[Qemu-devel] [PATCH 2/2] virtio-9p: Implement server side of setattr for 9P2000.L protocol.

[Sripathi Kodi]

SYNOPSIS

      size[4] Tsetattr tag[2] attr[n]

      size[4] Rsetattr tag[2]

   DESCRIPTION

      The setattr command changes some of the file status information.
      attr resembles the iattr structure used in Linux kernel. It
      specifies which status parameter is to be changed and to what
      value. It is laid out as follows:

         valid[4]
            specifies which status information is to be changed. Possible
            values are:
            ATTR_MODE    (1 << 0)
            ATTR_UID     (1 << 1)
            ATTR_GID     (1 << 2)
            ATTR_SIZE    (1 << 3)
            ATTR_ATIME   (1 << 4)
            ATTR_MTIME   (1 << 5)

         mode[4]
            File permission bits

         uid[4]
            Owner id of file

         gid[4]
            Group id of the file

         size[8]
            File size

         atime_sec[8]
            Time of last file access, seconds

         atime_nsec[8]
            Time of last file access, nanoseconds

         mtime_sec[8]
            Time of last file modification, seconds

         mtime_nsec[8]
            Time of last file modification, nanoseconds



Explanation of the patches:
--------------------------

*) The kernel just copies relevent contents of iattr structure to p9_iattr_dotl
   structure and passes it down to the client. The only check it has is calling
   inode_change_ok()
*) The p9_iattr_dotl structure does not have ctime and ia_file parameters 
because
   I don't think these are needed in our case.
*) The server currently supports changing mode, time, ownership and size of the
   file.
*) 9P RFC says "Either all the changes in wstat request happen, or none of them
   does: if the request succeeds, all changes were made; if it fails, none 
were."
   I have not implemented this as I think this is not needed.

Signed-off-by: Sripathi Kodi <address@hidden>
---

 hw/virtio-9p.c |  137 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/virtio-9p.h |   23 +++++++++
 2 files changed, 160 insertions(+), 0 deletions(-)

diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
index 8c1cdfb..a51f5ac 100644
--- a/hw/virtio-9p.c
+++ b/hw/virtio-9p.c
@@ -662,6 +662,15 @@ static size_t pdu_unmarshal(V9fsPDU *pdu, size_t offset, 
const char *fmt, ...)
                         &statp->n_muid);
             break;
         }
+        case 'I': {
+            V9fsIattr *iattr = va_arg(ap, V9fsIattr *);
+            offset += pdu_unmarshal(pdu, offset, "ddddqqqqq",
+                        &iattr->valid, &iattr->mode,
+                        &iattr->uid, &iattr->gid, &iattr->size,
+                        &iattr->atime_sec, &iattr->atime_nsec,
+                        &iattr->mtime_sec, &iattr->mtime_nsec);
+            break;
+        }
         default:
             break;
         }
@@ -1208,6 +1217,133 @@ out:
     qemu_free(vs);
 }
 
+/* From Linux kernel code */
+#define ATTR_MODE    (1 << 0)
+#define ATTR_UID     (1 << 1)
+#define ATTR_GID     (1 << 2)
+#define ATTR_SIZE    (1 << 3)
+#define ATTR_ATIME   (1 << 4)
+#define ATTR_MTIME   (1 << 5)
+
+static void v9fs_setattr_post_truncate(V9fsState *s, V9fsSetattrState *vs,
+                                                                  int err)
+{
+    if (err == -1) {
+        err = -errno;
+        goto out;
+    }
+    err = vs->offset;
+
+out:
+    complete_pdu(s, vs->pdu, err);
+    qemu_free(vs);
+}
+
+static void v9fs_setattr_post_chown(V9fsState *s, V9fsSetattrState *vs, int 
err)
+{
+    if (err == -1) {
+        err = -errno;
+        goto out;
+    }
+
+    if (vs->v9iattr.valid & (ATTR_SIZE)) {
+        err = v9fs_do_truncate(s, &vs->fidp->path, vs->v9iattr.size);
+    }
+    v9fs_setattr_post_truncate(s, vs, err);
+    return;
+
+out:
+    complete_pdu(s, vs->pdu, err);
+    qemu_free(vs);
+}
+
+static void v9fs_setattr_post_utimensat(V9fsState *s, V9fsSetattrState *vs,
+                                                                   int err)
+{
+    if (err == -1) {
+        err = -errno;
+        goto out;
+    }
+
+    if (vs->v9iattr.valid & (ATTR_UID | ATTR_GID)) {
+        if (! (vs->v9iattr.valid & ATTR_UID)) {
+            vs->v9iattr.uid = -1;
+        }
+        if (! (vs->v9iattr.valid & ATTR_GID)) {
+            vs->v9iattr.gid = -1;
+        }
+        err = v9fs_do_chown(s, &vs->fidp->path, vs->v9iattr.uid,
+                                                vs->v9iattr.gid);
+    }
+    v9fs_setattr_post_chown(s, vs, err);
+    return;
+
+out:
+    complete_pdu(s, vs->pdu, err);
+    qemu_free(vs);
+}
+
+static void v9fs_setattr_post_chmod(V9fsState *s, V9fsSetattrState *vs, int 
err)
+{
+    if (err == -1) {
+        err = -errno;
+        goto out;
+    }
+
+    if (vs->v9iattr.valid & (ATTR_ATIME | ATTR_MTIME)) {
+        struct timespec times[2];
+        if (vs->v9iattr.valid & ATTR_ATIME) {
+            times[0].tv_sec = vs->v9iattr.atime_sec;
+            times[0].tv_nsec = vs->v9iattr.atime_nsec;
+        } else {
+            times[0].tv_nsec = UTIME_OMIT;
+        }
+        if (vs->v9iattr.valid & ATTR_MTIME) {
+            times[1].tv_sec = vs->v9iattr.mtime_sec;
+            times[1].tv_nsec = vs->v9iattr.mtime_nsec;
+        } else {
+            times[1].tv_nsec = UTIME_OMIT;
+        }
+        err = v9fs_do_utimensat(s, &vs->fidp->path, times);
+    }
+    v9fs_setattr_post_utimensat(s, vs, err);
+    return;
+
+out:
+    complete_pdu(s, vs->pdu, err);
+    qemu_free(vs);
+}
+
+static void v9fs_setattr(V9fsState *s, V9fsPDU *pdu)
+{
+    int32_t fid;
+    V9fsSetattrState *vs;
+    int err = 0;
+
+    vs = qemu_malloc(sizeof(*vs));
+    vs->pdu = pdu;
+    vs->offset = 7;
+
+    pdu_unmarshal(pdu, vs->offset, "dI", &fid, &vs->v9iattr);
+
+    vs->fidp = lookup_fid(s, fid);
+    if (vs->fidp == NULL) {
+        err = -EINVAL;
+        goto out;
+    }
+
+    if (vs->v9iattr.valid & ATTR_MODE) {
+        err = v9fs_do_chmod(s, &vs->fidp->path, vs->v9iattr.mode);
+    }
+
+    v9fs_setattr_post_chmod(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);
@@ -2507,6 +2643,7 @@ static pdu_handler_t *pdu_handlers[] = {
     [P9_TREADDIR] = v9fs_readdir,
     [P9_TSTATFS] = v9fs_statfs,
     [P9_TGETATTR] = v9fs_getattr,
+    [P9_TSETATTR] = v9fs_setattr,
     [P9_TSYMLINK] = v9fs_symlink,
     [P9_TVERSION] = v9fs_version,
     [P9_TATTACH] = v9fs_attach,
diff --git a/hw/virtio-9p.h b/hw/virtio-9p.h
index d033271..dafbd06 100644
--- a/hw/virtio-9p.h
+++ b/hw/virtio-9p.h
@@ -19,6 +19,8 @@ enum {
     P9_RSYMLINK,
     P9_TGETATTR = 24,
     P9_RGETATTR,
+    P9_TSETATTR = 26,
+    P9_RSETATTR,
     P9_TREADDIR = 40,
     P9_RREADDIR,
     P9_TLINK = 70,
@@ -280,6 +282,27 @@ typedef struct V9fsWstatState
     V9fsString nname;
 } V9fsWstatState;
 
+typedef struct V9fsIattr
+{
+    int32_t valid;
+    int32_t mode;
+    int32_t uid;
+    int32_t gid;
+    int64_t size;
+    int64_t atime_sec;
+    int64_t atime_nsec;
+    int64_t mtime_sec;
+    int64_t mtime_nsec;
+} V9fsIattr;
+
+typedef struct V9fsSetattrState
+{
+    V9fsPDU *pdu;
+    size_t offset;
+    V9fsIattr v9iattr;
+    V9fsFidState *fidp;
+} V9fsSetattrState;
+
 typedef struct V9fsSymlinkState
 {
     V9fsPDU *pdu;