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authorEric Paris <eparis@redhat.com>2010-10-28 17:21:56 -0400
committerEric Paris <eparis@redhat.com>2010-10-28 17:22:13 -0400
commit4231a23530a30e86eb32fbe869bbef1b3e54d5aa (patch)
treebb268ea2e6cb50e8ea46e1f5a536ae0f0afb4e06 /fs/notify/fanotify/fanotify_user.c
parent6ad2d4e3e97ee4bfde0b45e8dfe37911330fc4aa (diff)
fanotify: implement fanotify listener ordering
The fanotify listeners needs to be able to specify what types of operations they are going to perform so they can be ordered appropriately between other listeners doing other types of operations. They need this to be able to make sure that things like hierarchichal storage managers will get access to inodes before processes which need the data. This patch defines 3 possible uses which groups must indicate in the fanotify_init() flags. FAN_CLASS_PRE_CONTENT FAN_CLASS_CONTENT FAN_CLASS_NOTIF Groups will receive notification in that order. The order between 2 groups in the same class is undeterministic. FAN_CLASS_PRE_CONTENT is intended to be used by listeners which need access to the inode before they are certain that the inode contains it's final data. A hierarchical storage manager should choose to use this class. FAN_CLASS_CONTENT is intended to be used by listeners which need access to the inode after it contains its intended contents. This would be the appropriate level for an AV solution or document control system. FAN_CLASS_NOTIF is intended for normal async notification about access, much the same as inotify and dnotify. Syncronous permissions events are not permitted at this class. Signed-off-by: Eric Paris <eparis@redhat.com>
Diffstat (limited to 'fs/notify/fanotify/fanotify_user.c')
-rw-r--r--fs/notify/fanotify/fanotify_user.c25
1 files changed, 24 insertions, 1 deletions
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index bbcb98e7fcc..1c09e6321c5 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -664,6 +664,20 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
init_waitqueue_head(&group->fanotify_data.access_waitq);
INIT_LIST_HEAD(&group->fanotify_data.access_list);
#endif
+ switch (flags & FAN_ALL_CLASS_BITS) {
+ case FAN_CLASS_NOTIF:
+ group->priority = FS_PRIO_0;
+ break;
+ case FAN_CLASS_CONTENT:
+ group->priority = FS_PRIO_1;
+ break;
+ case FAN_CLASS_PRE_CONTENT:
+ group->priority = FS_PRIO_2;
+ break;
+ default:
+ fd = -EINVAL;
+ goto out_put_group;
+ }
fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
if (fd < 0)
@@ -719,6 +733,16 @@ SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
ret = -EINVAL;
if (unlikely(filp->f_op != &fanotify_fops))
goto fput_and_out;
+ group = filp->private_data;
+
+ /*
+ * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not
+ * allowed to set permissions events.
+ */
+ ret = -EINVAL;
+ if (mask & FAN_ALL_PERM_EVENTS &&
+ group->priority == FS_PRIO_0)
+ goto fput_and_out;
ret = fanotify_find_path(dfd, pathname, &path, flags);
if (ret)
@@ -729,7 +753,6 @@ SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
inode = path.dentry->d_inode;
else
mnt = path.mnt;
- group = filp->private_data;
/* create/update an inode mark */
switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {