1 files changed, 234 insertions, 135 deletions

diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index e46ca685b9be..bf7f6d776c31 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -46,17 +46,11 @@
 /* these are configurable via /proc/sys/fs/inotify/ */
 static int inotify_max_user_instances __read_mostly;
 static int inotify_max_queued_events __read_mostly;
-int inotify_max_user_watches __read_mostly;
+static 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;
 
-/*
- * When inotify registers a new group it increments this and uses that
- * value as an offset to set the fsnotify group "name" and priority.
- */
-static atomic_t inotify_grp_num;
-
 #ifdef CONFIG_SYSCTL
 
 #include <linux/sysctl.h>
@@ -96,11 +90,14 @@ static inline __u32 inotify_arg_to_mask(u32 arg)
 {
         __u32 mask;
 
-        /* everything should accept their own ignored and cares about children */
-        mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD);
+        /*
+         * everything should accept their own ignored, cares about children,
+         * and should receive events when the inode is unmounted
+         */
+        mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD | FS_UNMOUNT);
 
         /* mask off the flags used to open the fd */
-        mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT));
+        mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT | IN_EXCL_UNLINK));
 
         return mask;
 }
@@ -144,6 +141,8 @@ static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
 
         event = fsnotify_peek_notify_event(group);
 
+        pr_debug("%s: group=%p event=%p\n", __func__, group, event);
+
         if (event->name_len)
                 event_size += roundup(event->name_len + 1, event_size);
 
@@ -173,6 +172,8 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
         size_t event_size = sizeof(struct inotify_event);
         size_t name_len = 0;
 
+        pr_debug("%s: group=%p event=%p\n", __func__, group, event);
+
         /* we get the inotify watch descriptor from the event private data */
         spin_lock(&event->lock);
         fsn_priv = fsnotify_remove_priv_from_event(group, event);
@@ -245,6 +246,8 @@ static ssize_t inotify_read(struct file *file, char __user *buf,
                 kevent = get_one_event(group, count);
                 mutex_unlock(&group->notification_mutex);
 
+                pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent);
+
                 if (kevent) {
                         ret = PTR_ERR(kevent);
                         if (IS_ERR(kevent))
@@ -289,6 +292,8 @@ static int inotify_release(struct inode *ignored, struct file *file)
         struct fsnotify_group *group = file->private_data;
         struct user_struct *user = group->inotify_data.user;
 
+        pr_debug("%s: group=%p\n", __func__, group);
+
         fsnotify_clear_marks_by_group(group);
 
         /* free this group, matching get was inotify_init->fsnotify_obtain_group */
@@ -312,6 +317,8 @@ static long inotify_ioctl(struct file *file, unsigned int cmd,
         group = file->private_data;
         p = (void __user *) arg;
 
+        pr_debug("%s: group=%p cmd=%u\n", __func__, group, cmd);
+
         switch (cmd) {
         case FIONREAD:
                 mutex_lock(&group->notification_mutex);
@@ -357,59 +364,159 @@ 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 *i_mark)
+{
+        int ret;
+
+        do {
+                if (unlikely(!idr_pre_get(idr, GFP_KERNEL)))
+                        return -ENOMEM;
+
+                spin_lock(idr_lock);
+                ret = idr_get_new_above(idr, i_mark, *last_wd + 1,
+                                        &i_mark->wd);
+                /* we added the mark to the idr, take a reference */
+                if (!ret) {
+                        *last_wd = i_mark->wd;
+                        fsnotify_get_mark(&i_mark->fsn_mark);
+                }
+                spin_unlock(idr_lock);
+        } while (ret == -EAGAIN);
+
+        return ret;
+}
+
+static struct inotify_inode_mark *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 *i_mark;
+
+        assert_spin_locked(idr_lock);
+
+        i_mark = idr_find(idr, wd);
+        if (i_mark) {
+                struct fsnotify_mark *fsn_mark = &i_mark->fsn_mark;
+
+                fsnotify_get_mark(fsn_mark);
+                /* One ref for being in the idr, one ref we just took */
+                BUG_ON(atomic_read(&fsn_mark->refcnt) < 2);
+        }
+
+        return i_mark;
+}
+
+static struct inotify_inode_mark *inotify_idr_find(struct fsnotify_group *group,
+                                                         int wd)
+{
+        struct inotify_inode_mark *i_mark;
+        spinlock_t *idr_lock = &group->inotify_data.idr_lock;
+
+        spin_lock(idr_lock);
+        i_mark = inotify_idr_find_locked(group, wd);
+        spin_unlock(idr_lock);
+
+        return i_mark;
+}
+
+static void do_inotify_remove_from_idr(struct fsnotify_group *group,
+                                       struct inotify_inode_mark *i_mark)
+{
+        struct idr *idr = &group->inotify_data.idr;
+        spinlock_t *idr_lock = &group->inotify_data.idr_lock;
+        int wd = i_mark->wd;
+
+        assert_spin_locked(idr_lock);
+
+        idr_remove(idr, wd);
+
+        /* removed from the idr, drop that ref */
+        fsnotify_put_mark(&i_mark->fsn_mark);
+}
+
 /*
  * 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 inotify_inode_mark *i_mark)
 {
-        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 *found_i_mark = NULL;
         int wd;
 
-        spin_lock(&group->inotify_data.idr_lock);
-        idr = &group->inotify_data.idr;
-        wd = ientry->wd;
+        spin_lock(idr_lock);
+        wd = i_mark->wd;
 
-        if (wd == -1)
+        /*
+         * does this i_mark think it is in the idr?  we shouldn't get called
+         * if it wasn't....
+         */
+        if (wd == -1) {
+                WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p"
+                        " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd,
+                        i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode);
                 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_i_mark = inotify_idr_find_locked(group, wd);
+        if (unlikely(!found_i_mark)) {
+                WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p"
+                        " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd,
+                        i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode);
                 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;
+        /*
+         * We found an mark in the idr at the right wd, but it's
+         * not the mark we were told to remove.  eparis seriously
+         * fucked up somewhere.
+         */
+        if (unlikely(found_i_mark != i_mark)) {
+                WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p "
+                        "mark->inode=%p found_i_mark=%p found_i_mark->wd=%d "
+                        "found_i_mark->group=%p found_i_mark->inode=%p\n",
+                        __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group,
+                        i_mark->fsn_mark.i.inode, found_i_mark, found_i_mark->wd,
+                        found_i_mark->fsn_mark.group,
+                        found_i_mark->fsn_mark.i.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(&i_mark->fsn_mark.refcnt) < 3)) {
+                printk(KERN_ERR "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p"
+                        " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd,
+                        i_mark->fsn_mark.group, i_mark->fsn_mark.i.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, i_mark);
 out:
-        spin_unlock(&group->inotify_data.idr_lock);
+        /* match the ref taken by inotify_idr_find_locked() */
+        if (found_i_mark)
+                fsnotify_put_mark(&found_i_mark->fsn_mark);
+        i_mark->wd = -1;
+        spin_unlock(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,
+void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark,
                                     struct fsnotify_group *group)
 {
-        struct inotify_inode_mark_entry *ientry;
-        struct fsnotify_event *ignored_event;
+        struct inotify_inode_mark *i_mark;
+        struct fsnotify_event *ignored_event, *notify_event;
         struct inotify_event_private_data *event_priv;
         struct fsnotify_event_private_data *fsn_event_priv;
         int ret;
@@ -420,7 +527,7 @@ void inotify_ignored_and_remove_idr(struct fsnotify_mark_entry *entry,
         if (!ignored_event)
                 return;
 
-        ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
+        i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
 
         event_priv = kmem_cache_alloc(event_priv_cachep, GFP_NOFS);
         if (unlikely(!event_priv))
@@ -429,37 +536,44 @@ void inotify_ignored_and_remove_idr(struct fsnotify_mark_entry *entry,
         fsn_event_priv = &event_priv->fsnotify_event_priv_data;
 
         fsn_event_priv->group = group;
-        event_priv->wd = ientry->wd;
-
-        ret = fsnotify_add_notify_event(group, ignored_event, fsn_event_priv);
-        if (ret)
+        event_priv->wd = i_mark->wd;
+
+        notify_event = fsnotify_add_notify_event(group, ignored_event, fsn_event_priv, NULL);
+        if (notify_event) {
+                if (IS_ERR(notify_event))
+                        ret = PTR_ERR(notify_event);
+                else
+                        fsnotify_put_event(notify_event);
                 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 */
-        inotify_remove_from_idr(group, ientry);
+        /* remove this mark from the idr */
+        inotify_remove_from_idr(group, i_mark);
 
         atomic_dec(&group->inotify_data.user->inotify_watches);
 }
 
 /* ding dong the mark is dead */
-static void inotify_free_mark(struct fsnotify_mark_entry *entry)
+static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
 {
-        struct inotify_inode_mark_entry *ientry = (struct inotify_inode_mark_entry *)entry;
+        struct inotify_inode_mark *i_mark;
+
+        i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
 
-        kmem_cache_free(inotify_inode_mark_cachep, ientry);
+        kmem_cache_free(inotify_inode_mark_cachep, i_mark);
 }
 
 static int inotify_update_existing_watch(struct fsnotify_group *group,
                                          struct inode *inode,
                                          u32 arg)
 {
-        struct fsnotify_mark_entry *entry;
-        struct inotify_inode_mark_entry *ientry;
+        struct fsnotify_mark *fsn_mark;
+        struct inotify_inode_mark *i_mark;
         __u32 old_mask, new_mask;
         __u32 mask;
         int add = (arg & IN_MASK_ADD);
@@ -467,52 +581,43 @@ static int inotify_update_existing_watch(struct fsnotify_group *group,
 
         /* don't allow invalid bits: we don't want flags set */
         mask = inotify_arg_to_mask(arg);
-        if (unlikely(!mask))
+        if (unlikely(!(mask & IN_ALL_EVENTS)))
                 return -EINVAL;
 
-        spin_lock(&inode->i_lock);
-        entry = fsnotify_find_mark_entry(group, inode);
-        spin_unlock(&inode->i_lock);
-        if (!entry)
+        fsn_mark = fsnotify_find_inode_mark(group, inode);
+        if (!fsn_mark)
                 return -ENOENT;
 
-        ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
+        i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
 
-        spin_lock(&entry->lock);
+        spin_lock(&fsn_mark->lock);
 
-        old_mask = entry->mask;
-        if (add) {
-                entry->mask |= mask;
-                new_mask = entry->mask;
-        } else {
-                entry->mask = mask;
-                new_mask = entry->mask;
-        }
+        old_mask = fsn_mark->mask;
+        if (add)
+                fsnotify_set_mark_mask_locked(fsn_mark, (fsn_mark->mask | mask));
+        else
+                fsnotify_set_mark_mask_locked(fsn_mark, mask);
+        new_mask = fsn_mark->mask;
 
-        spin_unlock(&entry->lock);
+        spin_unlock(&fsn_mark->lock);
 
         if (old_mask != new_mask) {
                 /* more bits in old than in new? */
                 int dropped = (old_mask & ~new_mask);
-                /* more bits in this entry than the inode's mask? */
+                /* more bits in this fsn_mark than the inode's mask? */
                 int do_inode = (new_mask & ~inode->i_fsnotify_mask);
-                /* more bits in this entry than the group? */
-                int do_group = (new_mask & ~group->mask);
 
-                /* update the inode with this new entry */
+                /* update the inode with this new fsn_mark */
                 if (dropped || do_inode)
                         fsnotify_recalc_inode_mask(inode);
 
-                /* update the group mask with the new mask */
-                if (dropped || do_group)
-                        fsnotify_recalc_group_mask(group);
         }
 
         /* return the wd */
-        ret = ientry->wd;
+        ret = i_mark->wd;
 
-        /* match the get from fsnotify_find_mark_entry() */
-        fsnotify_put_mark(entry);
+        /* match the get from fsnotify_find_mark() */
+        fsnotify_put_mark(fsn_mark);
 
         return ret;
 }
@@ -521,73 +626,51 @@ static int inotify_new_watch(struct fsnotify_group *group,
                              struct inode *inode,
                              u32 arg)
 {
-        struct inotify_inode_mark_entry *tmp_ientry;
+        struct inotify_inode_mark *tmp_i_mark;
         __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);
-        if (unlikely(!mask))
+        if (unlikely(!(mask & IN_ALL_EVENTS)))
                 return -EINVAL;
 
-        tmp_ientry = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
-        if (unlikely(!tmp_ientry))
+        tmp_i_mark = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
+        if (unlikely(!tmp_i_mark))
                 return -ENOMEM;
 
-        fsnotify_init_mark(&tmp_ientry->fsn_entry, inotify_free_mark);
-        tmp_ientry->fsn_entry.mask = mask;
-        tmp_ientry->wd = -1;
+        fsnotify_init_mark(&tmp_i_mark->fsn_mark, inotify_free_mark);
+        tmp_i_mark->fsn_mark.mask = mask;
+        tmp_i_mark->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;
 
-        /* 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_i_mark);
+        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);
+        ret = fsnotify_add_mark(&tmp_i_mark->fsn_mark, group, inode, NULL, 0);
         if (ret) {
                 /* we failed to get on the inode, get off the idr */
-                inotify_remove_from_idr(group, tmp_ientry);
+                inotify_remove_from_idr(group, tmp_i_mark);
                 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;
-
-        /* if this mark added a new event update the group mask */
-        if (mask & ~group->mask)
-                fsnotify_recalc_group_mask(group);
+        /* return the watch descriptor for this new mark */
+        ret = tmp_i_mark->wd;
 
 out_err:
-        /* match the ref from fsnotify_init_markentry() */
-        fsnotify_put_mark(&tmp_ientry->fsn_entry);
+        /* match the ref from fsnotify_init_mark() */
+        fsnotify_put_mark(&tmp_i_mark->fsn_mark);
 
         return ret;
 }
@@ -616,11 +699,8 @@ retry:
 static struct fsnotify_group *inotify_new_group(struct user_struct *user, unsigned int max_events)
 {
         struct fsnotify_group *group;
-        unsigned int grp_num;
 
-        /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */
-        grp_num = (INOTIFY_GROUP_NUM - atomic_inc_return(&inotify_grp_num));
-        group = fsnotify_obtain_group(grp_num, 0, &inotify_fsnotify_ops);
+        group = fsnotify_alloc_group(&inotify_fsnotify_ops);
         if (IS_ERR(group))
                 return group;
 
@@ -726,7 +806,7 @@ 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 *i_mark;
         struct file *filp;
         int ret = 0, fput_needed;
 
@@ -735,25 +815,23 @@ 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;
+        i_mark = inotify_idr_find(group, wd);
+        if (unlikely(!i_mark))
                 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(&i_mark->fsn_mark);
+
+        /* match ref taken by inotify_idr_find */
+        fsnotify_put_mark(&i_mark->fsn_mark);
 
 out:
         fput_light(filp, fput_needed);
@@ -767,7 +845,28 @@ out:
  */
 static int __init inotify_user_setup(void)
 {
-        inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark_entry, SLAB_PANIC);
+        BUILD_BUG_ON(IN_ACCESS != FS_ACCESS);
+        BUILD_BUG_ON(IN_MODIFY != FS_MODIFY);
+        BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB);
+        BUILD_BUG_ON(IN_CLOSE_WRITE != FS_CLOSE_WRITE);
+        BUILD_BUG_ON(IN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
+        BUILD_BUG_ON(IN_OPEN != FS_OPEN);
+        BUILD_BUG_ON(IN_MOVED_FROM != FS_MOVED_FROM);
+        BUILD_BUG_ON(IN_MOVED_TO != FS_MOVED_TO);
+        BUILD_BUG_ON(IN_CREATE != FS_CREATE);
+        BUILD_BUG_ON(IN_DELETE != FS_DELETE);
+        BUILD_BUG_ON(IN_DELETE_SELF != FS_DELETE_SELF);
+        BUILD_BUG_ON(IN_MOVE_SELF != FS_MOVE_SELF);
+        BUILD_BUG_ON(IN_UNMOUNT != FS_UNMOUNT);
+        BUILD_BUG_ON(IN_Q_OVERFLOW != FS_Q_OVERFLOW);
+        BUILD_BUG_ON(IN_IGNORED != FS_IN_IGNORED);
+        BUILD_BUG_ON(IN_EXCL_UNLINK != FS_EXCL_UNLINK);
+        BUILD_BUG_ON(IN_ISDIR != FS_IN_ISDIR);
+        BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT);
+
+        BUG_ON(hweight32(ALL_INOTIFY_BITS) != 21);
+
+        inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, SLAB_PANIC);
         event_priv_cachep = KMEM_CACHE(inotify_event_private_data, SLAB_PANIC);
 
         inotify_max_queued_events = 16384;