404 lines
10 KiB
C
404 lines
10 KiB
C
/* -*- c -*- --------------------------------------------------------------- *
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*
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* linux/fs/autofs/waitq.c
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*
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* Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
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* Copyright 2001-2006 Ian Kent <raven@themaw.net>
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*
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* This file is part of the Linux kernel and is made available under
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* the terms of the GNU General Public License, version 2, or at your
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* option, any later version, incorporated herein by reference.
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*
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* ------------------------------------------------------------------------- */
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#include <linux/slab.h>
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#include <linux/time.h>
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#include <linux/signal.h>
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#include <linux/file.h>
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#include "autofs_i.h"
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/* We make this a static variable rather than a part of the superblock; it
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is better if we don't reassign numbers easily even across filesystems */
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static autofs_wqt_t autofs4_next_wait_queue = 1;
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/* These are the signals we allow interrupting a pending mount */
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#define SHUTDOWN_SIGS (sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT))
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void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
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{
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struct autofs_wait_queue *wq, *nwq;
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DPRINTK("entering catatonic mode");
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sbi->catatonic = 1;
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wq = sbi->queues;
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sbi->queues = NULL; /* Erase all wait queues */
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while (wq) {
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nwq = wq->next;
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wq->status = -ENOENT; /* Magic is gone - report failure */
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kfree(wq->name);
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wq->name = NULL;
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wake_up_interruptible(&wq->queue);
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wq = nwq;
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}
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fput(sbi->pipe); /* Close the pipe */
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sbi->pipe = NULL;
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}
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static int autofs4_write(struct file *file, const void *addr, int bytes)
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{
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unsigned long sigpipe, flags;
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mm_segment_t fs;
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const char *data = (const char *)addr;
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ssize_t wr = 0;
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/** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/
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sigpipe = sigismember(¤t->pending.signal, SIGPIPE);
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/* Save pointer to user space and point back to kernel space */
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fs = get_fs();
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set_fs(KERNEL_DS);
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while (bytes &&
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(wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
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data += wr;
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bytes -= wr;
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}
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set_fs(fs);
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/* Keep the currently executing process from receiving a
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SIGPIPE unless it was already supposed to get one */
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if (wr == -EPIPE && !sigpipe) {
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spin_lock_irqsave(¤t->sighand->siglock, flags);
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sigdelset(¤t->pending.signal, SIGPIPE);
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recalc_sigpending();
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spin_unlock_irqrestore(¤t->sighand->siglock, flags);
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}
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return (bytes > 0);
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}
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static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
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struct autofs_wait_queue *wq,
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int type)
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{
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union {
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struct autofs_packet_hdr hdr;
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union autofs_packet_union v4_pkt;
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union autofs_v5_packet_union v5_pkt;
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} pkt;
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size_t pktsz;
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DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
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wq->wait_queue_token, wq->len, wq->name, type);
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memset(&pkt,0,sizeof pkt); /* For security reasons */
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pkt.hdr.proto_version = sbi->version;
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pkt.hdr.type = type;
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switch (type) {
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/* Kernel protocol v4 missing and expire packets */
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case autofs_ptype_missing:
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{
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struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
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pktsz = sizeof(*mp);
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mp->wait_queue_token = wq->wait_queue_token;
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mp->len = wq->len;
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memcpy(mp->name, wq->name, wq->len);
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mp->name[wq->len] = '\0';
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break;
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}
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case autofs_ptype_expire_multi:
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{
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struct autofs_packet_expire_multi *ep = &pkt.v4_pkt.expire_multi;
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pktsz = sizeof(*ep);
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ep->wait_queue_token = wq->wait_queue_token;
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ep->len = wq->len;
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memcpy(ep->name, wq->name, wq->len);
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ep->name[wq->len] = '\0';
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break;
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}
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/*
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* Kernel protocol v5 packet for handling indirect and direct
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* mount missing and expire requests
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*/
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case autofs_ptype_missing_indirect:
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case autofs_ptype_expire_indirect:
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case autofs_ptype_missing_direct:
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case autofs_ptype_expire_direct:
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{
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struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
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pktsz = sizeof(*packet);
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packet->wait_queue_token = wq->wait_queue_token;
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packet->len = wq->len;
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memcpy(packet->name, wq->name, wq->len);
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packet->name[wq->len] = '\0';
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packet->dev = wq->dev;
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packet->ino = wq->ino;
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packet->uid = wq->uid;
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packet->gid = wq->gid;
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packet->pid = wq->pid;
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packet->tgid = wq->tgid;
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break;
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}
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default:
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printk("autofs4_notify_daemon: bad type %d!\n", type);
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return;
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}
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if (autofs4_write(sbi->pipe, &pkt, pktsz))
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autofs4_catatonic_mode(sbi);
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}
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static int autofs4_getpath(struct autofs_sb_info *sbi,
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struct dentry *dentry, char **name)
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{
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struct dentry *root = sbi->sb->s_root;
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struct dentry *tmp;
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char *buf = *name;
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char *p;
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int len = 0;
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spin_lock(&dcache_lock);
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for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
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len += tmp->d_name.len + 1;
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if (!len || --len > NAME_MAX) {
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spin_unlock(&dcache_lock);
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return 0;
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}
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*(buf + len) = '\0';
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p = buf + len - dentry->d_name.len;
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strncpy(p, dentry->d_name.name, dentry->d_name.len);
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for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
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*(--p) = '/';
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p -= tmp->d_name.len;
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strncpy(p, tmp->d_name.name, tmp->d_name.len);
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}
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spin_unlock(&dcache_lock);
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return len;
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}
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static struct autofs_wait_queue *
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autofs4_find_wait(struct autofs_sb_info *sbi,
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char *name, unsigned int hash, unsigned int len)
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{
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struct autofs_wait_queue *wq;
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for (wq = sbi->queues; wq; wq = wq->next) {
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if (wq->hash == hash &&
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wq->len == len &&
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wq->name && !memcmp(wq->name, name, len))
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break;
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}
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return wq;
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}
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int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
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enum autofs_notify notify)
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{
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struct autofs_info *ino;
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struct autofs_wait_queue *wq;
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char *name;
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unsigned int len = 0;
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unsigned int hash = 0;
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int status, type;
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/* In catatonic mode, we don't wait for nobody */
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if (sbi->catatonic)
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return -ENOENT;
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name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
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if (!name)
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return -ENOMEM;
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/* If this is a direct mount request create a dummy name */
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if (IS_ROOT(dentry) && (sbi->type & AUTOFS_TYPE_DIRECT))
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len = sprintf(name, "%p", dentry);
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else {
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len = autofs4_getpath(sbi, dentry, &name);
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if (!len) {
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kfree(name);
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return -ENOENT;
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}
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}
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hash = full_name_hash(name, len);
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if (mutex_lock_interruptible(&sbi->wq_mutex)) {
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kfree(name);
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return -EINTR;
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}
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wq = autofs4_find_wait(sbi, name, hash, len);
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ino = autofs4_dentry_ino(dentry);
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if (!wq && ino && notify == NFY_NONE) {
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/*
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* Either we've betean the pending expire to post it's
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* wait or it finished while we waited on the mutex.
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* So we need to wait till either, the wait appears
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* or the expire finishes.
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*/
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while (ino->flags & AUTOFS_INF_EXPIRING) {
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mutex_unlock(&sbi->wq_mutex);
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schedule_timeout_interruptible(HZ/10);
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if (mutex_lock_interruptible(&sbi->wq_mutex)) {
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kfree(name);
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return -EINTR;
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}
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wq = autofs4_find_wait(sbi, name, hash, len);
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if (wq)
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break;
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}
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/*
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* Not ideal but the status has already gone. Of the two
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* cases where we wait on NFY_NONE neither depend on the
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* return status of the wait.
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*/
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if (!wq) {
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kfree(name);
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mutex_unlock(&sbi->wq_mutex);
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return 0;
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}
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}
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if (!wq) {
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/* Create a new wait queue */
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wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
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if (!wq) {
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kfree(name);
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mutex_unlock(&sbi->wq_mutex);
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return -ENOMEM;
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}
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wq->wait_queue_token = autofs4_next_wait_queue;
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if (++autofs4_next_wait_queue == 0)
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autofs4_next_wait_queue = 1;
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wq->next = sbi->queues;
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sbi->queues = wq;
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init_waitqueue_head(&wq->queue);
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wq->hash = hash;
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wq->name = name;
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wq->len = len;
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wq->dev = autofs4_get_dev(sbi);
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wq->ino = autofs4_get_ino(sbi);
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wq->uid = current->uid;
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wq->gid = current->gid;
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wq->pid = current->pid;
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wq->tgid = current->tgid;
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wq->status = -EINTR; /* Status return if interrupted */
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atomic_set(&wq->wait_ctr, 2);
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mutex_unlock(&sbi->wq_mutex);
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if (sbi->version < 5) {
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if (notify == NFY_MOUNT)
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type = autofs_ptype_missing;
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else
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type = autofs_ptype_expire_multi;
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} else {
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if (notify == NFY_MOUNT)
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type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
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autofs_ptype_missing_direct :
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autofs_ptype_missing_indirect;
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else
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type = (sbi->type & AUTOFS_TYPE_DIRECT) ?
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autofs_ptype_expire_direct :
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autofs_ptype_expire_indirect;
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}
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DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
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(unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
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/* autofs4_notify_daemon() may block */
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autofs4_notify_daemon(sbi, wq, type);
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} else {
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atomic_inc(&wq->wait_ctr);
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mutex_unlock(&sbi->wq_mutex);
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kfree(name);
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DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
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(unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
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}
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/* wq->name is NULL if and only if the lock is already released */
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if (sbi->catatonic) {
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/* We might have slept, so check again for catatonic mode */
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wq->status = -ENOENT;
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kfree(wq->name);
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wq->name = NULL;
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}
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if (wq->name) {
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/* Block all but "shutdown" signals while waiting */
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sigset_t oldset;
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unsigned long irqflags;
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spin_lock_irqsave(¤t->sighand->siglock, irqflags);
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oldset = current->blocked;
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siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
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recalc_sigpending();
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spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
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wait_event_interruptible(wq->queue, wq->name == NULL);
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spin_lock_irqsave(¤t->sighand->siglock, irqflags);
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current->blocked = oldset;
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recalc_sigpending();
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spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
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} else {
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DPRINTK("skipped sleeping");
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}
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status = wq->status;
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/* Are we the last process to need status? */
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if (atomic_dec_and_test(&wq->wait_ctr))
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kfree(wq);
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return status;
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}
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int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
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{
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struct autofs_wait_queue *wq, **wql;
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mutex_lock(&sbi->wq_mutex);
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for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
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if (wq->wait_queue_token == wait_queue_token)
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break;
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}
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if (!wq) {
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mutex_unlock(&sbi->wq_mutex);
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return -EINVAL;
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}
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*wql = wq->next; /* Unlink from chain */
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mutex_unlock(&sbi->wq_mutex);
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kfree(wq->name);
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wq->name = NULL; /* Do not wait on this queue */
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wq->status = status;
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if (atomic_dec_and_test(&wq->wait_ctr)) /* Is anyone still waiting for this guy? */
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kfree(wq);
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else
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wake_up_interruptible(&wq->queue);
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return 0;
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}
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