fsnotify: srcu to protect read side of inode and vfsmount locks
Currently reading the inode->i_fsnotify_marks or
vfsmount->mnt_fsnotify_marks lists are protected by a spinlock on both the
read and the write side. This patch protects the read side of those lists
with a new single srcu.
Signed-off-by: Eric Paris <eparis@redhat.com>
diff --git a/fs/notify/group.c b/fs/notify/group.c
index 7ac65ed..48d3a6d 100644
--- a/fs/notify/group.c
+++ b/fs/notify/group.c
@@ -30,8 +30,6 @@
/* protects writes to fsnotify_groups and fsnotify_mask */
static DEFINE_MUTEX(fsnotify_grp_mutex);
-/* protects reads while running the fsnotify_groups list */
-struct srcu_struct fsnotify_grp_srcu;
/* all groups registered to receive inode filesystem notifications */
LIST_HEAD(fsnotify_inode_groups);
/* all groups registered to receive mount point filesystem notifications */
@@ -50,18 +48,17 @@
struct fsnotify_group *group;
__u32 inode_mask = 0;
__u32 vfsmount_mask = 0;
- int idx;
- idx = srcu_read_lock(&fsnotify_grp_srcu);
+ mutex_lock(&fsnotify_grp_mutex);
list_for_each_entry_rcu(group, &fsnotify_inode_groups, inode_group_list)
inode_mask |= group->mask;
list_for_each_entry_rcu(group, &fsnotify_vfsmount_groups, vfsmount_group_list)
vfsmount_mask |= group->mask;
-
- srcu_read_unlock(&fsnotify_grp_srcu, idx);
fsnotify_inode_mask = inode_mask;
fsnotify_vfsmount_mask = vfsmount_mask;
+
+ mutex_unlock(&fsnotify_grp_mutex);
}
/*
@@ -168,6 +165,8 @@
/* clear all inode marks for this group */
fsnotify_clear_marks_by_group(group);
+ synchronize_srcu(&fsnotify_mark_srcu);
+
/* past the point of no return, matches the initial value of 1 */
if (atomic_dec_and_test(&group->num_marks))
fsnotify_final_destroy_group(group);
@@ -216,12 +215,7 @@
*/
__fsnotify_evict_group(group);
- /*
- * now it's off the list, so the only thing we might care about is
- * srcu access....
- */
mutex_unlock(&fsnotify_grp_mutex);
- synchronize_srcu(&fsnotify_grp_srcu);
/* and now it is really dead. _Nothing_ could be seeing it */
fsnotify_recalc_global_mask();