mke2fs: set free blocks accurately for groups has GDT

This patch is part of the preparation required to allow
GDT blocks expand beyond a single group,
it introduces 2 new interfaces:
- ext2fs_count_used_blocks(), to return the blocks used
in the bitmap range.
- ext2fs_reserve_super_and_bgd2() to return blocks used by
superblock/GDT blocks for every group, by looking up blocks used.

Signed-off-by: Li Dongyang <dongyangli@ddn.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://lore.kernel.org/r/20230925060801.1397581-1-dongyangli@ddn.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

6 files changed, 73 insertions, 20 deletions

diff --git a/lib/ext2fs/alloc_sb.c b/lib/ext2fs/alloc_sb.c
index 8530b40f6..e92739ecc 100644
--- a/lib/ext2fs/alloc_sb.c
+++ b/lib/ext2fs/alloc_sb.c
@@ -46,8 +46,7 @@ int ext2fs_reserve_super_and_bgd(ext2_filsys fs,
 				 ext2fs_block_bitmap bmap)
 {
 	blk64_t	super_blk, old_desc_blk, new_desc_blk;
-	blk_t	used_blks;
-	int	old_desc_blocks, num_blocks;
+	blk_t	used_blks, old_desc_blocks, num_blocks;
 
 	ext2fs_super_and_bgd_loc2(fs, group, &super_blk,
 				  &old_desc_blk, &new_desc_blk, &used_blks);
@@ -79,3 +78,28 @@ int ext2fs_reserve_super_and_bgd(ext2_filsys fs,
 
 	return num_blocks  ;
 }
+
+/*
+ * This function reserves the superblock and block group descriptors
+ * for a given block group and returns the number of blocks used by the
+ * super block and group descriptors by looking up the block bitmap.
+ */
+errcode_t ext2fs_reserve_super_and_bgd2(ext2_filsys fs,
+				        dgrp_t group,
+				        ext2fs_block_bitmap bmap,
+				        blk_t *desc_blocks)
+{
+	blk64_t	num_blocks;
+	errcode_t retval = 0;
+
+	ext2fs_reserve_super_and_bgd(fs, group, bmap);
+
+	retval = ext2fs_count_used_blocks(fs,
+					ext2fs_group_first_block2(fs, group),
+					ext2fs_group_last_block2(fs, group),
+					&num_blocks);
+	if (!retval)
+		*desc_blocks = num_blocks;
+
+	return retval;
+}
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 9cea4b69a..e04355134 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -847,6 +847,10 @@ errcode_t ext2fs_alloc_range(ext2_filsys fs, int flags, blk64_t goal,
 extern int ext2fs_reserve_super_and_bgd(ext2_filsys fs,
 					dgrp_t group,
 					ext2fs_block_bitmap bmap);
+extern errcode_t ext2fs_reserve_super_and_bgd2(ext2_filsys fs,
+					       dgrp_t group,
+					       ext2fs_block_bitmap bmap,
+					       blk_t *desc_blocks);
 extern void ext2fs_set_block_alloc_stats_callback(ext2_filsys fs,
 						  void (*func)(ext2_filsys fs,
 							       blk64_t blk,
@@ -1535,6 +1539,8 @@ errcode_t ext2fs_convert_subcluster_bitmap(ext2_filsys fs,
 					   ext2fs_block_bitmap *bitmap);
 errcode_t ext2fs_count_used_clusters(ext2_filsys fs, blk64_t start,
 				     blk64_t end, blk64_t *out);
+errcode_t ext2fs_count_used_blocks(ext2_filsys fs, blk64_t start,
+				   blk64_t end, blk64_t *out);
 extern unsigned int ext2fs_list_backups(ext2_filsys fs, unsigned int *three,
 				unsigned int *five, unsigned int *seven);
 
diff --git a/lib/ext2fs/gen_bitmap64.c b/lib/ext2fs/gen_bitmap64.c
index 4289e8155..5936dcf53 100644
--- a/lib/ext2fs/gen_bitmap64.c
+++ b/lib/ext2fs/gen_bitmap64.c
@@ -945,8 +945,8 @@ errcode_t ext2fs_find_first_set_generic_bmap(ext2fs_generic_bitmap bitmap,
 	return ENOENT;
 }
 
-errcode_t ext2fs_count_used_clusters(ext2_filsys fs, blk64_t start,
-				     blk64_t end, blk64_t *out)
+errcode_t ext2fs_count_used_blocks(ext2_filsys fs, blk64_t start,
+				   blk64_t end, blk64_t *out)
 {
 	blk64_t		next;
 	blk64_t		tot_set = 0;
@@ -976,6 +976,19 @@ errcode_t ext2fs_count_used_clusters(ext2_filsys fs, blk64_t start,
 	}
 
 	if (!retval)
+		*out = tot_set;
+	return retval;
+}
+
+errcode_t ext2fs_count_used_clusters(ext2_filsys fs, blk64_t start,
+				     blk64_t end, blk64_t *out)
+{
+	blk64_t		tot_set = 0;
+	errcode_t	retval = 0;
+
+	retval = ext2fs_count_used_blocks(fs, start, end, &tot_set);
+
+	if (!retval)
 		*out = EXT2FS_NUM_B2C(fs, tot_set);
 	return retval;
 }
diff --git a/lib/ext2fs/initialize.c b/lib/ext2fs/initialize.c
index d5f9a0f5b..e5286a007 100644
--- a/lib/ext2fs/initialize.c
+++ b/lib/ext2fs/initialize.c
@@ -524,6 +524,15 @@ ipg_retry:
 	csum_flag = ext2fs_has_group_desc_csum(fs);
 	reserved_inos = super->s_first_ino;
 	for (i = 0; i < fs->group_desc_count; i++) {
+		blk_t grp_free_blocks;
+		ext2_ino_t inodes;
+
+		retval = ext2fs_reserve_super_and_bgd2(fs, i,
+						       fs->block_map,
+						       &numblocks);
+		if (retval)
+			goto cleanup;
+
 		/*
 		 * Don't set the BLOCK_UNINIT group for the last group
 		 * because the block bitmap needs to be padded.
@@ -533,24 +542,25 @@ ipg_retry:
 				ext2fs_bg_flags_set(fs, i,
 						    EXT2_BG_BLOCK_UNINIT);
 			ext2fs_bg_flags_set(fs, i, EXT2_BG_INODE_UNINIT);
-			numblocks = super->s_inodes_per_group;
+			inodes = super->s_inodes_per_group;
 			if (reserved_inos) {
-				if (numblocks > reserved_inos) {
-					numblocks -= reserved_inos;
+				if (inodes > reserved_inos) {
+					inodes -= reserved_inos;
 					reserved_inos = 0;
 				} else {
-					reserved_inos -= numblocks;
-					numblocks = 0;
+					reserved_inos -= inodes;
+					inodes = 0;
 				}
 			}
-			ext2fs_bg_itable_unused_set(fs, i, numblocks);
+			ext2fs_bg_itable_unused_set(fs, i, inodes);
 		}
-		numblocks = ext2fs_reserve_super_and_bgd(fs, i, fs->block_map);
-		if (fs->super->s_log_groups_per_flex)
+
+		if (!fs->super->s_log_groups_per_flex)
 			numblocks += 2 + fs->inode_blocks_per_group;
 
-		free_blocks += numblocks;
-		ext2fs_bg_free_blocks_count_set(fs, i, numblocks);
+		grp_free_blocks = ext2fs_group_blocks_count(fs, i) - numblocks;
+		free_blocks += grp_free_blocks;
+		ext2fs_bg_free_blocks_count_set(fs, i, grp_free_blocks);
 		ext2fs_bg_free_inodes_count_set(fs, i, fs->super->s_inodes_per_group);
 		ext2fs_bg_used_dirs_count_set(fs, i, 0);
 		ext2fs_group_desc_csum_set(fs, i);
diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
index fd56a9acd..c3611e0d8 100644
--- a/lib/ext2fs/openfs.c
+++ b/lib/ext2fs/openfs.c
@@ -330,13 +330,13 @@ retry:
 	}
 
 	/* Enforce the block group descriptor size */
-	if (!(flags & EXT2_FLAG_IGNORE_SB_ERRORS) &&
-	    ext2fs_has_feature_64bit(fs->super)) {
+	if (ext2fs_has_feature_64bit(fs->super)) {
 		unsigned desc_size = fs->super->s_desc_size;
 
-		if ((desc_size < EXT2_MIN_DESC_SIZE_64BIT) ||
-		    (desc_size > EXT2_MAX_DESC_SIZE) ||
-		    (desc_size & (desc_size - 1)) != 0) {
+		if (desc_size < EXT2_MIN_DESC_SIZE_64BIT ||
+		    (!(flags & EXT2_FLAG_IGNORE_SB_ERRORS) &&
+		     ((desc_size > EXT2_MAX_DESC_SIZE) ||
+		      (desc_size & (desc_size - 1)) != 0))) {
 			retval = EXT2_ET_BAD_DESC_SIZE;
 			goto cleanup;
 		}
diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index aebf050f6..1c5de6869 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -3546,7 +3546,7 @@ no_journal:
 			       fs->super->s_mmp_update_interval);
 	}
 
-	overhead += fs->super->s_first_data_block;
+	overhead += EXT2FS_NUM_B2C(fs, fs->super->s_first_data_block);
 	if (!super_only)
 		fs->super->s_overhead_clusters = overhead;