From 1b4f42a1e33fec999e94802df13dbd7521315742 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@redhat.com>
Date: Fri, 6 Jul 2018 23:57:03 +0200
Subject: [PATCH] vfs: dedupe: extract helper for a single dedup
Git-commit: 1b4f42a1e33fec999e94802df13dbd7521315742
Patch-mainline: v4.19-rc1
References: bsc#1133769, bsc#1132219

Extract vfs_dedupe_file_range_one() helper to deal with a single dedup
request.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Anthony Iliopoulos <ailiopoulos@suse.com>

---
 fs/read_write.c |   91 ++++++++++++++++++++++++++++++--------------------------
 1 file changed, 50 insertions(+), 41 deletions(-)

--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1972,6 +1972,44 @@
 }
 EXPORT_SYMBOL(vfs_dedupe_file_range_compare);

+static int vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
+				     struct file *dst_file, loff_t dst_pos,
+				     u64 len)
+{
+	s64 ret;
+
+	ret = mnt_want_write_file(dst_file);
+	if (ret)
+		return ret;
+
+	ret = clone_verify_area(dst_file, dst_pos, len, true);
+	if (ret < 0)
+		goto out_drop_write;
+
+	ret = -EINVAL;
+	if (!(capable(CAP_SYS_ADMIN) || (dst_file->f_mode & FMODE_WRITE)))
+		goto out_drop_write;
+
+	ret = -EXDEV;
+	if (src_file->f_path.mnt != dst_file->f_path.mnt)
+		goto out_drop_write;
+
+	ret = -EISDIR;
+	if (S_ISDIR(file_inode(dst_file)->i_mode))
+		goto out_drop_write;
+
+	ret = -EINVAL;
+	if (!dst_file->f_op->dedupe_file_range)
+		goto out_drop_write;
+
+	ret = dst_file->f_op->dedupe_file_range(src_file, src_pos,
+						len, dst_file, dst_pos);
+out_drop_write:
+	mnt_drop_write_file(dst_file);
+
+	return ret;
+}
+
 int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
 {
 	struct file_dedupe_range_info *info;
@@ -1980,10 +2018,7 @@
 	u64 len;
 	int i;
 	int ret;
-	bool is_admin = capable(CAP_SYS_ADMIN);
 	u16 count = same->dest_count;
-	struct file *dst_file;
-	loff_t dst_off;
 	ssize_t deduped;

 	if (!(file->f_mode & FMODE_READ))
@@ -2021,54 +2056,28 @@
 	}

 	for (i = 0, info = same->info; i < count; i++, info++) {
-		struct inode *dst;
 		struct fd dst_fd = fdget(info->dest_fd);
+		struct file *dst_file = dst_fd.file;

-		dst_file = dst_fd.file;
 		if (!dst_file) {
 			info->status = -EBADF;
 			goto next_loop;
 		}
-		dst = file_inode(dst_file);
-
-		ret = mnt_want_write_file(dst_file);
-		if (ret) {
-			info->status = ret;
-			goto next_fdput;
-		}
-
-		dst_off = info->dest_offset;
-		ret = clone_verify_area(dst_file, dst_off, len, true);
-		if (ret < 0) {
-			info->status = ret;
-			goto next_file;
-		}
-		ret = 0;

 		if (info->reserved) {
 			info->status = -EINVAL;
-		} else if (!(is_admin || (dst_file->f_mode & FMODE_WRITE))) {
-			info->status = -EINVAL;
-		} else if (file->f_path.mnt != dst_file->f_path.mnt) {
-			info->status = -EXDEV;
-		} else if (S_ISDIR(dst->i_mode)) {
-			info->status = -EISDIR;
-		} else if (dst_file->f_op->dedupe_file_range == NULL) {
-			info->status = -EINVAL;
-		} else {
-			deduped = dst_file->f_op->dedupe_file_range(file, off,
-							len, dst_file,
-							info->dest_offset);
-			if (deduped == -EBADE)
-				info->status = FILE_DEDUPE_RANGE_DIFFERS;
-			else if (deduped < 0)
-				info->status = deduped;
-			else
-				info->bytes_deduped += deduped;
-		}
+			goto next_fdput;
+ 		}
+
+		deduped = vfs_dedupe_file_range_one(file, off, dst_file,
+						    info->dest_offset, len);
+		if (deduped == -EBADE)
+			info->status = FILE_DEDUPE_RANGE_DIFFERS;
+		else if (deduped < 0)
+			info->status = deduped;
+		else
+			info->bytes_deduped = len;

-next_file:
-		mnt_drop_write_file(dst_file);
 next_fdput:
 		fdput(dst_fd);
 next_loop: