[v6,02/12] VFS: move cross device copy_file_range() check into filesystems

Commit Message

Olga Kornievskaia Oct. 29, 2018, 7:03 p.m. UTC

From: Olga Kornievskaia <[e-mail]>

This patch makes it the responsibility of individual filesystems to
allow or deny cross device copies.  Both NFS and CIFS have operations
for cross-server copies, and later patches will implement this feature.

Note that as of this patch, the copy_file_range() function might be passed
superblocks from different filesystem types. -EXDEV should be returned
if cross device copies aren't supported.

Reviewed-by: Amir Goldstein <[e-mail]>
Reviewed-by: Matthew Wilcox <[e-mail]>
Reviewed-by: Steve French <[e-mail]>
Reviewed-by: Jeff Layton <[e-mail]>
Signed-off-by: Olga Kornievskaia <[e-mail]>
---
 Documentation/filesystems/porting | 7 +++++++
 fs/cifs/cifsfs.c                  | 3 +++
 fs/nfs/nfs4file.c                 | 3 +++
 fs/overlayfs/file.c               | 3 +++
 fs/read_write.c                   | 5 ++---
 5 files changed, 18 insertions(+), 3 deletions(-)

Patch

diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 7b7b845..897e1e7 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -622,3 +622,10 @@  in your dentry operations instead.
 	alloc_file_clone(file, flags, ops) does not affect any caller's references.
 	On success you get a new struct file sharing the mount/dentry with the
 	original, on failure - ERR_PTR().
+--
+[mandatory]
+	->copy_file_range() may now be passed files which belong to two
+	different superblocks of the same file system type or which belong
+	to two different filesystems types all together. As before, the
+	destination's copy_file_range() is the function which is called.
+	If it cannot copy ranges from the source, it should return -EXDEV.
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 7065426..ca8fc87 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -1114,6 +1114,9 @@  static ssize_t cifs_copy_file_range(struct file *src_file, loff_t off,
 	unsigned int xid = get_xid();
 	ssize_t rc;
 
+	if (file_inode(src_file)->i_sb != file_inode(dst_file)->i_sb)
+		return -EXDEV;
+
 	rc = cifs_file_copychunk_range(xid, src_file, off, dst_file, destoff,
 					len, flags);
 	free_xid(xid);
diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index 4288a6e..5a73c90 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -135,6 +135,9 @@  static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
 {
 	ssize_t ret;
 
+	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
+		return -EXDEV;
+
 	if (file_inode(file_in) == file_inode(file_out))
 		return -EINVAL;
 retry:
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index aeaefd2..0331e33 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -483,6 +483,9 @@  static ssize_t ovl_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)
 {
+	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
+		return -EXDEV;
+
 	return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, flags,
 			    OVL_COPY);
 }
diff --git a/fs/read_write.c b/fs/read_write.c
index 70f6939..cff59bd 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1594,11 +1594,10 @@  ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 		}
 	}
 
-	if (inode_in->i_sb == inode_out->i_sb &&
-	    file_out->f_op->copy_file_range) {
+	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)
+		if (ret != -EOPNOTSUPP && ret != -EXDEV)
 			goto done;
 	}