ext4: make ext4_punch_hole() support large block size

When preparing for bs > ps support, clean up unnecessary PAGE_SIZE
references in ext4_punch_hole().

Previously, when a hole extended beyond i_size, we aligned the hole end
upwards to PAGE_SIZE to handle partial folio invalidation. Now that
truncate_inode_pages_range() already handles partial folio invalidation
correctly, this alignment is no longer required.

However, to save pointless tail block zeroing, we still keep rounding up
to the block size here.

In addition, as Honza pointed out, when the hole end equals i_size, it
should also be rounded up to the block size. This patch fixes that as well.

Suggested-by: Jan Kara <jack@suse.cz>
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: <20251121090654.631996-5-libaokun@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Author: LiBaokun96

fs/ext4/inode.c

@@ -4408,10 +4408,10 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 
 	/*
 	 * If the hole extends beyond i_size, set the hole to end after
-	 * the page that contains i_size.
+	 * the block that contains i_size to save pointless tail block zeroing.
 	 */
-	if (end > inode->i_size)
-		end = round_up(inode->i_size, PAGE_SIZE);
+	if (end >= inode->i_size)
+		end = round_up(inode->i_size, sb->s_blocksize);
 	if (end > max_end)
 		end = max_end;
 	length = end - offset;