diff options
Diffstat (limited to 'fs/autofs/waitq.c')
| -rw-r--r-- | fs/autofs/waitq.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/fs/autofs/waitq.c b/fs/autofs/waitq.c new file mode 100644 index 00000000000..1fcaa156854 --- /dev/null +++ b/fs/autofs/waitq.c @@ -0,0 +1,206 @@ +/* -*- 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; +} + |