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splice: kdoc for filemap_splice_read() and copy_splice_read()

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Provide kerneldoc comments for filemap_splice_read() and
copy_splice_read().

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Christian Brauner <brauner@kernel.org>
cc: Christoph Hellwig <hch@lst.de>
cc: Jens Axboe <axboe@kernel.dk>
cc: Steve French <smfrench@gmail.com>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: linux-mm@kvack.org
cc: linux-block@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20230522135018.2742245-32-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
David Howells 2023-05-22 14:50:18 +01:00 committed by Jens Axboe
parent 3fc40265ae
commit 9eee8bd814
2 changed files with 37 additions and 5 deletions
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21
fs/splice.c
View file

@ -299,8 +299,25 @@ void splice_shrink_spd(struct splice_pipe_desc *spd)
kfree(spd->partial);
}
/*
* Copy data from a file into pages and then splice those into the output pipe.
/**
* copy_splice_read - Copy data from a file and splice the copy into a pipe
* @in: The file to read from
* @ppos: Pointer to the file position to read from
* @pipe: The pipe to splice into
* @len: The amount to splice
* @flags: The SPLICE_F_* flags
*
* This function allocates a bunch of pages sufficient to hold the requested
* amount of data (but limited by the remaining pipe capacity), passes it to
* the file's ->read_iter() to read into and then splices the used pages into
* the pipe.
*
* Return: On success, the number of bytes read will be returned and *@ppos
* will be updated if appropriate; 0 will be returned if there is no more data
* to be read; -EAGAIN will be returned if the pipe had no space, and some
* other negative error code will be returned on error. A short read may occur
* if the pipe has insufficient space, we reach the end of the data or we hit a
* hole.
*/
ssize_t copy_splice_read(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe,

21
mm/filemap.c
View file

@ -2871,9 +2871,24 @@ size_t splice_folio_into_pipe(struct pipe_inode_info *pipe,
return spliced;
}
/*
* Splice folios from the pagecache of a buffered (ie. non-O_DIRECT) file into
* a pipe.
/**
* filemap_splice_read - Splice data from a file's pagecache into a pipe
* @in: The file to read from
* @ppos: Pointer to the file position to read from
* @pipe: The pipe to splice into
* @len: The amount to splice
* @flags: The SPLICE_F_* flags
*
* This function gets folios from a file's pagecache and splices them into the
* pipe. Readahead will be called as necessary to fill more folios. This may
* be used for blockdevs also.
*
* Return: On success, the number of bytes read will be returned and *@ppos
* will be updated if appropriate; 0 will be returned if there is no more data
* to be read; -EAGAIN will be returned if the pipe had no space, and some
* other negative error code will be returned on error. A short read may occur
* if the pipe has insufficient space, we reach the end of the data or we hit a
* hole.
*/
ssize_t filemap_splice_read(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe,