MGS Configuration Data
^^^^^^^^^^^^^^^^^^^^^^

[source,c]
----
#define MTI_NAME_MAXLEN  64
struct mgs_config_body {
        char     mcb_name[MTI_NAME_MAXLEN]; /* logname */
        __u64    mcb_offset;    /* next index of config log to request */
        __u16    mcb_type;      /* type of log: CONFIG_T_[CONFIG|RECOVER] */
        __u8     mcb_reserved;
        __u8     mcb_bits;      /* bits unit size of config log */
        __u32    mcb_units;     /* # of units for bulk transfer */
};
----

The 'mgs_config_body' structure has information identifying to the MGS
which Lustre file system the client is requesting configuration information
from.  'mcb_name' contains the filesystem name (fsname).  'mcb_offset'
contains the next record number in the configuration llog to process
(see <<llog>> for details), not the byte offset or bulk transfer units.
'mcb_bits' is the log2 of the units of minimum bulk transfer size,
typically 4096 or 8192 bytes, while 'mcb_units' is the maximum number of
2^mcb_bits sized units that can be transferred in a single request.

[source,c]
----
struct mgs_config_res {
        __u64    mcr_offset;    /* index of last config log */
        __u64    mcr_size;      /* size of the log */
};
----

The 'mgs_config_res' structure returns information describing the
replied configuration llog data requested in 'mgs_config_body'.
'mcr_offset' contains the last configuration record number returned
by this reply.  'mcr_size' contains the maximum record index in the
entire configuration llog.  When 'mcr_offset' equals 'mcr_size' there
are no more records to process in the log.