vfs: combine the clone and dedupe into a single remap_file_range

Combine the clone_file_range and dedupe_file_range operations into a
single remap_file_range file operation dispatch since they're
fundamentally the same operation.  The differences between the two can
be made in the prep functions.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

2 files changed, 18 insertions, 7 deletions

diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 7b7b845c490a..e6d4466268dd 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -622,3 +622,8 @@ 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]
+	->clone_file_range() and ->dedupe_file_range have been replaced with
+	->remap_file_range().  See Documentation/filesystems/vfs.txt for more
+	information.
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index a6c6a8af48a2..6f5babfee27b 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -883,8 +883,9 @@ struct file_operations {
 	unsigned (*mmap_capabilities)(struct file *);
 #endif
 	ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, loff_t, size_t, unsigned int);
-	int (*clone_file_range)(struct file *, loff_t, struct file *, loff_t, u64);
-	int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t, u64);
+	int (*remap_file_range)(struct file *file_in, loff_t pos_in,
+				struct file *file_out, loff_t pos_out,
+				u64 len, unsigned int remap_flags);
 	int (*fadvise)(struct file *, loff_t, loff_t, int);
 };
 
@@ -960,11 +961,16 @@ otherwise noted.
 
   copy_file_range: called by the copy_file_range(2) system call.
 
-  clone_file_range: called by the ioctl(2) system call for FICLONERANGE and
-	FICLONE commands.
-
-  dedupe_file_range: called by the ioctl(2) system call for FIDEDUPERANGE
-	command.
+  remap_file_range: called by the ioctl(2) system call for FICLONERANGE and
+	FICLONE and FIDEDUPERANGE commands to remap file ranges.  An
+	implementation should remap len bytes at pos_in of the source file into
+	the dest file at pos_out.  Implementations must handle callers passing
+	in len == 0; this means "remap to the end of the source file".  The
+	return value should be zero if all bytes were remapped, or the usual
+	negative error code if the remapping did not succeed completely.
+	The remap_flags parameter accepts REMAP_FILE_* flags.  If
+	REMAP_FILE_DEDUP is set then the implementation must only remap if the
+	requested file ranges have identical contents.
 
   fadvise: possibly called by the fadvise64() system call.