Changes in uspace/srv/vfs/vfs_ops.c [b1956e3:51774cd] in mainline

File:

• uspace/srv/vfs/vfs_ops.c (modified) (13 diffs)

uspace/srv/vfs/vfs_ops.c

@@ -49 +49 @@
 #include <unistd.h>
 #include <ctype.h>
-#include <fcntl.h>
 #include <assert.h>
 #include <vfs/canonify.h>
-#include <vfs/vfs_mtab.h>
-
-FIBRIL_MUTEX_INITIALIZE(mtab_list_lock);
-LIST_INITIALIZE(mtab_list);
-static size_t mtab_size = 0;
 
 /* Forward declarations of static functions. */
@@ -68 +62 @@
 FIBRIL_RWLOCK_INITIALIZE(namespace_rwlock);
 
-vfs_pair_t rootfs = {
-        .fs_handle = 0,
-        .service_id = 0
-};
-
-static int vfs_mount_internal(ipc_callid_t rid, service_id_t service_id,
-    fs_handle_t fs_handle, char *mp, char *opts)
-{
-        vfs_lookup_res_t mp_res;
-        vfs_lookup_res_t mr_res;
-        vfs_node_t *mp_node = NULL;
-        vfs_node_t *mr_node;
-        fs_index_t rindex;
-        aoff64_t rsize;
-        unsigned rlnkcnt;
-        async_exch_t *exch;
-        sysarg_t rc;
-        aid_t msg;
+static size_t shared_path(char *a, char *b)
+{
+        size_t res = 0;
+        
+        while (a[res] == b[res] && a[res] != 0)
+                res++;
+        
+        if (a[res] == b[res])
+                return res;
+        
+        res--;
+        while (a[res] != '/')
+                res--;
+        return res;
+}
+
+/* This call destroys the file if and only if there are no hard links left. */
+static void out_destroy(vfs_triplet_t *file)
+{
+        async_exch_t *exch = vfs_exchange_grab(file->fs_handle);
+        async_msg_2(exch, VFS_OUT_DESTROY, (sysarg_t) file->service_id,
+            (sysarg_t) file->index);
+        vfs_exchange_release(exch);
+}
+
+int vfs_op_clone(int oldfd, int newfd, bool desc)
+{
+        int rc;
+
+        /* If the file descriptors are the same, do nothing. */
+        if (oldfd == newfd)
+                return EOK;
+        
+        /* Lookup the file structure corresponding to fd. */
+        vfs_file_t *oldfile = vfs_file_get(oldfd);
+        if (oldfile == NULL)
+                return EBADF;
+
+        assert(oldfile->node != NULL);
+
+        if (newfd != -1) {
+                /* Make sure newfd is closed. */
+                (void) vfs_fd_free(newfd);
+                /* Assign the old file to newfd. */
+                rc = vfs_fd_assign(oldfile, newfd);
+        } else {
+                vfs_file_t *newfile;
+                int newfd = vfs_fd_alloc(&newfile, desc);
+                if (newfd >= 0) {
+                        newfile->node = oldfile->node;
+                        newfile->permissions = oldfile->permissions;
+                        vfs_node_addref(newfile->node);
+        
+                        vfs_file_put(newfile);
+                }
+                rc = newfd;
+        }
+        vfs_file_put(oldfile);
+        
+        return rc;
+}
+
+int vfs_op_put(int fd)
+{
+        return vfs_fd_free(fd);
+}
+
+static int vfs_connect_internal(service_id_t service_id, unsigned flags,
+    unsigned instance, const char *options, const char *fsname,
+    vfs_node_t **root)
+{
+        fs_handle_t fs_handle = 0;
+        
+        fibril_mutex_lock(&fs_list_lock);
+        while (true) {
+                fs_handle = fs_name_to_handle(instance, fsname, false);
+                
+                if (fs_handle != 0 || !(flags & VFS_MOUNT_BLOCKING))
+                        break;
+                
+                fibril_condvar_wait(&fs_list_cv, &fs_list_lock);
+        }
+        fibril_mutex_unlock(&fs_list_lock);
+
+        if (fs_handle == 0)
+                return ENOENT;
+        
+        /* Tell the mountee that it is being mounted. */
         ipc_call_t answer;
-        
-        /* Resolve the path to the mountpoint. */
-        fibril_rwlock_write_lock(&namespace_rwlock);
-        if (rootfs.fs_handle) {
-                /* We already have the root FS. */
-                if (str_cmp(mp, "/") == 0) {
-                        /* Trying to mount root FS over root FS */
-                        fibril_rwlock_write_unlock(&namespace_rwlock);
-                        async_answer_0(rid, EBUSY);
-                        return EBUSY;
-                }
-                
-                rc = vfs_lookup_internal(mp, L_MP, &mp_res, NULL);
-                if (rc != EOK) {
-                        /* The lookup failed for some reason. */
-                        fibril_rwlock_write_unlock(&namespace_rwlock);
-                        async_answer_0(rid, rc);
-                        return rc;
-                }
-                
-                mp_node = vfs_node_get(&mp_res);
-                if (!mp_node) {
-                        fibril_rwlock_write_unlock(&namespace_rwlock);
-                        async_answer_0(rid, ENOMEM);
-                        return ENOMEM;
-                }
-                
-                /*
-                 * Now we hold a reference to mp_node.
-                 * It will be dropped upon the corresponding VFS_IN_UNMOUNT.
-                 * This prevents the mount point from being deleted.
-                 */
-        } else {
-                /* We still don't have the root file system mounted. */
-                if (str_cmp(mp, "/") == 0) {
-                        /*
-                         * For this simple, but important case,
-                         * we are almost done.
-                         */
-                        
-                        /* Tell the mountee that it is being mounted. */
-                        exch = vfs_exchange_grab(fs_handle);
-                        msg = async_send_1(exch, VFS_OUT_MOUNTED,
-                            (sysarg_t) service_id, &answer);
-                        /* Send the mount options */
-                        rc = async_data_write_start(exch, (void *)opts,
-                            str_size(opts));
-                        vfs_exchange_release(exch);
-                        
-                        if (rc != EOK) {
-                                async_forget(msg);
-                                fibril_rwlock_write_unlock(&namespace_rwlock);
-                                async_answer_0(rid, rc);
-                                return rc;
-                        }
-                        async_wait_for(msg, &rc);
-                        
-                        if (rc != EOK) {
-                                fibril_rwlock_write_unlock(&namespace_rwlock);
-                                async_answer_0(rid, rc);
-                                return rc;
-                        }
-
-                        rindex = (fs_index_t) IPC_GET_ARG1(answer);
-                        rsize = (aoff64_t) MERGE_LOUP32(IPC_GET_ARG2(answer),
-                            IPC_GET_ARG3(answer));
-                        rlnkcnt = (unsigned) IPC_GET_ARG4(answer);
-                        
-                        mr_res.triplet.fs_handle = fs_handle;
-                        mr_res.triplet.service_id = service_id;
-                        mr_res.triplet.index = rindex;
-                        mr_res.size = rsize;
-                        mr_res.lnkcnt = rlnkcnt;
-                        mr_res.type = VFS_NODE_DIRECTORY;
-                        
-                        rootfs.fs_handle = fs_handle;
-                        rootfs.service_id = service_id;
-                        
-                        /* Add reference to the mounted root. */
-                        mr_node = vfs_node_get(&mr_res); 
-                        assert(mr_node);
-                        
-                        fibril_rwlock_write_unlock(&namespace_rwlock);
-                        async_answer_0(rid, rc);
-                        return rc;
-                } else {
-                        /*
-                         * We can't resolve this without the root filesystem
-                         * being mounted first.
-                         */
-                        fibril_rwlock_write_unlock(&namespace_rwlock);
-                        async_answer_0(rid, ENOENT);
-                        return ENOENT;
-                }
-        }
-        
-        /*
-         * At this point, we have all necessary pieces: file system handle
-         * and service ID, and we know the mount point VFS node.
-         */
-        
-        async_exch_t *mountee_exch = vfs_exchange_grab(fs_handle);
-        assert(mountee_exch);
-        
-        exch = vfs_exchange_grab(mp_res.triplet.fs_handle);
-        msg = async_send_4(exch, VFS_OUT_MOUNT,
-            (sysarg_t) mp_res.triplet.service_id,
-            (sysarg_t) mp_res.triplet.index,
-            (sysarg_t) fs_handle,
-            (sysarg_t) service_id, &answer);
-        
-        /* Send connection */
-        rc = async_exchange_clone(exch, mountee_exch);
-        vfs_exchange_release(mountee_exch);
-        
+        async_exch_t *exch = vfs_exchange_grab(fs_handle);
+        aid_t msg = async_send_1(exch, VFS_OUT_MOUNTED, (sysarg_t) service_id,
+            &answer);
+        /* Send the mount options */
+        sysarg_t rc = async_data_write_start(exch, options, str_size(options));
+        if (rc != EOK) {
+                async_forget(msg);
+                vfs_exchange_release(exch);
+                return rc;
+        }
+
+        async_wait_for(msg, &rc);
         if (rc != EOK) {
                 vfs_exchange_release(exch);
+                return rc;
+        }
+        
+        vfs_lookup_res_t res;
+        res.triplet.fs_handle = fs_handle;
+        res.triplet.service_id = service_id;
+        res.triplet.index = (fs_index_t) IPC_GET_ARG1(answer);
+        res.size = (int64_t) MERGE_LOUP32(IPC_GET_ARG2(answer),
+            IPC_GET_ARG3(answer));
+        res.type = VFS_NODE_DIRECTORY;
+        
+        /* Add reference to the mounted root. */
+        *root = vfs_node_get(&res); 
+        if (!*root) {
+                aid_t msg = async_send_1(exch, VFS_OUT_UNMOUNTED,
+                    (sysarg_t) service_id, NULL);
                 async_forget(msg);
-                
-                /* Mount failed, drop reference to mp_node. */
-                if (mp_node)
-                        vfs_node_put(mp_node);
-                
-                async_answer_0(rid, rc);
-                fibril_rwlock_write_unlock(&namespace_rwlock);
+                vfs_exchange_release(exch);
+                return ENOMEM;
+        }
+                        
+        vfs_exchange_release(exch);
+
+        return EOK;
+}
+
+int vfs_op_mount(int mpfd, unsigned service_id, unsigned flags,
+    unsigned instance, const char *opts, const char *fs_name, int *outfd)
+{
+        int rc;
+        vfs_file_t *mp = NULL;
+        vfs_file_t *file = NULL;
+        int fd = -1;
+        
+        if (!(flags & VFS_MOUNT_CONNECT_ONLY)) {
+                mp = vfs_file_get(mpfd);
+                if (mp == NULL) {
+                        rc = EBADF;
+                        goto out;
+                }
+                
+                if (mp->node->mount != NULL) {
+                        rc = EBUSY;
+                        goto out;
+                }
+                
+                if (mp->node->type != VFS_NODE_DIRECTORY) {
+                        rc = ENOTDIR;
+                        goto out;
+                }
+                
+                if (vfs_node_has_children(mp->node)) {
+                        rc = ENOTEMPTY;
+                        goto out;
+                }
+        }
+        
+        if (!(flags & VFS_MOUNT_NO_REF)) {
+                fd = vfs_fd_alloc(&file, false);
+                if (fd < 0) {
+                        rc = fd;
+                        goto out;
+                }
+        }
+        
+        vfs_node_t *root = NULL;
+        
+        fibril_rwlock_write_lock(&namespace_rwlock);
+
+        rc = vfs_connect_internal(service_id, flags, instance, opts, fs_name,
+             &root);
+        if (rc == EOK && !(flags & VFS_MOUNT_CONNECT_ONLY)) {
+                vfs_node_addref(mp->node);
+                vfs_node_addref(root);
+                mp->node->mount = root;
+        }
+        
+        fibril_rwlock_write_unlock(&namespace_rwlock);
+        
+        if (rc != EOK)
+                goto out;
+        
+        if (flags & VFS_MOUNT_NO_REF) {
+                vfs_node_delref(root);
+        } else {
+                assert(file != NULL);
+                
+                file->node = root;
+                file->permissions = MODE_READ | MODE_WRITE | MODE_APPEND;
+                file->open_read = false;
+                file->open_write = false;
+        }
+        
+out:
+        if (mp)
+                vfs_file_put(mp);
+        if (file)
+                vfs_file_put(file);
+
+        if (rc != EOK && fd >= 0) {
+                vfs_fd_free(fd);
+                fd = 0;
+        }
+        
+        *outfd = fd;
+        return rc;
+}
+
+int vfs_op_open(int fd, int mode)
+{
+        if (mode == 0)
+                return EINVAL;
+
+        vfs_file_t *file = vfs_file_get(fd);
+        if (!file)
+                return EBADF;
+        
+        if ((mode & ~file->permissions) != 0) {
+                vfs_file_put(file);
+                return EPERM;
+        }
+        
+        if (file->open_read || file->open_write) {
+                vfs_file_put(file);
+                return EBUSY;
+        }
+        
+        file->open_read = (mode & MODE_READ) != 0;
+        file->open_write = (mode & (MODE_WRITE | MODE_APPEND)) != 0;
+        file->append = (mode & MODE_APPEND) != 0;
+        
+        if (!file->open_read && !file->open_write) {
+                vfs_file_put(file);
+                return EINVAL;
+        }
+        
+        if (file->node->type == VFS_NODE_DIRECTORY && file->open_write) {
+                file->open_read = file->open_write = false;
+                vfs_file_put(file);
+                return EINVAL;
+        }
+        
+        int rc = vfs_open_node_remote(file->node);
+        if (rc != EOK) {
+                file->open_read = file->open_write = false;
+                vfs_file_put(file);
                 return rc;
         }
         
-        /* send the mount options */
-        rc = async_data_write_start(exch, (void *) opts, str_size(opts));
-        if (rc != EOK) {
-                vfs_exchange_release(exch);
-                async_forget(msg);
-                
-                /* Mount failed, drop reference to mp_node. */
-                if (mp_node)
-                        vfs_node_put(mp_node);
-                
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-                async_answer_0(rid, rc);
-                return rc;
-        }
-        
-        /*
-         * Wait for the answer before releasing the exchange to avoid deadlock
-         * in case the answer depends on further calls to the same file system.
-         * Think of a case when mounting a FS on a file_bd backed by a file on
-         * the same FS. 
-         */
-        async_wait_for(msg, &rc);
-        vfs_exchange_release(exch);
-        
-        if (rc == EOK) {
-                rindex = (fs_index_t) IPC_GET_ARG1(answer);
-                rsize = (aoff64_t) MERGE_LOUP32(IPC_GET_ARG2(answer),
-                    IPC_GET_ARG3(answer));
-                rlnkcnt = (unsigned) IPC_GET_ARG4(answer);
-                
-                mr_res.triplet.fs_handle = fs_handle;
-                mr_res.triplet.service_id = service_id;
-                mr_res.triplet.index = rindex;
-                mr_res.size = rsize;
-                mr_res.lnkcnt = rlnkcnt;
-                mr_res.type = VFS_NODE_DIRECTORY;
-                
-                /* Add reference to the mounted root. */
-                mr_node = vfs_node_get(&mr_res); 
-                assert(mr_node);
-        } else {
-                /* Mount failed, drop reference to mp_node. */
-                if (mp_node)
-                        vfs_node_put(mp_node);
-        }
-        
-        async_answer_0(rid, rc);
-        fibril_rwlock_write_unlock(&namespace_rwlock);
-        return rc;
-}
-
-void vfs_mount_srv(ipc_callid_t rid, ipc_call_t *request)
-{
-        service_id_t service_id;
-
-        /*
-         * We expect the library to do the device-name to device-handle
-         * translation for us, thus the device handle will arrive as ARG1
-         * in the request.
-         */
-        service_id = (service_id_t) IPC_GET_ARG1(*request);
-        
-        /*
-         * Mount flags are passed as ARG2.
-         */
-        unsigned int flags = (unsigned int) IPC_GET_ARG2(*request);
-        
-        /*
-         * Instance number is passed as ARG3.
-         */
-        unsigned int instance = IPC_GET_ARG3(*request);
-
-        /* We want the client to send us the mount point. */
-        char *mp;
-        int rc = async_data_write_accept((void **) &mp, true, 0, MAX_PATH_LEN,
-            0, NULL);
-        if (rc != EOK) {
-                async_answer_0(rid, rc);
-                return;
-        }
-        
-        /* Now we expect to receive the mount options. */
-        char *opts;
-        rc = async_data_write_accept((void **) &opts, true, 0, MAX_MNTOPTS_LEN,
-            0, NULL);
-        if (rc != EOK) {
-                free(mp);
-                async_answer_0(rid, rc);
-                return;
-        }
-        
-        /*
-         * Now, we expect the client to send us data with the name of the file
-         * system.
-         */
-        char *fs_name;
-        rc = async_data_write_accept((void **) &fs_name, true, 0,
-            FS_NAME_MAXLEN, 0, NULL);
-        if (rc != EOK) {
-                free(mp);
-                free(opts);
-                async_answer_0(rid, rc);
-                return;
-        }
-        
-        /*
-         * Wait for VFS_IN_PING so that we can return an error if we don't know
-         * fs_name.
-         */
-        ipc_call_t data;
-        ipc_callid_t callid = async_get_call(&data);
-        if (IPC_GET_IMETHOD(data) != VFS_IN_PING) {
-                async_answer_0(callid, ENOTSUP);
-                async_answer_0(rid, ENOTSUP);
-                free(mp);
-                free(opts);
-                free(fs_name);
-                return;
-        }
-
-        /*
-         * Check if we know a file system with the same name as is in fs_name.
-         * This will also give us its file system handle.
-         */
-        fibril_mutex_lock(&fs_list_lock);
-        fs_handle_t fs_handle;
-recheck:
-        fs_handle = fs_name_to_handle(instance, fs_name, false);
-        if (!fs_handle) {
-                if (flags & IPC_FLAG_BLOCKING) {
-                        fibril_condvar_wait(&fs_list_cv, &fs_list_lock);
-                        goto recheck;
-                }
-                
-                fibril_mutex_unlock(&fs_list_lock);
-                async_answer_0(callid, ENOENT);
-                async_answer_0(rid, ENOENT);
-                free(mp);
-                free(fs_name);
-                free(opts);
-                return;
-        }
-        fibril_mutex_unlock(&fs_list_lock);
-
-        /* Add the filesystem info to the list of mounted filesystems */
-        mtab_ent_t *mtab_ent = malloc(sizeof(mtab_ent_t));
-        if (!mtab_ent) {
-                async_answer_0(callid, ENOMEM);
-                async_answer_0(rid, ENOMEM);
-                free(mp);
-                free(fs_name);
-                free(opts);
-                return;
-        }
-
-        /* Do the mount */
-        rc = vfs_mount_internal(rid, service_id, fs_handle, mp, opts);
-        if (rc != EOK) {
-                async_answer_0(callid, ENOTSUP);
-                async_answer_0(rid, ENOTSUP);
-                free(mtab_ent);
-                free(mp);
-                free(opts);
-                free(fs_name);
-                return;
-        }
-
-        /* Add the filesystem info to the list of mounted filesystems */
-
-        str_cpy(mtab_ent->mp, MAX_PATH_LEN, mp);
-        str_cpy(mtab_ent->fs_name, FS_NAME_MAXLEN, fs_name);
-        str_cpy(mtab_ent->opts, MAX_MNTOPTS_LEN, opts);
-        mtab_ent->instance = instance;
-        mtab_ent->service_id = service_id;
-
-        link_initialize(&mtab_ent->link);
-
-        fibril_mutex_lock(&mtab_list_lock);
-        list_append(&mtab_ent->link, &mtab_list);
-        mtab_size++;
-        fibril_mutex_unlock(&mtab_list_lock);
-
-        free(mp);
-        free(fs_name);
-        free(opts);
-
-        /* Acknowledge that we know fs_name. */
-        async_answer_0(callid, EOK);
-}
-
-void vfs_unmount_srv(ipc_callid_t rid, ipc_call_t *request)
-{
-        int rc;
-        char *mp;
-        vfs_lookup_res_t mp_res;
-        vfs_lookup_res_t mr_res;
-        vfs_node_t *mr_node;
-        async_exch_t *exch;
-        
-        /*
-         * Receive the mount point path.
-         */
-        rc = async_data_write_accept((void **) &mp, true, 0, MAX_PATH_LEN,
-            0, NULL);
-        if (rc != EOK)
-                async_answer_0(rid, rc);
-        
-        /*
-         * Taking the namespace lock will do two things for us. First, it will
-         * prevent races with other lookup operations. Second, it will stop new
-         * references to already existing VFS nodes and creation of new VFS
-         * nodes. This is because new references are added as a result of some
-         * lookup operation or at least of some operation which is protected by
-         * the namespace lock.
-         */
-        fibril_rwlock_write_lock(&namespace_rwlock);
-        
-        /*
-         * Lookup the mounted root and instantiate it.
-         */
-        rc = vfs_lookup_internal(mp, L_ROOT, &mr_res, NULL);
-        if (rc != EOK) {
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-                free(mp);
-                async_answer_0(rid, rc);
-                return;
-        }
-        mr_node = vfs_node_get(&mr_res);
-        if (!mr_node) {
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-                free(mp);
-                async_answer_0(rid, ENOMEM);
-                return;
-        }
-        
-        /*
-         * Count the total number of references for the mounted file system. We
-         * are expecting at least two. One which we got above and one which we
-         * got when the file system was mounted. If we find more, it means that
-         * the file system cannot be gracefully unmounted at the moment because
-         * someone is working with it.
-         */
-        if (vfs_nodes_refcount_sum_get(mr_node->fs_handle,
-            mr_node->service_id) != 2) {
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-                vfs_node_put(mr_node);
-                free(mp);
-                async_answer_0(rid, EBUSY);
-                return;
-        }
-        
-        if (str_cmp(mp, "/") == 0) {
-                
-                /*
-                 * Unmounting the root file system.
-                 *
-                 * In this case, there is no mount point node and we send
-                 * VFS_OUT_UNMOUNTED directly to the mounted file system.
-                 */
-                
-                exch = vfs_exchange_grab(mr_node->fs_handle);
-                rc = async_req_1_0(exch, VFS_OUT_UNMOUNTED,
-                    mr_node->service_id);
-                vfs_exchange_release(exch);
-                
-                if (rc != EOK) {
-                        fibril_rwlock_write_unlock(&namespace_rwlock);
-                        free(mp);
-                        vfs_node_put(mr_node);
-                        async_answer_0(rid, rc);
-                        return;
-                }
-                
-                rootfs.fs_handle = 0;
-                rootfs.service_id = 0;
-        } else {
-                
-                /*
-                 * Unmounting a non-root file system.
-                 *
-                 * We have a regular mount point node representing the parent
-                 * file system, so we delegate the operation to it.
-                 */
-                
-                rc = vfs_lookup_internal(mp, L_MP, &mp_res, NULL);
-                if (rc != EOK) {
-                        fibril_rwlock_write_unlock(&namespace_rwlock);
-                        free(mp);
-                        vfs_node_put(mr_node);
-                        async_answer_0(rid, rc);
-                        return;
-                }
-                
-                vfs_node_t *mp_node = vfs_node_get(&mp_res);
-                if (!mp_node) {
-                        fibril_rwlock_write_unlock(&namespace_rwlock);
-                        free(mp);
-                        vfs_node_put(mr_node);
-                        async_answer_0(rid, ENOMEM);
-                        return;
-                }
-                
-                exch = vfs_exchange_grab(mp_node->fs_handle);
-                rc = async_req_2_0(exch, VFS_OUT_UNMOUNT,
-                    mp_node->service_id, mp_node->index);
-                vfs_exchange_release(exch);
-                
-                if (rc != EOK) {
-                        fibril_rwlock_write_unlock(&namespace_rwlock);
-                        free(mp);
-                        vfs_node_put(mp_node);
-                        vfs_node_put(mr_node);
-                        async_answer_0(rid, rc);
-                        return;
-                }
-                
-                /* Drop the reference we got above. */
-                vfs_node_put(mp_node);
-                /* Drop the reference from when the file system was mounted. */
-                vfs_node_put(mp_node);
-        }
-        
-        /*
-         * All went well, the mounted file system was successfully unmounted.
-         * The only thing left is to forget the unmounted root VFS node.
-         */
-        vfs_node_forget(mr_node);
-        fibril_rwlock_write_unlock(&namespace_rwlock);
-
-        fibril_mutex_lock(&mtab_list_lock);
-
-        int found = 0;
-
-        list_foreach(mtab_list, link, mtab_ent_t, mtab_ent) {
-                if (str_cmp(mtab_ent->mp, mp) == 0) {
-                        list_remove(&mtab_ent->link);
-                        mtab_size--;
-                        free(mtab_ent);
-                        found = 1;
-                        break;
-                }
-        }
-        assert(found);
-        fibril_mutex_unlock(&mtab_list_lock);
-
-        free(mp);
-
-        async_answer_0(rid, EOK);
-}
-
-void vfs_open(ipc_callid_t rid, ipc_call_t *request)
-{
-        /*
-         * The POSIX interface is open(path, oflag, mode).
-         * We can receive oflags and mode along with the VFS_IN_OPEN call;
-         * the path will need to arrive in another call.
-         *
-         * We also receive one private, non-POSIX set of flags called lflag
-         * used to pass information to vfs_lookup_internal().
-         */
-        int lflag = IPC_GET_ARG1(*request);
-        int oflag = IPC_GET_ARG2(*request);
-        int mode = IPC_GET_ARG3(*request);
-
-        /* Ignore mode for now. */
-        (void) mode;
-        
-        /*
-         * Make sure that we are called with exactly one of L_FILE and
-         * L_DIRECTORY. Make sure that the user does not pass L_OPEN,
-         * L_ROOT or L_MP.
-         */
-        if (((lflag & (L_FILE | L_DIRECTORY)) == 0) ||
-            ((lflag & (L_FILE | L_DIRECTORY)) == (L_FILE | L_DIRECTORY)) ||
-            (lflag & (L_OPEN | L_ROOT | L_MP))) {
-                async_answer_0(rid, EINVAL);
-                return;
-        }
-        
-        if (oflag & O_CREAT)
-                lflag |= L_CREATE;
-        if (oflag & O_EXCL)
-                lflag |= L_EXCLUSIVE;
-        
-        char *path;
-        int rc = async_data_write_accept((void **) &path, true, 0, 0, 0, NULL);
-        if (rc != EOK) {
-                async_answer_0(rid, rc);
-                return;
-        }
-        
-        /*
-         * Avoid the race condition in which the file can be deleted before we
-         * find/create-and-lock the VFS node corresponding to the looked-up
-         * triplet.
-         */
-        if (lflag & L_CREATE)
-                fibril_rwlock_write_lock(&namespace_rwlock);
-        else
-                fibril_rwlock_read_lock(&namespace_rwlock);
-        
-        /* The path is now populated and we can call vfs_lookup_internal(). */
-        vfs_lookup_res_t lr;
-        rc = vfs_lookup_internal(path, lflag | L_OPEN, &lr, NULL);
-        if (rc != EOK) {
-                if (lflag & L_CREATE)
-                        fibril_rwlock_write_unlock(&namespace_rwlock);
-                else
-                        fibril_rwlock_read_unlock(&namespace_rwlock);
-                async_answer_0(rid, rc);
-                free(path);
-                return;
-        }
-        
-        /* Path is no longer needed. */
-        free(path);
-        
-        vfs_node_t *node = vfs_node_get(&lr);
-        if (lflag & L_CREATE)
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-        else
-                fibril_rwlock_read_unlock(&namespace_rwlock);
-
-        if (!node) {
-                async_answer_0(rid, ENOMEM);
-                return;
-        }
-        
-        /* Truncate the file if requested and if necessary. */
-        if (oflag & O_TRUNC) {
-                fibril_rwlock_write_lock(&node->contents_rwlock);
-                if (node->size) {
-                        rc = vfs_truncate_internal(node->fs_handle,
-                            node->service_id, node->index, 0);
-                        if (rc) {
-                                fibril_rwlock_write_unlock(&node->contents_rwlock);
-                                vfs_node_put(node);
-                                async_answer_0(rid, rc);
-                                return;
-                        }
-                        node->size = 0;
-                }
-                fibril_rwlock_write_unlock(&node->contents_rwlock);
-        }
-        
-        /*
-         * Get ourselves a file descriptor and the corresponding vfs_file_t
-         * structure.
-         */
-        int fd = vfs_fd_alloc((oflag & O_DESC) != 0);
-        if (fd < 0) {
-                vfs_node_put(node);
-                async_answer_0(rid, fd);
-                return;
-        }
-        vfs_file_t *file = vfs_file_get(fd);
-        assert(file);
-        file->node = node;
-        if (oflag & O_APPEND)
-                file->append = true;
-        
-        /*
-         * The following increase in reference count is for the fact that the
-         * file is being opened and that a file structure is pointing to it.
-         * It is necessary so that the file will not disappear when
-         * vfs_node_put() is called. The reference will be dropped by the
-         * respective VFS_IN_CLOSE.
-         */
-        vfs_node_addref(node);
-        vfs_node_put(node);
         vfs_file_put(file);
-        
-        /* Success! Return the new file descriptor to the client. */
-        async_answer_1(rid, EOK, fd);
-}
-
-void vfs_sync(ipc_callid_t rid, ipc_call_t *request)
-{
-        int fd = IPC_GET_ARG1(*request);
-        
-        /* Lookup the file structure corresponding to the file descriptor. */
-        vfs_file_t *file = vfs_file_get(fd);
-        if (!file) {
-                async_answer_0(rid, ENOENT);
-                return;
-        }
-        
-        /*
-         * Lock the open file structure so that no other thread can manipulate
-         * the same open file at a time.
-         */
-        fibril_mutex_lock(&file->lock);
-        async_exch_t *fs_exch = vfs_exchange_grab(file->node->fs_handle);
-        
-        /* Make a VFS_OUT_SYMC request at the destination FS server. */
-        aid_t msg;
-        ipc_call_t answer;
-        msg = async_send_2(fs_exch, VFS_OUT_SYNC, file->node->service_id,
-            file->node->index, &answer);
-        
-        vfs_exchange_release(fs_exch);
-        
-        /* Wait for reply from the FS server. */
-        sysarg_t rc;
-        async_wait_for(msg, &rc);
-        
-        fibril_mutex_unlock(&file->lock);
-        
-        vfs_file_put(file);
-        async_answer_0(rid, rc);
-}
-
-void vfs_close(ipc_callid_t rid, ipc_call_t *request)
-{
-        int fd = IPC_GET_ARG1(*request);
-        int ret = vfs_fd_free(fd);
-        async_answer_0(rid, ret);
-}
-
-typedef int (* rdwr_ipc_cb_t)(async_exch_t *, vfs_file_t *, ipc_call_t *,
-    bool, void *);
-
-static int rdwr_ipc_client(async_exch_t *exch, vfs_file_t *file,
+        return EOK;
+}
+
+typedef int (* rdwr_ipc_cb_t)(async_exch_t *, vfs_file_t *, aoff64_t,
+    ipc_call_t *, bool, void *);
+
+static int rdwr_ipc_client(async_exch_t *exch, vfs_file_t *file, aoff64_t pos,
     ipc_call_t *answer, bool read, void *data)
 {
@@ -754 +338 @@
                 rc = async_data_read_forward_4_1(exch, VFS_OUT_READ,
                     file->node->service_id, file->node->index,
-                    LOWER32(file->pos), UPPER32(file->pos), answer);
+                    LOWER32(pos), UPPER32(pos), answer);
         } else {
                 rc = async_data_write_forward_4_1(exch, VFS_OUT_WRITE,
                     file->node->service_id, file->node->index,
-                    LOWER32(file->pos), UPPER32(file->pos), answer);
+                    LOWER32(pos), UPPER32(pos), answer);
         }
 
@@ -765 +349 @@
 }
 
-static int rdwr_ipc_internal(async_exch_t *exch, vfs_file_t *file,
+static int rdwr_ipc_internal(async_exch_t *exch, vfs_file_t *file, aoff64_t pos,
     ipc_call_t *answer, bool read, void *data)
 {
@@ -774 +358 @@
         
         aid_t msg = async_send_fast(exch, read ? VFS_OUT_READ : VFS_OUT_WRITE,
-            file->node->service_id, file->node->index, LOWER32(file->pos),
-            UPPER32(file->pos), answer);
+            file->node->service_id, file->node->index, LOWER32(pos),
+            UPPER32(pos), answer);
         if (msg == 0)
                 return EINVAL;
@@ -793 +377 @@
 }
 
-static int vfs_rdwr(int fd, bool read, rdwr_ipc_cb_t ipc_cb, void *ipc_cb_data)
+static int vfs_rdwr(int fd, aoff64_t pos, bool read, rdwr_ipc_cb_t ipc_cb,
+    void *ipc_cb_data)
 {
         /*
@@ -808 +393 @@
         vfs_file_t *file = vfs_file_get(fd);
         if (!file)
-                return ENOENT;
-        
-        /*
-         * Lock the open file structure so that no other thread can manipulate
-         * the same open file at a time.
-         */
-        fibril_mutex_lock(&file->lock);
+                return EBADF;
+        
+        if ((read && !file->open_read) || (!read && !file->open_write)) {
+                vfs_file_put(file);
+                return EINVAL;
+        }
         
         vfs_info_t *fs_info = fs_handle_to_info(file->node->fs_handle);
         assert(fs_info);
+        
+        bool rlock = read ||
+            (fs_info->concurrent_read_write && fs_info->write_retains_size);
         
         /*
@@ -824 +411 @@
          * write implementation does not modify the file size.
          */
-        if ((read) ||
-            ((fs_info->concurrent_read_write) && (fs_info->write_retains_size)))
+        if (rlock)
                 fibril_rwlock_read_lock(&file->node->contents_rwlock);
         else
@@ -835 +421 @@
                  * while we are in readdir().
                  */
-                assert(read);
+                
+                if (!read) {
+                        if (rlock) {
+                                fibril_rwlock_read_unlock(
+                                    &file->node->contents_rwlock);
+                        } else {
+                                fibril_rwlock_write_unlock(
+                                    &file->node->contents_rwlock);
+                        }
+                        vfs_file_put(file);
+                        return EINVAL;
+                }
+                
                 fibril_rwlock_read_lock(&namespace_rwlock);
         }
@@ -842 +440 @@
         
         if (!read && file->append)
-                file->pos = file->node->size;
+                pos = file->node->size;
         
         /*
@@ -848 +446 @@
          */
         ipc_call_t answer;
-        int rc = ipc_cb(fs_exch, file, &answer, read, ipc_cb_data);
+        int rc = ipc_cb(fs_exch, file, pos, &answer, read, ipc_cb_data);
         
         vfs_exchange_release(fs_exch);
-        
-        size_t bytes = IPC_GET_ARG1(answer);
         
         if (file->node->type == VFS_NODE_DIRECTORY)
@@ -858 +454 @@
         
         /* Unlock the VFS node. */
-        if ((read) ||
-            ((fs_info->concurrent_read_write) && (fs_info->write_retains_size)))
+        if (rlock) {
                 fibril_rwlock_read_unlock(&file->node->contents_rwlock);
-        else {
+        } else {
                 /* Update the cached version of node's size. */
-                if (rc == EOK)
+                if (rc == EOK) {
                         file->node->size = MERGE_LOUP32(IPC_GET_ARG2(answer),
                             IPC_GET_ARG3(answer));
+                }
                 fibril_rwlock_write_unlock(&file->node->contents_rwlock);
         }
         
-        /* Update the position pointer and unlock the open file. */
+        vfs_file_put(file);     
+
+        return rc;
+}
+
+int vfs_rdwr_internal(int fd, aoff64_t pos, bool read, rdwr_io_chunk_t *chunk)
+{
+        return vfs_rdwr(fd, pos, read, rdwr_ipc_internal, chunk);
+}
+
+int vfs_op_read(int fd, aoff64_t pos, size_t *out_bytes)
+{
+        return vfs_rdwr(fd, pos, true, rdwr_ipc_client, out_bytes);
+}
+
+int vfs_op_rename(int basefd, char *old, char *new)
+{
+        vfs_file_t *base_file = vfs_file_get(basefd);
+        if (!base_file)
+                return EBADF;
+
+        vfs_node_t *base = base_file->node;
+        vfs_node_addref(base);
+        vfs_file_put(base_file);
+        
+        vfs_lookup_res_t base_lr;
+        vfs_lookup_res_t old_lr;
+        vfs_lookup_res_t new_lr_orig;
+        bool orig_unlinked = false;
+        
+        int rc;
+        
+        size_t shared = shared_path(old, new);
+        
+        /* Do not allow one path to be a prefix of the other. */
+        if (old[shared] == 0 || new[shared] == 0) {
+                vfs_node_put(base);
+                return EINVAL;
+        }
+        assert(old[shared] == '/');
+        assert(new[shared] == '/');
+        
+        fibril_rwlock_write_lock(&namespace_rwlock);
+        
+        /* Resolve the shared portion of the path first. */
+        if (shared != 0) {
+                old[shared] = 0;
+                rc = vfs_lookup_internal(base, old, L_DIRECTORY, &base_lr);
+                if (rc != EOK) {
+                        vfs_node_put(base);
+                        fibril_rwlock_write_unlock(&namespace_rwlock);
+                        return rc;
+                }
+                
+                vfs_node_put(base);
+                base = vfs_node_get(&base_lr);
+                if (!base) {
+                        fibril_rwlock_write_unlock(&namespace_rwlock);
+                        return ENOMEM;
+                }
+                old[shared] = '/';
+                old += shared;
+                new += shared;
+        }
+
+        rc = vfs_lookup_internal(base, old, L_DISABLE_MOUNTS, &old_lr);
+        if (rc != EOK) {
+                vfs_node_put(base);
+                fibril_rwlock_write_unlock(&namespace_rwlock);
+                return rc;
+        }
+                
+        rc = vfs_lookup_internal(base, new, L_UNLINK | L_DISABLE_MOUNTS,
+            &new_lr_orig);
+        if (rc == EOK) {
+                orig_unlinked = true;
+        } else if (rc != ENOENT) {
+                vfs_node_put(base);
+                fibril_rwlock_write_unlock(&namespace_rwlock);
+                return rc;
+        }
+
+        rc = vfs_link_internal(base, new, &old_lr.triplet);
+        if (rc != EOK) {
+                vfs_link_internal(base, old, &old_lr.triplet);
+                if (orig_unlinked)
+                        vfs_link_internal(base, new, &new_lr_orig.triplet);
+                vfs_node_put(base);
+                fibril_rwlock_write_unlock(&namespace_rwlock);
+                return rc;
+        }
+
+        rc = vfs_lookup_internal(base, old, L_UNLINK | L_DISABLE_MOUNTS,
+            &old_lr);
+        if (rc != EOK) {
+                if (orig_unlinked)
+                        vfs_link_internal(base, new, &new_lr_orig.triplet);
+                vfs_node_put(base);
+                fibril_rwlock_write_unlock(&namespace_rwlock);
+                return rc;
+        }
+        
+        /* If the node is not held by anyone, try to destroy it. */
+        if (orig_unlinked) {
+                vfs_node_t *node = vfs_node_peek(&new_lr_orig);
+                if (!node)
+                        out_destroy(&new_lr_orig.triplet);
+                else
+                        vfs_node_put(node);
+        }
+        
+        vfs_node_put(base);
+        fibril_rwlock_write_unlock(&namespace_rwlock);
+        return EOK;
+}
+
+int vfs_op_resize(int fd, int64_t size)
+{
+        vfs_file_t *file = vfs_file_get(fd);
+        if (!file)
+                return EBADF;
+
+        fibril_rwlock_write_lock(&file->node->contents_rwlock);
+        
+        int rc = vfs_truncate_internal(file->node->fs_handle,
+            file->node->service_id, file->node->index, size);
         if (rc == EOK)
-                file->pos += bytes;
-        fibril_mutex_unlock(&file->lock);
-        vfs_file_put(file);     
-
+                file->node->size = size;
+        
+        fibril_rwlock_write_unlock(&file->node->contents_rwlock);
+        vfs_file_put(file);
         return rc;
 }
-        
-static void vfs_rdwr_client(ipc_callid_t rid, ipc_call_t *request, bool read)
-{
-        size_t bytes = 0;       
-        int rc = vfs_rdwr(IPC_GET_ARG1(*request), read, rdwr_ipc_client,
-            &bytes);
-        async_answer_1(rid, rc, bytes);
-}
-
-int vfs_rdwr_internal(int fd, bool read, rdwr_io_chunk_t *chunk)
-{
-        return vfs_rdwr(fd, read, rdwr_ipc_internal, chunk);
-}
-
-void vfs_read(ipc_callid_t rid, ipc_call_t *request)
-{
-        vfs_rdwr_client(rid, request, true);
-}
-
-void vfs_write(ipc_callid_t rid, ipc_call_t *request)
-{
-        vfs_rdwr_client(rid, request, false);
-}
-
-void vfs_seek(ipc_callid_t rid, ipc_call_t *request)
-{
-        int fd = (int) IPC_GET_ARG1(*request);
-        off64_t off = (off64_t) MERGE_LOUP32(IPC_GET_ARG2(*request),
-            IPC_GET_ARG3(*request));
-        int whence = (int) IPC_GET_ARG4(*request);
-        
-        /* Lookup the file structure corresponding to the file descriptor. */
+
+int vfs_op_stat(int fd)
+{
         vfs_file_t *file = vfs_file_get(fd);
-        if (!file) {
-                async_answer_0(rid, ENOENT);
-                return;
-        }
-        
-        fibril_mutex_lock(&file->lock);
-        
-        off64_t newoff;
-        switch (whence) {
-        case SEEK_SET:
-                if (off >= 0) {
-                        file->pos = (aoff64_t) off;
-                        fibril_mutex_unlock(&file->lock);
-                        vfs_file_put(file);
-                        async_answer_1(rid, EOK, off);
-                        return;
-                }
-                break;
-        case SEEK_CUR:
-                if ((off >= 0) && (file->pos + off < file->pos)) {
-                        fibril_mutex_unlock(&file->lock);
-                        vfs_file_put(file);
-                        async_answer_0(rid, EOVERFLOW);
-                        return;
-                }
-                
-                if ((off < 0) && (file->pos < (aoff64_t) -off)) {
-                        fibril_mutex_unlock(&file->lock);
-                        vfs_file_put(file);
-                        async_answer_0(rid, EOVERFLOW);
-                        return;
-                }
-                
-                file->pos += off;
-                newoff = (file->pos > OFF64_MAX) ? OFF64_MAX : file->pos;
-                
-                fibril_mutex_unlock(&file->lock);
-                vfs_file_put(file);
-                async_answer_2(rid, EOK, LOWER32(newoff),
-                    UPPER32(newoff));
-                return;
-        case SEEK_END:
-                fibril_rwlock_read_lock(&file->node->contents_rwlock);
-                aoff64_t size = file->node->size;
-                
-                if ((off >= 0) && (size + off < size)) {
-                        fibril_rwlock_read_unlock(&file->node->contents_rwlock);
-                        fibril_mutex_unlock(&file->lock);
-                        vfs_file_put(file);
-                        async_answer_0(rid, EOVERFLOW);
-                        return;
-                }
-                
-                if ((off < 0) && (size < (aoff64_t) -off)) {
-                        fibril_rwlock_read_unlock(&file->node->contents_rwlock);
-                        fibril_mutex_unlock(&file->lock);
-                        vfs_file_put(file);
-                        async_answer_0(rid, EOVERFLOW);
-                        return;
-                }
-                
-                file->pos = size + off;
-                newoff = (file->pos > OFF64_MAX) ?  OFF64_MAX : file->pos;
-                
-                fibril_rwlock_read_unlock(&file->node->contents_rwlock);
-                fibril_mutex_unlock(&file->lock);
-                vfs_file_put(file);
-                async_answer_2(rid, EOK, LOWER32(newoff), UPPER32(newoff));
-                return;
-        }
-        
-        fibril_mutex_unlock(&file->lock);
+        if (!file)
+                return EBADF;
+
+        vfs_node_t *node = file->node;
+
+        async_exch_t *exch = vfs_exchange_grab(node->fs_handle);
+        int rc = async_data_read_forward_fast(exch, VFS_OUT_STAT,
+            node->service_id, node->index, true, 0, NULL);
+        vfs_exchange_release(exch);
+        
         vfs_file_put(file);
-        async_answer_0(rid, EINVAL);
-}
-
-int vfs_truncate_internal(fs_handle_t fs_handle, service_id_t service_id,
+        return rc;
+}
+
+int vfs_op_statfs(int fd)
+{
+        vfs_file_t *file = vfs_file_get(fd);
+        if (!file)
+                return EBADF;
+
+        vfs_node_t *node = file->node;
+
+        async_exch_t *exch = vfs_exchange_grab(node->fs_handle);
+        int rc = async_data_read_forward_fast(exch, VFS_OUT_STATFS,
+            node->service_id, node->index, false, 0, NULL);
+        vfs_exchange_release(exch);
+
+        vfs_file_put(file);
+        return rc;
+}
+
+int vfs_op_sync(int fd)
+{
+        vfs_file_t *file = vfs_file_get(fd);
+        if (!file)
+                return EBADF;
+        
+        async_exch_t *fs_exch = vfs_exchange_grab(file->node->fs_handle);
+        
+        aid_t msg;
+        ipc_call_t answer;
+        msg = async_send_2(fs_exch, VFS_OUT_SYNC, file->node->service_id,
+            file->node->index, &answer);
+        
+        vfs_exchange_release(fs_exch);
+        
+        sysarg_t rc;
+        async_wait_for(msg, &rc);
+        
+        vfs_file_put(file);
+        return rc;
+        
+}
+
+static int vfs_truncate_internal(fs_handle_t fs_handle, service_id_t service_id,
     fs_index_t index, aoff64_t size)
 {
@@ -998 +668 @@
 }
 
-void vfs_truncate(ipc_callid_t rid, ipc_call_t *request)
-{
-        int fd = IPC_GET_ARG1(*request);
-        aoff64_t size = (aoff64_t) MERGE_LOUP32(IPC_GET_ARG2(*request),
-            IPC_GET_ARG3(*request));
-        int rc;
-
-        vfs_file_t *file = vfs_file_get(fd);
-        if (!file) {
-                async_answer_0(rid, ENOENT);
-                return;
-        }
-        fibril_mutex_lock(&file->lock);
-
-        fibril_rwlock_write_lock(&file->node->contents_rwlock);
-        rc = vfs_truncate_internal(file->node->fs_handle,
-            file->node->service_id, file->node->index, size);
-        if (rc == EOK)
-                file->node->size = size;
-        fibril_rwlock_write_unlock(&file->node->contents_rwlock);
-
-        fibril_mutex_unlock(&file->lock);
-        vfs_file_put(file);
-        async_answer_0(rid, (sysarg_t)rc);
-}
-
-void vfs_fstat(ipc_callid_t rid, ipc_call_t *request)
-{
-        int fd = IPC_GET_ARG1(*request);
-        sysarg_t rc;
-
-        vfs_file_t *file = vfs_file_get(fd);
-        if (!file) {
-                async_answer_0(rid, ENOENT);
-                return;
-        }
-
-        ipc_callid_t callid;
-        if (!async_data_read_receive(&callid, NULL)) {
-                vfs_file_put(file);
-                async_answer_0(callid, EINVAL);
-                async_answer_0(rid, EINVAL);
-                return;
-        }
-
-        fibril_mutex_lock(&file->lock);
-
-        async_exch_t *exch = vfs_exchange_grab(file->node->fs_handle);
-        
-        aid_t msg;
-        msg = async_send_3(exch, VFS_OUT_STAT, file->node->service_id,
-            file->node->index, true, NULL);
-        async_forward_fast(callid, exch, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
-        
+int vfs_op_unlink(int parentfd, int expectfd, char *path)
+{
+        int rc = EOK;
+        vfs_file_t *parent = NULL;
+        vfs_file_t *expect = NULL;
+        
+        if (parentfd == expectfd)
+                return EINVAL;
+        
+        fibril_rwlock_write_lock(&namespace_rwlock);
+        
+        /* 
+         * Files are retrieved in order of file descriptors, to prevent
+         * deadlock.
+         */
+        if (parentfd < expectfd) {
+                parent = vfs_file_get(parentfd);
+                if (!parent) {
+                        rc = EBADF;
+                        goto exit;
+                }
+        }
+        
+        if (expectfd >= 0) {
+                expect = vfs_file_get(expectfd);
+                if (!expect) {
+                        rc = EBADF;
+                        goto exit;
+                }
+        }
+        
+        if (parentfd > expectfd) {
+                parent = vfs_file_get(parentfd);
+                if (!parent) {
+                        rc = EBADF;
+                        goto exit;
+                }
+        }
+        
+        assert(parent != NULL);
+        
+        if (expectfd >= 0) {
+                vfs_lookup_res_t lr;
+                rc = vfs_lookup_internal(parent->node, path, 0, &lr);
+                if (rc != EOK)
+                        goto exit;
+                
+                vfs_node_t *found_node = vfs_node_peek(&lr);
+                vfs_node_put(found_node);
+                if (expect->node != found_node) {
+                        rc = ENOENT;
+                        goto exit;
+                }
+                
+                vfs_file_put(expect);
+                expect = NULL;
+        }
+        
+        vfs_lookup_res_t lr;
+        rc = vfs_lookup_internal(parent->node, path, L_UNLINK, &lr);
+        if (rc != EOK)
+                goto exit;
+
+        /* If the node is not held by anyone, try to destroy it. */
+        vfs_node_t *node = vfs_node_peek(&lr);
+        if (!node)
+                out_destroy(&lr.triplet);
+        else
+                vfs_node_put(node);
+
+exit:
+        if (path)
+                free(path);
+        if (parent)
+                vfs_file_put(parent);
+        if (expect)
+                vfs_file_put(expect);
+        fibril_rwlock_write_unlock(&namespace_rwlock);
+        return rc;
+}
+
+int vfs_op_unmount(int mpfd)
+{
+        vfs_file_t *mp = vfs_file_get(mpfd);
+        if (mp == NULL)
+                return EBADF;
+        
+        if (mp->node->mount == NULL) {
+                vfs_file_put(mp);
+                return ENOENT;
+        }
+        
+        fibril_rwlock_write_lock(&namespace_rwlock);
+        
+        /*
+         * Count the total number of references for the mounted file system. We
+         * are expecting at least one, which is held by the mount point.
+         * If we find more, it means that
+         * the file system cannot be gracefully unmounted at the moment because
+         * someone is working with it.
+         */
+        if (vfs_nodes_refcount_sum_get(mp->node->mount->fs_handle,
+            mp->node->mount->service_id) != 1) {
+                vfs_file_put(mp);
+                fibril_rwlock_write_unlock(&namespace_rwlock);
+                return EBUSY;
+        }
+        
+        async_exch_t *exch = vfs_exchange_grab(mp->node->mount->fs_handle);
+        int rc = async_req_1_0(exch, VFS_OUT_UNMOUNTED,
+            mp->node->mount->service_id);
         vfs_exchange_release(exch);
         
-        async_wait_for(msg, &rc);
-        
-        fibril_mutex_unlock(&file->lock);
-        vfs_file_put(file);
-        async_answer_0(rid, rc);
-}
-
-void vfs_stat(ipc_callid_t rid, ipc_call_t *request)
-{
-        char *path;
-        int rc = async_data_write_accept((void **) &path, true, 0, 0, 0, NULL);
         if (rc != EOK) {
-                async_answer_0(rid, rc);
-                return;
-        }
-        
-        ipc_callid_t callid;
-        if (!async_data_read_receive(&callid, NULL)) {
-                free(path);
-                async_answer_0(callid, EINVAL);
-                async_answer_0(rid, EINVAL);
-                return;
-        }
-
+                vfs_file_put(mp);
+                fibril_rwlock_write_unlock(&namespace_rwlock);
+                return rc;
+        }
+        
+        vfs_node_forget(mp->node->mount);
+        vfs_node_put(mp->node);
+        mp->node->mount = NULL;
+        
+        fibril_rwlock_write_unlock(&namespace_rwlock);
+        
+        vfs_file_put(mp);
+        return EOK;
+}
+
+int vfs_op_wait_handle(bool high_fd)
+{
+        return vfs_wait_handle_internal(high_fd);
+}
+
+static inline bool walk_flags_valid(int flags)
+{
+        if ((flags & ~WALK_ALL_FLAGS) != 0)
+                return false;
+        if ((flags & WALK_MAY_CREATE) && (flags & WALK_MUST_CREATE))
+                return false;
+        if ((flags & WALK_REGULAR) && (flags & WALK_DIRECTORY))
+                return false;
+        if ((flags & WALK_MAY_CREATE) || (flags & WALK_MUST_CREATE)) {
+                if (!(flags & WALK_DIRECTORY) && !(flags & WALK_REGULAR))
+                        return false;
+        }
+        return true;
+}
+
+static inline int walk_lookup_flags(int flags)
+{
+        int lflags = 0;
+        if ((flags & WALK_MAY_CREATE) || (flags & WALK_MUST_CREATE))
+                lflags |= L_CREATE;
+        if (flags & WALK_MUST_CREATE)
+                lflags |= L_EXCLUSIVE;
+        if (flags & WALK_REGULAR)
+                lflags |= L_FILE;
+        if (flags & WALK_DIRECTORY)
+                lflags |= L_DIRECTORY;
+        if (flags & WALK_MOUNT_POINT)
+                lflags |= L_MP;
+        return lflags;
+}
+
+int vfs_op_walk(int parentfd, int flags, char *path, int *out_fd)
+{
+        if (!walk_flags_valid(flags))
+                return EINVAL;
+        
+        vfs_file_t *parent = vfs_file_get(parentfd);
+        if (!parent)
+                return EBADF;
+        
+        fibril_rwlock_read_lock(&namespace_rwlock);
+        
         vfs_lookup_res_t lr;
-        fibril_rwlock_read_lock(&namespace_rwlock);
-        rc = vfs_lookup_internal(path, L_NONE, &lr, NULL);
-        free(path);
+        int rc = vfs_lookup_internal(parent->node, path,
+            walk_lookup_flags(flags), &lr);
         if (rc != EOK) {
                 fibril_rwlock_read_unlock(&namespace_rwlock);
-                async_answer_0(callid, rc);
-                async_answer_0(rid, rc);
-                return;
-        }
+                vfs_file_put(parent);
+                return rc;
+        }
+        
         vfs_node_t *node = vfs_node_get(&lr);
         if (!node) {
                 fibril_rwlock_read_unlock(&namespace_rwlock);
-                async_answer_0(callid, ENOMEM);
-                async_answer_0(rid, ENOMEM);
-                return;
-        }
-
+                vfs_file_put(parent);
+                return ENOMEM;
+        }
+        
+        vfs_file_t *file;
+        int fd = vfs_fd_alloc(&file, false);
+        if (fd < 0) {
+                vfs_node_put(node);
+                vfs_file_put(parent);
+                return fd;
+        }
+        assert(file != NULL);
+        
+        file->node = node;
+        file->permissions = parent->permissions;
+        file->open_read = false;
+        file->open_write = false;
+        
+        vfs_file_put(file);
+        vfs_file_put(parent);
+        
         fibril_rwlock_read_unlock(&namespace_rwlock);
 
-        async_exch_t *exch = vfs_exchange_grab(node->fs_handle);
-        
-        aid_t msg;
-        msg = async_send_3(exch, VFS_OUT_STAT, node->service_id,
-            node->index, false, NULL);
-        async_forward_fast(callid, exch, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
-        
-        vfs_exchange_release(exch);
-        
-        sysarg_t rv;
-        async_wait_for(msg, &rv);
-
-        async_answer_0(rid, rv);
-
-        vfs_node_put(node);
-}
-
-void vfs_mkdir(ipc_callid_t rid, ipc_call_t *request)
-{
-        int mode = IPC_GET_ARG1(*request);
-        
-        char *path;
-        int rc = async_data_write_accept((void **) &path, true, 0, 0, 0, NULL);
-        if (rc != EOK) {
-                async_answer_0(rid, rc);
-                return;
-        }
-        
-        /* Ignore mode for now. */
-        (void) mode;
-        
-        fibril_rwlock_write_lock(&namespace_rwlock);
-        int lflag = L_DIRECTORY | L_CREATE | L_EXCLUSIVE;
-        rc = vfs_lookup_internal(path, lflag, NULL, NULL);
-        fibril_rwlock_write_unlock(&namespace_rwlock);
-        free(path);
-        async_answer_0(rid, rc);
-}
-
-void vfs_unlink(ipc_callid_t rid, ipc_call_t *request)
-{
-        int lflag = IPC_GET_ARG1(*request);
-        
-        char *path;
-        int rc = async_data_write_accept((void **) &path, true, 0, 0, 0, NULL);
-        if (rc != EOK) {
-                async_answer_0(rid, rc);
-                return;
-        }
-        
-        fibril_rwlock_write_lock(&namespace_rwlock);
-        lflag &= L_DIRECTORY;   /* sanitize lflag */
-        vfs_lookup_res_t lr;
-        rc = vfs_lookup_internal(path, lflag | L_UNLINK, &lr, NULL);
-        free(path);
-        if (rc != EOK) {
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-                async_answer_0(rid, rc);
-                return;
-        }
-
-        /*
-         * The name has already been unlinked by vfs_lookup_internal().
-         * We have to get and put the VFS node to ensure that it is
-         * VFS_OUT_DESTROY'ed after the last reference to it is dropped.
-         */
-        vfs_node_t *node = vfs_node_get(&lr);
-        fibril_mutex_lock(&nodes_mutex);
-        node->lnkcnt--;
-        fibril_mutex_unlock(&nodes_mutex);
-        fibril_rwlock_write_unlock(&namespace_rwlock);
-        vfs_node_put(node);
-        async_answer_0(rid, EOK);
-}
-
-void vfs_rename(ipc_callid_t rid, ipc_call_t *request)
-{
-        /* Retrieve the old path. */
-        char *old;
-        int rc = async_data_write_accept((void **) &old, true, 0, 0, 0, NULL);
-        if (rc != EOK) {
-                async_answer_0(rid, rc);
-                return;
-        }
-        
-        /* Retrieve the new path. */
-        char *new;
-        rc = async_data_write_accept((void **) &new, true, 0, 0, 0, NULL);
-        if (rc != EOK) {
-                free(old);
-                async_answer_0(rid, rc);
-                return;
-        }
-        
-        size_t olen;
-        size_t nlen;
-        char *oldc = canonify(old, &olen);
-        char *newc = canonify(new, &nlen);
-        
-        if ((!oldc) || (!newc)) {
-                async_answer_0(rid, EINVAL);
-                free(old);
-                free(new);
-                return;
-        }
-        
-        oldc[olen] = '\0';
-        newc[nlen] = '\0';
-        
-        if ((!str_lcmp(newc, oldc, str_length(oldc))) &&
-            ((newc[str_length(oldc)] == '/') ||
-            (str_length(oldc) == 1) ||
-            (str_length(oldc) == str_length(newc)))) {
-                /*
-                 * oldc is a prefix of newc and either
-                 * - newc continues with a / where oldc ends, or
-                 * - oldc was / itself, or
-                 * - oldc and newc are equal.
-                 */
-                async_answer_0(rid, EINVAL);
-                free(old);
-                free(new);
-                return;
-        }
-        
-        vfs_lookup_res_t old_lr;
-        vfs_lookup_res_t new_lr;
-        vfs_lookup_res_t new_par_lr;
-        fibril_rwlock_write_lock(&namespace_rwlock);
-        
-        /* Lookup the node belonging to the old file name. */
-        rc = vfs_lookup_internal(oldc, L_NONE, &old_lr, NULL);
-        if (rc != EOK) {
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-                async_answer_0(rid, rc);
-                free(old);
-                free(new);
-                return;
-        }
-        
-        vfs_node_t *old_node = vfs_node_get(&old_lr);
-        if (!old_node) {
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-                async_answer_0(rid, ENOMEM);
-                free(old);
-                free(new);
-                return;
-        }
-        
-        /* Determine the path to the parent of the node with the new name. */
-        char *parentc = str_dup(newc);
-        if (!parentc) {
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-                vfs_node_put(old_node);
-                async_answer_0(rid, rc);
-                free(old);
-                free(new);
-                return;
-        }
-        
-        char *lastsl = str_rchr(parentc + 1, '/');
-        if (lastsl)
-                *lastsl = '\0';
-        else
-                parentc[1] = '\0';
-        
-        /* Lookup parent of the new file name. */
-        rc = vfs_lookup_internal(parentc, L_NONE, &new_par_lr, NULL);
-        free(parentc);  /* not needed anymore */
-        if (rc != EOK) {
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-                vfs_node_put(old_node);
-                async_answer_0(rid, rc);
-                free(old);
-                free(new);
-                return;
-        }
-        
-        /* Check whether linking to the same file system instance. */
-        if ((old_node->fs_handle != new_par_lr.triplet.fs_handle) ||
-            (old_node->service_id != new_par_lr.triplet.service_id)) {
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-                vfs_node_put(old_node);
-                async_answer_0(rid, EXDEV);     /* different file systems */
-                free(old);
-                free(new);
-                return;
-        }
-        
-        /* Destroy the old link for the new name. */
-        vfs_node_t *new_node = NULL;
-        rc = vfs_lookup_internal(newc, L_UNLINK, &new_lr, NULL);
-        
-        switch (rc) {
-        case ENOENT:
-                /* simply not in our way */
-                break;
-        case EOK:
-                new_node = vfs_node_get(&new_lr);
-                if (!new_node) {
-                        fibril_rwlock_write_unlock(&namespace_rwlock);
-                        vfs_node_put(old_node);
-                        async_answer_0(rid, ENOMEM);
-                        free(old);
-                        free(new);
-                        return;
-                }
-                fibril_mutex_lock(&nodes_mutex);
-                new_node->lnkcnt--;
-                fibril_mutex_unlock(&nodes_mutex);
-                break;
-        default:
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-                vfs_node_put(old_node);
-                async_answer_0(rid, ENOTEMPTY);
-                free(old);
-                free(new);
-                return;
-        }
-        
-        /* Create the new link for the new name. */
-        rc = vfs_lookup_internal(newc, L_LINK, NULL, NULL, old_node->index);
-        if (rc != EOK) {
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-                vfs_node_put(old_node);
-                if (new_node)
-                        vfs_node_put(new_node);
-                async_answer_0(rid, rc);
-                free(old);
-                free(new);
-                return;
-        }
-        
-        fibril_mutex_lock(&nodes_mutex);
-        old_node->lnkcnt++;
-        fibril_mutex_unlock(&nodes_mutex);
-        
-        /* Destroy the link for the old name. */
-        rc = vfs_lookup_internal(oldc, L_UNLINK, NULL, NULL);
-        if (rc != EOK) {
-                fibril_rwlock_write_unlock(&namespace_rwlock);
-                vfs_node_put(old_node);
-                if (new_node)
-                        vfs_node_put(new_node);
-                async_answer_0(rid, rc);
-                free(old);
-                free(new);
-                return;
-        }
-        
-        fibril_mutex_lock(&nodes_mutex);
-        old_node->lnkcnt--;
-        fibril_mutex_unlock(&nodes_mutex);
-        fibril_rwlock_write_unlock(&namespace_rwlock);
-        vfs_node_put(old_node);
-        
-        if (new_node)
-                vfs_node_put(new_node);
-        
-        free(old);
-        free(new);
-        async_answer_0(rid, EOK);
-}
-
-void vfs_dup(ipc_callid_t rid, ipc_call_t *request)
-{
-        int oldfd = IPC_GET_ARG1(*request);
-        int newfd = IPC_GET_ARG2(*request);
-        
-        /* If the file descriptors are the same, do nothing. */
-        if (oldfd == newfd) {
-                async_answer_1(rid, EOK, newfd);
-                return;
-        }
-        
-        /* Lookup the file structure corresponding to oldfd. */
-        vfs_file_t *oldfile = vfs_file_get(oldfd);
-        if (!oldfile) {
-                async_answer_0(rid, EBADF);
-                return;
-        }
-        
-        /*
-         * Lock the open file structure so that no other thread can manipulate
-         * the same open file at a time.
-         */
-        fibril_mutex_lock(&oldfile->lock);
-        
-        /* Make sure newfd is closed. */
-        (void) vfs_fd_free(newfd);
-        
-        /* Assign the old file to newfd. */
-        int ret = vfs_fd_assign(oldfile, newfd);
-        fibril_mutex_unlock(&oldfile->lock);
-        vfs_file_put(oldfile);
-        
-        if (ret != EOK)
-                async_answer_0(rid, ret);
-        else
-                async_answer_1(rid, EOK, newfd);
-}
-
-void vfs_wait_handle(ipc_callid_t rid, ipc_call_t *request)
-{
-        int fd = vfs_wait_handle_internal();
-        async_answer_1(rid, EOK, fd);
-}
-
-void vfs_get_mtab(ipc_callid_t rid, ipc_call_t *request)
-{
-        ipc_callid_t callid;
-        ipc_call_t data;
-        sysarg_t rc = EOK;
-        size_t len;
-
-        fibril_mutex_lock(&mtab_list_lock);
-
-        /* Send to the caller the number of mounted filesystems */
-        callid = async_get_call(&data);
-        if (IPC_GET_IMETHOD(data) != VFS_IN_PING) {
-                rc = ENOTSUP;
-                async_answer_0(callid, rc);
-                goto exit;
-        }
-        async_answer_1(callid, EOK, mtab_size);
-
-        list_foreach(mtab_list, link, mtab_ent_t, mtab_ent) {
-                rc = ENOTSUP;
-
-                if (!async_data_read_receive(&callid, &len)) {
-                        async_answer_0(callid, rc);
-                        goto exit;
-                }
-
-                (void) async_data_read_finalize(callid, mtab_ent->mp,
-                    str_size(mtab_ent->mp));
-
-                if (!async_data_read_receive(&callid, &len)) {
-                        async_answer_0(callid, rc);
-                        goto exit;
-                }
-
-                (void) async_data_read_finalize(callid, mtab_ent->opts,
-                    str_size(mtab_ent->opts));
-
-                if (!async_data_read_receive(&callid, &len)) {
-                        async_answer_0(callid, rc);
-                        goto exit;
-                }
-
-                (void) async_data_read_finalize(callid, mtab_ent->fs_name,
-                    str_size(mtab_ent->fs_name));
-
-                callid = async_get_call(&data);
-
-                if (IPC_GET_IMETHOD(data) != VFS_IN_PING) {
-                        async_answer_0(callid, rc);
-                        goto exit;
-                }
-
-                rc = EOK;
-                async_answer_2(callid, rc, mtab_ent->instance,
-                    mtab_ent->service_id);
-        }
-
-exit:
-        fibril_mutex_unlock(&mtab_list_lock);
-        async_answer_0(rid, rc);
-}
-
-void vfs_statfs(ipc_callid_t rid, ipc_call_t *request)
-{
-        char *path;
-        int rc = async_data_write_accept((void **) &path, true, 0, 0, 0, NULL);
-        if (rc != EOK) {
-                async_answer_0(rid, rc);
-                return;
-        }
-        
-        ipc_callid_t callid;
-        if (!async_data_read_receive(&callid, NULL)) {
-                free(path);
-                async_answer_0(callid, EINVAL);
-                async_answer_0(rid, EINVAL);
-                return;
-        }
-
-        vfs_lookup_res_t lr;
-        fibril_rwlock_read_lock(&namespace_rwlock);
-        rc = vfs_lookup_internal(path, L_NONE, &lr, NULL);
-        free(path);
-        if (rc != EOK) {
-                fibril_rwlock_read_unlock(&namespace_rwlock);
-                async_answer_0(callid, rc);
-                async_answer_0(rid, rc);
-                return;
-        }
-        vfs_node_t *node = vfs_node_get(&lr);
-        if (!node) {
-                fibril_rwlock_read_unlock(&namespace_rwlock);
-                async_answer_0(callid, ENOMEM);
-                async_answer_0(rid, ENOMEM);
-                return;
-        }
-
-        fibril_rwlock_read_unlock(&namespace_rwlock);
-
-        async_exch_t *exch = vfs_exchange_grab(node->fs_handle);
-        
-        aid_t msg;
-        msg = async_send_3(exch, VFS_OUT_STATFS, node->service_id,
-            node->index, false, NULL);
-        async_forward_fast(callid, exch, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
-        
-        vfs_exchange_release(exch);
-        
-        sysarg_t rv;
-        async_wait_for(msg, &rv);
-
-        async_answer_0(rid, rv);
-
-        vfs_node_put(node);
+        *out_fd = fd;
+        return EOK;
+}
+
+int vfs_op_write(int fd, aoff64_t pos, size_t *out_bytes)
+{
+        return vfs_rdwr(fd, pos, false, rdwr_ipc_client, out_bytes);
 }