Commit f16acc9d authored by Dave Chinner's avatar Dave Chinner Committed by Darrick J. Wong
Browse files

vfs: introduce generic_copy_file_range() 



Right now if vfs_copy_file_range() does not use any offload
mechanism, it falls back to calling do_splice_direct(). This fails
to do basic sanity checks on the files being copied. Before we
start adding this necessarily functionality to the fallback path,
separate it out into generic_copy_file_range().

generic_copy_file_range() has the same prototype as
->copy_file_range() so that filesystems can use it in their custom
->copy_file_range() method if they so choose.

Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent d1fdb6d8

fs/read_write.c

+32 −3
Original line number Diff line number Diff line
@@ -1565,6 +1565,36 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, 
}

#endif



/**

 * generic_copy_file_range - copy data between two files

 * @file_in:	file structure to read from

 * @pos_in:	file offset to read from

 * @file_out:	file structure to write data to

 * @pos_out:	file offset to write data to

 * @len:	amount of data to copy

 * @flags:	copy flags

 *

 * This is a generic filesystem helper to copy data from one file to another.

 * It has no constraints on the source or destination file owners - the files

 * can belong to different superblocks and different filesystem types. Short

 * copies are allowed.

 *

 * This should be called from the @file_out filesystem, as per the

 * ->copy_file_range() method.

 *

 * Returns the number of bytes copied or a negative error indicating the

 * failure.

 */



ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,

				struct file *file_out, loff_t pos_out,

				size_t len, unsigned int flags)

{

	return do_splice_direct(file_in, &pos_in, file_out, &pos_out,

				len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);

}

EXPORT_SYMBOL(generic_copy_file_range);



/*

 * copy_file_range() differs from regular file read and write in that it

 * specifically allows return partial success.  When it does so is up to
@@ -1632,9 +1662,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, 
			goto done;

	}



	ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,

			len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);



	ret = generic_copy_file_range(file_in, pos_in, file_out, pos_out, len,

				      flags);

done:

	if (ret > 0) {

		fsnotify_access(file_in);

include/linux/fs.h

+3 −0
Original line number Diff line number Diff line
@@ -1889,6 +1889,9 @@ extern ssize_t vfs_readv(struct file *, const struct iovec __user *, 
		unsigned long, loff_t *, rwf_t);

extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,

				   loff_t, size_t, unsigned int);

extern ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,

				       struct file *file_out, loff_t pos_out,

				       size_t len, unsigned int flags);

extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,

					 struct file *file_out, loff_t pos_out,

					 loff_t *count,

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