[PATCH 4/9] vfs: Add vfs_copy_file_range() support for pagecache copies
From: Darrick J. Wong <hidden>
Date: 2015-12-19 08:55:45
Also in:
linux-fsdevel, linux-xfs
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
From : Anna Schumaker [off-list ref]
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. I moved the rw_verify_area() calls into the fallback code since some filesystems can handle reflinking a large range. Signed-off-by: Anna Schumaker <redacted> Reviewed-by: Darrick J. Wong <redacted> Reviewed-by: Padraig Brady <redacted> Reviewed-by: Christoph Hellwig <hch@lst.de> --- fs/read_write.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index 97c15ca..6f73af1 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c@@ -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);