f2fs: fix to adjust appropirate defragment pg_end

A length that exceeds the real size of the inode may be
specified from user, although these out-of-range areas
are not mapped, but they still need to be check in
while loop, which is unnecessary.
Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -2626,12 +2626,13 @@ static int f2fs_defragment_range(struct f2fs_sb_info *sbi,
 	bool fragmented = false;
 	int err;
 
-	pg_start = range->start >> PAGE_SHIFT;
-	pg_end = (range->start + range->len) >> PAGE_SHIFT;
-
 	f2fs_balance_fs(sbi, true);
 
 	inode_lock(inode);
+	pg_start = range->start >> PAGE_SHIFT;
+	pg_end = min_t(pgoff_t,
+				(range->start + range->len) >> PAGE_SHIFT,
+				DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE));
 
 	if (is_inode_flag_set(inode, FI_COMPRESS_RELEASED)) {
 		err = -EINVAL;
@@ -2646,8 +2647,9 @@ static int f2fs_defragment_range(struct f2fs_sb_info *sbi,
 	}
 
 	/* writeback all dirty pages in the range */
-	err = filemap_write_and_wait_range(inode->i_mapping, range->start,
-						range->start + range->len - 1);
+	err = filemap_write_and_wait_range(inode->i_mapping,
+						pg_start << PAGE_SHIFT,
+						(pg_end << PAGE_SHIFT) - 1);
 	if (err)
 		goto out;