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Commit eac70053 authored by Anna Schumaker's avatar Anna Schumaker Committed by Al Viro
Browse files

vfs: Add vfs_copy_file_range() support for pagecache copies 



This allows us to have an in-kernel copy mechanism that avoids frequent
switches between kernel and user space.  This is especially useful so
NFSD can support server-side copies.

The default (flags=0) means to first attempt copy acceleration, but use
the pagecache if that fails.

Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarPadraig Brady <P@draigBrady.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 3db11b2e

fs/read_write.c

+9 −4
Original line number Diff line number Diff line
@@ -1354,8 +1354,7 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, 


	if (!(file_in->f_mode & FMODE_READ) ||

	    !(file_out->f_mode & FMODE_WRITE) ||

	    (file_out->f_flags & O_APPEND) ||

	    !file_out->f_op->copy_file_range)

	    (file_out->f_flags & O_APPEND))

		return -EBADF;



	/* this could be relaxed once a method supports cross-fs copies */
@@ -1369,8 +1368,14 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, 
	if (ret)

		return ret;



	ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out, pos_out,

					      len, flags);

	ret = -EOPNOTSUPP;

	if (file_out->f_op->copy_file_range)

		ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out,

						      pos_out, len, flags);

	if (ret == -EOPNOTSUPP)

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

				len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);



	if (ret > 0) {

		fsnotify_access(file_in);

		add_rchar(current, ret);