Re: [PATCH v2 01/11] iomap: Rename IOMAP_ATOMIC -> IOMAP_ATOMIC_HW

Darrick J. Wong
2025-02-24T20:23:31Z

On Thu, Feb 13, 2025 at 01:56:09PM +0000, John Garry wrote:
> In future xfs will support a CoW-based atomic write, so rename
> IOMAP_ATOMIC -> IOMAP_ATOMIC_HW to be clear which mode is being used.
>
> Also relocate setting of IOMAP_ATOMIC_HW to the write path in
> __iomap_dio_rw(), to be clear that this flag is only relevant to writes
>
> Signed-off-by: John Garry <john.g.garry@oracle.com>

Looks fine,
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
> Documentation/filesystems/iomap/operations.rst | 4 ++--
> fs/ext4/inode.c | 2 +-
> fs/iomap/direct-io.c | 18 +++++++++---------
> fs/iomap/trace.h | 2 +-
> include/linux/iomap.h | 2 +-
> 5 files changed, 14 insertions(+), 14 deletions(-)
>
> diff --git a/Documentation/filesystems/iomap/operations.rst b/Documentation/filesystems/iomap/operations.rst
> index 2c7f5df9d8b0..82bfe0e8c08e 100644
> --- a/Documentation/filesystems/iomap/operations.rst
> +++ b/Documentation/filesystems/iomap/operations.rst
> @@ -513,8 +513,8 @@ IOMAP_WRITE`` with any combination of the following enhancements:
> if the mapping is unwritten and the filesystem cannot handle zeroing
> the unaligned regions without exposing stale contents.
>
> - * ``IOMAP_ATOMIC``: This write is being issued with torn-write
> - protection.
> + * ``IOMAP_ATOMIC_HW``: This write is being issued with torn-write
> + protection based on HW-offload support.
> Only a single bio can be created for the write, and the write must
> not be split into multiple I/O requests, i.e. flag REQ_ATOMIC must be
> set.
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 7c54ae5fcbd4..ba2f1e3db7c7 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3467,7 +3467,7 @@ static inline bool ext4_want_directio_fallback(unsigned flags, ssize_t written)
> return false;
>
> /* atomic writes are all-or-nothing */
> - if (flags & IOMAP_ATOMIC)
> + if (flags & IOMAP_ATOMIC_HW)
> return false;
>
> /* can only try again if we wrote nothing */
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index b521eb15759e..f87c4277e738 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -271,7 +271,7 @@ static int iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio,
> * clearing the WRITE_THROUGH flag in the dio request.
> */
> static inline blk_opf_t iomap_dio_bio_opflags(struct iomap_dio *dio,
> - const struct iomap *iomap, bool use_fua, bool atomic)
> + const struct iomap *iomap, bool use_fua, bool atomic_hw)
> {
> blk_opf_t opflags = REQ_SYNC | REQ_IDLE;
>
> @@ -283,7 +283,7 @@ static inline blk_opf_t iomap_dio_bio_opflags(struct iomap_dio *dio,
> opflags |= REQ_FUA;
> else
> dio->flags &= ~IOMAP_DIO_WRITE_THROUGH;
> - if (atomic)
> + if (atomic_hw)
> opflags |= REQ_ATOMIC;
>
> return opflags;
> @@ -295,8 +295,8 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
> const struct iomap *iomap = &iter->iomap;
> struct inode *inode = iter->inode;
> unsigned int fs_block_size = i_blocksize(inode), pad;
> + bool atomic_hw = iter->flags & IOMAP_ATOMIC_HW;
> const loff_t length = iomap_length(iter);
> - bool atomic = iter->flags & IOMAP_ATOMIC;
> loff_t pos = iter->pos;
> blk_opf_t bio_opf;
> struct bio *bio;
> @@ -306,7 +306,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
> size_t copied = 0;
> size_t orig_count;
>
> - if (atomic && length != fs_block_size)
> + if (atomic_hw && length != fs_block_size)
> return -EINVAL;
>
> if ((pos | length) & (bdev_logical_block_size(iomap->bdev) - 1) ||
> @@ -383,7 +383,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
> goto out;
> }
>
> - bio_opf = iomap_dio_bio_opflags(dio, iomap, use_fua, atomic);
> + bio_opf = iomap_dio_bio_opflags(dio, iomap, use_fua, atomic_hw);
>
> nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter, BIO_MAX_VECS);
> do {
> @@ -416,7 +416,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
> }
>
> n = bio->bi_iter.bi_size;
> - if (WARN_ON_ONCE(atomic && n != length)) {
> + if (WARN_ON_ONCE(atomic_hw && n != length)) {
> /*
> * This bio should have covered the complete length,
> * which it doesn't, so error. We may need to zero out
> @@ -610,9 +610,6 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
> if (iocb->ki_flags & IOCB_NOWAIT)
> iomi.flags |= IOMAP_NOWAIT;
>
> - if (iocb->ki_flags & IOCB_ATOMIC)
> - iomi.flags |= IOMAP_ATOMIC;
> -
> if (iov_iter_rw(iter) == READ) {
> /* reads can always complete inline */
> dio->flags |= IOMAP_DIO_INLINE_COMP;
> @@ -647,6 +644,9 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
> iomi.flags |= IOMAP_OVERWRITE_ONLY;
> }
>
> + if (iocb->ki_flags & IOCB_ATOMIC)
> + iomi.flags |= IOMAP_ATOMIC_HW;
> +
> /* for data sync or sync, we need sync completion processing */
> if (iocb_is_dsync(iocb)) {
> dio->flags |= IOMAP_DIO_NEED_SYNC;
> diff --git a/fs/iomap/trace.h b/fs/iomap/trace.h
> index 4118a42cdab0..0c73d91c0485 100644
> --- a/fs/iomap/trace.h
> +++ b/fs/iomap/trace.h
> @@ -99,7 +99,7 @@ DEFINE_RANGE_EVENT(iomap_dio_rw_queued);
> { IOMAP_FAULT, "FAULT" }, \
> { IOMAP_DIRECT, "DIRECT" }, \
> { IOMAP_NOWAIT, "NOWAIT" }, \
> - { IOMAP_ATOMIC, "ATOMIC" }
> + { IOMAP_ATOMIC_HW, "ATOMIC_HW" }
>
> #define IOMAP_F_FLAGS_STRINGS \
> { IOMAP_F_NEW, "NEW" }, \
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index 75bf54e76f3b..e7aa05503763 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -182,7 +182,7 @@ struct iomap_folio_ops {
> #else
> #define IOMAP_DAX 0
> #endif /* CONFIG_FS_DAX */
> -#define IOMAP_ATOMIC (1 << 9)
> +#define IOMAP_ATOMIC_HW (1 << 9) /* HW-based torn-write protection */
>
> struct iomap_ops {
> /*
> --
> 2.31.1
>
>