1 files changed, 39 insertions, 25 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a990a9045139..802a628e9f7d 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3488,6 +3488,8 @@ static int btrfs_extent_same_range(struct inode *src, u64 loff, u64 olen,
 			const u64 sz = BTRFS_I(src)->root->fs_info->sectorsize;
 
 			len = round_down(i_size_read(src), sz) - loff;
+			if (len == 0)
+				return 0;
 			olen = len;
 		}
 	}
@@ -3629,26 +3631,6 @@ out_unlock:
 	return ret;
 }
 
-int btrfs_dedupe_file_range(struct file *src_file, loff_t src_loff,
-			    struct file *dst_file, loff_t dst_loff,
-			    u64 olen)
-{
-	struct inode *src = file_inode(src_file);
-	struct inode *dst = file_inode(dst_file);
-	u64 bs = BTRFS_I(src)->root->fs_info->sb->s_blocksize;
-
-	if (WARN_ON_ONCE(bs < PAGE_SIZE)) {
-		/*
-		 * Btrfs does not support blocksize < page_size. As a
-		 * result, btrfs_cmp_data() won't correctly handle
-		 * this situation without an update.
-		 */
-		return -EINVAL;
-	}
-
-	return btrfs_extent_same(src, src_loff, olen, dst, dst_loff);
-}
-
 static int clone_finish_inode_update(struct btrfs_trans_handle *trans,
 				     struct inode *inode,
 				     u64 endoff,
@@ -4277,9 +4259,17 @@ static noinline int btrfs_clone_files(struct file *file, struct file *file_src,
 		goto out_unlock;
 	if (len == 0)
 		olen = len = src->i_size - off;
-	/* if we extend to eof, continue to block boundary */
-	if (off + len == src->i_size)
+	/*
+	 * If we extend to eof, continue to block boundary if and only if the
+	 * destination end offset matches the destination file's size, otherwise
+	 * we would be corrupting data by placing the eof block into the middle
+	 * of a file.
+	 */
+	if (off + len == src->i_size) {
+		if (!IS_ALIGNED(len, bs) && destoff + len < inode->i_size)
+			goto out_unlock;
 		len = ALIGN(src->i_size, bs) - off;
+	}
 
 	if (len == 0) {
 		ret = 0;
@@ -4350,10 +4340,34 @@ out_unlock:
 	return ret;
 }
 
-int btrfs_clone_file_range(struct file *src_file, loff_t off,
-		struct file *dst_file, loff_t destoff, u64 len)
+loff_t btrfs_remap_file_range(struct file *src_file, loff_t off,
+		struct file *dst_file, loff_t destoff, loff_t len,
+		unsigned int remap_flags)
 {
-	return btrfs_clone_files(dst_file, src_file, off, len, destoff);
+	int ret;
+
+	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
+		return -EINVAL;
+
+	if (remap_flags & REMAP_FILE_DEDUP) {
+		struct inode *src = file_inode(src_file);
+		struct inode *dst = file_inode(dst_file);
+		u64 bs = BTRFS_I(src)->root->fs_info->sb->s_blocksize;
+
+		if (WARN_ON_ONCE(bs < PAGE_SIZE)) {
+			/*
+			 * Btrfs does not support blocksize < page_size. As a
+			 * result, btrfs_cmp_data() won't correctly handle
+			 * this situation without an update.
+			 */
+			return -EINVAL;
+		}
+
+		ret = btrfs_extent_same(src, off, len, dst, destoff);
+	} else {
+		ret = btrfs_clone_files(dst_file, src_file, off, len, destoff);
+	}
+	return ret < 0 ? ret : len;
 }
 
 static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp)