[Qemu-devel] [PATCH 2/2] qemu-virtio9p: Implement TGETLOCK

[M. Mohan Kumar]

Synopsis

    size[4] TGetlock tag[2] fid[4] getlock[n]
    size[4] RGetlock tag[2] getlock[n]

Description

TGetlock is used to test for the existence of byte range posix locks on
a file identified by given fid. The reply contains getlock structure. If
the lock could be placed it returns F_UNLCK in type field of getlock structure.
Otherwise it returns the details of the conflicting locks in the getlock
structure

    getlock structure:
      type[1] - Type of lock: F_RDLCK, F_WRLCK
      start[8] - Starting offset for lock
      length[8] - Number of bytes to lock
        If length is 0, lock all bytes starting at the location
        'start' through to the end of file
      proc_id[4] - process id that wants to take lock/owns the task
               in case of reply
      client[4] - Client id of the system that owns the process

Signed-off-by: M. Mohan Kumar <address@hidden>
---
 hw/virtio-9p-debug.c |   17 +++++++++++++++++
 hw/virtio-9p.c       |   41 +++++++++++++++++++++++++++++++++++++++++
 hw/virtio-9p.h       |   21 +++++++++++++++++++++
 3 files changed, 79 insertions(+), 0 deletions(-)

diff --git a/hw/virtio-9p-debug.c b/hw/virtio-9p-debug.c
index 045774f..85c9900 100644
--- a/hw/virtio-9p-debug.c
+++ b/hw/virtio-9p-debug.c
@@ -602,6 +602,23 @@ void pprint_pdu(V9fsPDU *pdu)
         fprintf(llogfile, "RLOCK: (");
         pprint_int8(pdu, 0, &offset, "status");
         break;
+    case P9_TGETLOCK:
+        fprintf(llogfile, "TGETLOCK: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        pprint_int8(pdu, 0, &offset, ", type");
+        pprint_int64(pdu, 0, &offset, ", start");
+        pprint_int64(pdu, 0, &offset, ", length");
+        pprint_int32(pdu, 0, &offset, ", proc_id");
+        pprint_str(pdu, 0, &offset, ", client_id");
+        break;
+    case P9_RGETLOCK:
+        fprintf(llogfile, "RGETLOCK: (");
+        pprint_int8(pdu, 0, &offset, "type");
+        pprint_int64(pdu, 0, &offset, ", start");
+        pprint_int64(pdu, 0, &offset, ", length");
+        pprint_int32(pdu, 0, &offset, ", proc_id");
+        pprint_str(pdu, 0, &offset, ", client_id");
+        break;
     default:
         fprintf(llogfile, "unknown(%d): (", pdu->id);
         break;
diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
index b3d55f1..db3f008 100644
--- a/hw/virtio-9p.c
+++ b/hw/virtio-9p.c
@@ -3199,6 +3199,46 @@ out:
     qemu_free(vs);
 }
 
+/*
+ * When a TGETLOCK request comes, always return success because all lock
+ * handling is done by client's VFS layer.
+ */
+
+static void v9fs_getlock(V9fsState *s, V9fsPDU *pdu)
+{
+    int32_t fid, err = 0;
+    V9fsGetlockState *vs;
+
+    vs = qemu_mallocz(sizeof(*vs));
+    vs->pdu = pdu;
+    vs->offset = 7;
+
+    vs->glock = qemu_malloc(sizeof(*vs->glock));
+    pdu_unmarshal(vs->pdu, vs->offset, "dbqqds", &fid, &vs->glock->type,
+                &vs->glock->start, &vs->glock->length, &vs->glock->proc_id,
+               &vs->glock->client_id);
+
+    vs->fidp = lookup_fid(s, fid);
+    if (vs->fidp == NULL) {
+        err = -ENOENT;
+        goto out;
+    }
+
+    err = v9fs_do_fstat(s, vs->fidp->fs.fd, &vs->stbuf);
+    if (err < 0) {
+        err = -errno;
+        goto out;
+    }
+    vs->glock->type = F_UNLCK;
+    vs->offset += pdu_marshal(vs->pdu, vs->offset, "bqqds", vs->glock->type,
+                vs->glock->start, vs->glock->length, vs->glock->proc_id,
+               &vs->glock->client_id);
+out:
+    complete_pdu(s, vs->pdu, err);
+    qemu_free(vs->glock);
+    qemu_free(vs);
+}
+
 static void v9fs_mkdir_post_lstat(V9fsState *s, V9fsMkState *vs, int err)
 {
     if (err == -1) {
@@ -3462,6 +3502,7 @@ static pdu_handler_t *pdu_handlers[] = {
     [P9_TMKNOD] = v9fs_mknod,
     [P9_TRENAME] = v9fs_rename,
     [P9_TLOCK] = v9fs_lock,
+    [P9_TGETLOCK] = v9fs_getlock,
     [P9_TMKDIR] = v9fs_mkdir,
     [P9_TVERSION] = v9fs_version,
     [P9_TLOPEN] = v9fs_open,
diff --git a/hw/virtio-9p.h b/hw/virtio-9p.h
index 4555f39..6a68895 100644
--- a/hw/virtio-9p.h
+++ b/hw/virtio-9p.h
@@ -39,6 +39,8 @@ enum {
     P9_RREADDIR,
     P9_TLOCK = 52,
     P9_RLOCK,
+    P9_TGETLOCK = 54,
+    P9_RGETLOCK,
     P9_TLINK = 70,
     P9_RLINK,
     P9_TMKDIR = 72,
@@ -464,6 +466,25 @@ typedef struct V9fsLockState
     V9fsFlock *flock;
 } V9fsLockState;
 
+typedef struct V9fsGetlock
+{
+    uint8_t type;
+    uint64_t start; /* absolute offset */
+    uint64_t length;
+    uint32_t proc_id;
+    V9fsString client_id;
+} V9fsGetlock;
+
+typedef struct V9fsGetlockState
+{
+    V9fsPDU *pdu;
+    size_t offset;
+    struct stat stbuf;
+    V9fsFidState *fidp;
+    V9fsGetlock *glock;
+} V9fsGetlockState;
+
+
 extern size_t pdu_packunpack(void *addr, struct iovec *sg, int sg_count,
                             size_t offset, size_t size, int pack);
 
-- 
1.7.0.4