1 files changed, 175 insertions, 80 deletions

diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index ff27a2965844..0e781bc88d1e 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -47,9 +47,6 @@
 
 static struct vfsmount *inotify_mnt __read_mostly;
 
-/* this just sits here and wastes global memory.  used to just pad userspace messages with zeros */
-static struct inotify_event nul_inotify_event;
-
 /* these are configurable via /proc/sys/fs/inotify/ */
 static int inotify_max_user_instances __read_mostly;
 static int inotify_max_queued_events __read_mostly;
@@ -57,7 +54,6 @@ int inotify_max_user_watches __read_mostly;
 
 static struct kmem_cache *inotify_inode_mark_cachep __read_mostly;
 struct kmem_cache *event_priv_cachep __read_mostly;
-static struct fsnotify_event *inotify_ignored_event;
 
 /*
  * When inotify registers a new group it increments this and uses that
@@ -200,8 +196,10 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
                 inotify_free_event_priv(fsn_priv);
         }
 
-        /* round up event->name_len so it is a multiple of event_size */
-        name_len = roundup(event->name_len, event_size);
+        /* round up event->name_len so it is a multiple of event_size
+         * plus an extra byte for the terminating '\0'.
+         */
+        name_len = roundup(event->name_len + 1, event_size);
         inotify_event.len = name_len;
 
         inotify_event.mask = inotify_mask_to_arg(event->mask);
@@ -225,8 +223,8 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
                         return -EFAULT;
                 buf += event->name_len;
 
-                /* fill userspace with 0's from nul_inotify_event */
-                if (copy_to_user(buf, &nul_inotify_event, len_to_zero))
+                /* fill userspace with 0's */
+                if (clear_user(buf, len_to_zero))
                         return -EFAULT;
                 buf += len_to_zero;
                 event_size += name_len;
@@ -366,20 +364,71 @@ static int inotify_find_inode(const char __user *dirname, struct path *path, uns
 }
 
 /*
- * Send IN_IGNORED for this wd, remove this wd from the idr, and drop the
- * internal reference help on the mark because it is in the idr.
+ * Remove the mark from the idr (if present) and drop the reference
+ * on the mark because it was in the idr.
+ */
+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;
+        int wd;
+
+        spin_lock(&group->inotify_data.idr_lock);
+        idr = &group->inotify_data.idr;
+        wd = ientry->wd;
+
+        if (wd == -1)
+                goto out;
+
+        entry = idr_find(&group->inotify_data.idr, wd);
+        if (unlikely(!entry))
+                goto out;
+
+        found_ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
+        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;
+                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;
+
+        /* removed from the idr, drop that ref */
+        fsnotify_put_mark(entry);
+out:
+        spin_unlock(&group->inotify_data.idr_lock);
+}
+
+/*
+ * Send IN_IGNORED for this wd, remove this wd from the idr.
  */
 void inotify_ignored_and_remove_idr(struct fsnotify_mark_entry *entry,
                                     struct fsnotify_group *group)
 {
         struct inotify_inode_mark_entry *ientry;
+        struct fsnotify_event *ignored_event;
         struct inotify_event_private_data *event_priv;
         struct fsnotify_event_private_data *fsn_event_priv;
-        struct idr *idr;
+        int ret;
+
+        ignored_event = fsnotify_create_event(NULL, FS_IN_IGNORED, NULL,
+                                              FSNOTIFY_EVENT_NONE, NULL, 0,
+                                              GFP_NOFS);
+        if (!ignored_event)
+                return;
 
         ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
 
-        event_priv = kmem_cache_alloc(event_priv_cachep, GFP_KERNEL);
+        event_priv = kmem_cache_alloc(event_priv_cachep, GFP_NOFS);
         if (unlikely(!event_priv))
                 goto skip_send_ignore;
 
@@ -388,22 +437,19 @@ void inotify_ignored_and_remove_idr(struct fsnotify_mark_entry *entry,
         fsn_event_priv->group = group;
         event_priv->wd = ientry->wd;
 
-        fsnotify_add_notify_event(group, inotify_ignored_event, fsn_event_priv);
-
-        /* did the private data get added? */
-        if (list_empty(&fsn_event_priv->event_list))
+        ret = fsnotify_add_notify_event(group, ignored_event, fsn_event_priv);
+        if (ret)
                 inotify_free_event_priv(fsn_event_priv);
 
 skip_send_ignore:
 
+        /* matches the reference taken when the event was created */
+        fsnotify_put_event(ignored_event);
+
         /* remove this entry from the idr */
-        spin_lock(&group->inotify_data.idr_lock);
-        idr = &group->inotify_data.idr;
-        idr_remove(idr, ientry->wd);
-        spin_unlock(&group->inotify_data.idr_lock);
+        inotify_remove_from_idr(group, ientry);
 
-        /* removed from idr, drop that reference */
-        fsnotify_put_mark(entry);
+        atomic_dec(&group->inotify_data.user->inotify_watches);
 }
 
 /* ding dong the mark is dead */
@@ -414,67 +460,29 @@ static void inotify_free_mark(struct fsnotify_mark_entry *entry)
         kmem_cache_free(inotify_inode_mark_cachep, ientry);
 }
 
-static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg)
+static int inotify_update_existing_watch(struct fsnotify_group *group,
+                                         struct inode *inode,
+                                         u32 arg)
 {
-        struct fsnotify_mark_entry *entry = NULL;
+        struct fsnotify_mark_entry *entry;
         struct inotify_inode_mark_entry *ientry;
-        int ret = 0;
-        int add = (arg & IN_MASK_ADD);
-        __u32 mask;
         __u32 old_mask, new_mask;
+        __u32 mask;
+        int add = (arg & IN_MASK_ADD);
+        int ret;
 
         /* don't allow invalid bits: we don't want flags set */
         mask = inotify_arg_to_mask(arg);
         if (unlikely(!mask))
                 return -EINVAL;
 
-        ientry = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
-        if (unlikely(!ientry))
-                return -ENOMEM;
-        /* we set the mask at the end after attaching it */
-        fsnotify_init_mark(&ientry->fsn_entry, inotify_free_mark);
-        ientry->wd = 0;
-
-find_entry:
         spin_lock(&inode->i_lock);
         entry = fsnotify_find_mark_entry(group, inode);
         spin_unlock(&inode->i_lock);
-        if (entry) {
-                kmem_cache_free(inotify_inode_mark_cachep, ientry);
-                ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
-        } else {
-                if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches) {
-                        ret = -ENOSPC;
-                        goto out_err;
-                }
-
-                ret = fsnotify_add_mark(&ientry->fsn_entry, group, inode);
-                if (ret == -EEXIST)
-                        goto find_entry;
-                else if (ret)
-                        goto out_err;
+        if (!entry)
+                return -ENOENT;
 
-                entry = &ientry->fsn_entry;
-retry:
-                ret = -ENOMEM;
-                if (unlikely(!idr_pre_get(&group->inotify_data.idr, GFP_KERNEL)))
-                        goto out_err;
-
-                spin_lock(&group->inotify_data.idr_lock);
-                /* if entry is added to the idr we keep the reference obtained
-                 * through fsnotify_mark_add.  remember to drop this reference
-                 * when entry is removed from idr */
-                ret = idr_get_new_above(&group->inotify_data.idr, entry,
-                                        ++group->inotify_data.last_wd,
-                                        &ientry->wd);
-                spin_unlock(&group->inotify_data.idr_lock);
-                if (ret) {
-                        if (ret == -EAGAIN)
-                                goto retry;
-                        goto out_err;
-                }
-                atomic_inc(&group->inotify_data.user->inotify_watches);
-        }
+        ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
 
         spin_lock(&entry->lock);
 
@@ -506,14 +514,104 @@ retry:
                         fsnotify_recalc_group_mask(group);
         }
 
-        return ientry->wd;
+        /* return the wd */
+        ret = ientry->wd;
 
-out_err:
-        /* see this isn't supposed to happen, just kill the watch */
-        if (entry) {
-                fsnotify_destroy_mark_by_entry(entry);
-                fsnotify_put_mark(entry);
+        /* match the get from fsnotify_find_mark_entry() */
+        fsnotify_put_mark(entry);
+
+        return ret;
+}
+
+static int inotify_new_watch(struct fsnotify_group *group,
+                             struct inode *inode,
+                             u32 arg)
+{
+        struct inotify_inode_mark_entry *tmp_ientry;
+        __u32 mask;
+        int ret;
+
+        /* don't allow invalid bits: we don't want flags set */
+        mask = inotify_arg_to_mask(arg);
+        if (unlikely(!mask))
+                return -EINVAL;
+
+        tmp_ientry = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
+        if (unlikely(!tmp_ientry))
+                return -ENOMEM;
+
+        fsnotify_init_mark(&tmp_ientry->fsn_entry, inotify_free_mark);
+        tmp_ientry->fsn_entry.mask = mask;
+        tmp_ientry->wd = -1;
+
+        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;
+
+        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,
+                                &tmp_ientry->wd);
+        spin_unlock(&group->inotify_data.idr_lock);
+        if (ret) {
+                /* idr was out of memory allocate and try again */
+                if (ret == -EAGAIN)
+                        goto retry;
+                goto out_err;
+        }
+
+        /* we put the mark on the idr, take a reference */
+        fsnotify_get_mark(&tmp_ientry->fsn_entry);
+
+        /* we are on the idr, now get on the inode */
+        ret = fsnotify_add_mark(&tmp_ientry->fsn_entry, group, inode);
+        if (ret) {
+                /* we failed to get on the inode, get off the idr */
+                inotify_remove_from_idr(group, tmp_ientry);
+                goto out_err;
         }
+
+        /* update the idr hint, who cares about races, it's just a hint */
+        group->inotify_data.last_wd = tmp_ientry->wd;
+
+        /* increment the number of watches the user has */
+        atomic_inc(&group->inotify_data.user->inotify_watches);
+
+        /* return the watch descriptor for this new entry */
+        ret = tmp_ientry->wd;
+
+        /* match the ref from fsnotify_init_markentry() */
+        fsnotify_put_mark(&tmp_ientry->fsn_entry);
+
+out_err:
+        if (ret < 0)
+                kmem_cache_free(inotify_inode_mark_cachep, tmp_ientry);
+
+        return ret;
+}
+
+static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg)
+{
+        int ret = 0;
+
+retry:
+        /* try to update and existing watch with the new arg */
+        ret = inotify_update_existing_watch(group, inode, arg);
+        /* no mark present, try to add a new one */
+        if (ret == -ENOENT)
+                ret = inotify_new_watch(group, inode, arg);
+        /*
+         * inotify_new_watch could race with another thread which did an
+         * inotify_new_watch between the update_existing and the add watch
+         * here, go back and try to update an existing mark again.
+         */
+        if (ret == -EEXIST)
+                goto retry;
+
         return ret;
 }
 
@@ -532,7 +630,7 @@ static struct fsnotify_group *inotify_new_group(struct user_struct *user, unsign
 
         spin_lock_init(&group->inotify_data.idr_lock);
         idr_init(&group->inotify_data.idr);
-        group->inotify_data.last_wd = 0;
+        group->inotify_data.last_wd = 1;
         group->inotify_data.user = user;
         group->inotify_data.fa = NULL;
 
@@ -721,9 +819,6 @@ static int __init inotify_user_setup(void)
 
         inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark_entry, SLAB_PANIC);
         event_priv_cachep = KMEM_CACHE(inotify_event_private_data, SLAB_PANIC);
-        inotify_ignored_event = fsnotify_create_event(NULL, FS_IN_IGNORED, NULL, FSNOTIFY_EVENT_NONE, NULL, 0);
-        if (!inotify_ignored_event)
-                panic("unable to allocate the inotify ignored event\n");
 
         inotify_max_queued_events = 16384;
         inotify_max_user_instances = 128;