/* -*- c -*- --------------------------------------------------------------- * * * linux/fs/autofs/waitq.c * * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved * Copyright 2001-2006 Ian Kent <raven@themaw.net> * * 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 autofs4_next_wait_queue = 1; /* These are the signals we allow interrupting a pending mount */ #define SHUTDOWN_SIGS (sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT)) void autofs4_catatonic_mode(struct autofs_sb_info *sbi) { struct autofs_wait_queue *wq, *nwq; mutex_lock(&sbi->wq_mutex); if (sbi->catatonic) { mutex_unlock(&sbi->wq_mutex); return; } DPRINTK("entering catatonic mode"); 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 */ if (wq->name.name) { kfree(wq->name.name); wq->name.name = NULL; } wq->wait_ctr--; wake_up_interruptible(&wq->queue); wq = nwq; } fput(sbi->pipe); /* Close the pipe */ sbi->pipe = NULL; sbi->pipefd = -1; mutex_unlock(&sbi->wq_mutex); } static int autofs4_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 autofs4_notify_daemon(struct autofs_sb_info *sbi, struct autofs_wait_queue *wq, int type) { union { struct autofs_packet_hdr hdr; union autofs_packet_union v4_pkt; union autofs_v5_packet_union v5_pkt; } pkt; struct file *pipe = NULL; size_t pktsz; DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d", wq->wait_queue_token, wq->name.len, wq->name.name, type); memset(&pkt,0,sizeof pkt); /* For security reasons */ pkt.hdr.proto_version = sbi->version; pkt.hdr.type = type; switch (type) { /* Kernel protocol v4 missing and expire packets */ case autofs_ptype_missing: { struct autofs_packet_missing *mp = &pkt.v4_pkt.missing; pktsz = sizeof(*mp); mp->wait_queue_token = wq->wait_queue_token; mp->len = wq->name.len; memcpy(mp->name, wq->name.name, wq->name.len); mp->name[wq->name.len] = '\0'; break; } case autofs_ptype_expire_multi: { struct autofs_packet_expire_multi *ep = &pkt.v4_pkt.expire_multi; pktsz = sizeof(*ep); ep->wait_queue_token = wq->wait_queue_token; ep->len = wq->name.len; memcpy(ep->name, wq->name.name, wq->name.len); ep->name[wq->name.len] = '\0'; break; } /* * Kernel protocol v5 packet for handling indirect and direct * mount missing and expire requests */ case autofs_ptype_missing_indirect: case autofs_ptype_expire_indirect: case autofs_ptype_missing_direct: case autofs_ptype_expire_direct: { struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet; pktsz = sizeof(*packet); packet->wait_queue_token = wq->wait_queue_token; packet->len = wq->name.len; memcpy(packet->name, wq->name.name, wq->name.len); packet->name[wq->name.len] = '\0'; packet->dev = wq->dev; packet->ino = wq->ino; packet->uid = wq->uid; packet->gid = wq->gid; packet->pid = wq->pid; packet->tgid = wq->tgid; break; } default: printk("autofs4_notify_daemon: bad type %d!\n", type); return; } /* Check if we have become catatonic */ mutex_lock(&sbi->wq_mutex); if (!sbi->catatonic) { pipe = sbi->pipe; get_file(pipe); } mutex_unlock(&sbi->wq_mutex); if (pipe) { if (autofs4_write(pipe, &pkt, pktsz)) autofs4_catatonic_mode(sbi); fput(pipe); } } static int autofs4_getpath(struct autofs_sb_info *sbi, struct dentry *dentry, char **name) { struct dentry *root = sbi->sb->s_root; struct dentry *tmp; char *buf = *name; char *p; int len = 0; spin_lock(&dcache_lock); for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent) len += tmp->d_name.len + 1; if (!len || --len > NAME_MAX) { spin_unlock(&dcache_lock); return 0; } *(buf + len) = '\0'; p = buf + len - dentry->d_name.len; strncpy(p, dentry->d_name.name, dentry->d_name.len); for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) { *(--p) = '/'; p -= tmp->d_name.len; strncpy(p, tmp->d_name.name, tmp->d_name.len); } spin_unlock(&dcache_lock); return len; } static struct autofs_wait_queue * autofs4_find_wait(struct autofs_sb_info *sbi, struct qstr *qstr) { struct autofs_wait_queue *wq; for (wq = sbi->queues; wq; wq = wq->next) { if (wq->name.hash == qstr->hash && wq->name.len == qstr->len && wq->name.name && !memcmp(wq->name.name, qstr->name, qstr->len)) break; } return wq; } /* * Check if we have a valid request. * Returns * 1 if the request should continue. * In this case we can return an autofs_wait_queue entry if one is * found or NULL to idicate a new wait needs to be created. * 0 or a negative errno if the request shouldn't continue. */ static int validate_request(struct autofs_wait_queue **wait, struct autofs_sb_info *sbi, struct qstr *qstr, struct dentry*dentry, enum autofs_notify notify) { struct autofs_wait_queue *wq; struct autofs_info *ino; /* Wait in progress, continue; */ wq = autofs4_find_wait(sbi, qstr); if (wq) { *wait = wq; return 1; } *wait = NULL; /* If we don't yet have any info this is a new request */ ino = autofs4_dentry_ino(dentry); if (!ino) return 1; /* * If we've been asked to wait on an existing expire (NFY_NONE) * but there is no wait in the queue ... */ if (notify == NFY_NONE) { /* * Either we've betean the pending expire to post it's * wait or it finished while we waited on the mutex. * So we need to wait till either, the wait appears * or the expire finishes. */ while (ino->flags & AUTOFS_INF_EXPIRING) { mutex_unlock(&sbi->wq_mutex); schedule_timeout_interruptible(HZ/10); if (mutex_lock_interruptible(&sbi->wq_mutex)) return -EINTR; wq = autofs4_find_wait(sbi, qstr); if (wq) { *wait = wq; return 1; } } /* * Not ideal but the status has already gone. Of the two * cases where we wait on NFY_NONE neither depend on the * return status of the wait. */ return 0; } /* * If we've been asked to trigger a mount and the request * completed while we waited on the mutex ... */ if (notify == NFY_MOUNT) { /* * If the dentry isn't hashed just go ahead and try the * mount again with a new wait (not much else we can do). */ if (!d_unhashed(dentry)) { /* * But if the dentry is hashed, that means that we * got here through the revalidate path. Thus, we * need to check if the dentry has been mounted * while we waited on the wq_mutex. If it has, * simply return success. */ if (d_mountpoint(dentry)) return 0; } } return 1; } int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry, enum autofs_notify notify) { struct autofs_wait_queue *wq; struct qstr qstr; char *name; int status, ret, type; /* In catatonic mode, we don't wait for nobody */ if (sbi->catatonic) return -ENOENT; if (!dentry->d_inode) { /* * A wait for a negative dentry is invalid for certain * cases. A direct or offset mount "always" has its mount * point directory created and so the request dentry must * be positive or the map key doesn't exist. The situation * is very similar for indirect mounts except only dentrys * in the root of the autofs file system may be negative. */ if (autofs_type_trigger(sbi->type)) return -ENOENT; else if (!IS_ROOT(dentry->d_parent)) return -ENOENT; } name = kmalloc(NAME_MAX + 1, GFP_KERNEL); if (!name) return -ENOMEM; /* If this is a direct mount request create a dummy name */ if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type)) qstr.len = sprintf(name, "%p", dentry); else { qstr.len = autofs4_getpath(sbi, dentry, &name); if (!qstr.len) { kfree(name); return -ENOENT; } } qstr.name = name; qstr.hash = full_name_hash(name, qstr.len); if (mutex_lock_interruptible(&sbi->wq_mutex)) { kfree(qstr.name); return -EINTR; } ret = validate_request(&wq, sbi, &qstr, dentry, notify); if (ret <= 0) { if (ret == 0) mutex_unlock(&sbi->wq_mutex); kfree(qstr.name); return ret; } if (!wq) { /* Create a new wait queue */ wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL); if (!wq) { kfree(qstr.name); mutex_unlock(&sbi->wq_mutex); return -ENOMEM; } wq->wait_queue_token = autofs4_next_wait_queue; if (++autofs4_next_wait_queue == 0) autofs4_next_wait_queue = 1; wq->next = sbi->queues; sbi->queues = wq; init_waitqueue_head(&wq->queue); memcpy(&wq->name, &qstr, sizeof(struct qstr)); wq->dev = autofs4_get_dev(sbi); wq->ino = autofs4_get_ino(sbi); wq->uid = current_uid(); wq->gid = current_gid(); wq->pid = current->pid; wq->tgid = current->tgid; wq->status = -EINTR; /* Status return if interrupted */ wq->wait_ctr = 2; mutex_unlock(&sbi->wq_mutex); if (sbi->version < 5) { if (notify == NFY_MOUNT) type = autofs_ptype_missing; else type = autofs_ptype_expire_multi; } else { if (notify == NFY_MOUNT) type = autofs_type_trigger(sbi->type) ? autofs_ptype_missing_direct : autofs_ptype_missing_indirect; else type = autofs_type_trigger(sbi->type) ? autofs_ptype_expire_direct : autofs_ptype_expire_indirect; } DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n", (unsigned long) wq->wait_queue_token, wq->name.len, wq->name.name, notify); /* autofs4_notify_daemon() may block */ autofs4_notify_daemon(sbi, wq, type); } else { wq->wait_ctr++; mutex_unlock(&sbi->wq_mutex); kfree(qstr.name); DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d", (unsigned long) wq->wait_queue_token, wq->name.len, wq->name.name, notify); } /* * wq->name.name is NULL iff the lock is already released * or the mount has been made catatonic. */ if (wq->name.name) { /* Block all but "shutdown" signals while waiting */ sigset_t oldset; unsigned long irqflags; spin_lock_irqsave(¤t->sighand->siglock, irqflags); oldset = current->blocked; siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]); recalc_sigpending(); spin_unlock_irqrestore(¤t->sighand->siglock, irqflags); wait_event_interruptible(wq->queue, wq->name.name == NULL); spin_lock_irqsave(¤t->sighand->siglock, irqflags); current->blocked = oldset; recalc_sigpending(); spin_unlock_irqrestore(¤t->sighand->siglock, irqflags); } else { DPRINTK("skipped sleeping"); } status = wq->status; /* * For direct and offset mounts we need to track the requester's * uid and gid in the dentry info struct. This is so it can be * supplied, on request, by the misc device ioctl interface. * This is needed during daemon resatart when reconnecting * to existing, active, autofs mounts. The uid and gid (and * related string values) may be used for macro substitution * in autofs mount maps. */ if (!status) { struct autofs_info *ino; struct dentry *de = NULL; /* direct mount or browsable map */ ino = autofs4_dentry_ino(dentry); if (!ino) { /* If not lookup actual dentry used */ de = d_lookup(dentry->d_parent, &dentry->d_name); if (de) ino = autofs4_dentry_ino(de); } /* Set mount requester */ if (ino) { spin_lock(&sbi->fs_lock); ino->uid = wq->uid; ino->gid = wq->gid; spin_unlock(&sbi->fs_lock); } if (de) dput(de); } /* Are we the last process to need status? */ mutex_lock(&sbi->wq_mutex); if (!--wq->wait_ctr) kfree(wq); mutex_unlock(&sbi->wq_mutex); return status; } int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status) { struct autofs_wait_queue *wq, **wql; mutex_lock(&sbi->wq_mutex); for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) { if (wq->wait_queue_token == wait_queue_token) break; } if (!wq) { mutex_unlock(&sbi->wq_mutex); return -EINVAL; } *wql = wq->next; /* Unlink from chain */ kfree(wq->name.name); wq->name.name = NULL; /* Do not wait on this queue */ wq->status = status; wake_up_interruptible(&wq->queue); if (!--wq->wait_ctr) kfree(wq); mutex_unlock(&sbi->wq_mutex); return 0; }