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[PATCH v13 01/10] iomap: stash iomap read ctx in the private field of iomap_iter

Hongbo Li posted 10 patches 1 month ago
There is a newer version of this series
[PATCH v13 01/10] iomap: stash iomap read ctx in the private field of iomap_iter
Posted by Hongbo Li 1 month ago 
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>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 fs/fuse/file.c         | 4 ++--
 fs/iomap/buffered-io.c | 6 ++++--
 include/linux/iomap.h  | 8 ++++----
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 01bc894e9c2b..f5d8887c1922 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -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)
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index e5c1ca440d93..5f7dcbabbda3 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -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;
 
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 520e967cb501..441d614e9fdf 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -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 */
 
-- 
2.22.0
Re: [PATCH v13 01/10] iomap: stash iomap read ctx in the private field of iomap_iter
Posted by Gao Xiang 1 month ago 
Hi Christoph, Darrick, Christian,

On 2026/1/9 11:01, Hongbo Li wrote:
> 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>
> Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Could you help review or ack this patch?

This feature is almost in shape for the upcoming cycle,
I do hope this iomap patch could be reviewed, thanks!

Thanks,
Gao Xiang

> ---
>   fs/fuse/file.c         | 4 ++--
>   fs/iomap/buffered-io.c | 6 ++++--
>   include/linux/iomap.h  | 8 ++++----
>   3 files changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index 01bc894e9c2b..f5d8887c1922 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -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)
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index e5c1ca440d93..5f7dcbabbda3 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -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;
>   
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index 520e967cb501..441d614e9fdf 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -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 */
>
Re: [PATCH v13 01/10] iomap: stash iomap read ctx in the private field of iomap_iter
Posted by Hongbo Li 1 month ago 
Hi, all

On 2026/1/9 14:03, Gao Xiang wrote:
> Hi Christoph, Darrick, Christian,
> 
> On 2026/1/9 11:01, Hongbo Li wrote:
>> 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>
>> Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
> 
> Could you help review or ack this patch?
> 
> This feature is almost in shape for the upcoming cycle,
> I do hope this iomap patch could be reviewed, thanks!
> 

I have sent the latest version v14. Could you help review or ack based 
on the latest one?

Thanks,
Hongbo

> Thanks,
> Gao Xiang
> 
>> ---
>>   fs/fuse/file.c         | 4 ++--
>>   fs/iomap/buffered-io.c | 6 ++++--
>>   include/linux/iomap.h  | 8 ++++----
>>   3 files changed, 10 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
>> index 01bc894e9c2b..f5d8887c1922 100644
>> --- a/fs/fuse/file.c
>> +++ b/fs/fuse/file.c
>> @@ -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)
>> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
>> index e5c1ca440d93..5f7dcbabbda3 100644
>> --- a/fs/iomap/buffered-io.c
>> +++ b/fs/iomap/buffered-io.c
>> @@ -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;
>> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
>> index 520e967cb501..441d614e9fdf 100644
>> --- a/include/linux/iomap.h
>> +++ b/include/linux/iomap.h
>> @@ -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 */
>

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