WebSVN – HelenOS – Diff – /trunk/uspace/srv/vfs/vfs_ops.c

 /*
  * Copyright (c) 2008 Jakub Jermar
  * All rights reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
+ *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  * - Redistributions in binary form must reproduce the above copyright
  *   notice, this list of conditions and the following disclaimer in the
  *   documentation and/or other materials provided with the distribution.
  * - The name of the author may not be used to endorse or promote products
  *   derived from this software without specific prior written permission.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 /** @addtogroup fs
  * @{
  */
 /**
  * @file    vfs_ops.c
  * @brief   Operations that VFS offers to its clients.
  */
 #include <ipc/ipc.h>
-#include <ipc/services.h>
 #include <async.h>
-#include <fibril.h>
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <bool.h>
 #include <futex.h>
 #include <rwlock.h>
 #include <libadt/list.h>
 #include <unistd.h>
 #include <ctype.h>
-#include <as.h>
 #include <assert.h>
 #include <atomic.h>
 #include "vfs.h"
-#define min(a, b)   ((a) < (b) ? (a) : (b))
 /**
  * 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);
-atomic_t plb_futex = FUTEX_INITIALIZER;
-link_t plb_head;    /**< PLB entry ring buffer. */
-uint8_t *plb = NULL;
-/** Perform a path lookup.
- *
- * @param path      Path to be resolved; it needn't be an ASCIIZ string.
- * @param len       Number of path characters pointed by path.
- * @param result    Empty structure where the lookup result will be stored.
- * @param altroot   If non-empty, will be used instead of rootfs as the root
- *          of the whole VFS tree.
- *
- * @return      EOK on success or an error code from errno.h.
- */
-int vfs_lookup_internal(char *path, size_t len, vfs_lookup_res_t *result,
-    vfs_pair_t *altroot)
-{
-    vfs_pair_t *root;
-    if (!len)
-        return EINVAL;
-    if (altroot)
-        root = altroot;
-    else
-        root = (vfs_pair_t *) &rootfs;
-    if (!root->fs_handle)
-        return ENOENT;
-    futex_down(&plb_futex);
-    plb_entry_t entry;
-    link_initialize(&entry.plb_link);
-    entry.len = len;
-    off_t first;    /* the first free index */
-    off_t last; /* the last free index */
-    if (list_empty(&plb_head)) {
-        first = 0;
-        last = PLB_SIZE - 1;
-    } else {
-        plb_entry_t *oldest = list_get_instance(plb_head.next,
-            plb_entry_t, plb_link);
-        plb_entry_t *newest = list_get_instance(plb_head.prev,
-            plb_entry_t, plb_link);
-        first = (newest->index + newest->len) % PLB_SIZE;
-        last = (oldest->index - 1) % PLB_SIZE;
-    }
-    if (first <= last) {
-        if ((last - first) + 1 < len) {
-            /*
-             * The buffer cannot absorb the path.
-             */
-            futex_up(&plb_futex);
-            return ELIMIT;
-        }
-    } else {
-        if (PLB_SIZE - ((first - last) + 1) < len) {
-            /*
-             * The buffer cannot absorb the path.
-             */
-            futex_up(&plb_futex);
-            return ELIMIT;
-        }
-    }
-    /*
-     * We know the first free index in PLB and we also know that there is
-     * enough space in the buffer to hold our path.
-     */
-    entry.index = first;
-    entry.len = len;
-    /*
-     * Claim PLB space by inserting the entry into the PLB entry ring
-     * buffer.
-     */
-    list_append(&entry.plb_link, &plb_head);
-    futex_up(&plb_futex);
-    /*
-     * Copy the path into PLB.
-     */
-    size_t cnt1 = min(len, (PLB_SIZE - first) + 1);
-    size_t cnt2 = len - cnt1;
-    memcpy(&plb[first], path, cnt1);
-    memcpy(plb, &path[cnt1], cnt2);
-    ipc_call_t answer;
-    int phone = vfs_grab_phone(root->fs_handle);
-    aid_t req = async_send_3(phone, VFS_LOOKUP, (ipcarg_t) first,
-        (ipcarg_t) (first + len - 1) % PLB_SIZE,
-        (ipcarg_t) root->dev_handle, &answer);
-    vfs_release_phone(phone);
-    ipcarg_t rc;
-    async_wait_for(req, &rc);
-    futex_down(&plb_futex);
-    list_remove(&entry.plb_link);
-    /*
-     * Erasing the path from PLB will come handy for debugging purposes.
-     */
-    memset(&plb[first], 0, cnt1);
-    memset(plb, 0, cnt2);
-    futex_up(&plb_futex);
-    if (rc == EOK) {
-        result->triplet.fs_handle = (int) IPC_GET_ARG1(answer);
-        result->triplet.dev_handle = (int) IPC_GET_ARG2(answer);
-        result->triplet.index = (int) IPC_GET_ARG3(answer);
-        result->size = (size_t) IPC_GET_ARG4(answer);
-    }
-    return rc;
-}
 atomic_t rootfs_futex = FUTEX_INITIALIZER;
 vfs_triplet_t rootfs = {
     .fs_handle = 0,
     .dev_handle = 0,
     .index = 0,
 };
 static int lookup_root(int fs_handle, int dev_handle, vfs_lookup_res_t *result)
+{
     vfs_pair_t altroot = {
         .fs_handle = fs_handle,
         .dev_handle = dev_handle,
     };
     return vfs_lookup_internal("/", strlen("/"), result, &altroot);
+}
 void vfs_mount(ipc_callid_t rid, ipc_call_t *request)
+{
     int dev_handle;
     vfs_node_t *mp_node = NULL;
     /*
      * 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 = 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.
      */
     int 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);
     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);
     /*
      * 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.
      */
     int rc;
     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);
         rc = vfs_lookup_internal(buf, size, &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] == '/')) {
             /*
              * For this simple, but important case, we are done.
              */
             rootfs = mr_res.triplet;
             futex_up(&rootfs_futex);
             free(buf);
             ipc_answer_0(rid, EOK);
             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
      * of the file system being mounted.
      */
     int phone = vfs_grab_phone(mp_res.triplet.fs_handle);
     /* Later we can use ARG3 to pass mode/flags. */
     aid_t req1 = async_send_3(phone, VFS_MOUNT,
         (ipcarg_t) mp_res.triplet.dev_handle,
         (ipcarg_t) mp_res.triplet.index, 0, NULL);
     /* The second call uses the same method. */
     aid_t req2 = async_send_3(phone, VFS_MOUNT,
         (ipcarg_t) mr_res.triplet.fs_handle,
         (ipcarg_t) mr_res.triplet.dev_handle,
         (ipcarg_t) mr_res.triplet.index, NULL);
     vfs_release_phone(phone);
     ipcarg_t rc1;
     ipcarg_t rc2;
     async_wait_for(req1, &rc1);
     async_wait_for(req2, &rc2);
     if ((rc1 != EOK) || (rc2 != EOK)) {
         /* Mount failed, drop references to mr_node and mp_node. */
         vfs_node_put(mr_node);
         if (mp_node)
             vfs_node_put(mp_node);
+    }
     if (rc2 == EOK)
         ipc_answer_0(rid, rc1);
     else if (rc1 == EOK)
         ipc_answer_0(rid, rc2);
     else
         ipc_answer_0(rid, rc1);
+}
 void vfs_open(ipc_callid_t rid, ipc_call_t *request)
+{
     if (!vfs_files_init()) {
         ipc_answer_0(rid, ENOMEM);
         return;
+    }
     /*
      * The POSIX interface is open(path, flags, mode).
      * We can receive flags and mode along with the VFS_OPEN call; the path
      * will need to arrive in another call.
      */
     int flags = IPC_GET_ARG1(*request);
     int mode = IPC_GET_ARG2(*request);
     size_t len;
     ipc_callid_t callid;
     if (!ipc_data_write_receive(&callid, &len)) {
         ipc_answer_0(callid, EINVAL);
         ipc_answer_0(rid, EINVAL);
         return;
+    }
     /*
      * Now we are on the verge of accepting the path.
+     *
      * There is one optimization we could do in the future: copy the path
      * directly into the PLB using some kind of a callback.
      */
     char *path = malloc(len);
     if (!path) {
         ipc_answer_0(callid, ENOMEM);
         ipc_answer_0(rid, ENOMEM);
         return;
+    }
     int rc;
     if ((rc = ipc_data_write_finalize(callid, path, len))) {
         ipc_answer_0(rid, rc);
         free(path);
         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.
      */
     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, len, &lr, NULL);
     if (rc) {
         rwlock_read_unlock(&namespace_rwlock);
         ipc_answer_0(rid, rc);
         free(path);
         return;
+    }
     /*
      * Path is no longer needed.
      */
     free(path);
     vfs_node_t *node = vfs_node_get(&lr);
     rwlock_read_unlock(&namespace_rwlock);
     /*
      * Get ourselves a file descriptor and the corresponding vfs_file_t
      * structure.
      */
     int fd = vfs_fd_alloc();
     if (fd < 0) {
         vfs_node_put(node);
         ipc_answer_0(rid, fd);
         return;
+    }
     vfs_file_t *file = vfs_file_get(fd);
     file->node = node;
     /*
      * 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_CLOSE.
      */
     vfs_node_addref(node);
     vfs_node_put(node);
     /*
      * Success! Return the new file descriptor to the client.
      */
     ipc_answer_1(rid, EOK, fd);
+}
 static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read)
+{
     /*
      * The following code strongly depends on the fact that the files data
      * structure can be only accessed by a single fibril and all file
      * operations are serialized (i.e. the reads and writes cannot
      * interleave and a file cannot be closed while it is being 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;
     int res;
     if (read)
         res = ipc_data_read_receive(&callid, NULL);
     else
         res = ipc_data_write_receive(&callid, NULL);
     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);
     /*
      * Lock the file's node so that no other client can read/write to it at
      * the same time.
      */
     if (read)
         rwlock_read_lock(&file->node->contents_rwlock);
     else
         rwlock_write_lock(&file->node->contents_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;
     msg = async_send_3(fs_phone, IPC_GET_METHOD(*request),
         file->node->dev_handle, file->node->index, file->pos, &answer);
     /*
      * Forward the IPC_M_DATA_READ/IPC_M_DATA_WRITE request to the
      * 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);
     /*
      * Unlock the VFS node.
      */
     if (read)
         rwlock_read_unlock(&file->node->contents_rwlock);
     else {
         /* Update the cached version of node's size. */
         file->node->size = IPC_GET_ARG2(answer);
         rwlock_write_unlock(&file->node->contents_rwlock);
+    }
     /*
      * Update the position pointer and unlock the open file.
      */
     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);
+}
 void vfs_read(ipc_callid_t rid, ipc_call_t *request)
+{
     vfs_rdwr(rid, request, true);
+}
 void vfs_write(ipc_callid_t rid, ipc_call_t *request)
+{
     vfs_rdwr(rid, request, false);
+}
 void vfs_seek(ipc_callid_t rid, ipc_call_t *request)
+{
     int fd = (int) IPC_GET_ARG1(*request);
     off_t off = (off_t) IPC_GET_ARG2(*request);
     int whence = (int) IPC_GET_ARG3(*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;
+    }
     off_t newpos;
     futex_down(&file->lock);
     if (whence == SEEK_SET) {
         file->pos = off;
         futex_up(&file->lock);
         ipc_answer_1(rid, EOK, off);
         return;
+    }
     if (whence == SEEK_CUR) {
         if (file->pos + off < file->pos) {
             futex_up(&file->lock);
             ipc_answer_0(rid, EOVERFLOW);
             return;
+        }
         file->pos += off;
         newpos = file->pos;
         futex_up(&file->lock);
         ipc_answer_1(rid, EOK, newpos);
         return;
+    }
     if (whence == SEEK_END) {
         rwlock_read_lock(&file->node->contents_rwlock);
         size_t size = file->node->size;
         rwlock_read_unlock(&file->node->contents_rwlock);
         if (size + off < size) {
             futex_up(&file->lock);
             ipc_answer_0(rid, EOVERFLOW);
             return;
+        }
         newpos = size + off;
         futex_up(&file->lock);
         ipc_answer_1(rid, EOK, newpos);
         return;
+    }
     futex_up(&file->lock);
     ipc_answer_0(rid, EINVAL);
+}
 void vfs_truncate(ipc_callid_t rid, ipc_call_t *request)
+{
     int fd = IPC_GET_ARG1(*request);
     size_t size = IPC_GET_ARG2(*request);
     ipcarg_t rc;
     vfs_file_t *file = vfs_file_get(fd);
     if (!file) {
         ipc_answer_0(rid, ENOENT);
         return;
+    }
     futex_down(&file->lock);
     rwlock_write_lock(&file->node->contents_rwlock);
     int fs_phone = vfs_grab_phone(file->node->fs_handle);
     rc = async_req_3_0(fs_phone, VFS_TRUNCATE, (ipcarg_t)file->node->dev_handle,
         (ipcarg_t)file->node->index, (ipcarg_t)size);
     vfs_release_phone(fs_phone);
     if (rc == EOK)
         file->node->size = size;
     rwlock_write_unlock(&file->node->contents_rwlock);
     futex_up(&file->lock);
-    return rc;
-}
-atomic_t fs_head_futex = FUTEX_INITIALIZER;
-link_t fs_head;
-atomic_t fs_handle_next = {
-    .count = 1
-};
-/** Verify the VFS info structure.
- *
- * @param info      Info structure to be verified.
- *
- * @return      Non-zero if the info structure is sane, zero otherwise.
- */
-static bool vfs_info_sane(vfs_info_t *info)
-{
-    int i;
-    /*
-     * Check if the name is non-empty and is composed solely of ASCII
-     * characters [a-z]+[a-z0-9_-]*.
-     */
-    if (!islower(info->name[0])) {
-        dprintf("The name doesn't start with a lowercase character.\n");
-        return false;
-    }
-    for (i = 1; i < FS_NAME_MAXLEN; i++) {
-        if (!(islower(info->name[i]) || isdigit(info->name[i])) &&
-            (info->name[i] != '-') && (info->name[i] != '_')) {
-            if (info->name[i] == '\0') {
-                break;
-            } else {
-                dprintf("The name contains illegal "
-                    "characters.\n");
-                return false;
-            }
-        }
-    }
-    /*
-     * This check is not redundant. It ensures that the name is
-     * NULL-terminated, even if FS_NAME_MAXLEN characters are used.
-     */
-    if (info->name[i] != '\0') {
-        dprintf("The name is not properly NULL-terminated.\n");
-        return false;
-    }
-    /*
-     * Check if the FS implements mandatory VFS operations.
-     */
-    if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] != VFS_OP_DEFINED) {
-        dprintf("Operation VFS_LOOKUP not defined by the client.\n");
-        return false;
-    }
-    if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_OPEN)] != VFS_OP_DEFINED) {
-        dprintf("Operation VFS_OPEN not defined by the client.\n");
-        return false;
-    }
-    if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_CLOSE)] != VFS_OP_DEFINED) {
-        dprintf("Operation VFS_CLOSE not defined by the client.\n");
-        return false;
-    }
-    if (info->ops[IPC_METHOD_TO_VFS_OP(VFS_READ)] != VFS_OP_DEFINED) {
-        dprintf("Operation VFS_READ not defined by the client.\n");
-        return false;
-    }
-    /*
-     * Check if each operation is either not defined, defined or default.
-     */
-    for (i = VFS_FIRST; i < VFS_LAST_CLNT; i++) {
-        if ((info->ops[IPC_METHOD_TO_VFS_OP(i)] != VFS_OP_NULL) &&
-            (info->ops[IPC_METHOD_TO_VFS_OP(i)] != VFS_OP_DEFAULT) &&
-            (info->ops[IPC_METHOD_TO_VFS_OP(i)] != VFS_OP_DEFINED)) {
-            dprintf("Operation info not understood.\n");
-            return false;
-        }
-    }
-    return true;
-}
-/** VFS_REGISTER protocol function.
- *
- * @param rid       Hash of the call with the request.
- * @param request   Call structure with the request.
- */
-void vfs_register(ipc_callid_t rid, ipc_call_t *request)
-{
-    ipc_callid_t callid;
-    ipc_call_t call;
-    int rc;
-    size_t size;
-    dprintf("Processing VFS_REGISTER request received from %p.\n",
-        request->in_phone_hash);
-    /*
-     * The first call has to be IPC_M_DATA_SEND in which we receive the
-     * VFS info structure from the client FS.
-     */
-    if (!ipc_data_write_receive(&callid, &size)) {
-        /*
-         * The client doesn't obey the same protocol as we do.
-         */
-        dprintf("Receiving of VFS info failed.\n");
-        ipc_answer_0(callid, EINVAL);
-        ipc_answer_0(rid, EINVAL);
-        return;
-    }
-    dprintf("VFS info received, size = %d\n", size);
-    /*
-     * We know the size of the VFS info structure. See if the client
-     * understands this easy concept too.
-     */
-    if (size != sizeof(vfs_info_t)) {
-        /*
-         * The client is sending us something, which cannot be
-         * the info structure.
-         */
-        dprintf("Received VFS info has bad size.\n");
-        ipc_answer_0(callid, EINVAL);
-        ipc_answer_0(rid, EINVAL);
-        return;
-    }
-    /*
-     * Allocate and initialize a buffer for the fs_info structure.
-     */
-    fs_info_t *fs_info;
-    fs_info = (fs_info_t *) malloc(sizeof(fs_info_t));
-    if (!fs_info) {
-        dprintf("Could not allocate memory for FS info.\n");
-        ipc_answer_0(callid, ENOMEM);
-        ipc_answer_0(rid, ENOMEM);
-        return;
-    }
-    link_initialize(&fs_info->fs_link);
-    futex_initialize(&fs_info->phone_futex, 1);
-    rc = ipc_data_write_finalize(callid, &fs_info->vfs_info, size);
-    if (rc != EOK) {
-        dprintf("Failed to deliver the VFS info into our AS, rc=%d.\n",
-            rc);
-        free(fs_info);
-        ipc_answer_0(callid, rc);
-        ipc_answer_0(rid, rc);
+    ipc_answer_0(rid, rc);
-        return;
-    }
-    dprintf("VFS info delivered.\n");
-    if (!vfs_info_sane(&fs_info->vfs_info)) {
-        free(fs_info);
-        ipc_answer_0(callid, EINVAL);
-        ipc_answer_0(rid, EINVAL);
-        return;
-    }
-    futex_down(&fs_head_futex);
-    /*
-     * Check for duplicit registrations.
-     */
-    if (fs_name_to_handle(fs_info->vfs_info.name, false)) {
-        /*
-         * We already register a fs like this.
-         */
-        dprintf("FS is already registered.\n");
-        futex_up(&fs_head_futex);
-        free(fs_info);
-        ipc_answer_0(callid, EEXISTS);
-        ipc_answer_0(rid, EEXISTS);
-        return;
-    }
-    /*
-     * Add fs_info to the list of registered FS's.
-     */
-    dprintf("Inserting FS into the list of registered file systems.\n");
-    list_append(&fs_info->fs_link, &fs_head);
-    /*
-     * Now we want the client to send us the IPC_M_CONNECT_TO_ME call so
-     * that a callback connection is created and we have a phone through
-     * which to forward VFS requests to it.
-     */
-    callid = async_get_call(&call);
-    if (IPC_GET_METHOD(call) != IPC_M_CONNECT_TO_ME) {
-        dprintf("Unexpected call, method = %d\n", IPC_GET_METHOD(call));
-        list_remove(&fs_info->fs_link);
-        futex_up(&fs_head_futex);
-        free(fs_info);
-        ipc_answer_0(callid, EINVAL);
-        ipc_answer_0(rid, EINVAL);
-        return;
-    }
-    fs_info->phone = IPC_GET_ARG5(call);
-    ipc_answer_0(callid, EOK);
-    dprintf("Callback connection to FS created.\n");
-    /*
-     * The client will want us to send him the address space area with PLB.
-     */
-    if (!ipc_share_in_receive(&callid, &size)) {
-        dprintf("Unexpected call, method = %d\n", IPC_GET_METHOD(call));
-        list_remove(&fs_info->fs_link);
-        futex_up(&fs_head_futex);
-        ipc_hangup(fs_info->phone);
-        free(fs_info);
-        ipc_answer_0(callid, EINVAL);
-        ipc_answer_0(rid, EINVAL);
-        return;
-    }
-    /*
-     * We can only send the client address space area PLB_SIZE bytes long.
-     */
-    if (size != PLB_SIZE) {
-        dprintf("Client suggests wrong size of PFB, size = %d\n", size);
-        list_remove(&fs_info->fs_link);
-        futex_up(&fs_head_futex);
-        ipc_hangup(fs_info->phone);
-        free(fs_info);
-        ipc_answer_0(callid, EINVAL);
-        ipc_answer_0(rid, EINVAL);
-        return;
-    }
-    /*
-     * Commit to read-only sharing the PLB with the client.
-     */
-    (void) ipc_share_in_finalize(callid, plb,
-        AS_AREA_READ | AS_AREA_CACHEABLE);
-    dprintf("Sharing PLB.\n");
-    /*
-     * That was it. The FS has been registered.
-     * In reply to the VFS_REGISTER request, we assign the client file
-     * system a global file system handle.
-     */
-    fs_info->fs_handle = (int) atomic_postinc(&fs_handle_next);
-    ipc_answer_1(rid, EOK, (ipcarg_t) fs_info->fs_handle);
-    futex_up(&fs_head_futex);
-    dprintf("\"%.*s\" filesystem successfully registered, handle=%d.\n",
-        FS_NAME_MAXLEN, fs_info->vfs_info.name, fs_info->fs_handle);
-}
-/** For a given file system handle, implement policy for allocating a phone.
- *
- * @param handle    File system handle.
- *
- * @return      Phone over which a multi-call request can be safely
- *          sent. Return 0 if no phone was found.
- */
-int vfs_grab_phone(int handle)
-{
-    /*
-     * For now, we don't try to be very clever and very fast.
-     * We simply lookup the phone in the fs_head list. We currently don't
-     * open any additional phones (even though that itself would be pretty
-     * straightforward; housekeeping multiple open phones to a FS task would
-     * be more demanding). Instead, we simply take the respective
-     * phone_futex and keep it until vfs_release_phone().
-     */
-    futex_down(&fs_head_futex);
-    link_t *cur;
-    fs_info_t *fs;
-    for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {
-        fs = list_get_instance(cur, fs_info_t, fs_link);
-        if (fs->fs_handle == handle) {
-            futex_up(&fs_head_futex);
-            /*
-             * For now, take the futex unconditionally.
-             * Oh yeah, serialization rocks.
-             * It will be up'ed in vfs_release_phone().
-             */
-            futex_down(&fs->phone_futex);
-            /*
-             * Avoid deadlock with other fibrils in the same thread
-             * by disabling fibril preemption.
-             */
-            fibril_inc_sercount();
-            return fs->phone;
-        }
-    }
-    futex_up(&fs_head_futex);
-    return 0;
-}
-/** Tell VFS that the phone is in use for any request.
- *
- * @param phone     Phone to FS task.
- */
-void vfs_release_phone(int phone)
-{
-    bool found = false;
-    /*
-     * Undo the fibril_inc_sercount() done in vfs_grab_phone().
-     */
-    fibril_dec_sercount();
-    futex_down(&fs_head_futex);
-    link_t *cur;
-    for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {
-        fs_info_t *fs = list_get_instance(cur, fs_info_t, fs_link);
-        if (fs->phone == phone) {
-            found = true;
-            futex_up(&fs_head_futex);
-            futex_up(&fs->phone_futex);
-            return;
-        }
-    }
-    futex_up(&fs_head_futex);
-    /*
-     * Not good to get here.
-     */
-    assert(found == true);
-}
-/** Convert file system name to its handle.
- *
- * @param name      File system name.
- * @param lock      If true, the function will down and up the
- *          fs_head_futex.
- *
- * @return      File system handle or zero if file system not found.
- */
-int fs_name_to_handle(char *name, bool lock)
-{
-    int handle = 0;
-    if (lock)
-        futex_down(&fs_head_futex);
-    link_t *cur;
-    for (cur = fs_head.next; cur != &fs_head; cur = cur->next) {
-        fs_info_t *fs = list_get_instance(cur, fs_info_t, fs_link);
-        if (strncmp(fs->vfs_info.name, name,
-            sizeof(fs->vfs_info.name)) == 0) {
-            handle = fs->fs_handle;
-            break;
-        }
-    }
-    if (lock)
-        futex_up(&fs_head_futex);
-    return handle;
+}
 /**
  * @}
  */

Subversion Repositories HelenOS

(root)/trunk/uspace/srv/vfs/vfs_ops.c – Rev 2693 → 2698