/* -*- linux-c -*- --------------------------------------------------------- * * * linux/fs/autofs/waitq.c * * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved * * This file is part of the Linux kernel and is made available under * the terms of the GNU General Public License, version 2, or at your * option, any later version, incorporated herein by reference. * * ------------------------------------------------------------------------- */ #include <linux/slab.h> #include <linux/time.h> #include <linux/signal.h> #include <linux/file.h> #include "autofs_i.h" /* We make this a static variable rather than a part of the superblock; it is better if we don't reassign numbers easily even across filesystems */ static autofs_wqt_t autofs_next_wait_queue = 1; /* These are the signals we allow interrupting a pending mount */ #define SHUTDOWN_SIGS (sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT)) void autofs_catatonic_mode(struct autofs_sb_info *sbi) { struct autofs_wait_queue *wq, *nwq; DPRINTK(("autofs: entering catatonic mode\n")); sbi->catatonic = 1; wq = sbi->queues; sbi->queues = NULL; /* Erase all wait queues */ while ( wq ) { nwq = wq->next; wq->status = -ENOENT; /* Magic is gone - report failure */ kfree(wq->name); wq->name = NULL; wake_up(&wq->queue); wq = nwq; } fput(sbi->pipe); /* Close the pipe */ autofs_hash_dputall(&sbi->dirhash); /* Remove all dentry pointers */ } static int autofs_write(struct file *file, const void *addr, int bytes) { unsigned long sigpipe, flags; mm_segment_t fs; const char *data = (const char *)addr; ssize_t wr = 0; /** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/ sigpipe = sigismember(¤t->pending.signal, SIGPIPE); /* Save pointer to user space and point back to kernel space */ fs = get_fs(); set_fs(KERNEL_DS); while (bytes && (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) { data += wr; bytes -= wr; } set_fs(fs); /* Keep the currently executing process from receiving a SIGPIPE unless it was already supposed to get one */ if (wr == -EPIPE && !sigpipe) { spin_lock_irqsave(¤t->sighand->siglock, flags); sigdelset(¤t->pending.signal, SIGPIPE); recalc_sigpending(); spin_unlock_irqrestore(¤t->sighand->siglock, flags); } return (bytes > 0); } static void autofs_notify_daemon(struct autofs_sb_info *sbi, struct autofs_wait_queue *wq) { struct autofs_packet_missing pkt; DPRINTK(("autofs_wait: wait id = 0x%08lx, name = ", wq->wait_queue_token)); autofs_say(wq->name,wq->len); memset(&pkt,0,sizeof pkt); /* For security reasons */ pkt.hdr.proto_version = AUTOFS_PROTO_VERSION; pkt.hdr.type = autofs_ptype_missing; pkt.wait_queue_token = wq->wait_queue_token; pkt.len = wq->len; memcpy(pkt.name, wq->name, pkt.len); pkt.name[pkt.len] = '\0'; if ( autofs_write(sbi->pipe,&pkt,sizeof(struct autofs_packet_missing)) ) autofs_catatonic_mode(sbi); } int autofs_wait(struct autofs_sb_info *sbi, struct qstr *name) { struct autofs_wait_queue *wq; int status; /* In catatonic mode, we don't wait for nobody */ if ( sbi->catatonic ) return -ENOENT; /* We shouldn't be able to get here, but just in case */ if ( name->len > NAME_MAX ) return -ENOENT; for ( wq = sbi->queues ; wq ; wq = wq->next ) { if ( wq->hash == name->hash && wq->len == name->len && wq->name && !memcmp(wq->name,name->name,name->len) ) break; } if ( !wq ) { /* Create a new wait queue */ wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL); if ( !wq ) return -ENOMEM; wq->name = kmalloc(name->len,GFP_KERNEL); if ( !wq->name ) { kfree(wq); return -ENOMEM; } wq->wait_queue_token = autofs_next_wait_queue++; init_waitqueue_head(&wq->queue); wq->hash = name->hash; wq->len = name->len; wq->status = -EINTR; /* Status return if interrupted */ memcpy(wq->name, name->name, name->len); wq->next = sbi->queues; sbi->queues = wq; /* autofs_notify_daemon() may block */ wq->wait_ctr = 2; autofs_notify_daemon(sbi,wq); } else wq->wait_ctr++; /* wq->name is NULL if and only if the lock is already released */ if ( sbi->catatonic ) { /* We might have slept, so check again for catatonic mode */ wq->status = -ENOENT; if ( wq->name ) { kfree(wq->name); wq->name = NULL; } } if ( wq->name ) { /* Block all but "shutdown" signals while waiting */ sigset_t sigmask; siginitsetinv(&sigmask, SHUTDOWN_SIGS); sigprocmask(SIG_BLOCK, &sigmask, &sigmask); interruptible_sleep_on(&wq->queue); sigprocmask(SIG_SETMASK, &sigmask, NULL); } else { DPRINTK(("autofs_wait: skipped sleeping\n")); } status = wq->status; if ( ! --wq->wait_ctr ) /* Are we the last process to need status? */ kfree(wq); return status; } int autofs_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status) { struct autofs_wait_queue *wq, **wql; for ( wql = &sbi->queues ; (wq = *wql) != 0 ; wql = &wq->next ) { if ( wq->wait_queue_token == wait_queue_token ) break; } if ( !wq ) return -EINVAL; *wql = wq->next; /* Unlink from chain */ kfree(wq->name); wq->name = NULL; /* Do not wait on this queue */ wq->status = status; if ( ! --wq->wait_ctr ) /* Is anyone still waiting for this guy? */ kfree(wq); else wake_up(&wq->queue); return 0; }