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cachefiles: notify the user daemon when withdrawing cookie

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Notify the user daemon that cookie is going to be withdrawn, providing a
hint that the associated anonymous fd can be closed.

Be noted that this is only a hint. The user daemon may close the
associated anonymous fd when receiving the CLOSE request, then it will
receive another anonymous fd when the cookie gets looked up. Or it may
ignore the CLOSE request, and keep writing data through the anonymous
fd. However the next time the cookie gets looked up, the user daemon
will still receive another new anonymous fd.

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Acked-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20220425122143.56815-5-jefflexu@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
This commit is contained in:
Jeffle Xu 2022-04-25 20:21:26 +08:00 committed by Gao Xiang
parent d11b0b043b
commit 324b954ac8
4 changed files with 46 additions and 0 deletions
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2
fs/cachefiles/interface.c
View File

@ -362,6 +362,8 @@ static void cachefiles_withdraw_cookie(struct fscache_cookie *cookie)
spin_unlock(&cache->object_list_lock);
}
cachefiles_ondemand_clean_object(object);
if (object->file) {
cachefiles_begin_secure(cache, &saved_cred);
cachefiles_clean_up_object(object, cache);

5
fs/cachefiles/internal.h
View File

@ -290,6 +290,7 @@ extern int cachefiles_ondemand_copen(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);
#else
static inline ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,
@ -302,6 +303,10 @@ static inline int cachefiles_ondemand_init_object(struct cachefiles_object *obje
{
return 0;
}
static inline void cachefiles_ondemand_clean_object(struct cachefiles_object *object)
{
}
#endif
/*

38
fs/cachefiles/ondemand.c
View File

@ -229,6 +229,12 @@ ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,
goto err_put_fd;
}
/* CLOSE request has no reply */
if (msg->opcode == CACHEFILES_OP_CLOSE) {
xa_erase(&cache->reqs, id);
complete(&req->done);
}
return n;
err_put_fd:
@ -300,6 +306,13 @@ static int cachefiles_ondemand_send_req(struct cachefiles_object *object,
/* coupled with the barrier in cachefiles_flush_reqs() */
smp_mb();
if (opcode != CACHEFILES_OP_OPEN && object->ondemand_id <= 0) {
WARN_ON_ONCE(object->ondemand_id == 0);
xas_unlock(&xas);
ret = -EIO;
goto out;
}
xas.xa_index = 0;
xas_find_marked(&xas, UINT_MAX, XA_FREE_MARK);
if (xas.xa_node == XAS_RESTART)
@ -356,6 +369,25 @@ static int cachefiles_ondemand_init_open_req(struct cachefiles_req *req,
return 0;
}
static int cachefiles_ondemand_init_close_req(struct cachefiles_req *req,
void *private)
{
struct cachefiles_object *object = req->object;
int object_id = object->ondemand_id;
/*
* It's possible that object id is still 0 if the cookie looking up
* phase failed before OPEN request has ever been sent. Also avoid
* sending CLOSE request for CACHEFILES_ONDEMAND_ID_CLOSED, which means
* anon_fd has already been closed.
*/
if (object_id <= 0)
return -ENOENT;
req->msg.object_id = object_id;
return 0;
}
int cachefiles_ondemand_init_object(struct cachefiles_object *object)
{
struct fscache_cookie *cookie = object->cookie;
@ -379,3 +411,9 @@ int cachefiles_ondemand_init_object(struct cachefiles_object *object)
return cachefiles_ondemand_send_req(object, CACHEFILES_OP_OPEN,
data_len, cachefiles_ondemand_init_open_req, NULL);
}
void cachefiles_ondemand_clean_object(struct cachefiles_object *object)
{
cachefiles_ondemand_send_req(object, CACHEFILES_OP_CLOSE, 0,
cachefiles_ondemand_init_close_req, NULL);
}

1
include/uapi/linux/cachefiles.h
View File

@ -12,6 +12,7 @@
enum cachefiles_opcode {
CACHEFILES_OP_OPEN,
CACHEFILES_OP_CLOSE,
};
/*