ext4: Use helper function to access group descriptor and its fields

The descriptor size is variable, thus array indices are not generically
applicable. The larger group descriptors also contain e.g. high parts
of block numbers, which have to be read and written.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>

1 files changed, 65 insertions, 60 deletions

diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
index b745d8d450..90e7602e2a 100644
--- a/fs/ext4/ext4_common.c
+++ b/fs/ext4/ext4_common.c
@@ -393,7 +393,7 @@ uint16_t ext4fs_checksum_update(uint32_t i)
 	uint16_t crc = 0;
 	__le32 le32_i = cpu_to_le32(i);
 
-	desc = (struct ext2_block_group *)&fs->bgd[i];
+	desc = ext4fs_get_group_descriptor(fs, i);
 	if (le32_to_cpu(fs->sb->feature_ro_compat) & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
 		int offset = offsetof(struct ext2_block_group, bg_checksum);
 
@@ -933,39 +933,41 @@ uint32_t ext4fs_get_new_blk_no(void)
 	char *zero_buffer = zalloc(fs->blksz);
 	if (!journal_buffer || !zero_buffer)
 		goto fail;
-	struct ext2_block_group *bgd = (struct ext2_block_group *)fs->gdtable;
 
 	if (fs->first_pass_bbmap == 0) {
 		for (i = 0; i < fs->no_blkgrp; i++) {
-			if (le16_to_cpu(bgd[i].free_blocks)) {
-				if (le16_to_cpu(bgd[i].bg_flags) & EXT4_BG_BLOCK_UNINIT) {
-					uint16_t new_flags;
-					put_ext4((uint64_t)le32_to_cpu(bgd[i].block_id) * fs->blksz,
-						 zero_buffer, fs->blksz);
-					new_flags = le16_to_cpu(bgd[i].bg_flags) & ~EXT4_BG_BLOCK_UNINIT;
-					bgd[i].bg_flags = cpu_to_le16(new_flags);
+			struct ext2_block_group *bgd = NULL;
+			bgd = ext4fs_get_group_descriptor(fs, i);
+			if (ext4fs_bg_get_free_blocks(bgd, fs)) {
+				uint16_t bg_flags = ext4fs_bg_get_flags(bgd);
+				uint64_t b_bitmap_blk =
+					ext4fs_bg_get_block_id(bgd, fs);
+				if (bg_flags & EXT4_BG_BLOCK_UNINIT) {
 					memcpy(fs->blk_bmaps[i], zero_buffer,
 					       fs->blksz);
+					put_ext4(b_bitmap_blk * fs->blksz,
+						 fs->blk_bmaps[i], fs->blksz);
+					bg_flags &= ~EXT4_BG_BLOCK_UNINIT;
+					ext4fs_bg_set_flags(bgd, bg_flags);
 				}
 				fs->curr_blkno =
 				    _get_new_blk_no(fs->blk_bmaps[i]);
 				if (fs->curr_blkno == -1)
-					/* if block bitmap is completely fill */
+					/* block bitmap is completely filled */
 					continue;
 				fs->curr_blkno = fs->curr_blkno +
 						(i * fs->blksz * 8);
 				fs->first_pass_bbmap++;
-				ext4fs_bg_free_blocks_dec(&bgd[i]);
+				ext4fs_bg_free_blocks_dec(bgd);
 				ext4fs_sb_free_blocks_dec(fs->sb);
-				status = ext4fs_devread(
-							(lbaint_t)le32_to_cpu(bgd[i].block_id) *
-							fs->sect_perblk, 0,
-							fs->blksz,
+				status = ext4fs_devread(b_bitmap_blk *
+							fs->sect_perblk,
+							0, fs->blksz,
 							journal_buffer);
 				if (status == 0)
 					goto fail;
 				if (ext4fs_log_journal(journal_buffer,
-							le32_to_cpu(bgd[i].block_id)))
+						       b_bitmap_blk))
 					goto fail;
 				goto success;
 			} else {
@@ -992,7 +994,9 @@ restart:
 		if (bg_idx >= fs->no_blkgrp)
 			goto fail;
 
-		if (bgd[bg_idx].free_blocks == 0) {
+		struct ext2_block_group *bgd = NULL;
+		bgd = ext4fs_get_group_descriptor(fs, bg_idx);
+		if (ext4fs_bg_get_free_blocks(bgd, fs) == 0) {
 			debug("block group %u is full. Skipping\n", bg_idx);
 			fs->curr_blkno = (bg_idx + 1) * blk_per_grp;
 			if (fs->blksz == 1024)
@@ -1000,13 +1004,14 @@ restart:
 			goto restart;
 		}
 
-		if (le16_to_cpu(bgd[bg_idx].bg_flags) & EXT4_BG_BLOCK_UNINIT) {
-			uint16_t new_flags;
-			put_ext4((uint64_t)le32_to_cpu(bgd[bg_idx].block_id) * fs->blksz,
-				 zero_buffer, fs->blksz);
+		uint16_t bg_flags = ext4fs_bg_get_flags(bgd);
+		uint64_t b_bitmap_blk = ext4fs_bg_get_block_id(bgd, fs);
+		if (bg_flags & EXT4_BG_BLOCK_UNINIT) {
 			memcpy(fs->blk_bmaps[bg_idx], zero_buffer, fs->blksz);
-			new_flags = le16_to_cpu(bgd[bg_idx].bg_flags) & ~EXT4_BG_BLOCK_UNINIT;
-			bgd[bg_idx].bg_flags = cpu_to_le16(new_flags);
+			put_ext4(b_bitmap_blk * fs->blksz,
+				 zero_buffer, fs->blksz);
+			bg_flags &= ~EXT4_BG_BLOCK_UNINIT;
+			ext4fs_bg_set_flags(bgd, bg_flags);
 		}
 
 		if (ext4fs_set_block_bmap(fs->curr_blkno, fs->blk_bmaps[bg_idx],
@@ -1019,19 +1024,16 @@ restart:
 
 		/* journal backup */
 		if (prev_bg_bitmap_index != bg_idx) {
-			status = ext4fs_devread(
-						(lbaint_t)le32_to_cpu(bgd[bg_idx].block_id)
-						* fs->sect_perblk,
+			status = ext4fs_devread(b_bitmap_blk * fs->sect_perblk,
 						0, fs->blksz, journal_buffer);
 			if (status == 0)
 				goto fail;
-			if (ext4fs_log_journal(journal_buffer,
-						le32_to_cpu(bgd[bg_idx].block_id)))
+			if (ext4fs_log_journal(journal_buffer, b_bitmap_blk))
 				goto fail;
 
 			prev_bg_bitmap_index = bg_idx;
 		}
-		ext4fs_bg_free_blocks_dec(&bgd[bg_idx]);
+		ext4fs_bg_free_blocks_dec(bgd);
 		ext4fs_sb_free_blocks_dec(fs->sb);
 		goto success;
 	}
@@ -1059,46 +1061,49 @@ int ext4fs_get_new_inode_no(void)
 	char *zero_buffer = zalloc(fs->blksz);
 	if (!journal_buffer || !zero_buffer)
 		goto fail;
-	struct ext2_block_group *bgd = (struct ext2_block_group *)fs->gdtable;
 	int has_gdt_chksum = le32_to_cpu(fs->sb->feature_ro_compat) &
 		EXT4_FEATURE_RO_COMPAT_GDT_CSUM ? 1 : 0;
 
 	if (fs->first_pass_ibmap == 0) {
 		for (i = 0; i < fs->no_blkgrp; i++) {
-			if (bgd[i].free_inodes) {
+			uint32_t free_inodes;
+			struct ext2_block_group *bgd = NULL;
+			bgd = ext4fs_get_group_descriptor(fs, i);
+			free_inodes = ext4fs_bg_get_free_inodes(bgd, fs);
+			if (free_inodes) {
+				uint16_t bg_flags = ext4fs_bg_get_flags(bgd);
+				uint64_t i_bitmap_blk =
+					ext4fs_bg_get_inode_id(bgd, fs);
 				if (has_gdt_chksum)
-					bgd[i].bg_itable_unused =
-						bgd[i].free_inodes;
-				if (le16_to_cpu(bgd[i].bg_flags) & EXT4_BG_INODE_UNINIT) {
-					int new_flags;
-					put_ext4((uint64_t)le32_to_cpu(bgd[i].inode_id) * fs->blksz,
+					bgd->bg_itable_unused = free_inodes;
+				if (bg_flags & EXT4_BG_INODE_UNINIT) {
+					put_ext4(i_bitmap_blk * fs->blksz,
 						 zero_buffer, fs->blksz);
-					new_flags = le16_to_cpu(bgd[i].bg_flags) & ~EXT4_BG_INODE_UNINIT;
-					bgd[i].bg_flags = cpu_to_le16(new_flags);
+					bg_flags &= ~EXT4_BG_INODE_UNINIT;
+					ext4fs_bg_set_flags(bgd, bg_flags);
 					memcpy(fs->inode_bmaps[i],
 					       zero_buffer, fs->blksz);
 				}
 				fs->curr_inode_no =
 				    _get_new_inode_no(fs->inode_bmaps[i]);
 				if (fs->curr_inode_no == -1)
-					/* if block bitmap is completely fill */
+					/* inode bitmap is completely filled */
 					continue;
 				fs->curr_inode_no = fs->curr_inode_no +
 							(i * inodes_per_grp);
 				fs->first_pass_ibmap++;
-				ext4fs_bg_free_inodes_dec(&bgd[i]);
+				ext4fs_bg_free_inodes_dec(bgd);
 				if (has_gdt_chksum)
-					ext4fs_bg_itable_unused_dec(&bgd[i]);
+					ext4fs_bg_itable_unused_dec(bgd);
 				ext4fs_sb_free_inodes_dec(fs->sb);
-				status = ext4fs_devread(
-							(lbaint_t)le32_to_cpu(bgd[i].inode_id) *
-							fs->sect_perblk, 0,
-							fs->blksz,
+				status = ext4fs_devread(i_bitmap_blk *
+							fs->sect_perblk,
+							0, fs->blksz,
 							journal_buffer);
 				if (status == 0)
 					goto fail;
 				if (ext4fs_log_journal(journal_buffer,
-							le32_to_cpu(bgd[i].inode_id)))
+						       i_bitmap_blk))
 					goto fail;
 				goto success;
 			} else
@@ -1110,12 +1115,16 @@ restart:
 		fs->curr_inode_no++;
 		/* get the blockbitmap index respective to blockno */
 		ibmap_idx = fs->curr_inode_no / inodes_per_grp;
-		if (le16_to_cpu(bgd[ibmap_idx].bg_flags) & EXT4_BG_INODE_UNINIT) {
-			int new_flags;
-			put_ext4((uint64_t)le32_to_cpu(bgd[ibmap_idx].inode_id) * fs->blksz,
+		struct ext2_block_group *bgd =
+			ext4fs_get_group_descriptor(fs, ibmap_idx);
+		uint16_t bg_flags = ext4fs_bg_get_flags(bgd);
+		uint64_t i_bitmap_blk = ext4fs_bg_get_inode_id(bgd, fs);
+
+		if (bg_flags & EXT4_BG_INODE_UNINIT) {
+			put_ext4(i_bitmap_blk * fs->blksz,
 				 zero_buffer, fs->blksz);
-			new_flags = le16_to_cpu(bgd[ibmap_idx].bg_flags) & ~EXT4_BG_INODE_UNINIT;
-			bgd[ibmap_idx].bg_flags = cpu_to_le16(new_flags);
+			bg_flags &= ~EXT4_BG_INODE_UNINIT;
+			ext4fs_bg_set_flags(bgd, bg_flags);
 			memcpy(fs->inode_bmaps[ibmap_idx], zero_buffer,
 				fs->blksz);
 		}
@@ -1130,22 +1139,18 @@ restart:
 
 		/* journal backup */
 		if (prev_inode_bitmap_index != ibmap_idx) {
-			memset(journal_buffer, '\0', fs->blksz);
-			status = ext4fs_devread(
-						(lbaint_t)le32_to_cpu(bgd[ibmap_idx].inode_id)
-						* fs->sect_perblk,
+			status = ext4fs_devread(i_bitmap_blk * fs->sect_perblk,
 						0, fs->blksz, journal_buffer);
 			if (status == 0)
 				goto fail;
 			if (ext4fs_log_journal(journal_buffer,
-						le32_to_cpu(bgd[ibmap_idx].inode_id)))
+						le32_to_cpu(bgd->inode_id)))
 				goto fail;
 			prev_inode_bitmap_index = ibmap_idx;
 		}
-		ext4fs_bg_free_inodes_dec(&bgd[ibmap_idx]);
+		ext4fs_bg_free_inodes_dec(bgd);
 		if (has_gdt_chksum)
-			bgd[ibmap_idx].bg_itable_unused =
-					bgd[ibmap_idx].free_inodes;
+			bgd->bg_itable_unused = bgd->free_inodes;
 		ext4fs_sb_free_inodes_dec(fs->sb);
 		goto success;
 	}
@@ -1561,7 +1566,7 @@ int ext4fs_read_inode(struct ext2_data *data, int ino, struct ext2_inode *inode)
 		return 0;
 
 	inodes_per_block = EXT2_BLOCK_SIZE(data) / fs->inodesz;
-	blkno = le32_to_cpu(blkgrp.inode_table_id) +
+	blkno = ext4fs_bg_get_inode_table_id(&blkgrp, fs) +
 	    (ino % le32_to_cpu(sblock->inodes_per_group)) / inodes_per_block;
 	blkoff = (ino % inodes_per_block) * fs->inodesz;
 	/* Read the inode. */