copy_file_range syscall returns -EXDEV if src and dest
file are not on the same file system.
The vfs_copy_file_range() helper, however, knows how to copy
across file systems with do_splice_direct().
Move the enforcement of same file system from the vfs helper
to the syscall code.
A following patch is going to use the vfs_copy_file_range()
helper in overlayfs to copy up between lower and upper
not on the same file system.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/read_write.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index 9dc6e52..6975fe8 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1502,10 +1502,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
(file_out->f_flags & O_APPEND))
return -EBADF;
- /* this could be relaxed once a method supports cross-fs copies */
- if (inode_in->i_sb != inode_out->i_sb)
- return -EXDEV;
-
if (len == 0)
return 0;
@@ -1514,7 +1510,9 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
return ret;
ret = -EOPNOTSUPP;
- if (file_out->f_op->copy_file_range)
+ /* copy_file_range() method does not support cross-fs copies */
+ if (inode_in->i_sb == inode_out->i_sb &&
+ 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)
@@ -1569,6 +1567,14 @@ SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user *, off_in,
pos_out = f_out.file->f_pos;
}
+ /*
+ * vfs_copy_file_range() can do cross-fs copy, but we want to
+ * fulfill the guaranty to userland that copy_file_range syscall
+ * does not allow cross-fs copy
+ */
+ if (file_inode(f_in.file)->i_sb != file_inode(f_out.file)->i_sb)
+ return -EXDEV;
+
ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len,
flags);
if (ret > 0) {
--
2.7.4
--
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