[Ocfs2-devel] [PATCH 1/2] Ocfs2: Add new ioctls prototype and corresponding data structure to ocfs2 header.

[Tristan]

Sunil Mushran wrote:
> Tristan Ye wrote:
>> We use OCFS2_IOC_INFO to manipulate the new ioctl, the requests can
>> be stored in a array of (struct ocfs2_info_request), which should be
>> NULL-terminated, kernel therefore can recoginze and fill them one by
>> one.
>>
>> The reason why we need these ioctls is to offer the none-privileged
>> end-user a possibility to get filesys info gathering.
>>
>> Idea here is to make the spearated request small enough to guarantee
>> a better backward&forward compatibility since a small piece of request
>> would be less likely to be broken if filesys on raw disk get changed.
>>
>> Currently, the first version include following request type:
>>
>> OCFS2_INFO_CLUSTERSIZE,
>> OCFS2_INFO_BLOCKSIZE,
>> OCFS2_INFO_SLOTNUM,
>> OCFS2_INFO_LABEL,
>> OCFS2_INFO_UUID,
>> OCFS2_INFO_FS_FEATURES
>>
>> It may be grown from time to time:)
>>
>> Signed-off-by: Tristan Ye <tristan.ye at oracle.com>
>> ---
>> fs/ocfs2/ocfs2_fs.h | 69 
>> +++++++++++++++++++++++++++++++++++++++++++++++++++
>> 1 files changed, 69 insertions(+), 0 deletions(-)
>>
>> diff --git a/fs/ocfs2/ocfs2_fs.h b/fs/ocfs2/ocfs2_fs.h
>> index e9431e4..dac7f4c 100644
>> --- a/fs/ocfs2/ocfs2_fs.h
>> +++ b/fs/ocfs2/ocfs2_fs.h
>> @@ -309,6 +309,75 @@ struct reflink_arguments {
>> };
>> #define OCFS2_IOC_REFLINK _IOW('o', 4, struct reflink_arguments)
>>
>> +#define OCFS2_UUID_LEN 16
>> +#define OCFS2_MAX_LABEL_LEN 64
>
> What's wrong with the existing OCFS2_MAX_VOL_LABEL_LEN?
> For UUID, maybe define:
> #define OCFS2_VOL_UUIDSTR_LEN (OCFS2_VOL_UUID_LEN * 2 + 1)

The existing OCFS2_MAX_VOL_LABEL_LEN macro was placed after definitions 
of ioctls, and I just want all of the ioctls to gather in the same place.
Anyway, I'll move these ioctls properly.

>
>> +
>> +/*
>> + * Used to query fs information for none-privileged + * users by 
>> using OCFS2_IOC_INFO ioctols, a series of
>> + * following requests need to be NULL-terminated.
>> + *
>> + * Always try to separate info request into small pieces to
>> + * guarantee the backward&forward compatibility.
>> + */
>> +struct ocfs2_info_request {
>> + __u32 ir_code; /* Info request code */
>> + __u32 ir_flags; /* Request flags */
>> +};
>> +
>
> Rename it ocfs2_info. Then you have ocfs2_info_clustersize. In the next
> patch you have typedef-ed these structures presumably because the 
> structure
> name is long. Instead, shorten the name and use it as is. BTW, 
> typedef-ing
> struct is strongly discouraged in the kernel coding standards. For 
> good reason.
Good idea, I was always being annoyed by the length of these structures.

>
>> +struct ocfs2_info_request_clustersize {
>> + struct ocfs2_info_request ir_request;
>> + __u32 ir_clustersize;
>> +};
>> +
>> +struct ocfs2_info_request_blocksize {
>> + struct ocfs2_info_request ir_request;
>> + __u32 ir_blocksize;
>> +};
>> +
>> +struct ocfs2_info_request_slotnum {
>> + struct ocfs2_info_request ir_request;
>> + __u16 ir_slotnum;
>> +};
>> +
>> +struct ocfs2_info_request_label {
>> + struct ocfs2_info_request ir_request;
>> + __u8 ir_label[OCFS2_MAX_LABEL_LEN];
>> +};
>> +
>> +struct ocfs2_info_request_uuid {
>> + struct ocfs2_info_request ir_request;
>> + __u8 ir_uuid[OCFS2_UUID_LEN];
>> +};
>
> Return the uuid string as that is what we use everywhere.
Not quite sure why we want to keep the 32bytes uuid_str instead of 
16btyes uuid?

>
>> +
>> +struct ocfs2_info_request_fs_features {
>> + struct ocfs2_info_request ir_quest;
>> + __u32 ir_compat_features;
>> + __u32 ir_incompat_features;
>> + __u32 ir_ro_compat_features;
>> +};
>> +
>> +/* Codes for cfs2_info_request */
>> +
>> +#define OCFS2_INFO_CLUSTERSIZE 0x00000001
>> +#define OCFS2_INFO_BLOCKSIZE 0x00000002
>> +#define OCFS2_INFO_SLOTNUM 0x00000004
>> +#define OCFS2_INFO_LABEL 0x00000008
>> +#define OCFS2_INFO_UUID 0x00000010
>> +#define OCFS2_INFO_FS_FEATURES 0x00000020
>
> Fix typos, white-spaces, etc. Make use of tabs.
>
>> +
>> +/* Flags for struct ocfs2_info_request */
>> +/* Filled by the caller */
>> +#define OCFS2_INFO_FL_NON_COHERENT 0x00000001 /* Cluster coherency 
>> not required.
>> + This is a hint. It is up to
>> + ocfs2 whether the request can
>> + be fulfilled without locking. */
>> +/* Filled by ocfs2 */
>> +#define OCFS2_INFO_FL_FILLED 0x80000000 /* Filesystem understood this
>> + request and filled in the
>> + answer */
>> +
>> +#define OCFS2_IOC_INFO _IOR('o', 5, struct ocfs2_info_request)
>>
>> /*
>> * Journal Flags (ocfs2_dinode.id1.journal1.i_flags)
>