
| Still have 2 refs |
|- end_page_read() |
|- if (unlikely(PagePrivate()) |
| The page still has Private |
| | free_extent_buffer()
| | | Only one ref 1, will be
| | | released
| | |- detach_extent_buffer_page()
| | |- btrfs_detach_subpage()
|- btrfs_set_page_uptodate() |
The page no longer has Private|
>>> ASSERT() triggered <<< |

This race window is super small, thus pretty hard to hit, even with so
many runs of fstests.

But the race window is still there, we have to go another way to solve
it other than relying on random PagePrivate() check.

Data path is not affected, as it will lock the page before reading,
while unlocking the page after the last read has finished, thus no race
window.

[FIX]
This patch will fix the bug by repurposing btrfs_subpage::readers.

Now btrfs_subpage::readers will be a member shared by both metadata and
data.

For metadata path, we don't do the page unlock as metadata only relies
on extent locking.

At the same time, teach page_range_has_eb() to take
btrfs_subpage::readers into consideration.

So that even if the last eb of a page gets freed, page::private won't be
detached as long as there still are pending end_page_read() calls.

By this we eliminate the race window, this will slight increase the
metadata memory usage, as the page may not be released as frequently as
usual. But it should not be a big deal.

The code got introduced in ("btrfs: submit read time repair only for
each corrupted sector"), but the fix is in a separate patch to keep the
problem description and the crash is rare so it should not hurt
bisectability.

Signed-off-by: Qu Wegruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: introduce helpers for subpage ordered status

This patch introduces the following functions to handle btrfs subpage
ordered (Private2) status:

- btrfs_subpage_set_ordered()
- btrfs_subpage_cl

btrfs: introduce helpers for subpage ordered status

This patch introduces the following functions to handle btrfs subpage
ordered (Private2) status:

- btrfs_subpage_set_ordered()
- btrfs_subpage_clear_ordered()
- btrfs_subpage_test_ordered()
These helpers can only be called when the range is ensured to be
inside the page.

- btrfs_page_set_ordered()
- btrfs_page_clear_ordered()
- btrfs_page_test_ordered()
These helpers can handle both regular sector size and subpage without
problem.

These functions are here to coordinate btrfs_invalidatepage() with
btrfs_writepage_endio_finish_ordered(), to make sure only one of those
functions can finish the ordered extent.

Tested-by: Ritesh Harjani <riteshh@linux.ibm.com> # [ppc64]
Tested-by: Anand Jain <anand.jain@oracle.com> # [aarch64]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: make process_one_page() to handle subpage locking

Introduce a new data inodes specific subpage member, writers, to record
how many sectors are under page lock for delalloc writing.

This memb

btrfs: make process_one_page() to handle subpage locking

Introduce a new data inodes specific subpage member, writers, to record
how many sectors are under page lock for delalloc writing.

This member acts pretty much the same as readers, except it's only for
delalloc writes.

This is important for delalloc code to trace which page can really be
freed, as we have cases like run_delalloc_nocow() where we may exit
processing nocow range inside a page, but need to exit to do cow half
way.
In that case, we need a way to determine if we can really unlock a full
page.

With the new btrfs_subpage::writers, there is a new requirement:
- Page locked by process_one_page() must be unlocked by
process_one_page()
There are still tons of call sites manually lock and unlock a page,
without updating btrfs_subpage::writers.
So if we lock a page through process_one_page() then it must be
unlocked by process_one_page() to keep btrfs_subpage::writers
consistent.

This will be handled in next patch.

Tested-by: Ritesh Harjani <riteshh@linux.ibm.com> # [ppc64]
Tested-by: Anand Jain <anand.jain@oracle.com> # [aarch64]
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: provide btrfs_page_clamp_*() helpers

In the coming subpage RW supports, there are a lot of page status update
calls which need to be converted to subpage compatible version, which
needs @star

btrfs: provide btrfs_page_clamp_*() helpers

In the coming subpage RW supports, there are a lot of page status update
calls which need to be converted to subpage compatible version, which
needs @start and @len.

Some call sites already have such @start/@len and are already in
page range, like various endio functions.

But there are also call sites which need to clamp the range for subpage
case, like btrfs_dirty_pagse() and __process_contig_pages().

Here we introduce new helpers, btrfs_page_clamp_*(), to do and only do the
clamp for subpage version.

Although in theory all existing btrfs_page_*() calls can be converted to
use btrfs_page_clamp_*() directly, but that would make us to do
unnecessary clamp operations.

Tested-by: Ritesh Harjani <riteshh@linux.ibm.com> # [ppc64]
Tested-by: Anand Jain <anand.jain@oracle.com> # [aarch64]
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

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btrfs: subpage: add overview comments

This patch adds an overview how btrfs subpage support works:

- limitations
- behavior
- basic implementation points

Signed-off-by: Qu Wenruo <wqu@suse.com>
Re

btrfs: subpage: add overview comments

This patch adds an overview how btrfs subpage support works:

- limitations
- behavior
- basic implementation points

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

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btrfs: subpage: introduce helpers for writeback status

Introduces the following functions to handle subpage writeback status:

- btrfs_subpage_set_writeback()
- btrfs_subpage_clear_writeback()
- btr

btrfs: subpage: introduce helpers for writeback status

Introduces the following functions to handle subpage writeback status:

- btrfs_subpage_set_writeback()
- btrfs_subpage_clear_writeback()
- btrfs_subpage_test_writeback()
These helpers can only be called when the range is ensured to be
inside the page.

- btrfs_page_set_writeback()
- btrfs_page_clear_writeback()
- btrfs_page_test_writeback()
These helpers can handle both regular sector size and subpage without
problem.

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

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