fs/ntfs3: Fix sparse warning in ni_fiemap

The interface of fiemap_fill_next_extent_k() was modified
to eliminate the sparse warning.

Fixes: d57431c6 ("fs/ntfs3: Do copy_to_user out of run_lock")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202406271920.hndE8N6D-lkp@intel.com/Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

fs/ntfs3/frecord.c

@@ -1900,13 +1900,13 @@ enum REPARSE_SIGN ni_parse_reparse(struct ntfs_inode *ni, struct ATTRIB *attr,
 
 /*
  * fiemap_fill_next_extent_k - a copy of fiemap_fill_next_extent
- * but it accepts kernel address for fi_extents_start
+ * but it uses 'fe_k' instead of fieinfo->fi_extents_start
  */
 static int fiemap_fill_next_extent_k(struct fiemap_extent_info *fieinfo,
-				     u64 logical, u64 phys, u64 len, u32 flags)
+				     struct fiemap_extent *fe_k, u64 logical,
+				     u64 phys, u64 len, u32 flags)
 {
 	struct fiemap_extent extent;
-	struct fiemap_extent __user *dest = fieinfo->fi_extents_start;
 
 	/* only count the extents */
 	if (fieinfo->fi_extents_max == 0) {
@@ -1930,8 +1930,7 @@ static int fiemap_fill_next_extent_k(struct fiemap_extent_info *fieinfo,
 	extent.fe_length = len;
 	extent.fe_flags = flags;
 
-	dest += fieinfo->fi_extents_mapped;
-	memcpy(dest, &extent, sizeof(extent));
+	memcpy(fe_k + fieinfo->fi_extents_mapped, &extent, sizeof(extent));
 
 	fieinfo->fi_extents_mapped++;
 	if (fieinfo->fi_extents_mapped == fieinfo->fi_extents_max)
@@ -1949,7 +1948,6 @@ int ni_fiemap(struct ntfs_inode *ni, struct fiemap_extent_info *fieinfo,
 	      __u64 vbo, __u64 len)
 {
 	int err = 0;
-	struct fiemap_extent __user *fe_u = fieinfo->fi_extents_start;
 	struct fiemap_extent *fe_k = NULL;
 	struct ntfs_sb_info *sbi = ni->mi.sbi;
 	u8 cluster_bits = sbi->cluster_bits;
@@ -2008,7 +2006,6 @@ int ni_fiemap(struct ntfs_inode *ni, struct fiemap_extent_info *fieinfo,
 		err = -ENOMEM;
 		goto out;
 	}
-	fieinfo->fi_extents_start = fe_k;
 
 	end = vbo + len;
 	alloc_size = le64_to_cpu(attr->nres.alloc_size);
@@ -2098,8 +2095,8 @@ int ni_fiemap(struct ntfs_inode *ni, struct fiemap_extent_info *fieinfo,
 			if (vbo + dlen >= end)
 				flags |= FIEMAP_EXTENT_LAST;
 
-			err = fiemap_fill_next_extent_k(fieinfo, vbo, lbo, dlen,
-							flags);
+			err = fiemap_fill_next_extent_k(fieinfo, fe_k, vbo, lbo,
+							dlen, flags);
 
 			if (err < 0)
 				break;
@@ -2120,7 +2117,7 @@ int ni_fiemap(struct ntfs_inode *ni, struct fiemap_extent_info *fieinfo,
 		if (vbo + bytes >= end)
 			flags |= FIEMAP_EXTENT_LAST;
 
-		err = fiemap_fill_next_extent_k(fieinfo, vbo, lbo, bytes,
+		err = fiemap_fill_next_extent_k(fieinfo, fe_k, vbo, lbo, bytes,
 						flags);
 		if (err < 0)
 			break;
@@ -2137,15 +2134,13 @@ int ni_fiemap(struct ntfs_inode *ni, struct fiemap_extent_info *fieinfo,
 	/*
 	 * Copy to user memory out of lock
 	 */
-	if (copy_to_user(fe_u, fe_k,
+	if (copy_to_user(fieinfo->fi_extents_start, fe_k,
 			 fieinfo->fi_extents_max *
 				 sizeof(struct fiemap_extent))) {
 		err = -EFAULT;
 	}
 
 out:
-	/* Restore original pointer. */
-	fieinfo->fi_extents_start = fe_u;
 	kfree(fe_k);
 	return err;
 }