ext4: fix incorrect group count in ext4_fill_super error message

ext4_fill_super doublechecks the number of groups before mounting; if
that check fails, the resulting error message prints the group count
from the ext4_sb_info sbi, which hasn't been set yet. Print the freshly
computed group count instead (which at that point has just been computed
in "blocks_count").

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Fixes: 4ec1102 ("ext4: Add sanity checks for the superblock before mounting the filesystem")
Link: https://lore.kernel.org/r/8b957cd1513fcc4550fe675c10bcce2175c33a49.1585431964.git.josh@joshtriplett.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/super.c

@@ -4305,9 +4305,9 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 			EXT4_BLOCKS_PER_GROUP(sb) - 1);
 	do_div(blocks_count, EXT4_BLOCKS_PER_GROUP(sb));
 	if (blocks_count > ((uint64_t)1<<32) - EXT4_DESC_PER_BLOCK(sb)) {
-		ext4_msg(sb, KERN_WARNING, "groups count too large: %u "
+		ext4_msg(sb, KERN_WARNING, "groups count too large: %llu "
 		       "(block count %llu, first data block %u, "
-		       "blocks per group %lu)", sbi->s_groups_count,
+		       "blocks per group %lu)", blocks_count,
 		       ext4_blocks_count(es),
 		       le32_to_cpu(es->s_first_data_block),
 		       EXT4_BLOCKS_PER_GROUP(sb));