Merge tag 'copy-file-range-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull copy_file_range updates from Darrick Wong:
 "This fixes numerous parameter checking problems and inconsistent
  behaviors in the new(ish) copy_file_range system call.

  Now the system call will actually check its range parameters
  correctly; refuse to copy into files for which the caller does not
  have sufficient privileges; update mtime and strip setuid like file
  writes are supposed to do; and allows copying up to the EOF of the
  source file instead of failing the call like we used to.

  Summary:

   - Create a generic copy_file_range handler and make individual
     filesystems responsible for calling it (i.e. no more assuming that
     do_splice_direct will work or is appropriate)

   - Refactor copy_file_range and remap_range parameter checking where
     they are the same

   - Install missing copy_file_range parameter checking(!)

   - Remove suid/sgid and update mtime like any other file write

   - Change the behavior so that a copy range crossing the source file's
     eof will result in a short copy to the source file's eof instead of
     EINVAL

   - Permit filesystems to decide if they want to handle
     cross-superblock copy_file_range in their local handlers"

* tag 'copy-file-range-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  fuse: copy_file_range needs to strip setuid bits and update timestamps
  vfs: allow copy_file_range to copy across devices
  xfs: use file_modified() helper
  vfs: introduce file_modified() helper
  vfs: add missing checks to copy_file_range
  vfs: remove redundant checks from generic_remap_checks()
  vfs: introduce generic_file_rw_checks()
  vfs: no fallback for ->copy_file_range
  vfs: introduce generic_copy_file_range()

1 files changed, 20 insertions, 3 deletions

diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index cf42a8b939e3..f4157eb1f69d 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -129,10 +129,13 @@ nfs4_file_flush(struct file *file, fl_owner_t id)
 }
 
 #ifdef CONFIG_NFS_V4_2
-static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
-				    struct file *file_out, loff_t pos_out,
-				    size_t count, unsigned int flags)
+static ssize_t __nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
+				      struct file *file_out, loff_t pos_out,
+				      size_t count, unsigned int flags)
 {
+	/* Only offload copy if superblock is the same */
+	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
+		return -EXDEV;
 	if (!nfs_server_capable(file_inode(file_out), NFS_CAP_COPY))
 		return -EOPNOTSUPP;
 	if (file_inode(file_in) == file_inode(file_out))
@@ -140,6 +143,20 @@ static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
 	return nfs42_proc_copy(file_in, pos_in, file_out, pos_out, count);
 }
 
+static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
+				    struct file *file_out, loff_t pos_out,
+				    size_t count, unsigned int flags)
+{
+	ssize_t ret;
+
+	ret = __nfs4_copy_file_range(file_in, pos_in, file_out, pos_out, count,
+				     flags);
+	if (ret == -EOPNOTSUPP || ret == -EXDEV)
+		ret = generic_copy_file_range(file_in, pos_in, file_out,
+					      pos_out, count, flags);
+	return ret;
+}
+
 static loff_t nfs4_file_llseek(struct file *filep, loff_t offset, int whence)
 {
 	loff_t ret;