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

Filipe Manana
2022-09-08T10:17:40Z

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.

>
> 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.

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
>