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splice: Make do_splice_to() generic and export it

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Rename do_splice_to() to vfs_splice_read() and export it so that it can be
used as a helper when calling down to a lower layer filesystem as it
performs all the necessary checks[1].

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
cc: Miklos Szeredi <miklos@szeredi.hu>
cc: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: John Hubbard <jhubbard@nvidia.com>
cc: David Hildenbrand <david@redhat.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-unionfs@vger.kernel.org
cc: linux-block@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/CAJfpeguGksS3sCigmRi9hJdUec8qtM9f+_9jC1rJhsXT+dV01w@mail.gmail.com/ [1]
Link: https://lore.kernel.org/r/20230522135018.2742245-6-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
David Howells 2023-05-22 14:49:52 +01:00 committed by Jens Axboe
parent e69f37bce1
commit 6a3f30b8bd
2 changed files with 23 additions and 7 deletions
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27
fs/splice.c
View file

@ -867,12 +867,24 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
return out->f_op->splice_write(pipe, out, ppos, len, flags);
}
/*
* Attempt to initiate a splice from a file to a pipe.
/**
* vfs_splice_read - Read data from a file and splice it into a pipe
* @in: File to splice from
* @ppos: Input file offset
* @pipe: Pipe to splice to
* @len: Number of bytes to splice
* @flags: Splice modifier flags (SPLICE_F_*)
*
* Splice the requested amount of data from the input file to the pipe. This
* is synchronous as the caller must hold the pipe lock across the entire
* operation.
*
* If successful, it returns the amount of data spliced, 0 if it hit the EOF or
* a hole and a negative error code otherwise.
*/
static long do_splice_to(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
long vfs_splice_read(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
unsigned int p_space;
int ret;
@ -895,6 +907,7 @@ static long do_splice_to(struct file *in, loff_t *ppos,
return warn_unsupported(in, "read");
return in->f_op->splice_read(in, ppos, pipe, len, flags);
}
EXPORT_SYMBOL_GPL(vfs_splice_read);
/**
* splice_direct_to_actor - splices data directly between two non-pipes
@ -964,7 +977,7 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
size_t read_len;
loff_t pos = sd->pos, prev_pos = pos;
ret = do_splice_to(in, &pos, pipe, len, flags);
ret = vfs_splice_read(in, &pos, pipe, len, flags);
if (unlikely(ret <= 0))
goto out_release;
@ -1112,7 +1125,7 @@ long splice_file_to_pipe(struct file *in,
pipe_lock(opipe);
ret = wait_for_space(opipe, flags);
if (!ret)
ret = do_splice_to(in, offset, opipe, len, flags);
ret = vfs_splice_read(in, offset, opipe, len, flags);
pipe_unlock(opipe);
if (ret > 0)
wakeup_pipe_readers(opipe);

3
include/linux/splice.h
View file

@ -76,6 +76,9 @@ extern ssize_t splice_to_pipe(struct pipe_inode_info *,
struct splice_pipe_desc *);
extern ssize_t add_to_pipe(struct pipe_inode_info *,
struct pipe_buffer *);
long vfs_splice_read(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags);
extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
splice_direct_actor *);
extern long do_splice(struct file *in, loff_t *off_in,