nilfs2: fix data corruption in dsync block recovery for small block sizes

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix data corruption in dsync block recovery for small block sizes The helper function nilfs_recovery_copy_block() of nilfs_recovery_dsync_blocks(), which recovers data from logs created by data sync writes during a mount after an unclean shutdown, incorrectly calculates the on-page offset when copying repair data to the file's page cache. In environments where the block size is smaller than the page size, this flaw can cause data corruption and leak uninitialized memory bytes during the recovery process. Fix these issues by correcting this byte offset calculation on the page.