1 files changed, 103 insertions, 228 deletions

diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index 152b83ec005d..33297c005060 100644
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -16,72 +16,6 @@
  *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
-/*
- * fsnotify inode mark locking/lifetime/and refcnting
- *
- * REFCNT:
- * The mark->refcnt tells how many "things" in the kernel currently are
- * referencing this object.  The object typically will live inside the kernel
- * with a refcnt of 2, one for each list it is on (i_list, g_list).  Any task
- * which can find this object holding the appropriete locks, can take a reference
- * and the object itself is guarenteed to survive until the reference is dropped.
- *
- * LOCKING:
- * There are 3 spinlocks involved with fsnotify inode marks and they MUST
- * be taken in order as follows:
- *
- * entry->lock
- * group->mark_lock
- * inode->i_lock
- *
- * entry->lock protects 2 things, entry->group and entry->inode.  You must hold
- * that lock to dereference either of these things (they could be NULL even with
- * the lock)
- *
- * group->mark_lock protects the mark_entries list anchored inside a given group
- * and each entry is hooked via the g_list.  It also sorta protects the
- * free_g_list, which when used is anchored by a private list on the stack of the
- * task which held the group->mark_lock.
- *
- * inode->i_lock protects the i_fsnotify_mark_entries list anchored inside a
- * given inode and each entry is hooked via the i_list. (and sorta the
- * free_i_list)
- *
- *
- * LIFETIME:
- * Inode marks survive between when they are added to an inode and when their
- * refcnt==0.
- *
- * The inode mark can be cleared for a number of different reasons including:
- * - The inode is unlinked for the last time.  (fsnotify_inode_remove)
- * - The inode is being evicted from cache. (fsnotify_inode_delete)
- * - The fs the inode is on is unmounted.  (fsnotify_inode_delete/fsnotify_unmount_inodes)
- * - Something explicitly requests that it be removed.  (fsnotify_destroy_mark_by_entry)
- * - The fsnotify_group associated with the mark is going away and all such marks
- *   need to be cleaned up. (fsnotify_clear_marks_by_group)
- *
- * Worst case we are given an inode and need to clean up all the marks on that
- * inode.  We take i_lock and walk the i_fsnotify_mark_entries safely.  For each
- * mark on the list we take a reference (so the mark can't disappear under us).
- * We remove that mark form the inode's list of marks and we add this mark to a
- * private list anchored on the stack using i_free_list;  At this point we no
- * longer fear anything finding the mark using the inode's list of marks.
- *
- * We can safely and locklessly run the private list on the stack of everything
- * we just unattached from the original inode.  For each mark on the private list
- * we grab the mark-> and can thus dereference mark->group and mark->inode.  If
- * we see the group and inode are not NULL we take those locks.  Now holding all
- * 3 locks we can completely remove the mark from other tasks finding it in the
- * future.  Remember, 10 things might already be referencing this mark, but they
- * better be holding a ref.  We drop our reference we took before we unhooked it
- * from the inode.  When the ref hits 0 we can free the mark.
- *
- * Very similarly for freeing by group, except we use free_g_list.
- *
- * This has the very interesting property of being able to run concurrently with
- * any (or all) other directions.
- */
-
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -95,30 +29,19 @@
 #include <linux/fsnotify_backend.h>
 #include "fsnotify.h"
 
-void fsnotify_get_mark(struct fsnotify_mark_entry *entry)
-{
-        atomic_inc(&entry->refcnt);
-}
-
-void fsnotify_put_mark(struct fsnotify_mark_entry *entry)
-{
-        if (atomic_dec_and_test(&entry->refcnt))
-                entry->free_mark(entry);
-}
-
 /*
  * Recalculate the mask of events relevant to a given inode locked.
  */
 static void fsnotify_recalc_inode_mask_locked(struct inode *inode)
 {
-        struct fsnotify_mark_entry *entry;
+        struct fsnotify_mark *mark;
         struct hlist_node *pos;
         __u32 new_mask = 0;
 
         assert_spin_locked(&inode->i_lock);
 
-        hlist_for_each_entry(entry, pos, &inode->i_fsnotify_mark_entries, i_list)
-                new_mask |= entry->mask;
+        hlist_for_each_entry(mark, pos, &inode->i_fsnotify_marks, i.i_list)
+                new_mask |= mark->mask;
         inode->i_fsnotify_mask = new_mask;
 }
 
@@ -135,107 +58,26 @@ void fsnotify_recalc_inode_mask(struct inode *inode)
         __fsnotify_update_child_dentry_flags(inode);
 }
 
-/*
- * Any time a mark is getting freed we end up here.
- * The caller had better be holding a reference to this mark so we don't actually
- * do the final put under the entry->lock
- */
-void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry)
+void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
 {
-        struct fsnotify_group *group;
-        struct inode *inode;
+        struct inode *inode = mark->i.inode;
 
-        spin_lock(&entry->lock);
+        assert_spin_locked(&mark->lock);
+        assert_spin_locked(&mark->group->mark_lock);
 
-        group = entry->group;
-        inode = entry->inode;
-
-        BUG_ON(group && !inode);
-        BUG_ON(!group && inode);
-
-        /* if !group something else already marked this to die */
-        if (!group) {
-                spin_unlock(&entry->lock);
-                return;
-        }
-
-        /* 1 from caller and 1 for being on i_list/g_list */
-        BUG_ON(atomic_read(&entry->refcnt) < 2);
-
-        spin_lock(&group->mark_lock);
         spin_lock(&inode->i_lock);
 
-        hlist_del_init(&entry->i_list);
-        entry->inode = NULL;
-
-        list_del_init(&entry->g_list);
-        entry->group = NULL;
-
-        fsnotify_put_mark(entry); /* for i_list and g_list */
+        hlist_del_init_rcu(&mark->i.i_list);
+        mark->i.inode = NULL;
 
         /*
-         * this mark is now off the inode->i_fsnotify_mark_entries list and we
+         * this mark is now off the inode->i_fsnotify_marks list and we
          * hold the inode->i_lock, so this is the perfect time to update the
          * inode->i_fsnotify_mask
          */
         fsnotify_recalc_inode_mask_locked(inode);
 
         spin_unlock(&inode->i_lock);
-        spin_unlock(&group->mark_lock);
-        spin_unlock(&entry->lock);
-
-        /*
-         * Some groups like to know that marks are being freed.  This is a
-         * callback to the group function to let it know that this entry
-         * is being freed.
-         */
-        if (group->ops->freeing_mark)
-                group->ops->freeing_mark(entry, group);
-
-        /*
-         * __fsnotify_update_child_dentry_flags(inode);
-         *
-         * I really want to call that, but we can't, we have no idea if the inode
-         * still exists the second we drop the entry->lock.
-         *
-         * The next time an event arrive to this inode from one of it's children
-         * __fsnotify_parent will see that the inode doesn't care about it's
-         * children and will update all of these flags then.  So really this
-         * is just a lazy update (and could be a perf win...)
-         */
-
-
-        iput(inode);
-
-        /*
-         * it's possible that this group tried to destroy itself, but this
-         * this mark was simultaneously being freed by inode.  If that's the
-         * case, we finish freeing the group here.
-         */
-        if (unlikely(atomic_dec_and_test(&group->num_marks)))
-                fsnotify_final_destroy_group(group);
-}
-
-/*
- * Given a group, destroy all of the marks associated with that group.
- */
-void fsnotify_clear_marks_by_group(struct fsnotify_group *group)
-{
-        struct fsnotify_mark_entry *lentry, *entry;
-        LIST_HEAD(free_list);
-
-        spin_lock(&group->mark_lock);
-        list_for_each_entry_safe(entry, lentry, &group->mark_entries, g_list) {
-                list_add(&entry->free_g_list, &free_list);
-                list_del_init(&entry->g_list);
-                fsnotify_get_mark(entry);
-        }
-        spin_unlock(&group->mark_lock);
-
-        list_for_each_entry_safe(entry, lentry, &free_list, free_g_list) {
-                fsnotify_destroy_mark_by_entry(entry);
-                fsnotify_put_mark(entry);
-        }
 }
 
 /*
@@ -243,112 +85,145 @@ void fsnotify_clear_marks_by_group(struct fsnotify_group *group)
  */
 void fsnotify_clear_marks_by_inode(struct inode *inode)
 {
-        struct fsnotify_mark_entry *entry, *lentry;
+        struct fsnotify_mark *mark, *lmark;
         struct hlist_node *pos, *n;
         LIST_HEAD(free_list);
 
         spin_lock(&inode->i_lock);
-        hlist_for_each_entry_safe(entry, pos, n, &inode->i_fsnotify_mark_entries, i_list) {
-                list_add(&entry->free_i_list, &free_list);
-                hlist_del_init(&entry->i_list);
-                fsnotify_get_mark(entry);
+        hlist_for_each_entry_safe(mark, pos, n, &inode->i_fsnotify_marks, i.i_list) {
+                list_add(&mark->i.free_i_list, &free_list);
+                hlist_del_init_rcu(&mark->i.i_list);
+                fsnotify_get_mark(mark);
         }
         spin_unlock(&inode->i_lock);
 
-        list_for_each_entry_safe(entry, lentry, &free_list, free_i_list) {
-                fsnotify_destroy_mark_by_entry(entry);
-                fsnotify_put_mark(entry);
+        list_for_each_entry_safe(mark, lmark, &free_list, i.free_i_list) {
+                fsnotify_destroy_mark(mark);
+                fsnotify_put_mark(mark);
         }
 }
 
 /*
+ * Given a group clear all of the inode marks associated with that group.
+ */
+void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group)
+{
+        fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_INODE);
+}
+
+/*
  * given a group and inode, find the mark associated with that combination.
  * if found take a reference to that mark and return it, else return NULL
  */
-struct fsnotify_mark_entry *fsnotify_find_mark_entry(struct fsnotify_group *group,
-                                                     struct inode *inode)
+struct fsnotify_mark *fsnotify_find_inode_mark_locked(struct fsnotify_group *group,
+                                                      struct inode *inode)
 {
-        struct fsnotify_mark_entry *entry;
+        struct fsnotify_mark *mark;
         struct hlist_node *pos;
 
         assert_spin_locked(&inode->i_lock);
 
-        hlist_for_each_entry(entry, pos, &inode->i_fsnotify_mark_entries, i_list) {
-                if (entry->group == group) {
-                        fsnotify_get_mark(entry);
-                        return entry;
+        hlist_for_each_entry(mark, pos, &inode->i_fsnotify_marks, i.i_list) {
+                if (mark->group == group) {
+                        fsnotify_get_mark(mark);
+                        return mark;
                 }
         }
         return NULL;
 }
 
 /*
- * Nothing fancy, just initialize lists and locks and counters.
+ * given a group and inode, find the mark associated with that combination.
+ * if found take a reference to that mark and return it, else return NULL
  */
-void fsnotify_init_mark(struct fsnotify_mark_entry *entry,
-                        void (*free_mark)(struct fsnotify_mark_entry *entry))
+struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group,
+                                               struct inode *inode)
+{
+        struct fsnotify_mark *mark;
+
+        spin_lock(&inode->i_lock);
+        mark = fsnotify_find_inode_mark_locked(group, inode);
+        spin_unlock(&inode->i_lock);
 
+        return mark;
+}
+
+/*
+ * If we are setting a mark mask on an inode mark we should pin the inode
+ * in memory.
+ */
+void fsnotify_set_inode_mark_mask_locked(struct fsnotify_mark *mark,
+                                         __u32 mask)
 {
-        spin_lock_init(&entry->lock);
-        atomic_set(&entry->refcnt, 1);
-        INIT_HLIST_NODE(&entry->i_list);
-        entry->group = NULL;
-        entry->mask = 0;
-        entry->inode = NULL;
-        entry->free_mark = free_mark;
+        struct inode *inode;
+
+        assert_spin_locked(&mark->lock);
+
+        if (mask &&
+            mark->i.inode &&
+            !(mark->flags & FSNOTIFY_MARK_FLAG_OBJECT_PINNED)) {
+                mark->flags |= FSNOTIFY_MARK_FLAG_OBJECT_PINNED;
+                inode = igrab(mark->i.inode);
+                /*
+                 * we shouldn't be able to get here if the inode wasn't
+                 * already safely held in memory.  But bug in case it
+                 * ever is wrong.
+                 */
+                BUG_ON(!inode);
+        }
 }
 
 /*
- * Attach an initialized mark entry to a given group and inode.
+ * Attach an initialized mark to a given inode.
  * These marks may be used for the fsnotify backend to determine which
- * event types should be delivered to which group and for which inodes.
+ * event types should be delivered to which group and for which inodes.  These
+ * marks are ordered according to the group's location in memory.
  */
-int fsnotify_add_mark(struct fsnotify_mark_entry *entry,
-                      struct fsnotify_group *group, struct inode *inode)
+int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
+                            struct fsnotify_group *group, struct inode *inode,
+                            int allow_dups)
 {
-        struct fsnotify_mark_entry *lentry;
+        struct fsnotify_mark *lmark;
+        struct hlist_node *node, *last = NULL;
         int ret = 0;
 
-        inode = igrab(inode);
-        if (unlikely(!inode))
-                return -EINVAL;
+        mark->flags |= FSNOTIFY_MARK_FLAG_INODE;
+
+        assert_spin_locked(&mark->lock);
+        assert_spin_locked(&group->mark_lock);
 
-        /*
-         * LOCKING ORDER!!!!
-         * entry->lock
-         * group->mark_lock
-         * inode->i_lock
-         */
-        spin_lock(&entry->lock);
-        spin_lock(&group->mark_lock);
         spin_lock(&inode->i_lock);
 
-        lentry = fsnotify_find_mark_entry(group, inode);
-        if (!lentry) {
-                entry->group = group;
-                entry->inode = inode;
+        mark->i.inode = inode;
 
-                hlist_add_head(&entry->i_list, &inode->i_fsnotify_mark_entries);
-                list_add(&entry->g_list, &group->mark_entries);
+        /* is mark the first mark? */
+        if (hlist_empty(&inode->i_fsnotify_marks)) {
+                hlist_add_head_rcu(&mark->i.i_list, &inode->i_fsnotify_marks);
+                goto out;
+        }
 
-                fsnotify_get_mark(entry); /* for i_list and g_list */
+        /* should mark be in the middle of the current list? */
+        hlist_for_each_entry(lmark, node, &inode->i_fsnotify_marks, i.i_list) {
+                last = node;
+
+                if ((lmark->group == group) && !allow_dups) {
+                        ret = -EEXIST;
+                        goto out;
+                }
 
-                atomic_inc(&group->num_marks);
+                if (mark->group < lmark->group)
+                        continue;
 
-                fsnotify_recalc_inode_mask_locked(inode);
+                hlist_add_before_rcu(&mark->i.i_list, &lmark->i.i_list);
+                goto out;
         }
 
+        BUG_ON(last == NULL);
+        /* mark should be the last entry.  last is the current last entry */
+        hlist_add_after_rcu(last, &mark->i.i_list);
+out:
+        fsnotify_recalc_inode_mask_locked(inode);
         spin_unlock(&inode->i_lock);
-        spin_unlock(&group->mark_lock);
-        spin_unlock(&entry->lock);
-
-        if (lentry) {
-                ret = -EEXIST;
-                iput(inode);
-                fsnotify_put_mark(lentry);
-        } else {
-                __fsnotify_update_child_dentry_flags(inode);
-        }
 
         return ret;
 }