• Sripathi Kodi's avatar
    9p: getattr client implementation for 9P2000.L protocol. · f0853122
    Sripathi Kodi authored
    
    
            SYNOPSIS
    
                  size[4] Tgetattr tag[2] fid[4] request_mask[8]
    
                  size[4] Rgetattr tag[2] lstat[n]
    
               DESCRIPTION
    
                  The getattr transaction inquires about the file identified by fid.
                  request_mask is a bit mask that specifies which fields of the
                  stat structure is the client interested in.
    
                  The reply will contain a machine-independent directory entry,
                  laid out as follows:
    
                     st_result_mask[8]
                        Bit mask that indicates which fields in the stat structure
                        have been populated by the server
    
                     qid.type[1]
                        the type of the file (directory, etc.), represented as a bit
                        vector corresponding to the high 8 bits of the file's mode
                        word.
    
                     qid.vers[4]
                        version number for given path
    
                     qid.path[8]
                        the file server's unique identification for the file
    
                     st_mode[4]
                        Permission and flags
    
                     st_uid[4]
                        User id of owner
    
                     st_gid[4]
                        Group ID of owner
    
                     st_nlink[8]
                        Number of hard links
    
                     st_rdev[8]
                        Device ID (if special file)
    
                     st_size[8]
                        Size, in bytes
    
                     st_blksize[8]
                        Block size for file system IO
    
                     st_blocks[8]
                        Number of file system blocks allocated
    
                     st_atime_sec[8]
                        Time of last access, seconds
    
                     st_atime_nsec[8]
                        Time of last access, nanoseconds
    
                     st_mtime_sec[8]
                        Time of last modification, seconds
    
                     st_mtime_nsec[8]
                        Time of last modification, nanoseconds
    
                     st_ctime_sec[8]
                        Time of last status change, seconds
    
                     st_ctime_nsec[8]
                        Time of last status change, nanoseconds
    
                     st_btime_sec[8]
                        Time of creation (birth) of file, seconds
    
                     st_btime_nsec[8]
                        Time of creation (birth) of file, nanoseconds
    
                     st_gen[8]
                        Inode generation
    
                     st_data_version[8]
                        Data version number
    
                  request_mask and result_mask bit masks contain the following bits
                     #define P9_STATS_MODE          0x00000001ULL
                     #define P9_STATS_NLINK         0x00000002ULL
                     #define P9_STATS_UID           0x00000004ULL
                     #define P9_STATS_GID           0x00000008ULL
                     #define P9_STATS_RDEV          0x00000010ULL
                     #define P9_STATS_ATIME         0x00000020ULL
                     #define P9_STATS_MTIME         0x00000040ULL
                     #define P9_STATS_CTIME         0x00000080ULL
                     #define P9_STATS_INO           0x00000100ULL
                     #define P9_STATS_SIZE          0x00000200ULL
                     #define P9_STATS_BLOCKS        0x00000400ULL
    
                     #define P9_STATS_BTIME         0x00000800ULL
                     #define P9_STATS_GEN           0x00001000ULL
                     #define P9_STATS_DATA_VERSION  0x00002000ULL
    
                     #define P9_STATS_BASIC         0x000007ffULL
                     #define P9_STATS_ALL           0x00003fffULL
    
            This patch implements the client side of getattr implementation for
            9P2000.L. It introduces a new structure p9_stat_dotl for getting
            Linux stat information along with QID. The data layout is similar to
            stat structure in Linux user space with the following major
            differences:
    
            inode (st_ino) is not part of data. Instead qid is.
    
            device (st_dev) is not part of data because this doesn't make sense
            on the client.
    
            All time variables are 64 bit wide on the wire. The kernel seems to use
            32 bit variables for these variables. However, some of the architectures
            have used 64 bit variables and glibc exposes 64 bit variables to user
            space on some architectures. Hence to be on the safer side we have made
            these 64 bit in the protocol. Refer to the comments in
            include/asm-generic/stat.h
    
            There are some additional fields: st_btime_sec, st_btime_nsec, st_gen,
            st_data_version apart from the bitmask, st_result_mask. The bit mask
            is filled by the server to indicate which stat fields have been
            populated by the server. Currently there is no clean way for the
            server to obtain these additional fields, so it sends back just the
            basic fields.
    Signed-off-by: default avatarSripathi Kodi <sripathik@in.ibm.com>
    Signed-off-by: default avatarEric Van Hensbegren <ericvh@gmail.com>
    f0853122
vfs_inode.c 31.8 KB