Re: [PATCH 12/12] iomap: build the writeback code without CONFIG_BLOCK

Darrick J. Wong
2025-07-02T18:20:11Z

On Fri, Jun 27, 2025 at 09:02:45AM +0200, Christoph Hellwig wrote:
> Allow fuse to use the iomap writeback code even when CONFIG_BLOCK is
> not enabled. Do this with an ifdef instead of a separate file to keep
> the iomap_folio_state local to buffered-io.c.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Seems reasonable to me...
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
> fs/iomap/Makefile | 6 +--
> fs/iomap/buffered-io.c | 113 ++++++++++++++++++++++-------------------
> 2 files changed, 64 insertions(+), 55 deletions(-)
>
> diff --git a/fs/iomap/Makefile b/fs/iomap/Makefile
> index 69e8ebb41302..f7e1c8534c46 100644
> --- a/fs/iomap/Makefile
> +++ b/fs/iomap/Makefile
> @@ -9,9 +9,9 @@ ccflags-y += -I $(src) # needed for trace events
> obj-$(CONFIG_FS_IOMAP) += iomap.o
>
> iomap-y += trace.o \
> - iter.o
> -iomap-$(CONFIG_BLOCK) += buffered-io.o \
> - direct-io.o \
> + iter.o \
> + buffered-io.o
> +iomap-$(CONFIG_BLOCK) += direct-io.o \
> ioend.o \
> fiemap.o \
> seek.o
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 1a9ade77aeeb..6ceeb0e2fc13 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -284,6 +284,46 @@ static void iomap_adjust_read_range(struct inode *inode, struct folio *folio,
> *lenp = plen;
> }
>
> +static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter,
> + loff_t pos)
> +{
> + const struct iomap *srcmap = iomap_iter_srcmap(iter);
> +
> + return srcmap->type != IOMAP_MAPPED ||
> + (srcmap->flags & IOMAP_F_NEW) ||
> + pos >= i_size_read(iter->inode);
> +}
> +
> +/**
> + * iomap_read_inline_data - copy inline data into the page cache
> + * @iter: iteration structure
> + * @folio: folio to copy to
> + *
> + * Copy the inline data in @iter into @folio and zero out the rest of the folio.
> + * Only a single IOMAP_INLINE extent is allowed at the end of each file.
> + * Returns zero for success to complete the read, or the usual negative errno.
> + */
> +static int iomap_read_inline_data(const struct iomap_iter *iter,
> + struct folio *folio)
> +{
> + const struct iomap *iomap = iomap_iter_srcmap(iter);
> + size_t size = i_size_read(iter->inode) - iomap->offset;
> + size_t offset = offset_in_folio(folio, iomap->offset);
> +
> + if (folio_test_uptodate(folio))
> + return 0;
> +
> + if (WARN_ON_ONCE(size > iomap->length))
> + return -EIO;
> + if (offset > 0)
> + ifs_alloc(iter->inode, folio, iter->flags);
> +
> + folio_fill_tail(folio, offset, iomap->inline_data, size);
> + iomap_set_range_uptodate(folio, offset, folio_size(folio) - offset);
> + return 0;
> +}
> +
> +#ifdef CONFIG_BLOCK
> static void iomap_finish_folio_read(struct folio *folio, size_t off,
> size_t len, int error)
> {
> @@ -323,45 +363,6 @@ struct iomap_readpage_ctx {
> struct readahead_control *rac;
> };
>
> -/**
> - * iomap_read_inline_data - copy inline data into the page cache
> - * @iter: iteration structure
> - * @folio: folio to copy to
> - *
> - * Copy the inline data in @iter into @folio and zero out the rest of the folio.
> - * Only a single IOMAP_INLINE extent is allowed at the end of each file.
> - * Returns zero for success to complete the read, or the usual negative errno.
> - */
> -static int iomap_read_inline_data(const struct iomap_iter *iter,
> - struct folio *folio)
> -{
> - const struct iomap *iomap = iomap_iter_srcmap(iter);
> - size_t size = i_size_read(iter->inode) - iomap->offset;
> - size_t offset = offset_in_folio(folio, iomap->offset);
> -
> - if (folio_test_uptodate(folio))
> - return 0;
> -
> - if (WARN_ON_ONCE(size > iomap->length))
> - return -EIO;
> - if (offset > 0)
> - ifs_alloc(iter->inode, folio, iter->flags);
> -
> - folio_fill_tail(folio, offset, iomap->inline_data, size);
> - iomap_set_range_uptodate(folio, offset, folio_size(folio) - offset);
> - return 0;
> -}
> -
> -static inline bool iomap_block_needs_zeroing(const struct iomap_iter *iter,
> - loff_t pos)
> -{
> - const struct iomap *srcmap = iomap_iter_srcmap(iter);
> -
> - return srcmap->type != IOMAP_MAPPED ||
> - (srcmap->flags & IOMAP_F_NEW) ||
> - pos >= i_size_read(iter->inode);
> -}
> -
> static int iomap_readpage_iter(struct iomap_iter *iter,
> struct iomap_readpage_ctx *ctx)
> {
> @@ -554,6 +555,27 @@ void iomap_readahead(struct readahead_control *rac, const struct iomap_ops *ops)
> }
> EXPORT_SYMBOL_GPL(iomap_readahead);
>
> +static int iomap_read_folio_range(const struct iomap_iter *iter,
> + struct folio *folio, loff_t pos, size_t len)
> +{
> + const struct iomap *srcmap = iomap_iter_srcmap(iter);
> + struct bio_vec bvec;
> + struct bio bio;
> +
> + bio_init(&bio, srcmap->bdev, &bvec, 1, REQ_OP_READ);
> + bio.bi_iter.bi_sector = iomap_sector(srcmap, pos);
> + bio_add_folio_nofail(&bio, folio, len, offset_in_folio(folio, pos));
> + return submit_bio_wait(&bio);
> +}
> +#else
> +static int iomap_read_folio_range(const struct iomap_iter *iter,
> + struct folio *folio, loff_t pos, size_t len)
> +{
> + WARN_ON_ONCE(1);
> + return -EIO;
> +}
> +#endif /* CONFIG_BLOCK */
> +
> /*
> * iomap_is_partially_uptodate checks whether blocks within a folio are
> * uptodate or not.
> @@ -667,19 +689,6 @@ iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
> pos + len - 1);
> }
>
> -static int iomap_read_folio_range(const struct iomap_iter *iter,
> - struct folio *folio, loff_t pos, size_t len)
> -{
> - const struct iomap *srcmap = iomap_iter_srcmap(iter);
> - struct bio_vec bvec;
> - struct bio bio;
> -
> - bio_init(&bio, srcmap->bdev, &bvec, 1, REQ_OP_READ);
> - bio.bi_iter.bi_sector = iomap_sector(srcmap, pos);
> - bio_add_folio_nofail(&bio, folio, len, offset_in_folio(folio, pos));
> - return submit_bio_wait(&bio);
> -}
> -
> static int __iomap_write_begin(const struct iomap_iter *iter,
> const struct iomap_write_ops *write_ops, size_t len,
> struct folio *folio)
> --
> 2.47.2
>
>