Patchwork virtio-9p: getattr server implementation for 9P2000.L protocol.

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Submitter Sripathi Kodi
Date July 12, 2010, 3:23 p.m.
Message ID <20100712152328.18945.15966.stgit@localhost.localdomain>
Download mbox | patch
Permalink /patch/58623/
State New
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Sripathi Kodi - July 12, 2010, 3:23 p.m.
From: M. Mohan Kumar <mohan@in.ibm.com>

This is a new version of getattr patch for 9P2000.L that I posted some
time ago. This version adds 3 fields to the on-the-wire data:
file creation time
generation number
data version

It also adds a bit field to indicate which fields of the structure have
valid data. Usually the server fills in at least all the basic fields, but
it may fill in the additional fields if possible. The server will use
the bit field to tell the client which fields it has populated. Currently
there is no clean way for the server to obtain these additional fields, so
it sends back just the basic fields.

The client (Linux kernel) patch corresponding to this is at
http://sourceforge.net/mailarchive/forum.php?thread_name=20100712143815.6665.35892.stgit%40localhost.localdomain&forum_name=v9fs-developer

Comments welcome.


           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.

        Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
        Signed-off-by: Sripathi Kodi <sripathik@in.ibm.com>
---

 hw/virtio-9p-debug.c |   32 ++++++++++++++
 hw/virtio-9p.c       |  112 ++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/virtio-9p.h       |   33 +++++++++++++++
 3 files changed, 177 insertions(+), 0 deletions(-)

Patch

diff --git a/hw/virtio-9p-debug.c b/hw/virtio-9p-debug.c
index 030b3e6..6072491 100644
--- a/hw/virtio-9p-debug.c
+++ b/hw/virtio-9p-debug.c
@@ -178,6 +178,30 @@  static void pprint_stat(V9fsPDU *pdu, int rx, size_t *offsetp, const char *name)
     fprintf(llogfile, "}");
 }
 
+static void pprint_stat_dotl(V9fsPDU *pdu, int rx, size_t *offsetp,
+                                                  const char *name)
+{
+    fprintf(llogfile, "%s={", name);
+    pprint_qid(pdu, rx, offsetp, "qid");
+    pprint_int32(pdu, rx, offsetp, ", st_mode");
+    pprint_int64(pdu, rx, offsetp, ", st_nlink");
+    pprint_int32(pdu, rx, offsetp, ", st_uid");
+    pprint_int32(pdu, rx, offsetp, ", st_gid");
+    pprint_int64(pdu, rx, offsetp, ", st_rdev");
+    pprint_int64(pdu, rx, offsetp, ", st_size");
+    pprint_int64(pdu, rx, offsetp, ", st_blksize");
+    pprint_int64(pdu, rx, offsetp, ", st_blocks");
+    pprint_int64(pdu, rx, offsetp, ", atime");
+    pprint_int64(pdu, rx, offsetp, ", atime_nsec");
+    pprint_int64(pdu, rx, offsetp, ", mtime");
+    pprint_int64(pdu, rx, offsetp, ", mtime_nsec");
+    pprint_int64(pdu, rx, offsetp, ", ctime");
+    pprint_int64(pdu, rx, offsetp, ", ctime_nsec");
+    fprintf(llogfile, "}");
+}
+
+
+
 static void pprint_strs(V9fsPDU *pdu, int rx, size_t *offsetp, const char *name)
 {
     int sg_count = get_sg_count(pdu, rx);
@@ -351,6 +375,14 @@  void pprint_pdu(V9fsPDU *pdu)
         pprint_int32(pdu, 1, &offset, "msize");
         pprint_str(pdu, 1, &offset, ", version");
         break;
+    case P9_TGETATTR:
+        fprintf(llogfile, "TGETATTR: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        break;
+    case P9_RGETATTR:
+        fprintf(llogfile, "RGETATTR: (");
+        pprint_stat_dotl(pdu, 1, &offset, "getattr");
+        break;
     case P9_TAUTH:
         fprintf(llogfile, "TAUTH: (");
         pprint_int32(pdu, 0, &offset, "afid");
diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
index 00527c4..10cc003 100644
--- a/hw/virtio-9p.c
+++ b/hw/virtio-9p.c
@@ -736,6 +736,21 @@  static size_t pdu_marshal(V9fsPDU *pdu, size_t offset, const char *fmt, ...)
                         statp->n_gid, statp->n_muid);
             break;
         }
+        case 'A': {
+            V9fsStatDotl *statp = va_arg(ap, V9fsStatDotl *);
+            offset += pdu_marshal(pdu, offset, "qQdddqqqqqqqqqqqqqqq",
+                        statp->st_result_mask,
+                        &statp->qid, statp->st_mode,
+                        statp->st_uid, statp->st_gid,
+                        statp->st_nlink, statp->st_rdev,
+                        statp->st_size, statp->st_blksize, statp->st_blocks,
+                        statp->st_atime_sec, statp->st_atime_nsec,
+                        statp->st_mtime_sec, statp->st_mtime_nsec,
+                        statp->st_ctime_sec, statp->st_ctime_nsec,
+                        statp->st_btime_sec, statp->st_btime_nsec,
+                        statp->st_gen, statp->st_data_version);
+            break;
+        }
         default:
             break;
         }
@@ -963,6 +978,51 @@  static int stat_to_v9stat(V9fsState *s, V9fsString *name,
     return 0;
 }
 
+#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 /* Mask for fields up to BLOCKS */
+#define P9_STATS_ALL           0x00003fffULL /* Mask for All fields above */
+
+
+static void stat_to_v9stat_dotl(V9fsState *s, const struct stat *stbuf,
+                            V9fsStatDotl *v9lstat)
+{
+    memset(v9lstat, 0, sizeof(*v9lstat));
+
+    v9lstat->st_mode = stbuf->st_mode;
+    v9lstat->st_nlink = stbuf->st_nlink;
+    v9lstat->st_uid = stbuf->st_uid;
+    v9lstat->st_gid = stbuf->st_gid;
+    v9lstat->st_rdev = stbuf->st_rdev;
+    v9lstat->st_size = stbuf->st_size;
+    v9lstat->st_blksize = stbuf->st_blksize;
+    v9lstat->st_blocks = stbuf->st_blocks;
+    v9lstat->st_atime_sec = stbuf->st_atime;
+    v9lstat->st_atime_nsec = stbuf->st_atim.tv_nsec;
+    v9lstat->st_mtime_sec = stbuf->st_mtime;
+    v9lstat->st_mtime_nsec = stbuf->st_mtim.tv_nsec;
+    v9lstat->st_ctime_sec = stbuf->st_ctime;
+    v9lstat->st_ctime_nsec = stbuf->st_ctim.tv_nsec;
+    /* Currently we only support BASIC fields in stat */
+    v9lstat->st_result_mask = P9_STATS_BASIC;
+
+    stat_to_qid(stbuf, &v9lstat->qid);
+}
+
 static struct iovec *adjust_sg(struct iovec *sg, int len, int *iovcnt)
 {
     while (len && *iovcnt) {
@@ -1129,6 +1189,57 @@  out:
     qemu_free(vs);
 }
 
+static void v9fs_getattr_post_lstat(V9fsState *s, V9fsStatStateDotl *vs,
+                                                                int err)
+{
+    if (err == -1) {
+        err = -errno;
+        goto out;
+    }
+
+    stat_to_v9stat_dotl(s, &vs->stbuf, &vs->v9stat_dotl);
+    vs->offset += pdu_marshal(vs->pdu, vs->offset, "A", &vs->v9stat_dotl);
+    err = vs->offset;
+
+out:
+    complete_pdu(s, vs->pdu, err);
+    qemu_free(vs);
+}
+
+static void v9fs_getattr(V9fsState *s, V9fsPDU *pdu)
+{
+    int32_t fid;
+    V9fsStatStateDotl *vs;
+    ssize_t err = 0;
+    V9fsFidState *fidp;
+    uint64_t request_mask;
+
+    vs = qemu_malloc(sizeof(*vs));
+    vs->pdu = pdu;
+    vs->offset = 7;
+
+    memset(&vs->v9stat_dotl, 0, sizeof(vs->v9stat_dotl));
+
+    pdu_unmarshal(vs->pdu, vs->offset, "dq", &fid, &request_mask);
+
+    fidp = lookup_fid(s, fid);
+    if (fidp == NULL) {
+        err = -ENOENT;
+        goto out;
+    }
+
+    /* Currently we only support BASIC fields in stat, so there is no
+     * need to look at request_mask.
+     */
+    err = v9fs_do_lstat(s, &fidp->path, &vs->stbuf);
+    v9fs_getattr_post_lstat(s, vs, err);
+    return;
+
+out:
+    complete_pdu(s, vs->pdu, err);
+    qemu_free(vs);
+}
+
 static void v9fs_walk_complete(V9fsState *s, V9fsWalkState *vs, int err)
 {
     complete_pdu(s, vs->pdu, err);
@@ -2392,6 +2503,7 @@  typedef void (pdu_handler_t)(V9fsState *s, V9fsPDU *pdu);
 static pdu_handler_t *pdu_handlers[] = {
     [P9_TREADDIR] = v9fs_readdir,
     [P9_TSTATFS] = v9fs_statfs,
+    [P9_TGETATTR] = v9fs_getattr,
     [P9_TVERSION] = v9fs_version,
     [P9_TATTACH] = v9fs_attach,
     [P9_TSTAT] = v9fs_stat,
diff --git a/hw/virtio-9p.h b/hw/virtio-9p.h
index 4ee3830..1feed82 100644
--- a/hw/virtio-9p.h
+++ b/hw/virtio-9p.h
@@ -15,6 +15,8 @@ 
 enum {
     P9_TSTATFS = 8,
     P9_RSTATFS,
+    P9_TGETATTR = 24,
+    P9_RGETATTR,
     P9_TREADDIR = 40,
     P9_RREADDIR,
     P9_TVERSION = 100,
@@ -185,6 +187,37 @@  typedef struct V9fsStatState {
     struct stat stbuf;
 } V9fsStatState;
 
+typedef struct V9fsStatDotl {
+    uint64_t st_result_mask;
+    V9fsQID qid;
+    uint32_t st_mode;
+    uint32_t st_uid;
+    uint32_t st_gid;
+    uint64_t st_nlink;
+    uint64_t st_rdev;
+    uint64_t st_size;
+    uint64_t st_blksize;
+    uint64_t st_blocks;
+    uint64_t st_atime_sec;
+    uint64_t st_atime_nsec;
+    uint64_t st_mtime_sec;
+    uint64_t st_mtime_nsec;
+    uint64_t st_ctime_sec;
+    uint64_t st_ctime_nsec;
+    uint64_t st_btime_sec;
+    uint64_t st_btime_nsec;
+    uint64_t st_gen;
+    uint64_t st_data_version;
+} V9fsStatDotl;
+
+typedef struct V9fsStatStateDotl {
+    V9fsPDU *pdu;
+    size_t offset;
+    V9fsStatDotl v9stat_dotl;
+    struct stat stbuf;
+} V9fsStatStateDotl;
+
+
 typedef struct V9fsWalkState {
     V9fsPDU *pdu;
     size_t offset;