1 files changed, 139 insertions, 55 deletions

diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index e46ca68..653c507 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -357,6 +357,77 @@ static int inotify_find_inode(const char __user *dirname, struct path *path, uns
 	return error;
 }
 
+static int inotify_add_to_idr(struct idr *idr, spinlock_t *idr_lock,
+			      int last_wd,
+			      struct inotify_inode_mark_entry *ientry)
+{
+	int ret;
+
+	do {
+		if (unlikely(!idr_pre_get(idr, GFP_KERNEL)))
+			return -ENOMEM;
+
+		spin_lock(idr_lock);
+		ret = idr_get_new_above(idr, ientry, last_wd + 1,
+					&ientry->wd);
+		/* we added the mark to the idr, take a reference */
+		if (!ret)
+			fsnotify_get_mark(&ientry->fsn_entry);
+		spin_unlock(idr_lock);
+	} while (ret == -EAGAIN);
+
+	return ret;
+}
+
+static struct inotify_inode_mark_entry *inotify_idr_find_locked(struct fsnotify_group *group,
+								int wd)
+{
+	struct idr *idr = &group->inotify_data.idr;
+	spinlock_t *idr_lock = &group->inotify_data.idr_lock;
+	struct inotify_inode_mark_entry *ientry;
+
+	assert_spin_locked(idr_lock);
+
+	ientry = idr_find(idr, wd);
+	if (ientry) {
+		struct fsnotify_mark_entry *fsn_entry = &ientry->fsn_entry;
+
+		fsnotify_get_mark(fsn_entry);
+		/* One ref for being in the idr, one ref we just took */
+		BUG_ON(atomic_read(&fsn_entry->refcnt) < 2);
+	}
+
+	return ientry;
+}
+
+static struct inotify_inode_mark_entry *inotify_idr_find(struct fsnotify_group *group,
+							 int wd)
+{
+	struct inotify_inode_mark_entry *ientry;
+	spinlock_t *idr_lock = &group->inotify_data.idr_lock;
+
+	spin_lock(idr_lock);
+	ientry = inotify_idr_find_locked(group, wd);
+	spin_unlock(idr_lock);
+
+	return ientry;
+}
+
+static void do_inotify_remove_from_idr(struct fsnotify_group *group,
+				       struct inotify_inode_mark_entry *ientry)
+{
+	struct idr *idr = &group->inotify_data.idr;
+	spinlock_t *idr_lock = &group->inotify_data.idr_lock;
+	int wd = ientry->wd;
+
+	assert_spin_locked(idr_lock);
+
+	idr_remove(idr, wd);
+
+	/* removed from the idr, drop that ref */
+	fsnotify_put_mark(&ientry->fsn_entry);
+}
+
 /*
  * Remove the mark from the idr (if present) and drop the reference
  * on the mark because it was in the idr.
@@ -364,42 +435,72 @@ static int inotify_find_inode(const char __user *dirname, struct path *path, uns
 static void inotify_remove_from_idr(struct fsnotify_group *group,
 				    struct inotify_inode_mark_entry *ientry)
 {
-	struct idr *idr;
-	struct fsnotify_mark_entry *entry;
-	struct inotify_inode_mark_entry *found_ientry;
+	spinlock_t *idr_lock = &group->inotify_data.idr_lock;
+	struct inotify_inode_mark_entry *found_ientry = NULL;
 	int wd;
 
-	spin_lock(&group->inotify_data.idr_lock);
-	idr = &group->inotify_data.idr;
+	spin_lock(idr_lock);
 	wd = ientry->wd;
 
-	if (wd == -1)
+	/*
+	 * does this ientry think it is in the idr?  we shouldn't get called
+	 * if it wasn't....
+	 */
+	if (wd == -1) {
+		printk(KERN_WARNING "%s: ientry=%p ientry->wd=%d ientry->group=%p"
+			" ientry->inode=%p\n", __func__, ientry, ientry->wd,
+			ientry->fsn_entry.group, ientry->fsn_entry.inode);
+		WARN_ON(1);
 		goto out;
+	}
 
-	entry = idr_find(&group->inotify_data.idr, wd);
-	if (unlikely(!entry))
+	/* Lets look in the idr to see if we find it */
+	found_ientry = inotify_idr_find_locked(group, wd);
+	if (unlikely(!found_ientry)) {
+		printk(KERN_WARNING "%s: ientry=%p ientry->wd=%d ientry->group=%p"
+			" ientry->inode=%p\n", __func__, ientry, ientry->wd,
+			ientry->fsn_entry.group, ientry->fsn_entry.inode);
+		WARN_ON(1);
 		goto out;
+	}
 
-	found_ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
+	/*
+	 * We found an entry in the idr at the right wd, but it's
+	 * not the entry we were told to remove.  eparis seriously
+	 * fucked up somewhere.
+	 */
 	if (unlikely(found_ientry != ientry)) {
-		/* We found an entry in the idr with the right wd, but it's
-		 * not the entry we were told to remove.  eparis seriously
-		 * fucked up somewhere. */
 		WARN_ON(1);
-		ientry->wd = -1;
+		printk(KERN_WARNING "%s: ientry=%p ientry->wd=%d ientry->group=%p "
+			"entry->inode=%p found_ientry=%p found_ientry->wd=%d "
+			"found_ientry->group=%p found_ientry->inode=%p\n",
+			__func__, ientry, ientry->wd, ientry->fsn_entry.group,
+			ientry->fsn_entry.inode, found_ientry, found_ientry->wd,
+			found_ientry->fsn_entry.group,
+			found_ientry->fsn_entry.inode);
 		goto out;
 	}
 
-	/* One ref for being in the idr, one ref held by the caller */
-	BUG_ON(atomic_read(&entry->refcnt) < 2);
-
-	idr_remove(idr, wd);
-	ientry->wd = -1;
+	/*
+	 * One ref for being in the idr
+	 * one ref held by the caller trying to kill us
+	 * one ref grabbed by inotify_idr_find
+	 */
+	if (unlikely(atomic_read(&ientry->fsn_entry.refcnt) < 3)) {
+		printk(KERN_WARNING "%s: ientry=%p ientry->wd=%d ientry->group=%p"
+			" ientry->inode=%p\n", __func__, ientry, ientry->wd,
+			ientry->fsn_entry.group, ientry->fsn_entry.inode);
+		/* we can't really recover with bad ref cnting.. */
+		BUG();
+	}
 
-	/* removed from the idr, drop that ref */
-	fsnotify_put_mark(entry);
+	do_inotify_remove_from_idr(group, ientry);
 out:
-	spin_unlock(&group->inotify_data.idr_lock);
+	/* match the ref taken by inotify_idr_find_locked() */
+	if (found_ientry)
+		fsnotify_put_mark(&found_ientry->fsn_entry);
+	ientry->wd = -1;
+	spin_unlock(idr_lock);
 }
 
 /*
@@ -524,6 +625,8 @@ static int inotify_new_watch(struct fsnotify_group *group,
 	struct inotify_inode_mark_entry *tmp_ientry;
 	__u32 mask;
 	int ret;
+	struct idr *idr = &group->inotify_data.idr;
+	spinlock_t *idr_lock = &group->inotify_data.idr_lock;
 
 	/* don't allow invalid bits: we don't want flags set */
 	mask = inotify_arg_to_mask(arg);
@@ -541,28 +644,11 @@ static int inotify_new_watch(struct fsnotify_group *group,
 	ret = -ENOSPC;
 	if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches)
 		goto out_err;
-retry:
-	ret = -ENOMEM;
-	if (unlikely(!idr_pre_get(&group->inotify_data.idr, GFP_KERNEL)))
-		goto out_err;
-
-	/* we are putting the mark on the idr, take a reference */
-	fsnotify_get_mark(&tmp_ientry->fsn_entry);
-
-	spin_lock(&group->inotify_data.idr_lock);
-	ret = idr_get_new_above(&group->inotify_data.idr, &tmp_ientry->fsn_entry,
-				group->inotify_data.last_wd+1,
-				&tmp_ientry->wd);
-	spin_unlock(&group->inotify_data.idr_lock);
-	if (ret) {
-		/* we didn't get on the idr, drop the idr reference */
-		fsnotify_put_mark(&tmp_ientry->fsn_entry);
 
-		/* idr was out of memory allocate and try again */
-		if (ret == -EAGAIN)
-			goto retry;
+	ret = inotify_add_to_idr(idr, idr_lock, group->inotify_data.last_wd,
+				 tmp_ientry);
+	if (ret)
 		goto out_err;
-	}
 
 	/* we are on the idr, now get on the inode */
 	ret = fsnotify_add_mark(&tmp_ientry->fsn_entry, group, inode);
@@ -726,7 +812,7 @@ fput_and_out:
 SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
 {
 	struct fsnotify_group *group;
-	struct fsnotify_mark_entry *entry;
+	struct inotify_inode_mark_entry *ientry;
 	struct file *filp;
 	int ret = 0, fput_needed;
 
@@ -735,25 +821,23 @@ SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
 		return -EBADF;
 
 	/* verify that this is indeed an inotify instance */
-	if (unlikely(filp->f_op != &inotify_fops)) {
-		ret = -EINVAL;
+	ret = -EINVAL;
+	if (unlikely(filp->f_op != &inotify_fops))
 		goto out;
-	}
 
 	group = filp->private_data;
 
-	spin_lock(&group->inotify_data.idr_lock);
-	entry = idr_find(&group->inotify_data.idr, wd);
-	if (unlikely(!entry)) {
-		spin_unlock(&group->inotify_data.idr_lock);
-		ret = -EINVAL;
+	ret = -EINVAL;
+	ientry = inotify_idr_find(group, wd);
+	if (unlikely(!ientry))
 		goto out;
-	}
-	fsnotify_get_mark(entry);
-	spin_unlock(&group->inotify_data.idr_lock);
 
-	fsnotify_destroy_mark_by_entry(entry);
-	fsnotify_put_mark(entry);
+	ret = 0;
+
+	fsnotify_destroy_mark_by_entry(&ientry->fsn_entry);
+
+	/* match ref taken by inotify_idr_find */
+	fsnotify_put_mark(&ientry->fsn_entry);
 
 out:
 	fput_light(filp, fput_needed);