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From af7e95c32cea40c1e443ae301e64b27f068b4915 Mon Sep 17 00:00:00 2001
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From: Paulo Alcantara <pcacjr@zytor.com>
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Date: Wed, 11 Oct 2017 07:00:31 -0400
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Subject: [PATCH] ext4: Fix 64bit feature
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As per ext4 specification:
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> In ext2, ext3, and ext4 (when the 64bit feature is not enabled), the
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> block group descriptor was only 32 bytes long and therefore ends at
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> bg_checksum. On an ext4 filesystem with the 64bit feature enabled, the
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> block group descriptor expands to at least the 64 bytes described below;
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> the size is stored in the superblock.
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Since block group descriptor has been expanded to 64 bytes long (when 64
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bit feature is enabled), we cannot index ext2_group_desc and return it
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*directly* -- as we did it in ext2_get_group_desc -- it's still 32 bytes
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long.
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Instead, use s_desc_size field from superblock to correctly index and
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return block group descriptors.
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Cc: H. Peter Anvin <hpa@zytor.com>
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Cc: Gene Cumm <gene.cumm@gmail.com>
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Signed-off-by: Paulo Alcantara <pcacjr@zytor.com>
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---
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core/fs/ext2/ext2.c | 23 ++++++++++++++---------
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core/fs/ext2/ext2_fs.h | 1 +
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2 files changed, 15 insertions(+), 9 deletions(-)
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diff --git a/core/fs/ext2/ext2.c b/core/fs/ext2/ext2.c
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index 76bd1d5..4bc0a53 100644
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--- a/core/fs/ext2/ext2.c
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+++ b/core/fs/ext2/ext2.c
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@@ -25,22 +25,17 @@ static enum dirent_type ext2_cvt_type(unsigned int d_file_type)
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return inode_type[d_file_type];
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}
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-/*
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- * get the group's descriptor of group_num
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- */
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-static const struct ext2_group_desc *
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-ext2_get_group_desc(struct fs_info *fs, uint32_t group_num)
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+static const void *__ext2_get_group_desc(struct fs_info *fs, uint32_t group_num)
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{
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struct ext2_sb_info *sbi = EXT2_SB(fs);
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uint32_t desc_block, desc_index;
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- const struct ext2_group_desc *desc_data_block;
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+ uint8_t *p;
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if (group_num >= sbi->s_groups_count) {
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printf ("ext2_get_group_desc"
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"block_group >= groups_count - "
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"block_group = %d, groups_count = %d",
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group_num, sbi->s_groups_count);
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-
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return NULL;
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}
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@@ -49,8 +44,17 @@ ext2_get_group_desc(struct fs_info *fs, uint32_t group_num)
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desc_block += sbi->s_first_data_block + 1;
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- desc_data_block = get_cache(fs->fs_dev, desc_block);
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- return &desc_data_block[desc_index];
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+ p = get_cache(fs->fs_dev, desc_block);
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+ return p + sbi->s_desc_size * desc_index;
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+}
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+
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+/*
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+ * get the group's descriptor of group_num
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+ */
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+static inline const struct ext2_group_desc *
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+ext2_get_group_desc(struct fs_info *fs, uint32_t group_num)
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+{
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+ return __ext2_get_group_desc(fs, group_num);
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}
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/*
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@@ -306,6 +310,7 @@ static int ext2_fs_init(struct fs_info *fs)
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if (sb.s_desc_size < sizeof(struct ext2_group_desc))
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sb.s_desc_size = sizeof(struct ext2_group_desc);
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sbi->s_desc_per_block = BLOCK_SIZE(fs) / sb.s_desc_size;
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+ sbi->s_desc_size = sb.s_desc_size;
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sbi->s_groups_count = (sb.s_blocks_count - sb.s_first_data_block
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+ EXT2_BLOCKS_PER_GROUP(fs) - 1)
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/ EXT2_BLOCKS_PER_GROUP(fs);
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diff --git a/core/fs/ext2/ext2_fs.h b/core/fs/ext2/ext2_fs.h
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index 803a995..d8d07eb 100644
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--- a/core/fs/ext2/ext2_fs.h
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+++ b/core/fs/ext2/ext2_fs.h
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@@ -278,6 +278,7 @@ struct ext2_sb_info {
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uint32_t s_first_data_block; /* First Data Block */
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int s_inode_size;
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uint8_t s_uuid[16]; /* 128-bit uuid for volume */
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+ int s_desc_size; /* size of group descriptor */
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};
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static inline struct ext2_sb_info *EXT2_SB(struct fs_info *fs)
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--
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2.7.4.GIT
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