diff options
Diffstat (limited to 'fs/aio.c')
| -rw-r--r-- | fs/aio.c | 134 |
1 files changed, 133 insertions, 1 deletions
@@ -5,6 +5,7 @@ * Implements an efficient asynchronous io interface. * * Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved. + * Copyright 2018 Christoph Hellwig. * * See ../COPYING for licensing terms. */ @@ -164,10 +165,22 @@ struct fsync_iocb { bool datasync; }; +struct poll_iocb { + struct file *file; + __poll_t events; + struct wait_queue_head *head; + + union { + struct wait_queue_entry wait; + struct work_struct work; + }; +}; + struct aio_kiocb { union { struct kiocb rw; struct fsync_iocb fsync; + struct poll_iocb poll; }; struct kioctx *ki_ctx; @@ -1558,7 +1571,6 @@ static int aio_fsync(struct fsync_iocb *req, struct iocb *iocb, bool datasync) if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags)) return -EINVAL; - req->file = fget(iocb->aio_fildes); if (unlikely(!req->file)) return -EBADF; @@ -1573,6 +1585,124 @@ static int aio_fsync(struct fsync_iocb *req, struct iocb *iocb, bool datasync) return -EIOCBQUEUED; } +/* need to use list_del_init so we can check if item was present */ +static inline bool __aio_poll_remove(struct poll_iocb *req) +{ + if (list_empty(&req->wait.entry)) + return false; + list_del_init(&req->wait.entry); + return true; +} + +static inline void __aio_poll_complete(struct poll_iocb *req, __poll_t mask) +{ + struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll); + struct file *file = req->file; + + aio_complete(iocb, mangle_poll(mask), 0); + fput(file); +} + +static void aio_poll_work(struct work_struct *work) +{ + struct poll_iocb *req = container_of(work, struct poll_iocb, work); + + __aio_poll_complete(req, req->events); +} + +static int aio_poll_cancel(struct kiocb *iocb) +{ + struct aio_kiocb *aiocb = container_of(iocb, struct aio_kiocb, rw); + struct poll_iocb *req = &aiocb->poll; + struct wait_queue_head *head = req->head; + bool found = false; + + spin_lock(&head->lock); + found = __aio_poll_remove(req); + spin_unlock(&head->lock); + + if (found) { + req->events = 0; + INIT_WORK(&req->work, aio_poll_work); + schedule_work(&req->work); + } + return 0; +} + +static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync, + void *key) +{ + struct poll_iocb *req = container_of(wait, struct poll_iocb, wait); + struct file *file = req->file; + __poll_t mask = key_to_poll(key); + + assert_spin_locked(&req->head->lock); + + /* for instances that support it check for an event match first: */ + if (mask && !(mask & req->events)) + return 0; + + mask = file->f_op->poll_mask(file, req->events); + if (!mask) + return 0; + + __aio_poll_remove(req); + + req->events = mask; + INIT_WORK(&req->work, aio_poll_work); + schedule_work(&req->work); + return 1; +} + +static ssize_t aio_poll(struct aio_kiocb *aiocb, struct iocb *iocb) +{ + struct kioctx *ctx = aiocb->ki_ctx; + struct poll_iocb *req = &aiocb->poll; + __poll_t mask; + + /* reject any unknown events outside the normal event mask. */ + if ((u16)iocb->aio_buf != iocb->aio_buf) + return -EINVAL; + /* reject fields that are not defined for poll */ + if (iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags) + return -EINVAL; + + req->events = demangle_poll(iocb->aio_buf) | EPOLLERR | EPOLLHUP; + req->file = fget(iocb->aio_fildes); + if (unlikely(!req->file)) + return -EBADF; + if (!file_has_poll_mask(req->file)) + goto out_fail; + + req->head = req->file->f_op->get_poll_head(req->file, req->events); + if (!req->head) + goto out_fail; + if (IS_ERR(req->head)) { + mask = EPOLLERR; + goto done; + } + + init_waitqueue_func_entry(&req->wait, aio_poll_wake); + aiocb->ki_cancel = aio_poll_cancel; + + spin_lock_irq(&ctx->ctx_lock); + spin_lock(&req->head->lock); + mask = req->file->f_op->poll_mask(req->file, req->events); + if (!mask) { + __add_wait_queue(req->head, &req->wait); + list_add_tail(&aiocb->ki_list, &ctx->active_reqs); + } + spin_unlock(&req->head->lock); + spin_unlock_irq(&ctx->ctx_lock); +done: + if (mask) + __aio_poll_complete(req, mask); + return -EIOCBQUEUED; +out_fail: + fput(req->file); + return -EINVAL; /* same as no support for IOCB_CMD_POLL */ +} + static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, struct iocb *iocb, bool compat) { @@ -1641,6 +1771,8 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, break; case IOCB_CMD_FDSYNC: ret = aio_fsync(&req->fsync, iocb, true); + case IOCB_CMD_POLL: + ret = aio_poll(req, iocb); break; default: pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode); |