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

["Darrick J. Wong" <djwong@kernel.org>]

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
> 
>