[Qemu-devel] [PATCH 2/6] hw/9pfs: Don't free fid in clunk

[Aneesh Kumar K.V]

On interrupted syscall on client we can end up having fid
being acted upon by glib pool but still get a clunk request on that

Signed-off-by: Aneesh Kumar K.V <address@hidden>
---
 hw/9pfs/virtio-9p.c |  139 +++++++++++++++++++++++++++-----------------------
 hw/9pfs/virtio-9p.h |    7 +--
 2 files changed, 76 insertions(+), 70 deletions(-)

diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
index 03d8664..f3127a5 100644
--- a/hw/9pfs/virtio-9p.c
+++ b/hw/9pfs/virtio-9p.c
@@ -237,12 +237,11 @@ static V9fsFidState *get_fid(V9fsState *s, int32_t fid)
     V9fsFidState *f;
 
     for (f = s->fid_list; f; f = f->next) {
-        if (f->fid == fid) {
+        if (f->fid == fid && !f->clunked) {
             f->ref++;
             return f;
         }
     }
-
     return NULL;
 }
 
@@ -250,12 +249,12 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid)
 {
     V9fsFidState *f;
 
-    f = get_fid(s, fid);
-    if (f) {
-        f->ref--;
-        return NULL;
+    for (f = s->fid_list; f; f = f->next) {
+        /* If fid is already there return NULL */
+        if (f->fid == fid && !f->clunked) {
+            return NULL;
+        }
     }
-
     f = qemu_mallocz(sizeof(V9fsFidState));
     f->fid = fid;
     f->fid_type = P9_FID_NONE;
@@ -300,9 +299,33 @@ free_value:
     return retval;
 }
 
-static int free_fid(V9fsState *s, int32_t fid)
+static int release_fid(V9fsState *s, V9fsFidState *fidp)
 {
     int retval = 0;
+
+    if (fidp->fid_type == P9_FID_FILE) {
+        retval = v9fs_co_close(s, fidp);
+    } else if (fidp->fid_type == P9_FID_DIR) {
+        retval = v9fs_co_closedir(s, fidp);
+    } else if (fidp->fid_type == P9_FID_XATTR) {
+        retval = v9fs_xattr_fid_clunk(s, fidp);
+    }
+    v9fs_string_free(&fidp->path);
+    qemu_free(fidp);
+    return retval;
+}
+
+static void put_fid(V9fsState *s, V9fsFidState *fidp)
+{
+    BUG_ON(!fidp->ref);
+    fidp->ref--;
+    if (!fidp->ref && fidp->clunked) {
+        release_fid(s, fidp);
+    }
+}
+
+static int free_fid(V9fsState *s, int32_t fid)
+{
     V9fsFidState **fidpp, *fidp;
 
     for (fidpp = &s->fid_list; *fidpp; fidpp = &(*fidpp)->next) {
@@ -314,20 +337,10 @@ static int free_fid(V9fsState *s, int32_t fid)
     if (*fidpp == NULL) {
         return -ENOENT;
     }
-
     fidp = *fidpp;
     *fidpp = fidp->next;
-
-    if (fidp->fid_type == P9_FID_FILE) {
-        retval = v9fs_co_close(s, fidp);
-    } else if (fidp->fid_type == P9_FID_DIR) {
-        retval = v9fs_co_closedir(s, fidp);
-    } else if (fidp->fid_type == P9_FID_XATTR) {
-        retval = v9fs_xattr_fid_clunk(s, fidp);
-    }
-    v9fs_string_free(&fidp->path);
-    qemu_free(fidp);
-    return retval;
+    fidp->clunked = 1;
+    return 0;
 }
 
 #define P9_QID_TYPE_DIR         0x80
@@ -1022,14 +1035,13 @@ static void v9fs_attach(void *opaque)
     err = fid_to_qid(s, fidp, &qid);
     if (err < 0) {
         err = -EINVAL;
-        put_fid(fidp);
         free_fid(s, fid);
-        goto out_nofid;
+        goto out;
     }
     offset += pdu_marshal(pdu, offset, "Q", &qid);
     err = offset;
-    put_fid(fidp);
-
+out:
+    put_fid(s, fidp);
 out_nofid:
     complete_pdu(s, pdu, err);
     v9fs_string_free(&uname);
@@ -1066,7 +1078,7 @@ static void v9fs_stat(void *opaque)
     err = offset;
     v9fs_stat_free(&v9stat);
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
 out_nofid:
     complete_pdu(s, pdu, err);
 }
@@ -1102,7 +1114,7 @@ static void v9fs_getattr(void *opaque)
     retval = offset;
     retval += pdu_marshal(pdu, offset, "A", &v9stat_dotl);
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
 out_nofid:
     complete_pdu(s, pdu, retval);
 }
@@ -1196,7 +1208,7 @@ static void v9fs_setattr(void *opaque)
     }
     err = offset;
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
 out_nofid:
     complete_pdu(s, pdu, err);
 }
@@ -1279,9 +1291,7 @@ static void v9fs_walk(void *opaque)
             v9fs_string_copy(&newfidp->path, &path);
             err = v9fs_co_lstat(s, &newfidp->path, &stbuf);
             if (err < 0) {
-                put_fid(newfidp);
                 free_fid(s, newfidp->fid);
-                newfidp = NULL;
                 v9fs_string_free(&path);
                 goto out;
             }
@@ -1291,9 +1301,9 @@ static void v9fs_walk(void *opaque)
     }
     err = v9fs_walk_marshal(pdu, nwnames, qids);
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
     if (newfidp) {
-        put_fid(newfidp);
+        put_fid(s, newfidp);
     }
 out_nofid:
     complete_pdu(s, pdu, err);
@@ -1383,7 +1393,7 @@ static void v9fs_open(void *opaque)
         err = offset;
     }
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
 out_nofid:
     complete_pdu(s, pdu, err);
 }
@@ -1437,7 +1447,7 @@ static void v9fs_lcreate(void *opaque)
     offset += pdu_marshal(pdu, offset, "Qd", &qid, iounit);
     err = offset;
 out:
-    put_fid(fidp);
+    put_fid(pdu->s, fidp);
 out_nofid:
     complete_pdu(pdu->s, pdu, err);
     v9fs_string_free(&name);
@@ -1465,7 +1475,7 @@ static void v9fs_fsync(void *opaque)
         err = offset;
     }
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
     complete_pdu(s, pdu, err);
 }
 
@@ -1474,16 +1484,25 @@ static void v9fs_clunk(void *opaque)
     int err;
     int32_t fid;
     size_t offset = 7;
+    V9fsFidState *fidp;
     V9fsPDU *pdu = opaque;
     V9fsState *s = pdu->s;
 
     pdu_unmarshal(pdu, offset, "d", &fid);
-    err = free_fid(s, fid);
+
+    fidp = get_fid(s, fid);
+    if (fidp == NULL) {
+        err = -ENOENT;
+        goto out_nofid;
+    }
+    err = free_fid(s, fidp->fid);
     if (err < 0) {
         goto out;
     }
     err = offset;
 out:
+    put_fid(s, fidp);
+out_nofid:
     complete_pdu(s, pdu, err);
 }
 
@@ -1638,7 +1657,7 @@ static void v9fs_read(void *opaque)
         err = -EINVAL;
     }
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
 out_nofid:
     complete_pdu(s, pdu, err);
 }
@@ -1747,7 +1766,7 @@ static void v9fs_readdir(void *opaque)
     retval += pdu_marshal(pdu, offset, "d", count);
     retval += count;
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
 out_nofid:
     complete_pdu(s, pdu, retval);
 }
@@ -1857,7 +1876,7 @@ static void v9fs_write(void *opaque)
     offset += pdu_marshal(pdu, offset, "d", total);
     err = offset;
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
 out_nofid:
     complete_pdu(s, pdu, err);
 }
@@ -1923,10 +1942,10 @@ static void v9fs_create(void *opaque)
         }
         err = v9fs_co_link(pdu->s, &nfidp->path, &fullname);
         if (err < 0) {
-            put_fid(nfidp);
+            put_fid(pdu->s, nfidp);
             goto out;
         }
-        put_fid(nfidp);
+        put_fid(pdu->s, nfidp);
     } else if (perm & P9_STAT_MODE_DEVICE) {
         char ctype;
         uint32_t major, minor;
@@ -1990,7 +2009,7 @@ static void v9fs_create(void *opaque)
     err = offset;
 
 out:
-    put_fid(fidp);
+    put_fid(pdu->s, fidp);
 out_nofid:
    complete_pdu(pdu->s, pdu, err);
    v9fs_string_free(&name);
@@ -2035,7 +2054,7 @@ static void v9fs_symlink(void *opaque)
     offset += pdu_marshal(pdu, offset, "Q", &qid);
     err = offset;
 out:
-    put_fid(dfidp);
+    put_fid(pdu->s, dfidp);
 out_nofid:
     complete_pdu(pdu->s, pdu, err);
     v9fs_string_free(&name);
@@ -2086,7 +2105,7 @@ static void v9fs_link(void *opaque)
     v9fs_string_free(&fullname);
 
 out:
-    put_fid(dfidp);
+    put_fid(s, dfidp);
 out_nofid:
     v9fs_string_free(&name);
     complete_pdu(s, pdu, err);
@@ -2113,8 +2132,8 @@ static void v9fs_remove(void *opaque)
     }
 
     /* For TREMOVE we need to clunk the fid even on failed remove */
-    put_fid(fidp);
     free_fid(pdu->s, fidp->fid);
+    put_fid(pdu->s, fidp);
 out_nofid:
     complete_pdu(pdu->s, pdu, err);
 }
@@ -2185,7 +2204,7 @@ static int v9fs_complete_rename(V9fsState *s, 
V9fsFidState *fidp,
     }
 out:
     if (dirfidp) {
-        put_fid(dirfidp);
+        put_fid(s, dirfidp);
     }
 out_nofid:
     return err;
@@ -2216,7 +2235,7 @@ static void v9fs_rename(void *opaque)
         err = offset;
     }
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
 out_nofid:
     complete_pdu(s, pdu, err);
     v9fs_string_free(&name);
@@ -2305,7 +2324,7 @@ static void v9fs_wstat(void *opaque)
     }
     err = offset;
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
 out_nofid:
     v9fs_stat_free(&v9stat);
     complete_pdu(s, pdu, err);
@@ -2379,7 +2398,7 @@ static void v9fs_statfs(void *opaque)
     retval = offset;
     retval += v9fs_fill_statfs(s, pdu, &stbuf);
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
 out_nofid:
     complete_pdu(s, pdu, retval);
     return;
@@ -2425,7 +2444,7 @@ static void v9fs_mknod(void *opaque)
     err = offset;
     err += pdu_marshal(pdu, offset, "Q", &qid);
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
 out_nofid:
     complete_pdu(s, pdu, err);
     v9fs_string_free(&fullname);
@@ -2473,7 +2492,7 @@ static void v9fs_lock(void *opaque)
     }
     status = P9_LOCK_SUCCESS;
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
 out_nofid:
     err = offset;
     err += pdu_marshal(pdu, offset, "b", status);
@@ -2515,7 +2534,7 @@ static void v9fs_getlock(void *opaque)
                           &glock->client_id);
     err = offset;
 out:
-    put_fid(fidp);
+    put_fid(s, fidp);
 out_nofid:
     complete_pdu(s, pdu, err);
     qemu_free(glock);
@@ -2555,7 +2574,7 @@ static void v9fs_mkdir(void *opaque)
     offset += pdu_marshal(pdu, offset, "Q", &qid);
     err = offset;
 out:
-    put_fid(fidp);
+    put_fid(pdu->s, fidp);
 out_nofid:
     complete_pdu(pdu->s, pdu, err);
     v9fs_string_free(&fullname);
@@ -2593,9 +2612,7 @@ static void v9fs_xattrwalk(void *opaque)
         size = v9fs_co_llistxattr(s, &xattr_fidp->path, NULL, 0);
         if (size < 0) {
             err = size;
-            put_fid(xattr_fidp);
             free_fid(s, xattr_fidp->fid);
-            xattr_fidp = NULL;
             goto out;
         }
         /*
@@ -2610,9 +2627,7 @@ static void v9fs_xattrwalk(void *opaque)
                                      xattr_fidp->fs.xattr.value,
                                      xattr_fidp->fs.xattr.len);
             if (err < 0) {
-                put_fid(xattr_fidp);
                 free_fid(s, xattr_fidp->fid);
-                xattr_fidp = NULL;
                 goto out;
             }
         }
@@ -2627,9 +2642,7 @@ static void v9fs_xattrwalk(void *opaque)
                                  &name, NULL, 0);
         if (size < 0) {
             err = size;
-            put_fid(xattr_fidp);
             free_fid(s, xattr_fidp->fid);
-            xattr_fidp = NULL;
             goto out;
         }
         /*
@@ -2644,9 +2657,7 @@ static void v9fs_xattrwalk(void *opaque)
                                     &name, xattr_fidp->fs.xattr.value,
                                     xattr_fidp->fs.xattr.len);
             if (err < 0) {
-                put_fid(xattr_fidp);
                 free_fid(s, xattr_fidp->fid);
-                xattr_fidp = NULL;
                 goto out;
             }
         }
@@ -2654,9 +2665,9 @@ static void v9fs_xattrwalk(void *opaque)
         err = offset;
     }
 out:
-    put_fid(file_fidp);
+    put_fid(s, file_fidp);
     if (xattr_fidp) {
-        put_fid(xattr_fidp);
+        put_fid(s, xattr_fidp);
     }
 out_nofid:
     complete_pdu(s, pdu, err);
@@ -2698,7 +2709,7 @@ static void v9fs_xattrcreate(void *opaque)
         xattr_fidp->fs.xattr.value = NULL;
     }
     err = offset;
-    put_fid(file_fidp);
+    put_fid(s, file_fidp);
 out_nofid:
     complete_pdu(s, pdu, err);
     v9fs_string_free(&name);
@@ -2729,7 +2740,7 @@ static void v9fs_readlink(void *opaque)
     err = offset;
     v9fs_string_free(&target);
 out:
-    put_fid(fidp);
+    put_fid(pdu->s, fidp);
 out_nofid:
     complete_pdu(pdu->s, pdu, err);
 }
diff --git a/hw/9pfs/virtio-9p.h b/hw/9pfs/virtio-9p.h
index ce93c20..e16e5f4 100644
--- a/hw/9pfs/virtio-9p.h
+++ b/hw/9pfs/virtio-9p.h
@@ -204,6 +204,7 @@ struct V9fsFidState
     } fs;
     uid_t uid;
     int ref;
+    int clunked;
     V9fsFidState *next;
 };
 
@@ -362,11 +363,5 @@ static inline size_t do_pdu_unpack(void *dst, struct iovec 
*sg, int sg_count,
     return pdu_packunpack(dst, sg, sg_count, offset, size, 0);
 }
 
-static inline void put_fid(V9fsFidState *fidp)
-{
-    BUG_ON(!fidp->ref);
-    fidp->ref--;
-}
-
 extern void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq);
 #endif
-- 
1.7.4.1