A stackable file system which uses vm_ops->fault, and does not implement
address_space_operations, cannot use generic_file_splice_read/write, but has
to implement ->splice_read/write itself. These two helper functions are
very useful to such a module.

Signed-off-by: Erez Zadok
---
fs/splice.c | 20 +++++++++++---------
include/linux/splice.h | 5 +++++
2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/fs/splice.c b/fs/splice.c
index 0670c91..62b0db2 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -899,8 +899,8 @@ EXPORT_SYMBOL(generic_splice_sendpage);
/*
* Attempt to initiate a splice from pipe to file.
*/
-static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
- loff_t *ppos, size_t len, unsigned int flags)
+long vfs_splice_from(struct pipe_inode_info *pipe, struct file *out,
+ loff_t *ppos, size_t len, unsigned int flags)
{
int ret;

@@ -916,13 +916,14 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,

return out->f_op->splice_write(pipe, out, ppos, len, flags);
}
+EXPORT_SYMBOL_GPL(vfs_splice_from);

/*
* Attempt to initiate a splice from a file to a pipe.
*/
-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_to(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
{
int ret;

@@ -938,6 +939,7 @@ static long do_splice_to(struct file *in, loff_t *ppos,

return in->f_op->splice_read(in, ppos, pipe, len, flags);
}
+EXPORT_SYMBOL_GPL(vfs_splice_to);

/**
* splice_direct_to_actor - splices data directly between two non-pipes
@@ -1007,7 +1009,7 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
size_t read_len;
loff_t pos = sd->pos;

- ret = do_splice_to(in, &pos, pipe, len, flags);
+ ret = vfs_splice_to(in, &pos, pipe, len, flags);
if (unlikely(ret <= 0))
goto out_release;

@@ -1062,7 +1064,7 @@ static int direct_splice_actor(struct pipe_inode_info *pipe,
{
struct file *file = sd->u.file;

- return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags);
+ return vfs_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags);
}

/**
@@ -1136,7 +1138,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
} else
off = &out->f_pos;

- ret = do_splice_from(pipe, out, off, len, flags);
+ ret = vfs_splice_from(pipe, out, off, len, flags);

if (off_out && copy_to_user(off_out, off, sizeof(loff_t)))
ret = -EFAULT;
@@ -1157,7 +1159,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
} else
off = &in->f_pos;

- ret = do_splice_to(in, off, pipe, len, flags);
+ ret = vfs_splice_to(in, off, pipe, len, flags);

if (off_in && copy_to_user(off_in, off, sizeof(loff_t)))
ret = -EFAULT;
diff --git a/include/linux/splice.h b/include/linux/splice.h
index 528dcb9..4b5727c 100644
--- a/include/linux/splice.h
+++ b/include/linux/splice.h
@@ -70,5 +70,10 @@ extern ssize_t splice_to_pipe(struct pipe_inode_info *,
struct splice_pipe_desc *);
extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
splice_direct_actor *);
+extern long vfs_splice_from(struct pipe_inode_info *pipe, struct file *out,
+ loff_t *ppos, size_t len, unsigned int flags);
+extern long vfs_splice_to(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags);

#endif
--
1.5.2.2

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