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

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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: Hongbo Li <lihongbo22@huawei.com>
Link: https://patch.msgid.link/20260109102856.598531-2-lihongbo22@huawei.com
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Hongbo Li 2026-01-09 10:28:47 +00:00 committed by Christian Brauner
parent 8f0b4cce44
commit 8806f27924
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
3 changed files with 10 additions and 8 deletions
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4
fs/fuse/file.c
View File

@ -979,7 +979,7 @@ static int fuse_read_folio(struct file *file, struct folio *folio)
return -EIO; return -EIO;
} }
iomap_read_folio(&fuse_iomap_ops, &ctx); iomap_read_folio(&fuse_iomap_ops, &ctx, NULL);
fuse_invalidate_atime(inode); fuse_invalidate_atime(inode);
return 0; return 0;
} }
@ -1081,7 +1081,7 @@ static void fuse_readahead(struct readahead_control *rac)
if (fuse_is_bad(inode)) if (fuse_is_bad(inode))
return; 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) static ssize_t fuse_cache_read_iter(struct kiocb *iocb, struct iov_iter *to)

6
fs/iomap/buffered-io.c
View File

@ -555,13 +555,14 @@ static int iomap_read_folio_iter(struct iomap_iter *iter,
} }
void iomap_read_folio(const struct iomap_ops *ops, 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 folio *folio = ctx->cur_folio;
struct iomap_iter iter = { struct iomap_iter iter = {
.inode = folio->mapping->host, .inode = folio->mapping->host,
.pos = folio_pos(folio), .pos = folio_pos(folio),
.len = folio_size(folio), .len = folio_size(folio),
.private = private,
}; };
size_t bytes_submitted = 0; size_t bytes_submitted = 0;
int ret; int ret;
@ -620,13 +621,14 @@ static int iomap_readahead_iter(struct iomap_iter *iter,
* the filesystem to be reentered. * the filesystem to be reentered.
*/ */
void iomap_readahead(const struct iomap_ops *ops, 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 readahead_control *rac = ctx->rac;
struct iomap_iter iter = { struct iomap_iter iter = {
.inode = rac->mapping->host, .inode = rac->mapping->host,
.pos = readahead_pos(rac), .pos = readahead_pos(rac),
.len = readahead_length(rac), .len = readahead_length(rac),
.private = private,
}; };
size_t cur_bytes_submitted; size_t cur_bytes_submitted;

8
include/linux/iomap.h
View File

@ -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_ops *ops,
const struct iomap_write_ops *write_ops, void *private); const struct iomap_write_ops *write_ops, void *private);
void iomap_read_folio(const struct iomap_ops *ops, 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, 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); 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); 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); 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, .cur_folio = folio,
}; };
iomap_read_folio(ops, &ctx); iomap_read_folio(ops, &ctx, NULL);
} }
static inline void iomap_bio_readahead(struct readahead_control *rac, 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, .rac = rac,
}; };
iomap_readahead(ops, &ctx); iomap_readahead(ops, &ctx, NULL);
} }
#endif /* CONFIG_BLOCK */ #endif /* CONFIG_BLOCK */