Unverified Commit 8806f279 authored by Hongbo Li's avatar Hongbo Li Committed by Christian Brauner
Browse files

iomap: stash iomap read ctx in the private field of iomap_iter 



It's useful to get filesystem-specific information using the
existing private field in the @iomap_iter passed to iomap_{begin,end}
for advanced usage for iomap buffered reads, which is much like the
current iomap DIO.

For example, EROFS needs it to:

 - implement an efficient page cache sharing feature, since iomap
   needs to apply to anon inode page cache but we'd like to get the
   backing inode/fs instead, so filesystem-specific private data is
   needed to keep such information;

 - pass in both struct page * and void * for inline data to avoid
   kmap_to_page() usage (which is bogus).

Signed-off-by: default avatarHongbo Li <lihongbo22@huawei.com>
Link: https://patch.msgid.link/20260109102856.598531-2-lihongbo22@huawei.com


Reviewed-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 8f0b4cce

fs/fuse/file.c

+2 −2
Original line number Diff line number Diff line
@@ -979,7 +979,7 @@ static int fuse_read_folio(struct file *file, struct folio *folio) 
		return -EIO;

	}



	iomap_read_folio(&fuse_iomap_ops, &ctx);

	iomap_read_folio(&fuse_iomap_ops, &ctx, NULL);

	fuse_invalidate_atime(inode);

	return 0;

}
@@ -1081,7 +1081,7 @@ static void fuse_readahead(struct readahead_control *rac) 
	if (fuse_is_bad(inode))

		return;



	iomap_readahead(&fuse_iomap_ops, &ctx);

	iomap_readahead(&fuse_iomap_ops, &ctx, NULL);

}



static ssize_t fuse_cache_read_iter(struct kiocb *iocb, struct iov_iter *to)

fs/iomap/buffered-io.c

+4 −2
Original line number Diff line number Diff line
@@ -555,13 +555,14 @@ static int iomap_read_folio_iter(struct iomap_iter *iter, 
}



void iomap_read_folio(const struct iomap_ops *ops,

		struct iomap_read_folio_ctx *ctx)

		struct iomap_read_folio_ctx *ctx, void *private)

{

	struct folio *folio = ctx->cur_folio;

	struct iomap_iter iter = {

		.inode		= folio->mapping->host,

		.pos		= folio_pos(folio),

		.len		= folio_size(folio),

		.private	= private,

	};

	size_t bytes_submitted = 0;

	int ret;
@@ -620,13 +621,14 @@ static int iomap_readahead_iter(struct iomap_iter *iter, 
 * the filesystem to be reentered.

 */

void iomap_readahead(const struct iomap_ops *ops,

		struct iomap_read_folio_ctx *ctx)

		struct iomap_read_folio_ctx *ctx, void *private)

{

	struct readahead_control *rac = ctx->rac;

	struct iomap_iter iter = {

		.inode	= rac->mapping->host,

		.pos	= readahead_pos(rac),

		.len	= readahead_length(rac),

		.private = private,

	};

	size_t cur_bytes_submitted;

include/linux/iomap.h

+4 −4
Original line number Diff line number Diff line
@@ -341,9 +341,9 @@ ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from, 
		const struct iomap_ops *ops,

		const struct iomap_write_ops *write_ops, void *private);

void iomap_read_folio(const struct iomap_ops *ops,

		struct iomap_read_folio_ctx *ctx);

		struct iomap_read_folio_ctx *ctx, void *private);

void iomap_readahead(const struct iomap_ops *ops,

		struct iomap_read_folio_ctx *ctx);

		struct iomap_read_folio_ctx *ctx, void *private);

bool iomap_is_partially_uptodate(struct folio *, size_t from, size_t count);

struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos, size_t len);

bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags);
@@ -595,7 +595,7 @@ static inline void iomap_bio_read_folio(struct folio *folio, 
		.cur_folio	= folio,

	};



	iomap_read_folio(ops, &ctx);

	iomap_read_folio(ops, &ctx, NULL);

}



static inline void iomap_bio_readahead(struct readahead_control *rac,
@@ -606,7 +606,7 @@ static inline void iomap_bio_readahead(struct readahead_control *rac, 
		.rac		= rac,

	};



	iomap_readahead(ops, &ctx);

	iomap_readahead(ops, &ctx, NULL);

}

#endif /* CONFIG_BLOCK */