In order to better support resource allocation and locking for dynamic
hypfs nodes add enter() and exit() callbacks to struct hypfs_funcs.
The enter() callback is called when entering a node during hypfs user
actions (traversing, reading or writing it), while the exit() callback
is called when leaving a node (accessing another node at the same or a
higher directory level, or when returning to the user).
For avoiding recursion this requires a parent pointer in each node.
Let the enter() callback return the entry address which is stored as
the last accessed node in order to be able to use a template entry for
that purpose in case of dynamic entries.
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V2:
- new patch
V3:
- add ASSERT(entry); (Jan Beulich)
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
xen/common/hypfs.c | 80 +++++++++++++++++++++++++++++++++++++++++
xen/include/xen/hypfs.h | 5 +++
2 files changed, 85 insertions(+)
diff --git a/xen/common/hypfs.c b/xen/common/hypfs.c
index 6f822ae097..f04934db10 100644
--- a/xen/common/hypfs.c
+++ b/xen/common/hypfs.c
@@ -25,30 +25,40 @@ CHECK_hypfs_dirlistentry;
ROUNDUP((name_len) + 1, alignof(struct xen_hypfs_direntry)))
const struct hypfs_funcs hypfs_dir_funcs = {
+ .enter = hypfs_node_enter,
+ .exit = hypfs_node_exit,
.read = hypfs_read_dir,
.write = hypfs_write_deny,
.getsize = hypfs_getsize,
.findentry = hypfs_dir_findentry,
};
const struct hypfs_funcs hypfs_leaf_ro_funcs = {
+ .enter = hypfs_node_enter,
+ .exit = hypfs_node_exit,
.read = hypfs_read_leaf,
.write = hypfs_write_deny,
.getsize = hypfs_getsize,
.findentry = hypfs_leaf_findentry,
};
const struct hypfs_funcs hypfs_leaf_wr_funcs = {
+ .enter = hypfs_node_enter,
+ .exit = hypfs_node_exit,
.read = hypfs_read_leaf,
.write = hypfs_write_leaf,
.getsize = hypfs_getsize,
.findentry = hypfs_leaf_findentry,
};
const struct hypfs_funcs hypfs_bool_wr_funcs = {
+ .enter = hypfs_node_enter,
+ .exit = hypfs_node_exit,
.read = hypfs_read_leaf,
.write = hypfs_write_bool,
.getsize = hypfs_getsize,
.findentry = hypfs_leaf_findentry,
};
const struct hypfs_funcs hypfs_custom_wr_funcs = {
+ .enter = hypfs_node_enter,
+ .exit = hypfs_node_exit,
.read = hypfs_read_leaf,
.write = hypfs_write_custom,
.getsize = hypfs_getsize,
@@ -63,6 +73,8 @@ enum hypfs_lock_state {
};
static DEFINE_PER_CPU(enum hypfs_lock_state, hypfs_locked);
+static DEFINE_PER_CPU(const struct hypfs_entry *, hypfs_last_node_entered);
+
HYPFS_DIR_INIT(hypfs_root, "");
static void hypfs_read_lock(void)
@@ -100,11 +112,59 @@ static void hypfs_unlock(void)
}
}
+const struct hypfs_entry *hypfs_node_enter(const struct hypfs_entry *entry)
+{
+ return entry;
+}
+
+void hypfs_node_exit(const struct hypfs_entry *entry)
+{
+}
+
+static int node_enter(const struct hypfs_entry *entry)
+{
+ const struct hypfs_entry **last = &this_cpu(hypfs_last_node_entered);
+
+ entry = entry->funcs->enter(entry);
+ if ( IS_ERR(entry) )
+ return PTR_ERR(entry);
+
+ ASSERT(entry);
+ ASSERT(!*last || *last == entry->parent);
+
+ *last = entry;
+
+ return 0;
+}
+
+static void node_exit(const struct hypfs_entry *entry)
+{
+ const struct hypfs_entry **last = &this_cpu(hypfs_last_node_entered);
+
+ if ( !*last )
+ return;
