ext4: support large block size in mpage_map_and_submit_buffers()

Use the EXT4_PG_TO_LBLK/EXT4_LBLK_TO_PG macros to complete the conversion
between folio indexes and blocks to avoid negative left/right shifts after
supporting blocksize greater than PAGE_SIZE.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Message-ID: <20251121090654.631996-19-libaokun@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Author: LiBaokun96

fs/ext4/inode.c

@@ -2299,15 +2299,14 @@ static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd)
 	struct folio_batch fbatch;
 	unsigned nr, i;
 	struct inode *inode = mpd->inode;
-	int bpp_bits = PAGE_SHIFT - inode->i_blkbits;
 	pgoff_t start, end;
 	ext4_lblk_t lblk;
 	ext4_fsblk_t pblock;
 	int err;
 	bool map_bh = false;
 
-	start = mpd->map.m_lblk >> bpp_bits;
-	end = (mpd->map.m_lblk + mpd->map.m_len - 1) >> bpp_bits;
+	start = EXT4_LBLK_TO_PG(inode, mpd->map.m_lblk);
+	end = EXT4_LBLK_TO_PG(inode, mpd->map.m_lblk + mpd->map.m_len - 1);
 	pblock = mpd->map.m_pblk;
 
 	folio_batch_init(&fbatch);
@@ -2318,7 +2317,7 @@ static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd)
 		for (i = 0; i < nr; i++) {
 			struct folio *folio = fbatch.folios[i];
 
-			lblk = folio->index << bpp_bits;
+			lblk = EXT4_PG_TO_LBLK(inode, folio->index);
 			err = mpage_process_folio(mpd, folio, &lblk, &pblock,
 						 &map_bh);
 			/*