WebSVN – HelenOS – Diff – /branches/dd/uspace/srv/vfs/vfs_ops.c

  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 /** @addtogroup fs
  * @{
  */
 /**
- * @file    vfs_ops.c
+ * @file vfs_ops.c
- * @brief   Operations that VFS offers to its clients.
+ * @brief Operations that VFS offers to its clients.
  */
 #include "vfs.h"
 #include <ipc/ipc.h>
 #include <async.h>
 #include <vfs/canonify.h>
 /* Forward declarations of static functions. */
 static int vfs_truncate_internal(fs_handle_t, dev_handle_t, fs_index_t, size_t);
+/** Pending mount structure. */
+typedef struct {
+    link_t link;
+    char *fs_name;            /**< File system name */
+    char *mp;                 /**< Mount point */
+    ipc_callid_t callid;      /**< Call ID waiting for the mount */
+    ipc_callid_t rid;         /**< Request ID */
+    dev_handle_t dev_handle;  /**< Device handle */
+} pending_req_t;
+LIST_INITIALIZE(pending_req);
 /**
  * This rwlock prevents the race between a triplet-to-VFS-node resolution and a
  * concurrent VFS operation which modifies the file system namespace.
  */
 RWLOCK_INITIALIZE(namespace_rwlock);
 futex_t rootfs_futex = FUTEX_INITIALIZER;
-vfs_triplet_t rootfs = {
+vfs_pair_t rootfs = {
     .fs_handle = 0,
-    .dev_handle = 0,
+    .dev_handle = 0
-    .index = 0,
 };
-static int
-lookup_root(fs_handle_t fs_handle, dev_handle_t dev_handle,
+static void vfs_mount_internal(ipc_callid_t rid, dev_handle_t dev_handle,
-    vfs_lookup_res_t *result)
-{
-    vfs_pair_t altroot = {
-        .fs_handle = fs_handle,
+    fs_handle_t fs_handle, char *mp)
-        .dev_handle = dev_handle,
-    };
-    return vfs_lookup_internal("/", L_DIRECTORY, result, &altroot);
-}
-void vfs_mount(ipc_callid_t rid, ipc_call_t *request)
+{
+    /* Resolve the path to the mountpoint. */
-    dev_handle_t dev_handle;
+    vfs_lookup_res_t mp_res;
     vfs_node_t *mp_node = NULL;
     int rc;
     int phone;
-    /*
-     * 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.
-     */
-    dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
-    /*
-     * For now, don't make use of ARG2 and ARG3, but they can be used to
-     * carry mount options in the future.
-     */
-    ipc_callid_t callid;
-    size_t size;
-    /*
-     * Now, we expect the client to send us data with the name of the file
-     * system.
-     */
-    if (!ipc_data_write_receive(&callid, &size)) {
-        ipc_answer_0(callid, EINVAL);
-        ipc_answer_0(rid, EINVAL);
-        return;
-    }
-    /*
-     * Don't receive more than is necessary for storing a full file system
-     * name.
-     */
-    if (size < 1 || size > FS_NAME_MAXLEN) {
-        ipc_answer_0(callid, EINVAL);
-        ipc_answer_0(rid, EINVAL);
-        return;
-    }
-    /* Deliver the file system name. */
-    char fs_name[FS_NAME_MAXLEN + 1];
-    (void) ipc_data_write_finalize(callid, fs_name, size);
-    fs_name[size] = '\0';
-    /*
-     * 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.
-     */
-    fs_handle_t fs_handle = fs_name_to_handle(fs_name, true);
-    if (!fs_handle) {
-        ipc_answer_0(rid, ENOENT);
-        return;
-    }
-    /* Now, we want the client to send us the mount point. */
-    if (!ipc_data_write_receive(&callid, &size)) {
-        ipc_answer_0(callid, EINVAL);
-        ipc_answer_0(rid, EINVAL);
-        return;
-    }
-    /* Check whether size is reasonable wrt. the mount point. */
-    if (size < 1 || size > MAX_PATH_LEN) {
-        ipc_answer_0(callid, EINVAL);
-        ipc_answer_0(rid, EINVAL);
-        return;
-    }
-    /* Allocate buffer for the mount point data being received. */
-    uint8_t *buf;
-    buf = malloc(size + 1);
-    if (!buf) {
-        ipc_answer_0(callid, ENOMEM);
-        ipc_answer_0(rid, ENOMEM);
-        return;
-    }
-    /* Deliver the mount point. */
-    (void) ipc_data_write_finalize(callid, buf, size);
-    buf[size] = '\0';
-    /*
-     * Lookup the root node of the filesystem being mounted.
-     * In this case, we don't need to take the namespace_futex as the root
-     * node cannot be removed. However, we do take a reference to it so
-     * that we can track how many times it has been mounted.
-     */
-    vfs_lookup_res_t mr_res;
-    rc = lookup_root(fs_handle, dev_handle, &mr_res);
-    if (rc != EOK) {
-        free(buf);
-        ipc_answer_0(rid, rc);
-        return;
-    }
-    vfs_node_t *mr_node = vfs_node_get(&mr_res);
-    if (!mr_node) {
-        free(buf);
-        ipc_answer_0(rid, ENOMEM);
-        return;
-    }
-    /* Finally, we need to resolve the path to the mountpoint. */
-    vfs_lookup_res_t mp_res;
     futex_down(&rootfs_futex);
     if (rootfs.fs_handle) {
         /* We already have the root FS. */
         rwlock_write_lock(&namespace_rwlock);
-        if ((size == 1) && (buf[0] == '/')) {
+        if ((strlen(mp) == 1) && (mp[0] == '/')) {
             /* Trying to mount root FS over root FS */
             rwlock_write_unlock(&namespace_rwlock);
             futex_up(&rootfs_futex);
-            vfs_node_put(mr_node);
-            free(buf);
             ipc_answer_0(rid, EBUSY);
             return;
+        }
-        rc = vfs_lookup_internal(buf, L_DIRECTORY, &mp_res, NULL);
+        rc = vfs_lookup_internal(mp, L_DIRECTORY, &mp_res, NULL);
         if (rc != EOK) {
             /* The lookup failed for some reason. */
             rwlock_write_unlock(&namespace_rwlock);
             futex_up(&rootfs_futex);
-            vfs_node_put(mr_node);  /* failed -> drop reference */
-            free(buf);
             ipc_answer_0(rid, rc);
             return;
+        }
         mp_node = vfs_node_get(&mp_res);
         if (!mp_node) {
             rwlock_write_unlock(&namespace_rwlock);
             futex_up(&rootfs_futex);
-            vfs_node_put(mr_node);  /* failed -> drop reference */
-            free(buf);
             ipc_answer_0(rid, ENOMEM);
             return;
+        }
         /*
          * Now we hold a reference to mp_node.
          * It will be dropped upon the corresponding VFS_UNMOUNT.
          * This prevents the mount point from being deleted.
          */
         rwlock_write_unlock(&namespace_rwlock);
     } else {
         /* We still don't have the root file system mounted. */
-        if ((size == 1) && (buf[0] == '/')) {
+        if ((strlen(mp) == 1) && (mp[0] == '/')) {
+            vfs_lookup_res_t mr_res;
+            vfs_node_t *mr_node;
+            ipcarg_t rindex;
+            ipcarg_t rsize;
+            ipcarg_t rlnkcnt;
             /*
              * For this simple, but important case,
              * we are almost done.
              */
-            free(buf);
-            /* Inform the mount point about the root mount. */
+            /* Tell the mountee that it is being mounted. */
-            phone = vfs_grab_phone(mr_res.triplet.fs_handle);
+            phone = vfs_grab_phone(fs_handle);
-            rc = async_req_5_0(phone, VFS_MOUNT,
+            rc = async_req_1_3(phone, VFS_MOUNTED,
-                (ipcarg_t) mr_res.triplet.dev_handle,
-                (ipcarg_t) mr_res.triplet.index,
-                (ipcarg_t) mr_res.triplet.fs_handle,
-                (ipcarg_t) mr_res.triplet.dev_handle,
-                (ipcarg_t) mr_res.triplet.index);
+                (ipcarg_t) dev_handle, &rindex, &rsize, &rlnkcnt);
             vfs_release_phone(phone);
-            if (rc == EOK)
+            if (rc != EOK) {
+                futex_up(&rootfs_futex);
-                rootfs = mr_res.triplet;
+                ipc_answer_0(rid, rc);
-            else
+                return;
+            }
+            mr_res.triplet.fs_handle = fs_handle;
+            mr_res.triplet.dev_handle = dev_handle;
+            mr_res.triplet.index = (fs_index_t) rindex;
-                vfs_node_put(mr_node);
+            mr_res.size = (size_t) rsize;
+            mr_res.lnkcnt = (unsigned) rlnkcnt;
+            mr_res.type = VFS_NODE_DIRECTORY;
+            rootfs.fs_handle = fs_handle;
+            rootfs.dev_handle = dev_handle;
             futex_up(&rootfs_futex);
+            /* Add reference to the mounted root. */
+            mr_node = vfs_node_get(&mr_res);
+            assert(mr_node);
             ipc_answer_0(rid, rc);
             return;
         } else {
             /*
              * We can't resolve this without the root filesystem
              * being mounted first.
              */
             futex_up(&rootfs_futex);
-            free(buf);
-            vfs_node_put(mr_node);  /* failed -> drop reference */
             ipc_answer_0(rid, ENOENT);
             return;
+        }
+    }
     futex_up(&rootfs_futex);
-    free(buf);  /* The buffer is not needed anymore. */
     /*
      * At this point, we have all necessary pieces: file system and device
-     * handles, and we know the mount point VFS node and also the root node
+     * handles, and we know the mount point VFS node.
-     * of the file system being mounted.
-     */
-    /**
-     * @todo
-     * Add more IPC parameters so that we can send mount mode/flags.
      */
     phone = vfs_grab_phone(mp_res.triplet.fs_handle);
-    rc = async_req_5_0(phone, VFS_MOUNT,
+    rc = async_req_4_0(phone, VFS_MOUNT,
         (ipcarg_t) mp_res.triplet.dev_handle,
         (ipcarg_t) mp_res.triplet.index,
-        (ipcarg_t) mr_res.triplet.fs_handle,
+        (ipcarg_t) fs_handle,
-        (ipcarg_t) mr_res.triplet.dev_handle,
+        (ipcarg_t) dev_handle);
-        (ipcarg_t) mr_res.triplet.index);
     vfs_release_phone(phone);
     if (rc != EOK) {
-        /* Mount failed, drop references to mr_node and mp_node. */
+        /* Mount failed, drop reference to mp_node. */
-        vfs_node_put(mr_node);
         if (mp_node)
             vfs_node_put(mp_node);
+    }
     ipc_answer_0(rid, rc);
+}
+/** Process pending mount requests */
+void vfs_process_pending_mount()
+{
+    link_t *cur;
+loop:
+    for (cur = pending_req.next; cur != &pending_req; cur = cur->next) {
+        pending_req_t *pr = list_get_instance(cur, pending_req_t, link);
+        fs_handle_t fs_handle = fs_name_to_handle(pr->fs_name, true);
+        if (!fs_handle)
+            continue;
+        /* Acknowledge that we know fs_name. */
+        ipc_answer_0(pr->callid, EOK);
+        /* Do the mount */
+        vfs_mount_internal(pr->rid, pr->dev_handle, fs_handle, pr->mp);
+        free(pr->fs_name);
+        free(pr->mp);
+        list_remove(cur);
+        free(pr);
+        goto loop;
+    }
+}
+void vfs_mount(ipc_callid_t rid, ipc_call_t *request)
+{
+    /*
+     * 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.
+     */
+    dev_handle_t dev_handle = (dev_handle_t) IPC_GET_ARG1(*request);
+    /*
+     * Mount flags are passed as ARG2.
+     */
+    unsigned int flags = (unsigned int) IPC_GET_ARG2(*request);
+    /*
+     * For now, don't make use of ARG3, but it can be used to
+     * carry mount options in the future.
+     */
+    /* We want the client to send us the mount point. */
+    ipc_callid_t callid;
+    size_t size;
+    if (!ipc_data_write_receive(&callid, &size)) {
+        ipc_answer_0(callid, EINVAL);
+        ipc_answer_0(rid, EINVAL);
+        return;
+    }
+    /* Check whether size is reasonable wrt. the mount point. */
+    if ((size < 1) || (size > MAX_PATH_LEN)) {
+        ipc_answer_0(callid, EINVAL);
+        ipc_answer_0(rid, EINVAL);
+        return;
+    }
+    /* Allocate buffer for the mount point data being received. */
+    char *mp = malloc(size + 1);
+    if (!mp) {
+        ipc_answer_0(callid, ENOMEM);
+        ipc_answer_0(rid, ENOMEM);
+        return;
+    }
+    /* Deliver the mount point. */
+    ipcarg_t retval = ipc_data_write_finalize(callid, mp, size);
+    if (retval != EOK) {
+        ipc_answer_0(rid, EREFUSED);
+        free(mp);
+        return;
+    }
+    mp[size] = '\0';
+    /*
+     * Now, we expect the client to send us data with the name of the file
+     * system.
+     */
+    if (!ipc_data_write_receive(&callid, &size)) {
+        ipc_answer_0(callid, EINVAL);
+        ipc_answer_0(rid, EINVAL);
+        free(mp);
+        return;
+    }
+    /*
+     * Don't receive more than is necessary for storing a full file system
+     * name.
+     */
+    if ((size < 1) || (size > FS_NAME_MAXLEN)) {
+        ipc_answer_0(callid, EINVAL);
+        ipc_answer_0(rid, EINVAL);
+        free(mp);
+        return;
+    }
+    /*
+     * Allocate buffer for file system name.
+     */
+    char *fs_name = (char *) malloc(size + 1);
+    if (fs_name == NULL) {
+        ipc_answer_0(callid, ENOMEM);
+        ipc_answer_0(rid, EREFUSED);
+        free(mp);
+        return;
+    }
+    /* Deliver the file system name. */
+    retval = ipc_data_write_finalize(callid, fs_name, size);
+    if (retval != EOK) {
+        ipc_answer_0(rid, EREFUSED);
+        free(mp);
+        free(fs_name);
+        return;
+    }
+    fs_name[size] = '\0';
+    /*
+     * 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.
+     */
+    fs_handle_t fs_handle = fs_name_to_handle(fs_name, true);
+    if (!fs_handle) {
+        if (flags & IPC_FLAG_BLOCKING) {
+            /* Blocking mount, add to pending list */
+            pending_req_t *pr = (pending_req_t *) malloc(sizeof(pending_req_t));
+            if (!pr) {
+                ipc_answer_0(callid, ENOMEM);
+                ipc_answer_0(rid, ENOMEM);
+                free(mp);
+                free(fs_name);
+                return;
+            }
+            pr->fs_name = fs_name;
+            pr->mp = mp;
+            pr->callid = callid;
+            pr->rid = rid;
+            pr->dev_handle = dev_handle;
+            list_append(&pr->link, &pending_req);
+            return;
+        }
+        ipc_answer_0(callid, ENOENT);
+        ipc_answer_0(rid, ENOENT);
+        free(mp);
+        free(fs_name);
+        return;
+    }
+    /* Acknowledge that we know fs_name. */
+    ipc_answer_0(callid, EOK);
+    /* Do the mount */
+    vfs_mount_internal(rid, dev_handle, fs_handle, mp);
+    free(mp);
+    free(fs_name);
+}
 void vfs_open(ipc_callid_t rid, ipc_call_t *request)
+{
     if (!vfs_files_init()) {
         ipc_answer_0(rid, ENOMEM);
         return;
     int lflag = IPC_GET_ARG1(*request);
     int oflag = IPC_GET_ARG2(*request);
     int mode = IPC_GET_ARG3(*request);
     size_t len;
+    /*
+     * Make sure that we are called with exactly one of L_FILE and
+     * L_DIRECTORY.
+     */
+    if ((lflag & (L_FILE | L_DIRECTORY)) == 0 ||
+        (lflag & (L_FILE | L_DIRECTORY)) == (L_FILE | L_DIRECTORY)) {
+        ipc_answer_0(rid, EINVAL);
+        return;
+    }
     if (oflag & O_CREAT)
         lflag |= L_CREATE;
     if (oflag & O_EXCL)
         lflag |= L_EXCLUSIVE;
+}
 void vfs_close(ipc_callid_t rid, ipc_call_t *request)
+{
     int fd = IPC_GET_ARG1(*request);
-    if (fd >= MAX_OPEN_FILES) {
-        ipc_answer_0(rid, EBADF);
-        return;
-    }
-    vfs_fd_free(fd);
+    int rc = vfs_fd_free(fd);
-    ipc_answer_0(rid, EOK);
+    ipc_answer_0(rid, rc);
+}
 static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read)
+{
      * Additional synchronization needs to be added once the table of
      * open files supports parallel access!
      */
     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) {
         ipc_answer_0(rid, ENOENT);
         return;
+    }
     /*
      * Now we need to receive a call with client's
      * IPC_M_DATA_READ/IPC_M_DATA_WRITE request.
      */
     ipc_callid_t callid;
     if (!res) {
         ipc_answer_0(callid, EINVAL);
         ipc_answer_0(rid, EINVAL);
         return;
+    }
     /*
      * Lock the open file structure so that no other thread can manipulate
      * the same open file at a time.
      */
     futex_down(&file->lock);
     if (read)
         rwlock_read_lock(&file->node->contents_rwlock);
     else
         rwlock_write_lock(&file->node->contents_rwlock);
+    if (file->node->type == VFS_NODE_DIRECTORY) {
+        /*
+         * Make sure that no one is modifying the namespace
+         * while we are in readdir().
+         */
+        assert(read);
+        rwlock_read_lock(&namespace_rwlock);
+    }
     int fs_phone = vfs_grab_phone(file->node->fs_handle);
     /* Make a VFS_READ/VFS_WRITE request at the destination FS server. */
     aid_t msg;
     ipc_call_t answer;
      * destination FS server. The call will be routed as if sent by
      * ourselves. Note that call arguments are immutable in this case so we
      * don't have to bother.
      */
     ipc_forward_fast(callid, fs_phone, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
     vfs_release_phone(fs_phone);
     /* Wait for reply from the FS server. */
     ipcarg_t rc;
     async_wait_for(msg, &rc);
     size_t bytes = IPC_GET_ARG1(answer);
+    if (file->node->type == VFS_NODE_DIRECTORY)
+        rwlock_read_unlock(&namespace_rwlock);
     /* Unlock the VFS node. */
     if (read)
         rwlock_read_unlock(&file->node->contents_rwlock);
     else {
         /* Update the cached version of node's size. */
         if (rc == EOK)
             file->node->size = IPC_GET_ARG2(answer);
         rwlock_write_unlock(&file->node->contents_rwlock);
+    }
     /* Update the position pointer and unlock the open file. */
     if (rc == EOK)
         file->pos += bytes;
     futex_up(&file->lock);
     /*
      * FS server's reply is the final result of the whole operation we
      * return to the client.
      */
     ipc_answer_1(rid, rc, bytes);

Subversion Repositories HelenOS

(root)/branches/dd/uspace/srv/vfs/vfs_ops.c – Rev 3022 → 4055