Patch "cachefiles: add restore command to recover inflight ondemand read requests" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    cachefiles: add restore command to recover inflight ondemand read requests

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     cachefiles-add-restore-command-to-recover-inflight-o.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit dd1c13ebd6c3601dac3cb0097a9ce66cf71c3936
Author: Jia Zhu <zhujia.zj@xxxxxxxxxxxxx>
Date:   Mon Nov 20 12:14:22 2023 +0800

    cachefiles: add restore command to recover inflight ondemand read requests
    
    [ Upstream commit e73fa11a356ca0905c3cc648eaacc6f0f2d2c8b3 ]
    
    Previously, in ondemand read scenario, if the anonymous fd was closed by
    user daemon, inflight and subsequent read requests would return EIO.
    As long as the device connection is not released, user daemon can hold
    and restore inflight requests by setting the request flag to
    CACHEFILES_REQ_NEW.
    
    Suggested-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
    Signed-off-by: Jia Zhu <zhujia.zj@xxxxxxxxxxxxx>
    Signed-off-by: Xin Yin <yinxin.x@xxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20231120041422.75170-6-zhujia.zj@xxxxxxxxxxxxx
    Reviewed-by: Jingbo Xu <jefflexu@xxxxxxxxxxxxxxxxx>
    Reviewed-by: David Howells <dhowells@xxxxxxxxxx>
    Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
    Stable-dep-of: 4b4391e77a6b ("cachefiles: defer exposing anon_fd until after copy_to_user() succeeds")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index 7d1f456e376dd..26b487e112596 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 33fe418aca770..361356d0e866a 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -304,6 +304,9 @@ 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 8118649d30727..6d8f7f01a73ac 100644
--- a/fs/cachefiles/ondemand.c
+++ b/fs/cachefiles/ondemand.c
@@ -214,6 +214,29 @@ 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;
+
+	/*
+	 * Reset the requests to CACHEFILES_REQ_NEW state, so that the
+	 * requests have been processed halfway before the crash of the
+	 * user daemon could be reprocessed after the recovery.
+	 */
+	xas_lock(&xas);
+	xas_for_each(&xas, req, ULONG_MAX)
+		xas_set_mark(&xas, CACHEFILES_REQ_NEW);
+	xas_unlock(&xas);
+
+	wake_up_all(&cache->daemon_pollwq);
+	return 0;
+}
+
 static int cachefiles_ondemand_get_fd(struct cachefiles_req *req)
 {
 	struct cachefiles_object *object;