From 4379bf8bd70b5de6bba7d53015b0c36c57a634ee Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 15 Feb 2021 13:40:22 -0700 Subject: io_uring: remove io_identity We are no longer grabbing state, so no need to maintain an IO identity that we COW if there are changes. Signed-off-by: Jens Axboe --- fs/io-wq.c | 26 +++++++++++++++ fs/io-wq.h | 2 +- fs/io_uring.c | 104 ++++++++++++++-------------------------------------------- 3 files changed, 52 insertions(+), 80 deletions(-) (limited to 'fs') diff --git a/fs/io-wq.c b/fs/io-wq.c index 41042119bf0f..acc67ed3a52c 100644 --- a/fs/io-wq.c +++ b/fs/io-wq.c @@ -53,6 +53,9 @@ struct io_worker { struct io_wq_work *cur_work; spinlock_t lock; + const struct cred *cur_creds; + const struct cred *saved_creds; + struct rcu_head rcu; }; @@ -171,6 +174,11 @@ static void io_worker_exit(struct io_worker *worker) worker->flags = 0; preempt_enable(); + if (worker->saved_creds) { + revert_creds(worker->saved_creds); + worker->cur_creds = worker->saved_creds = NULL; + } + raw_spin_lock_irq(&wqe->lock); hlist_nulls_del_rcu(&worker->nulls_node); list_del_rcu(&worker->all_list); @@ -312,6 +320,10 @@ static void __io_worker_idle(struct io_wqe *wqe, struct io_worker *worker) worker->flags |= IO_WORKER_F_FREE; hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list); } + if (worker->saved_creds) { + revert_creds(worker->saved_creds); + worker->cur_creds = worker->saved_creds = NULL; + } } static inline unsigned int io_get_work_hash(struct io_wq_work *work) @@ -359,6 +371,18 @@ static void io_flush_signals(void) } } +static void io_wq_switch_creds(struct io_worker *worker, + struct io_wq_work *work) +{ + const struct cred *old_creds = override_creds(work->creds); + + worker->cur_creds = work->creds; + if (worker->saved_creds) + put_cred(old_creds); /* creds set by previous switch */ + else + worker->saved_creds = old_creds; +} + static void io_assign_current_work(struct io_worker *worker, struct io_wq_work *work) { @@ -407,6 +431,8 @@ get_next: unsigned int hash = io_get_work_hash(work); next_hashed = wq_next_work(work); + if (work->creds && worker->cur_creds != work->creds) + io_wq_switch_creds(worker, work); wq->do_work(work); io_assign_current_work(worker, NULL); diff --git a/fs/io-wq.h b/fs/io-wq.h index bbe05dd54716..584f0bd5a83d 100644 --- a/fs/io-wq.h +++ b/fs/io-wq.h @@ -78,7 +78,7 @@ static inline void wq_list_del(struct io_wq_work_list *list, struct io_wq_work { struct io_wq_work_node list; - struct io_identity *identity; + const struct cred *creds; unsigned flags; }; diff --git a/fs/io_uring.c b/fs/io_uring.c index 6e88295758b5..6d851033e48d 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1094,7 +1094,7 @@ static bool io_match_task(struct io_kiocb *head, continue; if (req->file && req->file->f_op == &io_uring_fops) return true; - if (req->work.identity->files == files) + if (req->task->files == files) return true; } return false; @@ -1218,31 +1218,6 @@ static inline void req_set_fail_links(struct io_kiocb *req) req->flags |= REQ_F_FAIL_LINK; } -/* - * None of these are dereferenced, they are simply used to check if any of - * them have changed. If we're under current and check they are still the - * same, we're fine to grab references to them for actual out-of-line use. - */ -static void io_init_identity(struct io_identity *id) -{ - id->files = current->files; - id->mm = current->mm; -#ifdef CONFIG_BLK_CGROUP - rcu_read_lock(); - id->blkcg_css = blkcg_css(); - rcu_read_unlock(); -#endif - id->creds = current_cred(); - id->nsproxy = current->nsproxy; - id->fs = current->fs; - id->fsize = rlimit(RLIMIT_FSIZE); -#ifdef CONFIG_AUDIT - id->loginuid = current->loginuid; - id->sessionid = current->sessionid; -#endif - refcount_set(&id->count, 1); -} - static inline void __io_req_init_async(struct io_kiocb *req) { memset(&req->work, 0, sizeof(req->work)); @@ -1255,17 +1230,10 @@ static inline void __io_req_init_async(struct io_kiocb *req) */ static inline void io_req_init_async(struct io_kiocb *req) { - struct io_uring_task *tctx = current->io_uring; - if (req->flags & REQ_F_WORK_INITIALIZED) return; __io_req_init_async(req); - - /* Grab a ref if this isn't our static identity */ - req->work.identity = tctx->identity; - if (tctx->identity != &tctx->__identity) - refcount_inc(&req->work.identity->count); } static void io_ring_ctx_ref_free(struct percpu_ref *ref) @@ -1350,19 +1318,15 @@ static bool req_need_defer(struct io_kiocb *req, u32 seq) return false; } -static void io_put_identity(struct io_uring_task *tctx, struct io_kiocb *req) -{ - if (req->work.identity == &tctx->__identity) - return; - if (refcount_dec_and_test(&req->work.identity->count)) - kfree(req->work.identity); -} - static void io_req_clean_work(struct io_kiocb *req) { if (!(req->flags & REQ_F_WORK_INITIALIZED)) return; + if (req->work.creds) { + put_cred(req->work.creds); + req->work.creds = NULL; + } if (req->flags & REQ_F_INFLIGHT) { struct io_ring_ctx *ctx = req->ctx; struct io_uring_task *tctx = req->task->io_uring; @@ -1377,7 +1341,6 @@ static void io_req_clean_work(struct io_kiocb *req) } req->flags &= ~REQ_F_WORK_INITIALIZED; - io_put_identity(req->task->io_uring, req); } static void io_req_track_inflight(struct io_kiocb *req) @@ -1411,6 +1374,8 @@ static void io_prep_async_work(struct io_kiocb *req) if (def->unbound_nonreg_file) req->work.flags |= IO_WQ_WORK_UNBOUND; } + if (!req->work.creds) + req->work.creds = get_current_cred(); } static void io_prep_async_link(struct io_kiocb *req) @@ -6376,9 +6341,9 @@ static void __io_queue_sqe(struct io_kiocb *req) const struct cred *old_creds = NULL; int ret; - if ((req->flags & REQ_F_WORK_INITIALIZED) && - req->work.identity->creds != current_cred()) - old_creds = override_creds(req->work.identity->creds); + if ((req->flags & REQ_F_WORK_INITIALIZED) && req->work.creds && + req->work.creds != current_cred()) + old_creds = override_creds(req->work.creds); ret = io_issue_sqe(req, IO_URING_F_NONBLOCK|IO_URING_F_COMPLETE_DEFER); @@ -6508,16 +6473,11 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req, id = READ_ONCE(sqe->personality); if (id) { - struct io_identity *iod; - - iod = idr_find(&ctx->personality_idr, id); - if (unlikely(!iod)) - return -EINVAL; - refcount_inc(&iod->count); - __io_req_init_async(req); - get_cred(iod->creds); - req->work.identity = iod; + req->work.creds = idr_find(&ctx->personality_idr, id); + if (unlikely(!req->work.creds)) + return -EINVAL; + get_cred(req->work.creds); } state = &ctx->submit_state; @@ -7936,8 +7896,6 @@ static int io_uring_alloc_task_context(struct task_struct *task, tctx->last = NULL; atomic_set(&tctx->in_idle, 0); tctx->sqpoll = false; - io_init_identity(&tctx->__identity); - tctx->identity = &tctx->__identity; task->io_uring = tctx; spin_lock_init(&tctx->task_lock); INIT_WQ_LIST(&tctx->task_list); @@ -7951,9 +7909,6 @@ void __io_uring_free(struct task_struct *tsk) struct io_uring_task *tctx = tsk->io_uring; WARN_ON_ONCE(!xa_empty(&tctx->xa)); - WARN_ON_ONCE(refcount_read(&tctx->identity->count) != 1); - if (tctx->identity != &tctx->__identity) - kfree(tctx->identity); percpu_counter_destroy(&tctx->inflight); kfree(tctx); tsk->io_uring = NULL; @@ -8593,13 +8548,11 @@ static int io_uring_fasync(int fd, struct file *file, int on) static int io_unregister_personality(struct io_ring_ctx *ctx, unsigned id) { - struct io_identity *iod; + const struct cred *creds; - iod = idr_remove(&ctx->personality_idr, id); - if (iod) { - put_cred(iod->creds); - if (refcount_dec_and_test(&iod->count)) - kfree(iod); + creds = idr_remove(&ctx->personality_idr, id); + if (creds) { + put_cred(creds); return 0; } @@ -9300,8 +9253,7 @@ out_fput: #ifdef CONFIG_PROC_FS static int io_uring_show_cred(int id, void *p, void *data) { - struct io_identity *iod = p; - const struct cred *cred = iod->creds; + const struct cred *cred = p; struct seq_file *m = data; struct user_namespace *uns = seq_user_ns(m); struct group_info *gi; @@ -9732,21 +9684,15 @@ out: static int io_register_personality(struct io_ring_ctx *ctx) { - struct io_identity *id; + const struct cred *creds; int ret; - id = kmalloc(sizeof(*id), GFP_KERNEL); - if (unlikely(!id)) - return -ENOMEM; - - io_init_identity(id); - id->creds = get_current_cred(); + creds = get_current_cred(); - ret = idr_alloc_cyclic(&ctx->personality_idr, id, 1, USHRT_MAX, GFP_KERNEL); - if (ret < 0) { - put_cred(id->creds); - kfree(id); - } + ret = idr_alloc_cyclic(&ctx->personality_idr, (void *) creds, 1, + USHRT_MAX, GFP_KERNEL); + if (ret < 0) + put_cred(creds); return ret; } -- cgit v1.2.3-58-ga151