hw/9pfs: add 9P2000.L unlinkat operation

unlinkat - Remove a directory entry

size[4] Tunlinkat tag[2] dirfid[4] name[s] flag[4]
size[4] Runlinkat tag[2]

older Tremove have the below request format

size[4] Tremove tag[2] fid[4]

The remove message is used to remove a directory entry either file or directory
The remove opreation is actually a directory opertation and should ideally have
dirfid, if not we cannot represent the fid on server with anything other than
name. We will have to derive the directory name from fid in the Tremove request.

NOTE: The operation doesn't clunk the unlink fid.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
index 0293fe42b1..d28edb799a 100644
--- a/hw/9pfs/virtio-9p.c
+++ b/hw/9pfs/virtio-9p.c
@@ -2338,6 +2338,45 @@ out_nofid:
     complete_pdu(pdu->s, pdu, err);
 }
 
+static void v9fs_unlinkat(void *opaque)
+{
+    int err = 0;
+    V9fsString name;
+    int32_t dfid, flags;
+    size_t offset = 7;
+    V9fsFidState *dfidp;
+    V9fsPDU *pdu = opaque;
+    V9fsString full_name;
+
+    pdu_unmarshal(pdu, offset, "dsd", &dfid, &name, &flags);
+
+    dfidp = get_fid(pdu->s, dfid);
+    if (dfidp == NULL) {
+        err = -EINVAL;
+        goto out_nofid;
+    }
+    v9fs_string_init(&full_name);
+    v9fs_string_sprintf(&full_name, "%s/%s", dfidp->path.data, name.data);
+    /*
+     * IF the file is unlinked, we cannot reopen
+     * the file later. So don't reclaim fd
+     */
+    err = v9fs_mark_fids_unreclaim(pdu->s, &full_name);
+    if (err < 0) {
+        goto out_err;
+    }
+    err = v9fs_co_remove(pdu->s, &full_name);
+    if (!err) {
+        err = offset;
+    }
+out_err:
+    put_fid(pdu->s, dfidp);
+    v9fs_string_free(&full_name);
+out_nofid:
+    complete_pdu(pdu->s, pdu, err);
+    v9fs_string_free(&name);
+}
+
 static int v9fs_complete_rename(V9fsState *s, V9fsFidState *fidp,
                                 int32_t newdirfid, V9fsString *name)
 {
@@ -3040,6 +3079,7 @@ static CoroutineEntry *pdu_co_handlers[] = {
     [P9_TGETLOCK] = v9fs_getlock,
     [P9_TRENAMEAT] = v9fs_renameat,
     [P9_TREADLINK] = v9fs_readlink,
+    [P9_TUNLINKAT] = v9fs_unlinkat,
     [P9_TMKDIR] = v9fs_mkdir,
     [P9_TVERSION] = v9fs_version,
     [P9_TLOPEN] = v9fs_open,