[Ocfs2-devel] [PATCH 05/15] Add xattr header in ocfs2. v3

[Mark Fasheh]

On Thu, Aug 07, 2008 at 06:31:27AM +0800, Tao Ma wrote:
> Modification from V2 to V3:
> 1. Add annotations for every field.
> 2. Change csum to be _le64 include xb_csum and xh_csum.
> 3. Change the definition of xe_local and xe_type and add set/get helper
>    function for them.
> 
> Signed-off-by: Tao Ma <tao.ma at oracle.com>
> ---
>  fs/ocfs2/ocfs2_fs.h |  118 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 118 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/ocfs2/ocfs2_fs.h b/fs/ocfs2/ocfs2_fs.h
> index 3f19451..1b0e136 100644
> --- a/fs/ocfs2/ocfs2_fs.h
> +++ b/fs/ocfs2/ocfs2_fs.h
> @@ -64,6 +64,7 @@
>  #define OCFS2_INODE_SIGNATURE		"INODE01"
>  #define OCFS2_EXTENT_BLOCK_SIGNATURE	"EXBLK01"
>  #define OCFS2_GROUP_DESC_SIGNATURE      "GROUP01"
> +#define OCFS2_XATTR_BLOCK_SIGNATURE	"XATTR01"
>  
>  /* Compatibility flags */
>  #define OCFS2_HAS_COMPAT_FEATURE(sb,mask)			\
> @@ -712,6 +713,123 @@ struct ocfs2_group_desc
>  /*40*/	__u8    bg_bitmap[0];
>  };
>  
> +/*
> + * On disk extended attribute structure for OCFS2.
> + */
> +
> +/*
> + * ocfs2_xattr_entry indicates one extend attribute.
> + *
> + * Note that it can be stored in inode, one block or one xattr bucket.
> + */
> +struct ocfs2_xattr_entry {
> +	__le32	xe_name_hash;    /* hash value of xattr prefix+suffix. */
> +	__le16	xe_name_offset;  /* byte offset from the 1st etnry in the local
> +				    local xattr storage(inode, xattr block or
> +				    xattr bucket). */
> +	__u8	xe_name_len;	 /* xattr name len, does't include prefix. */
> +	__u8	xe_type;         /* the low 7 bits indicates the name prefix's
> +				  * type and the highest 1 bits indicate whether
> +				  * the EA is stored in the local storage. */
> +	__le64	xe_value_size;	 /* real xattr value length. */
> +};
> +
> +/*
> + * On disk structure for xattr header.
> + *
> + * One ocfs2_xattr_header describes how many ocfs2_xattr_entry records in
> + * the local xattr storage.
> + */
> +struct ocfs2_xattr_header {
> +	__le16	xh_count;                       /* contains the count of how
> +						   many records are in the
> +						   local xattr storage. */
> +	__le16	xh_reserved1;
> +	__le32	xh_reserved2;
> +	__le64  xh_csum;
> +	struct ocfs2_xattr_entry xh_entries[0]; /* xattr entry list. */
> +};
> +
> +/*
> + * On disk structure for xattr value root.
> + *
> + * It is used when one extended attribute's size is larger, and we will save it
> + * in an outside cluster. It will stored in a b-tree like file content.
> + */
> +struct ocfs2_xattr_value_root {
> +/*00*/	__le32	xr_clusters;              /* clusters covered by xattr value. */
> +	__le32	xr_reserved0;
> +	__le64	xr_last_eb_blk;           /* Pointer to last extent block */
> +/*10*/	struct ocfs2_extent_list xr_list; /* Extent record list */
> +};
> +
> +/*
> + * On disk structure for xattr tree root.
> + *
> + * It is used when there are too many extended attributes for one file. These
> + * attributes will be organized and stored in an indexed-btree.
> + */
> +struct ocfs2_xattr_tree_root {
> +/*00*/	__le32	xt_clusters;              /* clusters covered by xattr. */
> +	__le32	xt_reserved0;
> +	__le64	xt_last_eb_blk;           /* Pointer to last extent block */
> +/*10*/	struct ocfs2_extent_list xt_list; /* Extent record list */
> +};
> +
> +#define OCFS2_XATTR_INDEXED 0x1
> +
> +/*
> + * On disk structure for xattr block.
> + */
> +struct ocfs2_xattr_block {
> +/*00*/	__u8	xb_signature[8];     /* Signature for verification */
> +	__le16	xb_suballoc_slot;    /* Slot suballocator this
> +					block belongs to. */
> +	__le16	xb_suballoc_bit;     /* Bit offset in suballocator
> +					block group */
> +	__le32	xb_fs_generation;    /* Must match super block */
> +/*10*/	__le64	xb_blkno;            /* Offset on disk, in blocks */
> +	__le64	xb_csum;
> +/*20*/	__le16	xb_flags;            /* Indicates whether this block contains
> +					real xattr or a xattr tree. */
> +	__le16	xb_reserved0;
> +	__le32  xb_reserved1;
> +	__le64	xb_reserved2;
> +/*30*/	union {
> +		struct ocfs2_xattr_header xb_header; /* xattr header if this
> +							block contains xattr */
> +		struct ocfs2_xattr_tree_root xb_root;/* xattr tree root if this
> +							block cotains xattr
> +							tree. */
> +	} xb_attrs;
> +};
> +
> +#define OCFS2_XATTR_ENTRY_LOCAL		0x80
> +#define OCFS2_XATTR_TYPE_MASK		0x7F
> +static inline void ocfs2_xattr_set_local(struct ocfs2_xattr_entry *xe,
> +					 int local)
> +{
> +	if (local)
> +		xe->xe_type |= OCFS2_XATTR_ENTRY_LOCAL;
> +	else
> +		xe->xe_type &= ~OCFS2_XATTR_ENTRY_LOCAL;
> +}
> +
> +static inline int ocfs2_xattr_is_local(struct ocfs2_xattr_entry *xe)
> +{
> +	return xe->xe_type & OCFS2_XATTR_ENTRY_LOCAL;
> +}
> +
> +static inline void ocfs2_xattr_set_type(struct ocfs2_xattr_entry *xe, int type)
> +{
> +	xe->xe_type |= type;

I think it's a good idea to mask out the topmost bit in 'type' here, just in
caes the function gets passed a bogus value, it at least won't affect
whether the xe is considered local or not.

Otherwise, this patch looks great.

Thanks,
	--Mark

--
Mark Fasheh