1 files changed, 206 insertions, 0 deletions

diff --git a/fs/autofs/waitq.c b/fs/autofs/waitq.c
new file mode 100644
index 000000000000..1fcaa1568541
--- /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(&current->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(&current->sighand->siglock, flags);
+                sigdelset(&current->pending.signal, SIGPIPE);
+                recalc_sigpending();
+                spin_unlock_irqrestore(&current->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;
+}
+