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

Stefan Roesch
2022-09-08T18:45:27Z

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
>>