[PATCH 1/1] cachefiles: Add a command to restore on-demand requests

[Jia Zhu]

In on-demand read scenario, as long as the device connection
is not released, user daemon can restore the inflight request
by setting the request flag to CACHEFILES_REQ_NEW.

Signed-off-by: Jia Zhu <zhujia.zj at bytedance.com>
---
  fs/cachefiles/daemon.c   |  1 +
  fs/cachefiles/internal.h |  3 +++
  fs/cachefiles/ondemand.c | 25 +++++++++++++++++++++++++
  3 files changed, 29 insertions(+)

diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index 5956bf10cb4b..280104171996 100644
--- a/fs/cachefiles/daemon.c
+++ b/fs/cachefiles/daemon.c
@@ -77,6 +77,7 @@ static const struct cachefiles_daemon_cmd 
cachefiles_daemon_cmds[] = {
  	{ "tag",	cachefiles_daemon_tag		},
  #ifdef CONFIG_CACHEFILES_ONDEMAND
  	{ "copen",	cachefiles_ondemand_copen	},
+	{ "restore",	cachefiles_ondemand_restore	},
  #endif
  	{ "",		NULL				}
  };
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index 6cba2c6de2f9..402f552a9756 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -289,6 +289,9 @@ extern ssize_t 
cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,
  extern int cachefiles_ondemand_copen(struct cachefiles_cache *cache,
  				     char *args);

+extern int cachefiles_ondemand_restore(struct cachefiles_cache *cache,
+				     char *args);
+
  extern int cachefiles_ondemand_init_object(struct cachefiles_object 
*object);
  extern void cachefiles_ondemand_clean_object(struct cachefiles_object 
*object);

diff --git a/fs/cachefiles/ondemand.c b/fs/cachefiles/ondemand.c
index 2506e6d56965..0d0ed82f4814 100644
--- a/fs/cachefiles/ondemand.c
+++ b/fs/cachefiles/ondemand.c
@@ -174,6 +174,31 @@ int cachefiles_ondemand_copen(struct 
cachefiles_cache *cache, char *args)
  	return ret;
  }

+int cachefiles_ondemand_restore(struct cachefiles_cache *cache, char *args)
+{
+	struct cachefiles_req *req;
+	XA_STATE(xas, &cache->reqs, 0);
+
+	if (!test_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags))
+		return -EOPNOTSUPP;
+
+	if (test_bit(CACHEFILES_DEAD, &cache->flags))
+		return -EIO;
+
+	xas_lock(&xas);
+	/*
+	 * Search the requests that being proceessed before
+	 * the user daemon crashed.
+	 * Set the CACHEFILES_REQ_NEW flag and user daemon will reprocess it.
+	 */
+	xas_for_each(&xas, req, ULONG_MAX) {
+		if (!xas_get_mark(&xas, CACHEFILES_REQ_NEW))
+			xas_set_mark(&xas, CACHEFILES_REQ_NEW);
+	}
+	xas_unlock(&xas);
+	return 0;
+}
+
  static int cachefiles_ondemand_get_fd(struct cachefiles_req *req)
  {
  	struct cachefiles_object *object;
-- 
2.20.1