[PATCH v3 15/30] liveupdate: luo_files: implement file systems callbacks

[Pasha Tatashin <pasha.tatashin@soleen.com>]

Implements the core logic within luo_files.c to invoke the prepare,
reboot, finish, and cancel callbacks for preserved file instances,
replacing the previous stub implementations. It also handles
the persistence and retrieval of the u64 data payload associated with
each file via the LUO FDT.

This completes the core mechanism enabling registered files handlers to actively
manage file state across the live update transition using the LUO framework.

Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
---
 kernel/liveupdate/luo_files.c | 191 +++++++++++++++++++++++++++++++++-
 1 file changed, 188 insertions(+), 3 deletions(-)

diff --git a/kernel/liveupdate/luo_files.c b/kernel/liveupdate/luo_files.c
index 4b7568d0f0f0..33577c9e9a64 100644
--- a/kernel/liveupdate/luo_files.c
+++ b/kernel/liveupdate/luo_files.c
@@ -326,32 +326,190 @@ static int luo_files_fdt_setup(void)
 	return ret;
 }
 
+static int luo_files_prepare_one(struct luo_file *h)
+{
+	int ret = 0;
+
+	guard(mutex)(&h->mutex);
+	if (h->state == LIVEUPDATE_STATE_NORMAL) {
+		if (h->fh->ops->prepare) {
+			ret = h->fh->ops->prepare(h->fh, h->file,
+						  &h->private_data);
+		}
+		if (!ret)
+			h->state = LIVEUPDATE_STATE_PREPARED;
+	} else {
+		WARN_ON_ONCE(h->state != LIVEUPDATE_STATE_PREPARED &&
+			     h->state != LIVEUPDATE_STATE_FROZEN);
+	}
+
+	return ret;
+}
+
+static int luo_files_freeze_one(struct luo_file *h)
+{
+	int ret = 0;
+
+	guard(mutex)(&h->mutex);
+	if (h->state == LIVEUPDATE_STATE_PREPARED) {
+		if (h->fh->ops->freeze) {
+			ret = h->fh->ops->freeze(h->fh, h->file,
+						 &h->private_data);
+		}
+		if (!ret)
+			h->state = LIVEUPDATE_STATE_FROZEN;
+	} else {
+		WARN_ON_ONCE(h->state != LIVEUPDATE_STATE_FROZEN);
+	}
+
+	return ret;
+}
+
+static void luo_files_finish_one(struct luo_file *h)
+{
+	guard(mutex)(&h->mutex);
+	if (h->state == LIVEUPDATE_STATE_UPDATED) {
+		if (h->fh->ops->finish) {
+			h->fh->ops->finish(h->fh, h->file, h->private_data,
+					   h->reclaimed);
+		}
+		h->state = LIVEUPDATE_STATE_NORMAL;
+	} else {
+		WARN_ON_ONCE(h->state != LIVEUPDATE_STATE_NORMAL);
+	}
+}
+
+static void luo_files_cancel_one(struct luo_file *h)
+{
+	int ret;
+
+	guard(mutex)(&h->mutex);
+	if (h->state == LIVEUPDATE_STATE_NORMAL)
+		return;
+
+	ret = WARN_ON_ONCE(h->state != LIVEUPDATE_STATE_PREPARED &&
+			   h->state != LIVEUPDATE_STATE_FROZEN);
+	if (ret)
+		return;
+
+	if (h->fh->ops->cancel)
+		h->fh->ops->cancel(h->fh, h->file, h->private_data);
+	h->private_data = 0;
+	h->state = LIVEUPDATE_STATE_NORMAL;
+}
+
+static void __luo_files_cancel(struct luo_file *boundary_file)
+{
+	unsigned long token;
+	struct luo_file *h;
+
+	xa_for_each(&luo_files_xa_out, token, h) {
+		if (h == boundary_file)
+			break;
+
+		luo_files_cancel_one(h);
+	}
+	luo_files_fdt_cleanup();
+}
+
+static int luo_files_commit_data_to_fdt(void)
+{
+	int node_offset, ret;
+	unsigned long token;
+	char token_str[19];
+	struct luo_file *h;
+
+	guard(rwsem_read)(&luo_file_fdt_rwsem);
+	xa_for_each(&luo_files_xa_out, token, h) {
+		snprintf(token_str, sizeof(token_str), "%#0llx", (u64)token);
+		node_offset = fdt_subnode_offset(luo_file_fdt_out,
+						 0,
+						 token_str);
+		ret = fdt_setprop(luo_file_fdt_out, node_offset, "data",
+				  &h->private_data, sizeof(h->private_data));
+		if (ret < 0) {
+			pr_err("Failed to set data property for token %s: %s\n",
+			       token_str, fdt_strerror(ret));
+			return -ENOSPC;
+		}
+	}
+
+	return 0;
+}
+
 static int luo_files_prepare(struct liveupdate_subsystem *h, u64 *data)
 {
+	unsigned long token;
+	struct luo_file *luo_file;
 	int ret;
 
 	ret = luo_files_fdt_setup();
 	if (ret)
 		return ret;
 
-	scoped_guard(rwsem_read, &luo_file_fdt_rwsem)
-		*data = __pa(luo_file_fdt_out);
+	xa_for_each(&luo_files_xa_out, token, luo_file) {
+		ret = luo_files_prepare_one(luo_file);
+		if (ret < 0) {
+			pr_err("Prepare failed for file token %#0llx handler '%s' [%d]\n",
+			       (u64)token, luo_file->fh->compatible, ret);
+			__luo_files_cancel(luo_file);
+
+			return ret;
+		}
+	}
+
+	ret = luo_files_commit_data_to_fdt();
+	if (ret) {
+		__luo_files_cancel(NULL);
+	} else {
+		scoped_guard(rwsem_read, &luo_file_fdt_rwsem)
+			*data = __pa(luo_file_fdt_out);
+	}
 
 	return ret;
 }
 
 static int luo_files_freeze(struct liveupdate_subsystem *h, u64 *data)
 {
-	return 0;
+	unsigned long token;
+	struct luo_file *luo_file;
+	int ret;
+
+	xa_for_each(&luo_files_xa_out, token, luo_file) {
+		ret = luo_files_freeze_one(luo_file);
+		if (ret < 0) {
+			pr_err("Freeze callback failed for file token %#0llx handler '%s' [%d]\n",
+			       (u64)token, luo_file->fh->compatible, ret);
+			__luo_files_cancel(luo_file);
+
+			return ret;
+		}
+	}
+
+	ret = luo_files_commit_data_to_fdt();
+	if (ret)
+		__luo_files_cancel(NULL);
+
+	return ret;
 }
 
 static void luo_files_finish(struct liveupdate_subsystem *h, u64 data)
 {
+	unsigned long token;
+	struct luo_file *luo_file;
+
 	luo_files_recreate_luo_files_xa_in();
+	xa_for_each(&luo_files_xa_in, token, luo_file) {
+		luo_files_finish_one(luo_file);
+		mutex_destroy(&luo_file->mutex);
+		kfree(luo_file);
+	}
+	xa_destroy(&luo_files_xa_in);
 }
 
 static void luo_files_cancel(struct liveupdate_subsystem *h, u64 data)
 {
+	__luo_files_cancel(NULL);
 }
 
 static void luo_files_boot(struct liveupdate_subsystem *h, u64 fdt_pa)
@@ -484,6 +642,27 @@ int luo_register_file(u64 token, int fd)
 	return ret;
 }
 
+static void luo_files_fdt_remove_node(u64 token)
+{
+	char token_str[19];
+	int offset, ret;
+
+	guard(rwsem_write)(&luo_file_fdt_rwsem);
+	if (!luo_file_fdt_out)
+		return;
+
+	snprintf(token_str, sizeof(token_str), "%#0llx", token);
+	offset = fdt_subnode_offset(luo_file_fdt_out, 0, token_str);
+	if (offset < 0)
+		return;
+
+	ret = fdt_del_node(luo_file_fdt_out, offset);
+	if (ret < 0) {
+		pr_warn("LUO Files: Failed to delete FDT node for token %s: %s\n",
+			token_str, fdt_strerror(ret));
+	}
+}
+
 static int __luo_unregister_file(u64 token)
 {
 	struct luo_file *luo_file;
@@ -492,6 +671,12 @@ static int __luo_unregister_file(u64 token)
 	if (!luo_file)
 		return -ENOENT;
 
+	if (luo_file->state == LIVEUPDATE_STATE_FROZEN ||
+	    luo_file->state == LIVEUPDATE_STATE_PREPARED) {
+		luo_files_cancel_one(luo_file);
+		luo_files_fdt_remove_node(token);
+	}
+
 	fput(luo_file->file);
 	mutex_destroy(&luo_file->mutex);
 	kfree(luo_file);
-- 
2.50.1.565.gc32cd1483b-goog