Notify user daemon that cookie is going to be withdrawed, providing a
hint that the associated anon_fd can be closed. The anon_fd attached in
the CLOSE request shall be same with that in the previous OPEN request.
Be noted that this is only a hint. User daemon can close the anon_fd
when receiving the CLOSE request, then it will receive another anon_fd
if the cookie gets looked up. Or it can also ignore the CLOSE request,
and keep writing data into the anon_fd. However the next time cookie
gets looked up, the user daemon will still receive another anon_fd.
Signed-off-by: Jeffle Xu <[email protected]>
---
fs/cachefiles/daemon.c | 27 +++++++++++++++++++++++++++
fs/cachefiles/interface.c | 2 ++
fs/cachefiles/internal.h | 4 ++++
include/uapi/linux/cachefiles.h | 5 +++++
4 files changed, 38 insertions(+)
diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index 3c3a461f8cd8..2ecfdf194206 100644
--- a/fs/cachefiles/daemon.c
+++ b/fs/cachefiles/daemon.c
@@ -338,6 +338,12 @@ static ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,
goto err_put_fd;
}
+ /* CLOSE request doesn't look forward a reply */
+ if (msg->opcode == CACHEFILES_OP_CLOSE) {
+ xa_erase(&cache->reqs, id);
+ complete(&req->done);
+ }
+
return n;
err_put_fd:
@@ -452,6 +458,19 @@ static int init_open_req(struct cachefiles_req *req, void *private)
return 0;
}
+static int init_close_req(struct cachefiles_req *req, void *private)
+{
+ struct cachefiles_object *object = req->object;
+ struct cachefiles_close *load = (void *)req->msg.data;
+ int fd = object->fd;
+
+ if (WARN_ON_ONCE(fd == -1))
+ return -EIO;
+
+ load->fd = fd;
+ return 0;
+}
+
int cachefiles_ondemand_init_object(struct cachefiles_object *object)
{
struct fscache_cookie *cookie = object->cookie;
@@ -477,6 +496,14 @@ int cachefiles_ondemand_init_object(struct cachefiles_object *object)
init_open_req, NULL);
}
+void cachefiles_ondemand_cleanup_object(struct cachefiles_object *object)
+{
+ cachefiles_ondemand_send_req(object,
+ CACHEFILES_OP_CLOSE,
+ sizeof(struct cachefiles_close),
+ init_close_req, NULL);
+}
+
#else
static inline void cachefiles_ondemand_open(struct cachefiles_cache *cache) {}
static inline void cachefiles_ondemand_release(struct cachefiles_cache *cache) {}
diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index ae93cee9d25d..c5b8fefd4ccc 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -322,6 +322,8 @@ static void cachefiles_commit_object(struct cachefiles_object *object,
static void cachefiles_clean_up_object(struct cachefiles_object *object,
struct cachefiles_cache *cache)
{
+ cachefiles_ondemand_cleanup_object(object);
+
if (test_bit(FSCACHE_COOKIE_RETIRED, &object->cookie->flags)) {
if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
cachefiles_see_object(object, cachefiles_obj_see_clean_delete);
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index 8450ebd77949..eaac9fae74eb 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -167,6 +167,7 @@ extern const struct file_operations cachefiles_daemon_fops;
#ifdef CONFIG_CACHEFILES_ONDEMAND
extern int cachefiles_ondemand_init_object(struct cachefiles_object *object);
+extern void cachefiles_ondemand_cleanup_object(struct cachefiles_object *object);
#else
static inline
@@ -174,6 +175,9 @@ int cachefiles_ondemand_init_object(struct cachefiles_object *object)
{
return 0;
}
+
+static inline
+void cachefiles_ondemand_cleanup_object(struct cachefiles_object *object) {}
#endif
/*
diff --git a/include/uapi/linux/cachefiles.h b/include/uapi/linux/cachefiles.h
index 5ea7285863f1..47e53043cfad 100644
--- a/include/uapi/linux/cachefiles.h
+++ b/include/uapi/linux/cachefiles.h
@@ -8,6 +8,7 @@
enum cachefiles_opcode {
CACHEFILES_OP_OPEN,
+ CACHEFILES_OP_CLOSE,
};
/*
@@ -36,4 +37,8 @@ enum cachefiles_open_flags {
CACHEFILES_OPEN_WANT_CACHE_SIZE,
};
+struct cachefiles_close {
+ __u32 fd;
+};
+
#endif
--
2.27.0
Jeffle Xu <[email protected]> wrote:
> Notify user daemon that cookie is going to be withdrawed, providing a
"withdrawn".
> + /* CLOSE request doesn't look forward a reply */
I'm not sure what you mean.
David
On 3/21/22 10:20 PM, David Howells wrote:
> Jeffle Xu <[email protected]> wrote:
>
>> Notify user daemon that cookie is going to be withdrawed, providing a
>
> "withdrawn".
Thanks.
>
>> + /* CLOSE request doesn't look forward a reply */
>
> I'm not sure what you mean.
When cookie gets withdrawn, Cachefiles will send a CLOSE request to user
daemon, telling that the associated anon_fd could be closed. But it's
just a hint. User daemon could keep the anon_fd open when it receives
the CLOSE request. After sending the CLOSE request, Cachefiles will go
on the process of withdrawing cookie and won't wait for a reply
synchronously. So CLOSE request is just a hint to user daemon, and it
doesn't need to be replied.
--
Thanks,
Jeffle