Re: [PATCH v2 09/12] btrfs: btrfs: plumb NOWAIT through the write path

[Stefan Roesch <shr@fb.com>]

On 9/8/22 3:16 AM, Filipe Manana wrote:
> > 
> On Thu, Sep 8, 2022 at 1:26 AM Stefan Roesch <shr@fb.com> wrote:
>>
>> We have everywhere setup for nowait, plumb NOWAIT through the write path.
> 
> Note, there's a double "btrfs: " prefix in the subject line.
> 

Fixed, thanks for catching it.

>>
>> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
>> Signed-off-by: Stefan Roesch <shr@fb.com>
>> ---
>>  fs/btrfs/file.c | 19 +++++++++++++------
>>  1 file changed, 13 insertions(+), 6 deletions(-)
>>
>> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
>> index 4e1745e585cb..6e191e353b22 100644
>> --- a/fs/btrfs/file.c
>> +++ b/fs/btrfs/file.c
>> @@ -1653,8 +1653,9 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
>>         bool force_page_uptodate = false;
>>         loff_t old_isize = i_size_read(inode);
>>         unsigned int ilock_flags = 0;
>> +       bool nowait = iocb->ki_flags & IOCB_NOWAIT;
> 
> Can be made const.
> 

In the next version of the patch series it will be const.

> Thanks.
> 
>>
>> -       if (iocb->ki_flags & IOCB_NOWAIT)
>> +       if (nowait)
>>                 ilock_flags |= BTRFS_ILOCK_TRY;
>>
>>         ret = btrfs_inode_lock(inode, ilock_flags);
>> @@ -1710,17 +1711,22 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
>>                 extent_changeset_release(data_reserved);
>>                 ret = btrfs_check_data_free_space(BTRFS_I(inode),
>>                                                   &data_reserved, pos,
>> -                                                 write_bytes, false);
>> +                                                 write_bytes, nowait);
>>                 if (ret < 0) {
>>                         int tmp;
>>
>> +                       if (nowait && (ret == -ENOSPC || ret == -EAGAIN)) {
>> +                               ret = -EAGAIN;
>> +                               break;
>> +                       }
>> +
>>                         /*
>>                          * If we don't have to COW at the offset, reserve
>>                          * metadata only. write_bytes may get smaller than
>>                          * requested here.
>>                          */
>>                         tmp = btrfs_check_nocow_lock(BTRFS_I(inode), pos,
>> -                                                    &write_bytes, false);
>> +                                                    &write_bytes, nowait);
>>                         if (tmp < 0)
>>                                 ret = tmp;
>>                         if (tmp > 0)
>> @@ -1737,7 +1743,7 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
>>                 WARN_ON(reserve_bytes == 0);
>>                 ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
>>                                                       reserve_bytes,
>> -                                                     reserve_bytes, false);
>> +                                                     reserve_bytes, nowait);
>>                 if (ret) {
>>                         if (!only_release_metadata)
>>                                 btrfs_free_reserved_data_space(BTRFS_I(inode),
>> @@ -1767,10 +1773,11 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
>>                 extents_locked = lock_and_cleanup_extent_if_need(
>>                                 BTRFS_I(inode), pages,
>>                                 num_pages, pos, write_bytes, &lockstart,
>> -                               &lockend, false, &cached_state);
>> +                               &lockend, nowait, &cached_state);
>>                 if (extents_locked < 0) {
>> -                       if (extents_locked == -EAGAIN)
>> +                       if (!nowait && extents_locked == -EAGAIN)
>>                                 goto again;
>> +
>>                         btrfs_delalloc_release_extents(BTRFS_I(inode),
>>                                                        reserve_bytes);
>>                         ret = extents_locked;
>> --
>> 2.30.2
>>