linux.git/fs/btrfs/ordered-data.h, branch v5.12

btrfs: zoned: use ZONE_APPEND write for zoned mode

2021-02-09T01:46:06+00:00

Enable zone append writing for zoned mode. When using zone append, a
bio is issued to the start of a target zone and the device decides to
place it inside the zone. Upon completion the device reports the actual
written position back to the host.

Three parts are necessary to enable zone append mode. First, modify the
bio to use REQ_OP_ZONE_APPEND in btrfs_submit_bio_hook() and adjust the
bi_sector to point the beginning of the zone.

Second, record the returned physical address (and disk/partno) to the
ordered extent in end_bio_extent_writepage() after the bio has been
completed. We cannot resolve the physical address to the logical address
because we can neither take locks nor allocate a buffer in this end_bio
context. So, we need to record the physical address to resolve it later
in btrfs_finish_ordered_io().

And finally, rewrite the logical addresses of the extent mapping and
checksum data according to the physical address using btrfs_rmap_block.
If the returned address matches the originally allocated address, we can
skip this rewriting process.

Reviewed-by: Josef Bacik 
Signed-off-by: Johannes Thumshirn 
Signed-off-by: Naohiro Aota 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: zoned: split ordered extent when bio is sent

2021-02-09T01:46:05+00:00

For a zone append write, the device decides the location the data is being
written to. Therefore we cannot ensure that two bios are written
consecutively on the device. In order to ensure that an ordered extent
maps to a contiguous region on disk, we need to maintain a "one bio ==
one ordered extent" rule.

Implement splitting of an ordered extent and extent map on bio submission
to adhere to the rule.

extract_ordered_extent() hooks into btrfs_submit_data_bio() and splits the
corresponding ordered extent so that the ordered extent's region fits into
one bio and the corresponding device limits.

Several sanity checks need to be done in extract_ordered_extent() e.g.

- We cannot split once end_bio'd ordered extent because we cannot divide
  ordered->bytes_left for the split ones
- We do not expect a compressed ordered extent
- We should not have checksum list because we omit the list splitting.
  Since the function is called before btrfs_wq_submit_bio() or
  btrfs_csum_one_bio(), this should be always ensured.

We also need to split an extent map by creating a new one. If not,
unpin_extent_cache() complains about the difference between the start of
the extent map and the file's logical offset.

Reviewed-by: Josef Bacik 
Signed-off-by: Naohiro Aota 
Signed-off-by: David Sterba

btrfs: rework the order of btrfs_ordered_extent::flags

2021-02-08T21:58:52+00:00

[BUG]
There is a long existing bug in the last parameter of
btrfs_add_ordered_extent(), in commit 771ed689d2cd ("Btrfs: Optimize
compressed writeback and reads") back to 2008.

In that ancient commit btrfs_add_ordered_extent() expects the @type
parameter to be one of the following:

- BTRFS_ORDERED_REGULAR
- BTRFS_ORDERED_NOCOW
- BTRFS_ORDERED_PREALLOC
- BTRFS_ORDERED_COMPRESSED

But we pass 0 in cow_file_range(), which means BTRFS_ORDERED_IO_DONE.

Ironically extra check in __btrfs_add_ordered_extent() won't set the bit
if we see (type == IO_DONE || type == IO_COMPLETE), and avoid any
obvious bug.

But this still leads to regular COW ordered extent having no bit to
indicate its type in various trace events, rendering REGULAR bit
useless.

[FIX]
Change the following aspects to avoid such problem:

- Reorder btrfs_ordered_extent::flags
  Now the type bits go first (REGULAR/NOCOW/PREALLCO/COMPRESSED), then
  DIRECT bit, finally extra status bits like IO_DONE/COMPLETE/IOERR.

- Add extra ASSERT() for btrfs_add_ordered_extent_*()

- Remove @type parameter for btrfs_add_ordered_extent_compress()
  As the only valid @type here is BTRFS_ORDERED_COMPRESSED.

- Remove the unnecessary special check for IO_DONE/COMPLETE in
  __btrfs_add_ordered_extent()
  This is just to make the code work, with extra ASSERT(), there are
  limited values can be passed in.

Reviewed-by: Nikolay Borisov 
Reviewed-by: Filipe Manana 
Signed-off-by: Qu Wenruo 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: refactor btrfs_dec_test_* functions for ordered extents

2021-02-08T21:58:51+00:00

The refactoring involves the following modifications:

- Return bool instead of int

- Parameter update for @cached of btrfs_dec_test_first_ordered_pending()
  For btrfs_dec_test_first_ordered_pending(), @cached is only used to
  return the finished ordered extent.
  Rename it to @finished_ret.

- Comment updates

  * Change one stale comment
    Which still refers to btrfs_dec_test_ordered_pending(), but the
    context is calling  btrfs_dec_test_first_ordered_pending().
  * Follow the common comment style for both functions
    Add more detailed descriptions for parameters and the return value
  * Move the reason why test_and_set_bit() is used into the call sites

- Change how the return value is calculated
  The most anti-human part of the return value is:

    if (...)
	ret = 1;
    ...
    return ret == 0;

  This means, when we set ret to 1, the function returns 0.
  Change the local variable name to @finished, and directly return the
  value of it.

Signed-off-by: Qu Wenruo 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: remove btrfs_find_ordered_sum call from btrfs_lookup_bio_sums

2020-12-09T18:16:10+00:00

The function btrfs_lookup_bio_sums() is only called for read bios.
While btrfs_find_ordered_sum() is to search ordered extent sums, which
is only for write path.

This means to read a page we either:

- Submit read bio if it's not uptodate
  This means we only need to search csum tree for checksums.

- The page is already uptodate
  It can be marked uptodate for previous read, or being marked dirty.
  As we always mark page uptodate for dirty page.
  In that case, we don't need to submit read bio at all, thus no need
  to search any checksums.

Remove the btrfs_find_ordered_sum() call in btrfs_lookup_bio_sums().
And since btrfs_lookup_bio_sums() is the only caller for
btrfs_find_ordered_sum(), also remove the implementation.

Reviewed-by: Nikolay Borisov 
Signed-off-by: Qu Wenruo 
Signed-off-by: David Sterba

btrfs: remove unnecessary local variables for checksum size

2020-12-08T14:54:00+00:00

Remove local variable that is then used just once and replace it with
fs_info::csum_size.

Reviewed-by: Johannes Thumshirn 
Signed-off-by: David Sterba

btrfs: switch cached fs_info::csum_size from u16 to u32

2020-12-08T14:53:59+00:00

The fs_info value is 32bit, switch also the local u16 variables. This
leads to a better assembly code generated due to movzwl.

This simple change will shave some bytes on x86_64 and release config:

   text    data     bss     dec     hex filename
1090000   17980   14912 1122892  11224c pre/btrfs.ko
1089794   17980   14912 1122686  11217e post/btrfs.ko

DELTA: -206

Reviewed-by: Johannes Thumshirn 
Signed-off-by: David Sterba

btrfs: use cached value of fs_info::csum_size everywhere

2020-12-08T14:53:59+00:00

btrfs_get_16 shows up in the system performance profiles (helper to read
16bit values from on-disk structures). This is partially because of the
checksum size that's frequently read along with data reads/writes, other
u16 uses are from item size or directory entries.

Replace all calls to btrfs_super_csum_size by the cached value from
fs_info.

Reviewed-by: Johannes Thumshirn 
Reviewed-by: Qu Wenruo 
Signed-off-by: David Sterba

btrfs: remove inode argument from btrfs_start_ordered_extent

2020-10-07T10:13:22+00:00

The passed in ordered_extent struct is always well-formed and contains
the inode making the explicit argument redundant.

Signed-off-by: Nikolay Borisov 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: switch btrfs_remove_ordered_extent to btrfs_inode

2020-10-07T10:13:21+00:00

Signed-off-by: Nikolay Borisov 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba