diff options
| author | Eric Paris <eparis@redhat.com> | 2010-10-28 17:21:56 -0400 |
|---|---|---|
| committer | Eric Paris <eparis@redhat.com> | 2010-10-28 17:22:13 -0400 |
| commit | 6ad2d4e3e97ee4bfde0b45e8dfe37911330fc4aa (patch) | |
| tree | 6a4b98f659a886147088a983170fa75e5113f017 | |
| parent | 9343919c1495b085a4a1cf4cbada8d7888daf099 (diff) | |
fsnotify: implement ordering between notifiers
fanotify needs to be able to specify that some groups get events before
others. They use this idea to make sure that a hierarchical storage
manager gets access to files before programs which actually use them. This
is purely infrastructure. Everything will have a priority of 0, but the
infrastructure will exist for it to be non-zero.
Signed-off-by: Eric Paris <eparis@redhat.com>
| -rw-r--r-- | fs/notify/inode_mark.c | 9 | ||||
| -rw-r--r-- | fs/notify/vfsmount_mark.c | 6 | ||||
| -rw-r--r-- | include/linux/fsnotify_backend.h | 8 |
3 files changed, 20 insertions, 3 deletions
diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c index 21ed10660b8..4c29fcf557d 100644 --- a/fs/notify/inode_mark.c +++ b/fs/notify/inode_mark.c @@ -177,7 +177,8 @@ void fsnotify_set_inode_mark_mask_locked(struct fsnotify_mark *mark, * 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. These - * marks are ordered according to the group's location in memory. + * marks are ordered according to priority, highest number first, and then by + * the group's location in memory. */ int fsnotify_add_inode_mark(struct fsnotify_mark *mark, struct fsnotify_group *group, struct inode *inode, @@ -211,7 +212,11 @@ int fsnotify_add_inode_mark(struct fsnotify_mark *mark, goto out; } - if (mark->group < lmark->group) + if (mark->group->priority < lmark->group->priority) + continue; + + if ((mark->group->priority == lmark->group->priority) && + (mark->group < lmark->group)) continue; hlist_add_before_rcu(&mark->i.i_list, &lmark->i.i_list); diff --git a/fs/notify/vfsmount_mark.c b/fs/notify/vfsmount_mark.c index 56772b578fb..85eebff6d0d 100644 --- a/fs/notify/vfsmount_mark.c +++ b/fs/notify/vfsmount_mark.c @@ -169,7 +169,11 @@ int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark, goto out; } - if (mark->group < lmark->group) + if (mark->group->priority < lmark->group->priority) + continue; + + if ((mark->group->priority == lmark->group->priority) && + (mark->group < lmark->group)) continue; hlist_add_before_rcu(&mark->m.m_list, &lmark->m.m_list); diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h index e40190d1687..82532953416 100644 --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -129,6 +129,14 @@ struct fsnotify_group { wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */ unsigned int q_len; /* events on the queue */ unsigned int max_events; /* maximum events allowed on the list */ + /* + * Valid fsnotify group priorities. Events are send in order from highest + * priority to lowest priority. We default to the lowest priority. + */ + #define FS_PRIO_0 0 /* normal notifiers, no permissions */ + #define FS_PRIO_1 1 /* fanotify content based access control */ + #define FS_PRIO_2 2 /* fanotify pre-content access */ + unsigned int priority; /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */ spinlock_t mark_lock; /* protect marks_list */ |