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510852b8b8
fs0 used to receive open() requests and notify pager about them via a syscall ipc. This caused deadlocks because normally request flow is mm0 -> fs0 on all other calls. The solution was to have mm0 ask and validate file descriptors from fs0 on the first request instance that involved that file descriptor. By this method we delay the validation of the fd until its first use, and avoid deadlock. It also fits well with the lazy request handling design philosophy.
131 lines
3.5 KiB
C
131 lines
3.5 KiB
C
/*
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* FS0. Filesystem implementation
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*
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* Copyright (C) 2007 Bahadir Balban
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*/
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#include <stdio.h>
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#include <string.h>
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#include <l4lib/arch/syscalls.h>
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#include <l4lib/arch/syslib.h>
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#include <l4lib/kip.h>
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#include <l4lib/utcb.h>
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#include <l4lib/ipcdefs.h>
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#include <fs.h>
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#include <init.h>
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#include <kdata.h>
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#include <syscalls.h>
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#include <task.h>
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#include <posix/sys/time.h>
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/*
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* TODO:
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* - Have a dentry cache searchable by name
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* - Have a vnode cache searchable by vnum (and name?)
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* - fs-specific readdir would read contents by page range, and add vnodes/dentries
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* to their caches, while populating the directory vnode being read.
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* - Have 2 vfs_lookup() flavors, one that searches a path, one that searches a vnum.
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* - dirbuf is either allocated by low-level readdir, or else by a higher level, i.e.
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* either high-level vfs code, or the mm0 page cache.
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* - readdir provides a posix-compliant dirent structure list in dirbuf.
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* - memfs dentries should be identical to posix struct dirents.
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*
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* ALL DONE!!! But untested.
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*
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* - Add mkdir
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* - Add create
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* - Add read/write -> This will need page cache and mm0 involvement.
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*
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* Done those, too. but untested.
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*/
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/* Synchronise with pager via a `wait' tagged ipc with destination as pager */
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void wait_pager(l4id_t partner)
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{
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l4_send(partner, L4_IPC_TAG_WAIT);
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printf("%s: Pager synced with us.\n", __TASKNAME__);
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}
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void handle_fs_requests(void)
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{
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u32 mr[MR_UNUSED_TOTAL];
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l4id_t sender;
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int err;
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u32 tag;
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if ((err = l4_receive(L4_ANYTHREAD)) < 0) {
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printf("%s: %s: IPC Error: %d. Quitting...\n", __TASKNAME__,
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__FUNCTION__, err);
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BUG();
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}
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/* Read conventional ipc data */
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tag = l4_get_tag();
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sender = l4_get_sender();
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/* Read mrs not used by syslib */
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for (int i = 0; i < MR_UNUSED_TOTAL; i++)
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mr[i] = read_mr(MR_UNUSED_START + i);
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/* FIXME: Fix all these syscalls to read any buffer data from the caller task's utcb.
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* Make sure to return -EINVAL if data is not valid. */
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switch(tag) {
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case L4_IPC_TAG_WAIT:
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printf("%s: Synced with waiting thread.\n", __TASKNAME__);
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break;
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case L4_IPC_TAG_OPEN:
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sys_open(sender, (void *)mr[0], (int)mr[1], (unsigned int)mr[2]);
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break;
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case L4_IPC_TAG_MKDIR:
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sys_mkdir(sender, (const char *)mr[0], (unsigned int)mr[1]);
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break;
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case L4_IPC_TAG_CHDIR:
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sys_chdir(sender, (const char *)mr[0]);
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break;
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case L4_IPC_TAG_READDIR:
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sys_readdir(sender, (int)mr[0], (void *)mr[1], (int)mr[2]);
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break;
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case L4_IPC_TAG_PAGER_READ:
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pager_sys_read(sender, (unsigned long)mr[0], (unsigned long)mr[1],
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(unsigned long)mr[2], (void *)mr[3]);
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break;
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case L4_IPC_TAG_PAGER_OPEN:
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pager_sys_open(sender, (l4id_t)mr[0], (int)mr[1]);
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break;
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case L4_IPC_TAG_PAGER_WRITE:
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pager_sys_write(sender, (unsigned long)mr[0], (unsigned long)mr[1],
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(unsigned long)mr[2], (void *)mr[3]);
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break;
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case L4_IPC_TAG_PAGER_CLOSE:
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pager_sys_close(sender, (l4id_t)mr[0], (int)mr[1]);
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break;
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case L4_IPC_TAG_PAGER_UPDATE_STATS:
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pager_update_stats(sender, (unsigned long)mr[0],
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(unsigned long)mr[1]);
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break;
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case L4_IPC_TAG_NOTIFY_FORK:
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pager_notify_fork(sender, (l4id_t)mr[0], (l4id_t)mr[1],
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(unsigned long)mr[2]);
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break;
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default:
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printf("%s: Unrecognised ipc tag (%d) "
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"received from tid: %d. Ignoring.\n", __TASKNAME__,
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mr[MR_TAG], sender);
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}
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}
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void main(void)
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{
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printf("\n%s: Started with tid: %d\n", __TASKNAME__, self_tid());
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initialise();
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wait_pager(PAGER_TID);
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printf("%s: Listening requests.\n", __TASKNAME__);
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while (1) {
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handle_fs_requests();
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}
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}
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