Re: [PATCH 1/7] ext4: Introduce le32_t and le16_t
From: Dave Kleikamp <hidden>
Date: 2007-09-25 13:56:36
On Tue, 2007-09-25 at 14:33 +0530, Aneesh Kumar K.V wrote:
ext4 file system layout contain different split members like bg_block_bitmap and bg_block_bitmap_hi. Introduce data type le32_t and le16_t to be used as the type of these split members. This prevents these members frome being accessed directly. Accesing them directly gives a compiler warning. This helps in catching some BUGS due to direct partial access of these split fields.
Ugh. I don't like this typedef at all. It just makes the data type more confusing. Why not just change the name of bg_block_bitmap to something like bg_block_bitmap_lo or _bg_block_bitmap? It should be clear from the name that it shouldn't be used without careful consideration.
quoted hunk ↗ jump to hunk
Signed-off-by: Aneesh Kumar K.V <redacted> --- fs/ext4/super.c | 8 ++++---- include/linux/ext4_fs.h | 4 ++-- include/linux/ext4_fs_i.h | 4 ++++ 3 files changed, 10 insertions(+), 6 deletions(-)diff --git a/fs/ext4/super.c b/fs/ext4/super.c index d035653..c8f8e4d 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c@@ -70,9 +70,9 @@ static void ext4_write_super_lockfs(struct super_block *sb); ext4_fsblk_t ext4_block_bitmap(struct super_block *sb, struct ext4_group_desc *bg) { - return le32_to_cpu(bg->bg_block_bitmap) | + return le32_to_cpu(bg->bg_block_bitmap.value) | (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT ? - (ext4_fsblk_t)le32_to_cpu(bg->bg_block_bitmap_hi) << 32 : 0); + (ext4_fsblk_t)le32_to_cpu(bg->bg_block_bitmap_hi.value) << 32 : 0); } ext4_fsblk_t ext4_inode_bitmap(struct super_block *sb,@@ -94,9 +94,9 @@ ext4_fsblk_t ext4_inode_table(struct super_block *sb, void ext4_block_bitmap_set(struct super_block *sb, struct ext4_group_desc *bg, ext4_fsblk_t blk) { - bg->bg_block_bitmap = cpu_to_le32((u32)blk); + bg->bg_block_bitmap.value = cpu_to_le32((u32)blk); if (EXT4_DESC_SIZE(sb) >= EXT4_MIN_DESC_SIZE_64BIT) - bg->bg_block_bitmap_hi = cpu_to_le32(blk >> 32); + bg->bg_block_bitmap_hi.value = cpu_to_le32(blk >> 32); } void ext4_inode_bitmap_set(struct super_block *sb,diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h index 046a6a7..4494f8e 100644 --- a/include/linux/ext4_fs.h +++ b/include/linux/ext4_fs.h@@ -150,7 +150,7 @@ struct ext4_allocation_request { */ struct ext4_group_desc { - __le32 bg_block_bitmap; /* Blocks bitmap block */ + le32_t bg_block_bitmap; /* Blocks bitmap block */ __le32 bg_inode_bitmap; /* Inodes bitmap block */ __le32 bg_inode_table; /* Inodes table block */ __le16 bg_free_blocks_count; /* Free blocks count */@@ -160,7 +160,7 @@ struct ext4_group_desc __u32 bg_reserved[2]; /* Likely block/inode bitmap checksum */ __le16 bg_itable_unused; /* Unused inodes count */ __le16 bg_checksum; /* crc16(sb_uuid+group+desc) */ - __le32 bg_block_bitmap_hi; /* Blocks bitmap block MSB */ + le32_t bg_block_bitmap_hi; /* Blocks bitmap block MSB */ __le32 bg_inode_bitmap_hi; /* Inodes bitmap block MSB */ __le32 bg_inode_table_hi; /* Inodes table block MSB */ };diff --git a/include/linux/ext4_fs_i.h b/include/linux/ext4_fs_i.h index 22ba80e..d7eb271 100644 --- a/include/linux/ext4_fs_i.h +++ b/include/linux/ext4_fs_i.h@@ -27,6 +27,10 @@ typedef int ext4_grpblk_t; /* data type for filesystem-wide blocks number */ typedef unsigned long long ext4_fsblk_t; +/* data type to carry split 64 and 48 bits */ +typedef struct { __le16 value; } le16_t; +typedef struct { __le32 value; } le32_t; + struct ext4_reserve_window { ext4_fsblk_t _rsv_start; /* First byte reserved */ ext4_fsblk_t _rsv_end; /* Last byte reserved or 0 */
-- David Kleikamp IBM Linux Technology Center