Re: [External] Re: [RFC PATCH 5/5] cachefiles: add restore command to recover inflight ondemand read requests

[Jia Zhu]

在 2022/10/8 17:00, JeffleXu 写道:
> On 8/18/22 9:52 PM, Jia Zhu wrote:
> > 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>
> > ---
> >   fs/cachefiles/daemon.c   |  1 +
> >   fs/cachefiles/internal.h |  3 +++
> >   fs/cachefiles/ondemand.c | 23 +++++++++++++++++++++++
> >   3 files changed, 27 insertions(+)
> >
> > diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
> > index c74bd1f4ecf5..014369266cb2 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 b4af67f1cbd6..d504c61a5f03 100644
> > --- a/fs/cachefiles/internal.h
> > +++ b/fs/cachefiles/internal.h
> > @@ -303,6 +303,9 @@ 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 79ffb19380cd..5b1c447da976 100644
> > --- a/fs/cachefiles/ondemand.c
> > +++ b/fs/cachefiles/ondemand.c
> > @@ -178,6 +178,29 @@ 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;
> > +
> > +	/*
> > +	 * Search the requests which being processed before
> > +	 * the user daemon crashed.
> > +	 * Set the CACHEFILES_REQ_NEW flag and user daemon will reprocess it.
> > +	 */
>
> The comment can be improved as:
>
> 	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.
Thanks, I'll apply it.
> > +	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;