diff options
Diffstat (limited to 'fs/cachefiles')
| -rw-r--r-- | fs/cachefiles/internal.h | 1 | ||||
| -rw-r--r-- | fs/cachefiles/ondemand.c | 20 |
2 files changed, 17 insertions, 4 deletions
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index 8ecd296cc1c4..9200c00f3e98 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -128,6 +128,7 @@ struct cachefiles_cache { unsigned long req_id_next; struct xarray ondemand_ids; /* xarray for ondemand_id allocation */ u32 ondemand_id_next; + u32 msg_id_next; }; static inline bool cachefiles_in_ondemand_mode(struct cachefiles_cache *cache) diff --git a/fs/cachefiles/ondemand.c b/fs/cachefiles/ondemand.c index 6166b66729e4..d40b17010b5f 100644 --- a/fs/cachefiles/ondemand.c +++ b/fs/cachefiles/ondemand.c @@ -433,20 +433,32 @@ static int cachefiles_ondemand_send_req(struct cachefiles_object *object, smp_mb(); if (opcode == CACHEFILES_OP_CLOSE && - !cachefiles_ondemand_object_is_open(object)) { + !cachefiles_ondemand_object_is_open(object)) { WARN_ON_ONCE(object->ondemand->ondemand_id == 0); xas_unlock(&xas); ret = -EIO; goto out; } - xas.xa_index = 0; + /* + * Cyclically find a free xas to avoid msg_id reuse that would + * cause the daemon to successfully copen a stale msg_id. + */ + xas.xa_index = cache->msg_id_next; xas_find_marked(&xas, UINT_MAX, XA_FREE_MARK); + if (xas.xa_node == XAS_RESTART) { + xas.xa_index = 0; + xas_find_marked(&xas, cache->msg_id_next - 1, XA_FREE_MARK); + } if (xas.xa_node == XAS_RESTART) xas_set_err(&xas, -EBUSY); + xas_store(&xas, req); - xas_clear_mark(&xas, XA_FREE_MARK); - xas_set_mark(&xas, CACHEFILES_REQ_NEW); + if (xas_valid(&xas)) { + cache->msg_id_next = xas.xa_index + 1; + xas_clear_mark(&xas, XA_FREE_MARK); + xas_set_mark(&xas, CACHEFILES_REQ_NEW); + } xas_unlock(&xas); } while (xas_nomem(&xas, GFP_KERNEL)); |