]> pilppa.org Git - linux-2.6-omap-h63xx.git/blobdiff - fs/autofs4/waitq.c
autofs4: fix waitq locking
[linux-2.6-omap-h63xx.git] / fs / autofs4 / waitq.c
index 142ab6aa2aa1516e6480d24c0ce3830b19852107..55aac10cf328e43790dd560a44a0b554ab76d192 100644 (file)
@@ -28,6 +28,12 @@ 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;
@@ -36,16 +42,17 @@ void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
        while (wq) {
                nwq = wq->next;
                wq->status = -ENOENT; /* Magic is gone - report failure */
-               kfree(wq->name);
-               wq->name = NULL;
+               if (wq->name.name) {
+                       kfree(wq->name.name);
+                       wq->name.name = NULL;
+               }
                wake_up_interruptible(&wq->queue);
                wq = nwq;
        }
-       if (sbi->pipe) {
-               fput(sbi->pipe);        /* Close the pipe */
-               sbi->pipe = NULL;
-       }
-       shrink_dcache_sb(sbi->sb);
+       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)
@@ -87,11 +94,15 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
                                 struct autofs_wait_queue *wq,
                                 int type)
 {
-       union autofs_packet_union pkt;
+       union {
+               struct autofs_packet_hdr hdr;
+               union autofs_packet_union v4_pkt;
+               union autofs_v5_packet_union v5_pkt;
+       } pkt;
        size_t pktsz;
 
        DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
-               wq->wait_queue_token, wq->len, wq->name, type);
+               wq->wait_queue_token, wq->name.len, wq->name.name, type);
 
        memset(&pkt,0,sizeof pkt); /* For security reasons */
 
@@ -101,26 +112,26 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
        /* Kernel protocol v4 missing and expire packets */
        case autofs_ptype_missing:
        {
-               struct autofs_packet_missing *mp = &pkt.missing;
+               struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
 
                pktsz = sizeof(*mp);
 
                mp->wait_queue_token = wq->wait_queue_token;
-               mp->len = wq->len;
-               memcpy(mp->name, wq->name, wq->len);
-               mp->name[wq->len] = '\0';
+               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.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->len;
-               memcpy(ep->name, wq->name, wq->len);
-               ep->name[wq->len] = '\0';
+               ep->len = wq->name.len;
+               memcpy(ep->name, wq->name.name, wq->name.len);
+               ep->name[wq->name.len] = '\0';
                break;
        }
        /*
@@ -132,14 +143,14 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
        case autofs_ptype_missing_direct:
        case autofs_ptype_expire_direct:
        {
-               struct autofs_v5_packet *packet = &pkt.v5_packet;
+               struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
 
                pktsz = sizeof(*packet);
 
                packet->wait_queue_token = wq->wait_queue_token;
-               packet->len = wq->len;
-               memcpy(packet->name, wq->name, wq->len);
-               packet->name[wq->len] = '\0';
+               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;
@@ -170,7 +181,7 @@ static int autofs4_getpath(struct autofs_sb_info *sbi,
        for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
                len += tmp->d_name.len + 1;
 
-       if (--len > NAME_MAX) {
+       if (!len || --len > NAME_MAX) {
                spin_unlock(&dcache_lock);
                return 0;
        }
@@ -189,14 +200,29 @@ static int autofs4_getpath(struct autofs_sb_info *sbi,
        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;
+}
+
 int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
                enum autofs_notify notify)
 {
+       struct autofs_info *ino;
        struct autofs_wait_queue *wq;
+       struct qstr qstr;
        char *name;
-       unsigned int len = 0;
-       unsigned int hash = 0;
-       int status;
+       int status, type;
 
        /* In catatonic mode, we don't wait for nobody */
        if (sbi->catatonic)
@@ -208,40 +234,61 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
 
        /* If this is a direct mount request create a dummy name */
        if (IS_ROOT(dentry) && (sbi->type & AUTOFS_TYPE_DIRECT))
-               len = sprintf(name, "%p", dentry);
+               qstr.len = sprintf(name, "%p", dentry);
        else {
-               len = autofs4_getpath(sbi, dentry, &name);
-               if (!len) {
+               qstr.len = autofs4_getpath(sbi, dentry, &name);
+               if (!qstr.len) {
                        kfree(name);
                        return -ENOENT;
                }
        }
-       hash = full_name_hash(name, len);
+       qstr.name = name;
+       qstr.hash = full_name_hash(name, qstr.len);
 
        if (mutex_lock_interruptible(&sbi->wq_mutex)) {
-               kfree(name);
+               kfree(qstr.name);
                return -EINTR;
        }
 
-       for (wq = sbi->queues ; wq ; wq = wq->next) {
-               if (wq->hash == dentry->d_name.hash &&
-                   wq->len == len &&
-                   wq->name && !memcmp(wq->name, name, len))
-                       break;
-       }
+       wq = autofs4_find_wait(sbi, &qstr);
+       ino = autofs4_dentry_ino(dentry);
+       if (!wq && ino && 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)) {
+                               kfree(qstr.name);
+                               return -EINTR;
+                       }
+                       wq = autofs4_find_wait(sbi, &qstr);
+                       if (wq)
+                               break;
+               }
 
-       if (!wq) {
-               /* Can't wait for an expire if there's no mount */
-               if (notify == NFY_NONE && !d_mountpoint(dentry)) {
-                       kfree(name);
+               /*
+                * 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.
+                */
+               if (!wq) {
+                       kfree(qstr.name);
                        mutex_unlock(&sbi->wq_mutex);
-                       return -ENOENT;
+                       return 0;
                }
+       }
 
+       if (!wq) {
                /* Create a new wait queue */
                wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
                if (!wq) {
-                       kfree(name);
+                       kfree(qstr.name);
                        mutex_unlock(&sbi->wq_mutex);
                        return -ENOMEM;
                }
@@ -252,9 +299,7 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
                wq->next = sbi->queues;
                sbi->queues = wq;
                init_waitqueue_head(&wq->queue);
-               wq->hash = hash;
-               wq->name = name;
-               wq->len = len;
+               memcpy(&wq->name, &qstr, sizeof(struct qstr));
                wq->dev = autofs4_get_dev(sbi);
                wq->ino = autofs4_get_ino(sbi);
                wq->uid = current->uid;
@@ -263,20 +308,7 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
                wq->tgid = current->tgid;
                wq->status = -EINTR; /* Status return if interrupted */
                atomic_set(&wq->wait_ctr, 2);
-               atomic_set(&wq->notify, 1);
                mutex_unlock(&sbi->wq_mutex);
-       } else {
-               atomic_inc(&wq->wait_ctr);
-               mutex_unlock(&sbi->wq_mutex);
-               kfree(name);
-               DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
-                       (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
-       }
-
-       if (notify != NFY_NONE && atomic_read(&wq->notify)) {
-               int type;
-
-               atomic_dec(&wq->notify);
 
                if (sbi->version < 5) {
                        if (notify == NFY_MOUNT)
@@ -295,22 +327,25 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
                }
 
                DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
-                       (unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
+                       (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 {
+               atomic_inc(&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 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;
-               kfree(wq->name);
-               wq->name = NULL;
-       }
-
-       if (wq->name) {
+       /*
+        * 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;
@@ -321,7 +356,7 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
                recalc_sigpending();
                spin_unlock_irqrestore(&current->sighand->siglock, irqflags);
 
-               wait_event_interruptible(wq->queue, wq->name == NULL);
+               wait_event_interruptible(wq->queue, wq->name.name == NULL);
 
                spin_lock_irqsave(&current->sighand->siglock, irqflags);
                current->blocked = oldset;
@@ -346,7 +381,7 @@ int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_tok
        struct autofs_wait_queue *wq, **wql;
 
        mutex_lock(&sbi->wq_mutex);
-       for (wql = &sbi->queues ; (wq = *wql) != 0 ; wql = &wq->next) {
+       for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
                if (wq->wait_queue_token == wait_queue_token)
                        break;
        }
@@ -358,8 +393,8 @@ int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_tok
 
        *wql = wq->next;        /* Unlink from chain */
        mutex_unlock(&sbi->wq_mutex);
-       kfree(wq->name);
-       wq->name = NULL;        /* Do not wait on this queue */
+       kfree(wq->name.name);
+       wq->name.name = NULL;   /* Do not wait on this queue */
 
        wq->status = status;