From af7e95c32cea40c1e443ae301e64b27f068b4915 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Wed, 11 Oct 2017 07:00:31 -0400 Subject: [PATCH] ext4: Fix 64bit feature As per ext4 specification: > In ext2, ext3, and ext4 (when the 64bit feature is not enabled), the > block group descriptor was only 32 bytes long and therefore ends at > bg_checksum. On an ext4 filesystem with the 64bit feature enabled, the > block group descriptor expands to at least the 64 bytes described below; > the size is stored in the superblock. Since block group descriptor has been expanded to 64 bytes long (when 64 bit feature is enabled), we cannot index ext2_group_desc and return it *directly* -- as we did it in ext2_get_group_desc -- it's still 32 bytes long. Instead, use s_desc_size field from superblock to correctly index and return block group descriptors. Cc: H. Peter Anvin Cc: Gene Cumm Signed-off-by: Paulo Alcantara --- core/fs/ext2/ext2.c | 23 ++++++++++++++--------- core/fs/ext2/ext2_fs.h | 1 + 2 files changed, 15 insertions(+), 9 deletions(-) diff --git a/core/fs/ext2/ext2.c b/core/fs/ext2/ext2.c index 76bd1d5a..4bc0a535 100644 --- a/core/fs/ext2/ext2.c +++ b/core/fs/ext2/ext2.c @@ -25,22 +25,17 @@ static enum dirent_type ext2_cvt_type(unsigned int d_file_type) return inode_type[d_file_type]; } -/* - * get the group's descriptor of group_num - */ -static const struct ext2_group_desc * -ext2_get_group_desc(struct fs_info *fs, uint32_t group_num) +static const void *__ext2_get_group_desc(struct fs_info *fs, uint32_t group_num) { struct ext2_sb_info *sbi = EXT2_SB(fs); uint32_t desc_block, desc_index; - const struct ext2_group_desc *desc_data_block; + uint8_t *p; if (group_num >= sbi->s_groups_count) { printf ("ext2_get_group_desc" "block_group >= groups_count - " "block_group = %d, groups_count = %d", group_num, sbi->s_groups_count); - return NULL; } @@ -49,8 +44,17 @@ ext2_get_group_desc(struct fs_info *fs, uint32_t group_num) desc_block += sbi->s_first_data_block + 1; - desc_data_block = get_cache(fs->fs_dev, desc_block); - return &desc_data_block[desc_index]; + p = get_cache(fs->fs_dev, desc_block); + return p + sbi->s_desc_size * desc_index; +} + +/* + * get the group's descriptor of group_num + */ +static inline const struct ext2_group_desc * +ext2_get_group_desc(struct fs_info *fs, uint32_t group_num) +{ + return __ext2_get_group_desc(fs, group_num); } /* @@ -306,6 +310,7 @@ static int ext2_fs_init(struct fs_info *fs) if (sb.s_desc_size < sizeof(struct ext2_group_desc)) sb.s_desc_size = sizeof(struct ext2_group_desc); sbi->s_desc_per_block = BLOCK_SIZE(fs) / sb.s_desc_size; + sbi->s_desc_size = sb.s_desc_size; sbi->s_groups_count = (sb.s_blocks_count - sb.s_first_data_block + EXT2_BLOCKS_PER_GROUP(fs) - 1) / EXT2_BLOCKS_PER_GROUP(fs); diff --git a/core/fs/ext2/ext2_fs.h b/core/fs/ext2/ext2_fs.h index 803a9954..d8d07ebd 100644 --- a/core/fs/ext2/ext2_fs.h +++ b/core/fs/ext2/ext2_fs.h @@ -278,6 +278,7 @@ struct ext2_sb_info { uint32_t s_first_data_block; /* First Data Block */ int s_inode_size; uint8_t s_uuid[16]; /* 128-bit uuid for volume */ + int s_desc_size; /* size of group descriptor */ }; static inline struct ext2_sb_info *EXT2_SB(struct fs_info *fs) -- 2.11.4.GIT