From: Suparna Bhattacharya Core retry infrastructure for AIO. Allows an AIO request to be executed as a series of non-blocking iterations, where each iteration retries the remaining part of the request from where the last iteration left off, by reissuing the corresponding AIO fop routine with modified arguments representing the remaining I/O. The retries are "kicked" via the AIO waitqueue callback aio_wake_function() which replaces the default wait queue entry used for blocking waits. The high level retry infrastructure is responsible for running the iterations in the mm context (address space) of the caller, and ensures that only one retry instance is active at a given time, thus relieving the fops themselves from having to deal with potential races of that sort. Follow on fixes: DESC Fix aio process hang on EINVAL EDESC From: Daniel McNeil Here is a patch to fix EINVAL handling in io_submit_one() that was causing a process hang when attempting AIO to a device not able to handle aio. I hit this doing a AIO read from /dev/zero. The process would hang on exit in wait_for_all_aios(). The fix is to check for EINVAL coming back from aio_setup_iocb() in addition to the EFAULT and EBADF already there. This causes the io_submit to fail with EINVAL. That check looks error prone. Are there other error return values where it should jump to the aio_put_req()? Should the check be: if (ret != 0 && ret != -EIOCBQUEUED) goto out_put_req; DESC AIO: flush workqueues before destroying ioctx'es EDESC From: Suparna Bhattacharya Flush out the workqueue before destroying the ioctx which may be sitting on it. DESC AIO: hold the context lock across unuse_mm EDESC Hold the context lock across unuse_mm DESC task task_lock in use_mm() EDESC From: Suparna Bhattacharya Another patch based on a suggestion from Ben. use_mm wasn't acquiring the task_lock - its possible this might be causing a race with procps. DESC Allow fops to override the retry method with their own EDESC From: Suparna Bhattacharya David Brownell has a patch to implement AIO support for gadgetfs which specified its own ->retry() method to perform the copy_to_user from the AIO workqueue after I/O completion. To enable that to work correctly, with our retry code, we should drop the lines that nullify and reinstate the ->ki_retry() field in aio_run_iocb. fs/aio.c | 566 +++++++++++++++++++++++++++++++++++++++------- include/linux/aio.h | 25 +- include/linux/errno.h | 1 include/linux/init_task.h | 1 include/linux/sched.h | 7 include/linux/wait.h | 9 kernel/fork.c | 15 + 7 files changed, 541 insertions(+), 83 deletions(-) diff -upN reference/fs/aio.c current/fs/aio.c --- reference/fs/aio.c 2004-05-09 13:44:19.000000000 -0700 +++ current/fs/aio.c 2004-05-09 13:45:18.000000000 -0700 @@ -38,6 +38,9 @@ #define dprintk(x...) do { ; } while (0) #endif +long aio_run = 0; /* for testing only */ +long aio_wakeups = 0; /* for testing only */ + /*------ sysctl variables----*/ atomic_t aio_nr = ATOMIC_INIT(0); /* current system wide number of aio requests */ unsigned aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ @@ -278,6 +281,7 @@ static void aio_cancel_all(struct kioctx struct kiocb *iocb = list_kiocb(pos); list_del_init(&iocb->ki_list); cancel = iocb->ki_cancel; + kiocbSetCancelled(iocb); if (cancel) { iocb->ki_users++; spin_unlock_irq(&ctx->ctx_lock); @@ -338,6 +342,11 @@ void fastcall exit_aio(struct mm_struct aio_cancel_all(ctx); wait_for_all_aios(ctx); + /* + * this is an overkill, but ensures we don't leave + * the ctx on the aio_wq + */ + flush_workqueue(aio_wq); if (1 != atomic_read(&ctx->users)) printk(KERN_DEBUG @@ -397,6 +406,7 @@ static struct kiocb fastcall *__aio_get_ req->ki_cancel = NULL; req->ki_retry = NULL; req->ki_user_obj = NULL; + INIT_LIST_HEAD(&req->ki_run_list); /* Check if the completion queue has enough free space to * accept an event from this io. @@ -538,65 +548,301 @@ struct kioctx *lookup_ioctx(unsigned lon return ioctx; } +/* + * use_mm + * Makes the calling kernel thread take on the specified + * mm context. + * Called by the retry thread execute retries within the + * iocb issuer's mm context, so that copy_from/to_user + * operations work seamlessly for aio. + * (Note: this routine is intended to be called only + * from a kernel thread context) + */ void use_mm(struct mm_struct *mm) { - struct mm_struct *active_mm = current->active_mm; + struct mm_struct *active_mm; + struct task_struct *tsk = current; + + task_lock(tsk); + active_mm = tsk->active_mm; atomic_inc(&mm->mm_count); - current->mm = mm; - if (mm != active_mm) { - current->active_mm = mm; - activate_mm(active_mm, mm); - } + tsk->mm = mm; + tsk->active_mm = mm; + activate_mm(active_mm, mm); + task_unlock(tsk); + mmdrop(active_mm); } -static void unuse_mm(struct mm_struct *mm) +/* + * unuse_mm + * Reverses the effect of use_mm, i.e. releases the + * specified mm context which was earlier taken on + * by the calling kernel thread + * (Note: this routine is intended to be called only + * from a kernel thread context) + * + * Comments: Called with ctx->ctx_lock held. This nests + * task_lock instead ctx_lock. + */ +void unuse_mm(struct mm_struct *mm) { - current->mm = NULL; + struct task_struct *tsk = current; + + task_lock(tsk); + tsk->mm = NULL; /* active_mm is still 'mm' */ - enter_lazy_tlb(mm, current); + enter_lazy_tlb(mm, tsk); + task_unlock(tsk); } -/* Run on kevent's context. FIXME: needs to be per-cpu and warn if an - * operation blocks. +/* + * Queue up a kiocb to be retried. Assumes that the kiocb + * has already been marked as kicked, and places it on + * the retry run list for the corresponding ioctx, if it + * isn't already queued. Returns 1 if it actually queued + * the kiocb (to tell the caller to activate the work + * queue to process it), or 0, if it found that it was + * already queued. + * + * Should be called with the spin lock iocb->ki_ctx->ctx_lock + * held */ -static void aio_kick_handler(void *data) +static inline int __queue_kicked_iocb(struct kiocb *iocb) { - struct kioctx *ctx = data; + struct kioctx *ctx = iocb->ki_ctx; - use_mm(ctx->mm); + if (list_empty(&iocb->ki_run_list)) { + list_add_tail(&iocb->ki_run_list, + &ctx->run_list); + iocb->ki_queued++; + return 1; + } + return 0; +} - spin_lock_irq(&ctx->ctx_lock); - while (!list_empty(&ctx->run_list)) { - struct kiocb *iocb; - long ret; +/* aio_run_iocb + * This is the core aio execution routine. It is + * invoked both for initial i/o submission and + * subsequent retries via the aio_kick_handler. + * Expects to be invoked with iocb->ki_ctx->lock + * already held. The lock is released and reaquired + * as needed during processing. + * + * Calls the iocb retry method (already setup for the + * iocb on initial submission) for operation specific + * handling, but takes care of most of common retry + * execution details for a given iocb. The retry method + * needs to be non-blocking as far as possible, to avoid + * holding up other iocbs waiting to be serviced by the + * retry kernel thread. + * + * The trickier parts in this code have to do with + * ensuring that only one retry instance is in progress + * for a given iocb at any time. Providing that guarantee + * simplifies the coding of individual aio operations as + * it avoids various potential races. + */ +static ssize_t aio_run_iocb(struct kiocb *iocb) +{ + struct kioctx *ctx = iocb->ki_ctx; + ssize_t (*retry)(struct kiocb *); + ssize_t ret; - iocb = list_entry(ctx->run_list.next, struct kiocb, - ki_run_list); - list_del(&iocb->ki_run_list); - iocb->ki_users ++; - spin_unlock_irq(&ctx->ctx_lock); + if (iocb->ki_retried++ > 1024*1024) { + printk("Maximal retry count. Bytes done %Zd\n", + iocb->ki_nbytes - iocb->ki_left); + return -EAGAIN; + } + + if (!(iocb->ki_retried & 0xff)) { + pr_debug("%ld retry: %d of %d (kick %ld, Q %ld run %ld, wake %ld)\n", + iocb->ki_retried, + iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes, + iocb->ki_kicked, iocb->ki_queued, aio_run, aio_wakeups); + } + + if (!(retry = iocb->ki_retry)) { + printk("aio_run_iocb: iocb->ki_retry = NULL\n"); + return 0; + } - kiocbClearKicked(iocb); - ret = iocb->ki_retry(iocb); + /* + * We don't want the next retry iteration for this + * operation to start until this one has returned and + * updated the iocb state. However, wait_queue functions + * can trigger a kick_iocb from interrupt context in the + * meantime, indicating that data is available for the next + * iteration. We want to remember that and enable the + * next retry iteration _after_ we are through with + * this one. + * + * So, in order to be able to register a "kick", but + * prevent it from being queued now, we clear the kick + * flag, but make the kick code *think* that the iocb is + * still on the run list until we are actually done. + * When we are done with this iteration, we check if + * the iocb was kicked in the meantime and if so, queue + * it up afresh. + */ + + kiocbClearKicked(iocb); + + /* + * This is so that aio_complete knows it doesn't need to + * pull the iocb off the run list (We can't just call + * INIT_LIST_HEAD because we don't want a kick_iocb to + * queue this on the run list yet) + */ + iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL; + spin_unlock_irq(&ctx->ctx_lock); + + /* Quit retrying if the i/o has been cancelled */ + if (kiocbIsCancelled(iocb)) { + ret = -EINTR; + aio_complete(iocb, ret, 0); + /* must not access the iocb after this */ + goto out; + } + + /* + * Now we are all set to call the retry method in async + * context. By setting this thread's io_wait context + * to point to the wait queue entry inside the currently + * running iocb for the duration of the retry, we ensure + * that async notification wakeups are queued by the + * operation instead of blocking waits, and when notified, + * cause the iocb to be kicked for continuation (through + * the aio_wake_function callback). + */ + BUG_ON(current->io_wait != NULL); + current->io_wait = &iocb->ki_wait; + ret = retry(iocb); + current->io_wait = NULL; + + if (-EIOCBRETRY != ret) { if (-EIOCBQUEUED != ret) { + BUG_ON(!list_empty(&iocb->ki_wait.task_list)); aio_complete(iocb, ret, 0); - iocb = NULL; + /* must not access the iocb after this */ } + } else { + /* + * Issue an additional retry to avoid waiting forever if + * no waits were queued (e.g. in case of a short read). + */ + if (list_empty(&iocb->ki_wait.task_list)) + kiocbSetKicked(iocb); + } +out: + spin_lock_irq(&ctx->ctx_lock); - spin_lock_irq(&ctx->ctx_lock); - if (NULL != iocb) - __aio_put_req(ctx, iocb); + if (-EIOCBRETRY == ret) { + /* + * OK, now that we are done with this iteration + * and know that there is more left to go, + * this is where we let go so that a subsequent + * "kick" can start the next iteration + */ + + /* will make __queue_kicked_iocb succeed from here on */ + INIT_LIST_HEAD(&iocb->ki_run_list); + /* we must queue the next iteration ourselves, if it + * has already been kicked */ + if (kiocbIsKicked(iocb)) { + __queue_kicked_iocb(iocb); + } + } + return ret; +} + +/* + * __aio_run_iocbs: + * Process all pending retries queued on the ioctx + * run list. + * Assumes it is operating within the aio issuer's mm + * context. Expects to be called with ctx->ctx_lock held + */ +static void __aio_run_iocbs(struct kioctx *ctx) +{ + struct kiocb *iocb; + ssize_t ret; + int count = 0; + + while (!list_empty(&ctx->run_list)) { + iocb = list_entry(ctx->run_list.next, struct kiocb, + ki_run_list); + list_del(&iocb->ki_run_list); + ret = aio_run_iocb(iocb); + count++; } + aio_run++; +} + +/* + * aio_run_iocbs: + * Process all pending retries queued on the ioctx + * run list. + * Assumes it is operating within the aio issuer's mm + * context. + */ +static inline void aio_run_iocbs(struct kioctx *ctx) +{ + spin_lock_irq(&ctx->ctx_lock); + __aio_run_iocbs(ctx); spin_unlock_irq(&ctx->ctx_lock); +} +/* + * aio_kick_handler: + * Work queue handler triggered to process pending + * retries on an ioctx. Takes on the aio issuer's + * mm context before running the iocbs. + * Run on aiod's context. + */ +static void aio_kick_handler(void *data) +{ + struct kioctx *ctx = data; + + use_mm(ctx->mm); + spin_lock_irq(&ctx->ctx_lock); + __aio_run_iocbs(ctx); unuse_mm(ctx->mm); + spin_unlock_irq(&ctx->ctx_lock); } -void fastcall kick_iocb(struct kiocb *iocb) + +/* + * Called by kick_iocb to queue the kiocb for retry + * and if required activate the aio work queue to process + * it + */ +void queue_kicked_iocb(struct kiocb *iocb) { struct kioctx *ctx = iocb->ki_ctx; + unsigned long flags; + int run = 0; + WARN_ON((!list_empty(&iocb->ki_wait.task_list))); + + spin_lock_irqsave(&ctx->ctx_lock, flags); + run = __queue_kicked_iocb(iocb); + spin_unlock_irqrestore(&ctx->ctx_lock, flags); + if (run) { + queue_work(aio_wq, &ctx->wq); + aio_wakeups++; + } +} + +/* + * kick_iocb: + * Called typically from a wait queue callback context + * (aio_wake_function) to trigger a retry of the iocb. + * The retry is usually executed by aio workqueue + * threads (See aio_kick_handler). + */ +void fastcall kick_iocb(struct kiocb *iocb) +{ /* sync iocbs are easy: they can only ever be executing from a * single context. */ if (is_sync_kiocb(iocb)) { @@ -605,12 +851,10 @@ void fastcall kick_iocb(struct kiocb *io return; } + iocb->ki_kicked++; + /* If its already kicked we shouldn't queue it again */ if (!kiocbTryKick(iocb)) { - unsigned long flags; - spin_lock_irqsave(&ctx->ctx_lock, flags); - list_add_tail(&iocb->ki_run_list, &ctx->run_list); - spin_unlock_irqrestore(&ctx->ctx_lock, flags); - schedule_work(&ctx->wq); + queue_kicked_iocb(iocb); } } @@ -663,6 +907,9 @@ int fastcall aio_complete(struct kiocb * */ spin_lock_irqsave(&ctx->ctx_lock, flags); + if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list)) + list_del_init(&iocb->ki_run_list); + ring = kmap_atomic(info->ring_pages[0], KM_IRQ1); tail = info->tail; @@ -691,6 +938,11 @@ int fastcall aio_complete(struct kiocb * pr_debug("added to ring %p at [%lu]\n", iocb, tail); + pr_debug("%ld retries: %d of %d (kicked %ld, Q %ld run %ld wake %ld)\n", + iocb->ki_retried, + iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes, + iocb->ki_kicked, iocb->ki_queued, aio_run, aio_wakeups); + /* everything turned out well, dispose of the aiocb. */ ret = __aio_put_req(ctx, iocb); @@ -805,6 +1057,7 @@ static int read_events(struct kioctx *ct int i = 0; struct io_event ent; struct timeout to; + int event_loop = 0; /* testing only */ /* needed to zero any padding within an entry (there shouldn't be * any, but C is fun! @@ -854,7 +1107,6 @@ static int read_events(struct kioctx *ct add_wait_queue_exclusive(&ctx->wait, &wait); do { set_task_state(tsk, TASK_INTERRUPTIBLE); - ret = aio_read_evt(ctx, &ent); if (ret) break; @@ -864,6 +1116,7 @@ static int read_events(struct kioctx *ct if (to.timed_out) /* Only check after read evt */ break; schedule(); + event_loop++; if (signal_pending(tsk)) { ret = -EINTR; break; @@ -891,6 +1144,9 @@ static int read_events(struct kioctx *ct if (timeout) clear_timeout(&to); out: + pr_debug("event loop executed %d times\n", event_loop); + pr_debug("aio_run %ld\n", aio_run); + pr_debug("aio_wakeups %ld\n", aio_wakeups); return i ? i : ret; } @@ -920,6 +1176,11 @@ static void io_destroy(struct kioctx *io aio_cancel_all(ioctx); wait_for_all_aios(ioctx); + /* + * this is an overkill, but ensures we don't leave + * the ctx on the aio_wq + */ + flush_workqueue(aio_wq); put_ioctx(ioctx); /* once for the lookup */ } @@ -982,13 +1243,179 @@ asmlinkage long sys_io_destroy(aio_conte return -EINVAL; } +/* + * Retry method for aio_read (also used for first time submit) + * Responsible for updating iocb state as retries progress + */ +static ssize_t aio_pread(struct kiocb *iocb) +{ + struct file *file = iocb->ki_filp; + ssize_t ret = 0; + + ret = file->f_op->aio_read(iocb, iocb->ki_buf, + iocb->ki_left, iocb->ki_pos); + + /* + * Can't just depend on iocb->ki_left to determine + * whether we are done. This may have been a short read. + */ + if (ret > 0) { + iocb->ki_buf += ret; + iocb->ki_left -= ret; + + ret = -EIOCBRETRY; + } + + /* This means we must have transferred all that we could */ + /* No need to retry anymore */ + if ((ret == 0) || (iocb->ki_left == 0)) + ret = iocb->ki_nbytes - iocb->ki_left; + + return ret; +} + +/* + * Retry method for aio_write (also used for first time submit) + * Responsible for updating iocb state as retries progress + */ +static ssize_t aio_pwrite(struct kiocb *iocb) +{ + struct file *file = iocb->ki_filp; + ssize_t ret = 0; + + ret = file->f_op->aio_write(iocb, iocb->ki_buf, + iocb->ki_left, iocb->ki_pos); + + /* + * TBD: Even if iocb->ki_left = 0, could we need to + * wait for data to be sync'd ? Or can we assume + * that aio_fdsync/aio_fsync would be called explicitly + * as required. + */ + if (ret > 0) { + iocb->ki_buf += ret; + iocb->ki_left -= ret; + + ret = -EIOCBRETRY; + } + + /* This means we must have transferred all that we could */ + /* No need to retry anymore */ + if (ret == 0) + ret = iocb->ki_nbytes - iocb->ki_left; + + return ret; +} + +static ssize_t aio_fdsync(struct kiocb *iocb) +{ + struct file *file = iocb->ki_filp; + ssize_t ret = -EINVAL; + + if (file->f_op->aio_fsync) + ret = file->f_op->aio_fsync(iocb, 1); + return ret; +} + +static ssize_t aio_fsync(struct kiocb *iocb) +{ + struct file *file = iocb->ki_filp; + ssize_t ret = -EINVAL; + + if (file->f_op->aio_fsync) + ret = file->f_op->aio_fsync(iocb, 0); + return ret; +} + +/* + * aio_setup_iocb: + * Performs the initial checks and aio retry method + * setup for the kiocb at the time of io submission. + */ +ssize_t aio_setup_iocb(struct kiocb *kiocb) +{ + struct file *file = kiocb->ki_filp; + ssize_t ret = 0; + + switch (kiocb->ki_opcode) { + case IOCB_CMD_PREAD: + ret = -EBADF; + if (unlikely(!(file->f_mode & FMODE_READ))) + break; + ret = -EFAULT; + if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf, + kiocb->ki_left))) + break; + ret = -EINVAL; + if (file->f_op->aio_read) + kiocb->ki_retry = aio_pread; + break; + case IOCB_CMD_PWRITE: + ret = -EBADF; + if (unlikely(!(file->f_mode & FMODE_WRITE))) + break; + ret = -EFAULT; + if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf, + kiocb->ki_left))) + break; + ret = -EINVAL; + if (file->f_op->aio_write) + kiocb->ki_retry = aio_pwrite; + break; + case IOCB_CMD_FDSYNC: + ret = -EINVAL; + if (file->f_op->aio_fsync) + kiocb->ki_retry = aio_fdsync; + break; + case IOCB_CMD_FSYNC: + ret = -EINVAL; + if (file->f_op->aio_fsync) + kiocb->ki_retry = aio_fsync; + break; + default: + dprintk("EINVAL: io_submit: no operation provided\n"); + ret = -EINVAL; + } + + if (!kiocb->ki_retry) + return ret; + + return 0; +} + +/* + * aio_wake_function: + * wait queue callback function for aio notification, + * Simply triggers a retry of the operation via kick_iocb. + * + * This callback is specified in the wait queue entry in + * a kiocb (current->io_wait points to this wait queue + * entry when an aio operation executes; it is used + * instead of a synchronous wait when an i/o blocking + * condition is encountered during aio). + * + * Note: + * This routine is executed with the wait queue lock held. + * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests + * the ioctx lock inside the wait queue lock. This is safe + * because this callback isn't used for wait queues which + * are nested inside ioctx lock (i.e. ctx->wait) + */ +int aio_wake_function(wait_queue_t *wait, unsigned mode, int sync) +{ + struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait); + + list_del_init(&wait->task_list); + kick_iocb(iocb); + return 1; +} + int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, struct iocb *iocb) { struct kiocb *req; struct file *file; ssize_t ret; - char __user *buf; /* enforce forwards compatibility on users */ if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2 || @@ -1029,52 +1456,31 @@ int fastcall io_submit_one(struct kioctx req->ki_user_data = iocb->aio_data; req->ki_pos = iocb->aio_offset; - buf = (char __user *)(unsigned long)iocb->aio_buf; + req->ki_buf = (char *)(unsigned long)iocb->aio_buf; + req->ki_left = req->ki_nbytes = iocb->aio_nbytes; + req->ki_opcode = iocb->aio_lio_opcode; + init_waitqueue_func_entry(&req->ki_wait, aio_wake_function); + INIT_LIST_HEAD(&req->ki_wait.task_list); + req->ki_run_list.next = req->ki_run_list.prev = NULL; + req->ki_retry = NULL; + req->ki_retried = 0; + req->ki_kicked = 0; + req->ki_queued = 0; + aio_run = 0; + aio_wakeups = 0; - switch (iocb->aio_lio_opcode) { - case IOCB_CMD_PREAD: - ret = -EBADF; - if (unlikely(!(file->f_mode & FMODE_READ))) - goto out_put_req; - ret = -EFAULT; - if (unlikely(!access_ok(VERIFY_WRITE, buf, iocb->aio_nbytes))) - goto out_put_req; - ret = -EINVAL; - if (file->f_op->aio_read) - ret = file->f_op->aio_read(req, buf, - iocb->aio_nbytes, req->ki_pos); - break; - case IOCB_CMD_PWRITE: - ret = -EBADF; - if (unlikely(!(file->f_mode & FMODE_WRITE))) - goto out_put_req; - ret = -EFAULT; - if (unlikely(!access_ok(VERIFY_READ, buf, iocb->aio_nbytes))) - goto out_put_req; - ret = -EINVAL; - if (file->f_op->aio_write) - ret = file->f_op->aio_write(req, buf, - iocb->aio_nbytes, req->ki_pos); - break; - case IOCB_CMD_FDSYNC: - ret = -EINVAL; - if (file->f_op->aio_fsync) - ret = file->f_op->aio_fsync(req, 1); - break; - case IOCB_CMD_FSYNC: - ret = -EINVAL; - if (file->f_op->aio_fsync) - ret = file->f_op->aio_fsync(req, 0); - break; - default: - dprintk("EINVAL: io_submit: no operation provided\n"); - ret = -EINVAL; - } + ret = aio_setup_iocb(req); + if (ret) + goto out_put_req; + + spin_lock_irq(&ctx->ctx_lock); + ret = aio_run_iocb(req); + spin_unlock_irq(&ctx->ctx_lock); + + if (-EIOCBRETRY == ret) + queue_work(aio_wq, &ctx->wq); aio_put_req(req); /* drop extra ref to req */ - if (likely(-EIOCBQUEUED == ret)) - return 0; - aio_complete(req, ret, 0); /* will drop i/o ref to req */ return 0; out_put_req: diff -upN /dev/null current/fs/aio.c.porig --- /dev/null 2004-02-24 15:23:11.000000000 -0800 +++ current/fs/aio.c.porig 2004-05-09 13:45:18.000000000 -0700 @@ -0,0 +1,1423 @@ +/* + * An async IO implementation for Linux + * Written by Benjamin LaHaise + * + * Implements an efficient asynchronous io interface. + * + * Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved. + * + * See ../COPYING for licensing terms. + */ +#include +#include +#include +#include +#include +#include + +//#define DEBUG 1 + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +#if DEBUG > 1 +#define dprintk printk +#else +#define dprintk(x...) do { ; } while (0) +#endif + +long aio_run = 0; /* for testing only */ +long aio_wakeups = 0; /* for testing only */ + +/*------ sysctl variables----*/ +atomic_t aio_nr = ATOMIC_INIT(0); /* current system wide number of aio requests */ +unsigned aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ +/*----end sysctl variables---*/ + +static kmem_cache_t *kiocb_cachep; +static kmem_cache_t *kioctx_cachep; + +static struct workqueue_struct *aio_wq; + +/* Used for rare fput completion. */ +static void aio_fput_routine(void *); +static DECLARE_WORK(fput_work, aio_fput_routine, NULL); + +static spinlock_t fput_lock = SPIN_LOCK_UNLOCKED; +LIST_HEAD(fput_head); + +static void aio_kick_handler(void *); + +/* aio_setup + * Creates the slab caches used by the aio routines, panic on + * failure as this is done early during the boot sequence. + */ +static int __init aio_setup(void) +{ + kiocb_cachep = kmem_cache_create("kiocb", sizeof(struct kiocb), + 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); + kioctx_cachep = kmem_cache_create("kioctx", sizeof(struct kioctx), + 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); + + aio_wq = create_workqueue("aio"); + + pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page)); + + return 0; +} + +static void aio_free_ring(struct kioctx *ctx) +{ + struct aio_ring_info *info = &ctx->ring_info; + long i; + + for (i=0; inr_pages; i++) + put_page(info->ring_pages[i]); + + if (info->mmap_size) { + down_write(&ctx->mm->mmap_sem); + do_munmap(ctx->mm, info->mmap_base, info->mmap_size); + up_write(&ctx->mm->mmap_sem); + } + + if (info->ring_pages && info->ring_pages != info->internal_pages) + kfree(info->ring_pages); + info->ring_pages = NULL; + info->nr = 0; +} + +static int aio_setup_ring(struct kioctx *ctx) +{ + struct aio_ring *ring; + struct aio_ring_info *info = &ctx->ring_info; + unsigned nr_events = ctx->max_reqs; + unsigned long size; + int nr_pages; + + /* Compensate for the ring buffer's head/tail overlap entry */ + nr_events += 2; /* 1 is required, 2 for good luck */ + + size = sizeof(struct aio_ring); + size += sizeof(struct io_event) * nr_events; + nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT; + + if (nr_pages < 0) + return -EINVAL; + + info->nr_pages = nr_pages; + + nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event); + + info->nr = 0; + info->ring_pages = info->internal_pages; + if (nr_pages > AIO_RING_PAGES) { + info->ring_pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_KERNEL); + if (!info->ring_pages) + return -ENOMEM; + memset(info->ring_pages, 0, sizeof(struct page *) * nr_pages); + } + + info->mmap_size = nr_pages * PAGE_SIZE; + dprintk("attempting mmap of %lu bytes\n", info->mmap_size); + down_write(&ctx->mm->mmap_sem); + info->mmap_base = do_mmap(NULL, 0, info->mmap_size, + PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, + 0); + if (IS_ERR((void *)info->mmap_base)) { + up_write(&ctx->mm->mmap_sem); + printk("mmap err: %ld\n", -info->mmap_base); + info->mmap_size = 0; + aio_free_ring(ctx); + return -EAGAIN; + } + + dprintk("mmap address: 0x%08lx\n", info->mmap_base); + info->nr_pages = get_user_pages(current, ctx->mm, + info->mmap_base, nr_pages, + 1, 0, info->ring_pages, NULL); + up_write(&ctx->mm->mmap_sem); + + if (unlikely(info->nr_pages != nr_pages)) { + aio_free_ring(ctx); + return -EAGAIN; + } + + ctx->user_id = info->mmap_base; + + info->nr = nr_events; /* trusted copy */ + + ring = kmap_atomic(info->ring_pages[0], KM_USER0); + ring->nr = nr_events; /* user copy */ + ring->id = ctx->user_id; + ring->head = ring->tail = 0; + ring->magic = AIO_RING_MAGIC; + ring->compat_features = AIO_RING_COMPAT_FEATURES; + ring->incompat_features = AIO_RING_INCOMPAT_FEATURES; + ring->header_length = sizeof(struct aio_ring); + kunmap_atomic(ring, KM_USER0); + + return 0; +} + + +/* aio_ring_event: returns a pointer to the event at the given index from + * kmap_atomic(, km). Release the pointer with put_aio_ring_event(); + */ +#define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event)) +#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) +#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) + +#define aio_ring_event(info, nr, km) ({ \ + unsigned pos = (nr) + AIO_EVENTS_OFFSET; \ + struct io_event *__event; \ + __event = kmap_atomic( \ + (info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \ + __event += pos % AIO_EVENTS_PER_PAGE; \ + __event; \ +}) + +#define put_aio_ring_event(event, km) do { \ + struct io_event *__event = (event); \ + (void)__event; \ + kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \ +} while(0) + +/* ioctx_alloc + * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed. + */ +static struct kioctx *ioctx_alloc(unsigned nr_events) +{ + struct mm_struct *mm; + struct kioctx *ctx; + int ret = 0; + + /* Prevent overflows */ + if ((nr_events > (0x10000000U / sizeof(struct io_event))) || + (nr_events > (0x10000000U / sizeof(struct kiocb)))) { + pr_debug("ENOMEM: nr_events too high\n"); + return ERR_PTR(-EINVAL); + } + + if (nr_events > aio_max_nr) + return ERR_PTR(-EAGAIN); + + ctx = kmem_cache_alloc(kioctx_cachep, GFP_KERNEL); + if (!ctx) + return ERR_PTR(-ENOMEM); + + memset(ctx, 0, sizeof(*ctx)); + ctx->max_reqs = nr_events; + mm = ctx->mm = current->mm; + atomic_inc(&mm->mm_count); + + atomic_set(&ctx->users, 1); + spin_lock_init(&ctx->ctx_lock); + spin_lock_init(&ctx->ring_info.ring_lock); + init_waitqueue_head(&ctx->wait); + + INIT_LIST_HEAD(&ctx->active_reqs); + INIT_LIST_HEAD(&ctx->run_list); + INIT_WORK(&ctx->wq, aio_kick_handler, ctx); + + ret = aio_setup_ring(ctx); + if (unlikely(ret < 0)) + goto out_freectx; + + /* limit the number of system wide aios */ + atomic_add(ctx->max_reqs, &aio_nr); /* undone by __put_ioctx */ + if (unlikely(atomic_read(&aio_nr) > aio_max_nr)) + goto out_cleanup; + + /* now link into global list. kludge. FIXME */ + write_lock(&mm->ioctx_list_lock); + ctx->next = mm->ioctx_list; + mm->ioctx_list = ctx; + write_unlock(&mm->ioctx_list_lock); + + dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", + ctx, ctx->user_id, current->mm, ctx->ring_info.nr); + return ctx; + +out_cleanup: + atomic_sub(ctx->max_reqs, &aio_nr); + ctx->max_reqs = 0; /* prevent __put_ioctx from sub'ing aio_nr */ + __put_ioctx(ctx); + return ERR_PTR(-EAGAIN); + +out_freectx: + mmdrop(mm); + kmem_cache_free(kioctx_cachep, ctx); + ctx = ERR_PTR(ret); + + dprintk("aio: error allocating ioctx %p\n", ctx); + return ctx; +} + +/* aio_cancel_all + * Cancels all outstanding aio requests on an aio context. Used + * when the processes owning a context have all exited to encourage + * the rapid destruction of the kioctx. + */ +static void aio_cancel_all(struct kioctx *ctx) +{ + int (*cancel)(struct kiocb *, struct io_event *); + struct io_event res; + spin_lock_irq(&ctx->ctx_lock); + ctx->dead = 1; + while (!list_empty(&ctx->active_reqs)) { + struct list_head *pos = ctx->active_reqs.next; + struct kiocb *iocb = list_kiocb(pos); + list_del_init(&iocb->ki_list); + cancel = iocb->ki_cancel; + kiocbSetCancelled(iocb); + if (cancel) { + iocb->ki_users++; + spin_unlock_irq(&ctx->ctx_lock); + cancel(iocb, &res); + spin_lock_irq(&ctx->ctx_lock); + } + } + spin_unlock_irq(&ctx->ctx_lock); +} + +void wait_for_all_aios(struct kioctx *ctx) +{ + struct task_struct *tsk = current; + DECLARE_WAITQUEUE(wait, tsk); + + if (!ctx->reqs_active) + return; + + add_wait_queue(&ctx->wait, &wait); + set_task_state(tsk, TASK_UNINTERRUPTIBLE); + while (ctx->reqs_active) { + schedule(); + set_task_state(tsk, TASK_UNINTERRUPTIBLE); + } + __set_task_state(tsk, TASK_RUNNING); + remove_wait_queue(&ctx->wait, &wait); +} + +/* wait_on_sync_kiocb: + * Waits on the given sync kiocb to complete. + */ +ssize_t fastcall wait_on_sync_kiocb(struct kiocb *iocb) +{ + while (iocb->ki_users) { + set_current_state(TASK_UNINTERRUPTIBLE); + if (!iocb->ki_users) + break; + schedule(); + } + __set_current_state(TASK_RUNNING); + return iocb->ki_user_data; +} + +/* exit_aio: called when the last user of mm goes away. At this point, + * there is no way for any new requests to be submited or any of the + * io_* syscalls to be called on the context. However, there may be + * outstanding requests which hold references to the context; as they + * go away, they will call put_ioctx and release any pinned memory + * associated with the request (held via struct page * references). + */ +void fastcall exit_aio(struct mm_struct *mm) +{ + struct kioctx *ctx = mm->ioctx_list; + mm->ioctx_list = NULL; + while (ctx) { + struct kioctx *next = ctx->next; + ctx->next = NULL; + aio_cancel_all(ctx); + + wait_for_all_aios(ctx); + /* + * this is an overkill, but ensures we don't leave + * the ctx on the aio_wq + */ + flush_workqueue(aio_wq); + + if (1 != atomic_read(&ctx->users)) + printk(KERN_DEBUG + "exit_aio:ioctx still alive: %d %d %d\n", + atomic_read(&ctx->users), ctx->dead, + ctx->reqs_active); + put_ioctx(ctx); + ctx = next; + } +} + +/* __put_ioctx + * Called when the last user of an aio context has gone away, + * and the struct needs to be freed. + */ +void fastcall __put_ioctx(struct kioctx *ctx) +{ + unsigned nr_events = ctx->max_reqs; + + if (unlikely(ctx->reqs_active)) + BUG(); + + aio_free_ring(ctx); + mmdrop(ctx->mm); + ctx->mm = NULL; + pr_debug("__put_ioctx: freeing %p\n", ctx); + kmem_cache_free(kioctx_cachep, ctx); + + atomic_sub(nr_events, &aio_nr); +} + +/* aio_get_req + * Allocate a slot for an aio request. Increments the users count + * of the kioctx so that the kioctx stays around until all requests are + * complete. Returns NULL if no requests are free. + * + * Returns with kiocb->users set to 2. The io submit code path holds + * an extra reference while submitting the i/o. + * This prevents races between the aio code path referencing the + * req (after submitting it) and aio_complete() freeing the req. + */ +static struct kiocb *FASTCALL(__aio_get_req(struct kioctx *ctx)); +static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx) +{ + struct kiocb *req = NULL; + struct aio_ring *ring; + int okay = 0; + + req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); + if (unlikely(!req)) + return NULL; + + req->ki_flags = 1 << KIF_LOCKED; + req->ki_users = 2; + req->ki_key = 0; + req->ki_ctx = ctx; + req->ki_cancel = NULL; + req->ki_retry = NULL; + req->ki_user_obj = NULL; + INIT_LIST_HEAD(&req->ki_run_list); + + /* Check if the completion queue has enough free space to + * accept an event from this io. + */ + spin_lock_irq(&ctx->ctx_lock); + ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0); + if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) { + list_add(&req->ki_list, &ctx->active_reqs); + get_ioctx(ctx); + ctx->reqs_active++; + okay = 1; + } + kunmap_atomic(ring, KM_USER0); + spin_unlock_irq(&ctx->ctx_lock); + + if (!okay) { + kmem_cache_free(kiocb_cachep, req); + req = NULL; + } + + return req; +} + +static inline struct kiocb *aio_get_req(struct kioctx *ctx) +{ + struct kiocb *req; + /* Handle a potential starvation case -- should be exceedingly rare as + * requests will be stuck on fput_head only if the aio_fput_routine is + * delayed and the requests were the last user of the struct file. + */ + req = __aio_get_req(ctx); + if (unlikely(NULL == req)) { + aio_fput_routine(NULL); + req = __aio_get_req(ctx); + } + return req; +} + +static inline void really_put_req(struct kioctx *ctx, struct kiocb *req) +{ + req->ki_ctx = NULL; + req->ki_filp = NULL; + req->ki_user_obj = NULL; + kmem_cache_free(kiocb_cachep, req); + ctx->reqs_active--; + + if (unlikely(!ctx->reqs_active && ctx->dead)) + wake_up(&ctx->wait); +} + +static void aio_fput_routine(void *data) +{ + spin_lock_irq(&fput_lock); + while (likely(!list_empty(&fput_head))) { + struct kiocb *req = list_kiocb(fput_head.next); + struct kioctx *ctx = req->ki_ctx; + + list_del(&req->ki_list); + spin_unlock_irq(&fput_lock); + + /* Complete the fput */ + __fput(req->ki_filp); + + /* Link the iocb into the context's free list */ + spin_lock_irq(&ctx->ctx_lock); + really_put_req(ctx, req); + spin_unlock_irq(&ctx->ctx_lock); + + put_ioctx(ctx); + spin_lock_irq(&fput_lock); + } + spin_unlock_irq(&fput_lock); +} + +/* __aio_put_req + * Returns true if this put was the last user of the request. + */ +static int __aio_put_req(struct kioctx *ctx, struct kiocb *req) +{ + dprintk(KERN_DEBUG "aio_put(%p): f_count=%d\n", + req, atomic_read(&req->ki_filp->f_count)); + + req->ki_users --; + if (unlikely(req->ki_users < 0)) + BUG(); + if (likely(req->ki_users)) + return 0; + list_del(&req->ki_list); /* remove from active_reqs */ + req->ki_cancel = NULL; + req->ki_retry = NULL; + + /* Must be done under the lock to serialise against cancellation. + * Call this aio_fput as it duplicates fput via the fput_work. + */ + if (unlikely(atomic_dec_and_test(&req->ki_filp->f_count))) { + get_ioctx(ctx); + spin_lock(&fput_lock); + list_add(&req->ki_list, &fput_head); + spin_unlock(&fput_lock); + queue_work(aio_wq, &fput_work); + } else + really_put_req(ctx, req); + return 1; +} + +/* aio_put_req + * Returns true if this put was the last user of the kiocb, + * false if the request is still in use. + */ +int fastcall aio_put_req(struct kiocb *req) +{ + struct kioctx *ctx = req->ki_ctx; + int ret; + spin_lock_irq(&ctx->ctx_lock); + ret = __aio_put_req(ctx, req); + spin_unlock_irq(&ctx->ctx_lock); + if (ret) + put_ioctx(ctx); + return ret; +} + +/* Lookup an ioctx id. ioctx_list is lockless for reads. + * FIXME: this is O(n) and is only suitable for development. + */ +struct kioctx *lookup_ioctx(unsigned long ctx_id) +{ + struct kioctx *ioctx; + struct mm_struct *mm; + + mm = current->mm; + read_lock(&mm->ioctx_list_lock); + for (ioctx = mm->ioctx_list; ioctx; ioctx = ioctx->next) + if (likely(ioctx->user_id == ctx_id && !ioctx->dead)) { + get_ioctx(ioctx); + break; + } + read_unlock(&mm->ioctx_list_lock); + + return ioctx; +} + +void use_mm(struct mm_struct *mm) +{ + struct mm_struct *active_mm = current->active_mm; + atomic_inc(&mm->mm_count); + current->mm = mm; + if (mm != active_mm) { + current->active_mm = mm; + activate_mm(active_mm, mm); + } + mmdrop(active_mm); +} + +static void unuse_mm(struct mm_struct *mm) +{ + current->mm = NULL; + /* active_mm is still 'mm' */ + enter_lazy_tlb(mm, current); +} + +/* Run on kevent's context. FIXME: needs to be per-cpu and warn if an + * operation blocks. + */ +static void aio_kick_handler(void *data) +{ + struct kioctx *ctx = data; + + use_mm(ctx->mm); + + spin_lock_irq(&ctx->ctx_lock); + while (!list_empty(&ctx->run_list)) { + struct kiocb *iocb; + long ret; + + iocb = list_entry(ctx->run_list.next, struct kiocb, + ki_run_list); + list_del(&iocb->ki_run_list); + iocb->ki_users ++; + spin_unlock_irq(&ctx->ctx_lock); + + kiocbClearKicked(iocb); + ret = iocb->ki_retry(iocb); + if (-EIOCBQUEUED != ret) { + aio_complete(iocb, ret, 0); + iocb = NULL; + } + + spin_lock_irq(&ctx->ctx_lock); + if (NULL != iocb) + __aio_put_req(ctx, iocb); + } + spin_unlock_irq(&ctx->ctx_lock); + + unuse_mm(ctx->mm); +} + +void fastcall kick_iocb(struct kiocb *iocb) +{ + struct kioctx *ctx = iocb->ki_ctx; + + /* sync iocbs are easy: they can only ever be executing from a + * single context. */ + if (is_sync_kiocb(iocb)) { + kiocbSetKicked(iocb); + wake_up_process(iocb->ki_user_obj); + return; + } + + iocb->ki_kicked++; + /* If its already kicked we shouldn't queue it again */ + if (!kiocbTryKick(iocb)) { + queue_kicked_iocb(iocb); + } +} + +/* aio_complete + * Called when the io request on the given iocb is complete. + * Returns true if this is the last user of the request. The + * only other user of the request can be the cancellation code. + */ +int fastcall aio_complete(struct kiocb *iocb, long res, long res2) +{ + struct kioctx *ctx = iocb->ki_ctx; + struct aio_ring_info *info; + struct aio_ring *ring; + struct io_event *event; + unsigned long flags; + unsigned long tail; + int ret; + + /* Special case handling for sync iocbs: events go directly + * into the iocb for fast handling. Note that this will not + * work if we allow sync kiocbs to be cancelled. in which + * case the usage count checks will have to move under ctx_lock + * for all cases. + */ + if (is_sync_kiocb(iocb)) { + int ret; + + iocb->ki_user_data = res; + if (iocb->ki_users == 1) { + iocb->ki_users = 0; + ret = 1; + } else { + spin_lock_irq(&ctx->ctx_lock); + iocb->ki_users--; + ret = (0 == iocb->ki_users); + spin_unlock_irq(&ctx->ctx_lock); + } + /* sync iocbs put the task here for us */ + wake_up_process(iocb->ki_user_obj); + return ret; + } + + info = &ctx->ring_info; + + /* add a completion event to the ring buffer. + * must be done holding ctx->ctx_lock to prevent + * other code from messing with the tail + * pointer since we might be called from irq + * context. + */ + spin_lock_irqsave(&ctx->ctx_lock, flags); + + if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list)) + list_del_init(&iocb->ki_run_list); + + ring = kmap_atomic(info->ring_pages[0], KM_IRQ1); + + tail = info->tail; + event = aio_ring_event(info, tail, KM_IRQ0); + tail = (tail + 1) % info->nr; + + event->obj = (u64)(unsigned long)iocb->ki_user_obj; + event->data = iocb->ki_user_data; + event->res = res; + event->res2 = res2; + + dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n", + ctx, tail, iocb, iocb->ki_user_obj, iocb->ki_user_data, + res, res2); + + /* after flagging the request as done, we + * must never even look at it again + */ + smp_wmb(); /* make event visible before updating tail */ + + info->tail = tail; + ring->tail = tail; + + put_aio_ring_event(event, KM_IRQ0); + kunmap_atomic(ring, KM_IRQ1); + + pr_debug("added to ring %p at [%lu]\n", iocb, tail); + + pr_debug("%ld retries: %d of %d (kicked %ld, Q %ld run %ld wake %ld)\n", + iocb->ki_retried, + iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes, + iocb->ki_kicked, iocb->ki_queued, aio_run, aio_wakeups); + + /* everything turned out well, dispose of the aiocb. */ + ret = __aio_put_req(ctx, iocb); + + spin_unlock_irqrestore(&ctx->ctx_lock, flags); + + if (waitqueue_active(&ctx->wait)) + wake_up(&ctx->wait); + + if (ret) + put_ioctx(ctx); + + return ret; +} + +/* aio_read_evt + * Pull an event off of the ioctx's event ring. Returns the number of + * events fetched (0 or 1 ;-) + * FIXME: make this use cmpxchg. + * TODO: make the ringbuffer user mmap()able (requires FIXME). + */ +static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent) +{ + struct aio_ring_info *info = &ioctx->ring_info; + struct aio_ring *ring; + unsigned long head; + int ret = 0; + + ring = kmap_atomic(info->ring_pages[0], KM_USER0); + dprintk("in aio_read_evt h%lu t%lu m%lu\n", + (unsigned long)ring->head, (unsigned long)ring->tail, + (unsigned long)ring->nr); + + if (ring->head == ring->tail) + goto out; + + spin_lock(&info->ring_lock); + + head = ring->head % info->nr; + if (head != ring->tail) { + struct io_event *evp = aio_ring_event(info, head, KM_USER1); + *ent = *evp; + head = (head + 1) % info->nr; + smp_mb(); /* finish reading the event before updatng the head */ + ring->head = head; + ret = 1; + put_aio_ring_event(evp, KM_USER1); + } + spin_unlock(&info->ring_lock); + +out: + kunmap_atomic(ring, KM_USER0); + dprintk("leaving aio_read_evt: %d h%lu t%lu\n", ret, + (unsigned long)ring->head, (unsigned long)ring->tail); + return ret; +} + +struct timeout { + struct timer_list timer; + int timed_out; + struct task_struct *p; +}; + +static void timeout_func(unsigned long data) +{ + struct timeout *to = (struct timeout *)data; + + to->timed_out = 1; + wake_up_process(to->p); +} + +static inline void init_timeout(struct timeout *to) +{ + init_timer(&to->timer); + to->timer.data = (unsigned long)to; + to->timer.function = timeout_func; + to->timed_out = 0; + to->p = current; +} + +static inline void set_timeout(long start_jiffies, struct timeout *to, + const struct timespec *ts) +{ + unsigned long how_long; + + if (ts->tv_sec < 0 || (!ts->tv_sec && !ts->tv_nsec)) { + to->timed_out = 1; + return; + } + + how_long = ts->tv_sec * HZ; +#define HZ_NS (1000000000 / HZ) + how_long += (ts->tv_nsec + HZ_NS - 1) / HZ_NS; + + to->timer.expires = jiffies + how_long; + add_timer(&to->timer); +} + +static inline void clear_timeout(struct timeout *to) +{ + del_timer_sync(&to->timer); +} + +static int read_events(struct kioctx *ctx, + long min_nr, long nr, + struct io_event __user *event, + struct timespec __user *timeout) +{ + long start_jiffies = jiffies; + struct task_struct *tsk = current; + DECLARE_WAITQUEUE(wait, tsk); + int ret; + int i = 0; + struct io_event ent; + struct timeout to; + int event_loop = 0; /* testing only */ + + /* needed to zero any padding within an entry (there shouldn't be + * any, but C is fun! + */ + memset(&ent, 0, sizeof(ent)); + ret = 0; + + while (likely(i < nr)) { + ret = aio_read_evt(ctx, &ent); + if (unlikely(ret <= 0)) + break; + + dprintk("read event: %Lx %Lx %Lx %Lx\n", + ent.data, ent.obj, ent.res, ent.res2); + + /* Could we split the check in two? */ + ret = -EFAULT; + if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { + dprintk("aio: lost an event due to EFAULT.\n"); + break; + } + ret = 0; + + /* Good, event copied to userland, update counts. */ + event ++; + i ++; + } + + if (min_nr <= i) + return i; + if (ret) + return ret; + + /* End fast path */ + + init_timeout(&to); + if (timeout) { + struct timespec ts; + ret = -EFAULT; + if (unlikely(copy_from_user(&ts, timeout, sizeof(ts)))) + goto out; + + set_timeout(start_jiffies, &to, &ts); + } + + while (likely(i < nr)) { + add_wait_queue_exclusive(&ctx->wait, &wait); + do { + set_task_state(tsk, TASK_INTERRUPTIBLE); + ret = aio_read_evt(ctx, &ent); + if (ret) + break; + if (min_nr <= i) + break; + ret = 0; + if (to.timed_out) /* Only check after read evt */ + break; + schedule(); + event_loop++; + if (signal_pending(tsk)) { + ret = -EINTR; + break; + } + /*ret = aio_read_evt(ctx, &ent);*/ + } while (1) ; + + set_task_state(tsk, TASK_RUNNING); + remove_wait_queue(&ctx->wait, &wait); + + if (unlikely(ret <= 0)) + break; + + ret = -EFAULT; + if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { + dprintk("aio: lost an event due to EFAULT.\n"); + break; + } + + /* Good, event copied to userland, update counts. */ + event ++; + i ++; + } + + if (timeout) + clear_timeout(&to); +out: + pr_debug("event loop executed %d times\n", event_loop); + pr_debug("aio_run %ld\n", aio_run); + pr_debug("aio_wakeups %ld\n", aio_wakeups); + return i ? i : ret; +} + +/* Take an ioctx and remove it from the list of ioctx's. Protects + * against races with itself via ->dead. + */ +static void io_destroy(struct kioctx *ioctx) +{ + struct mm_struct *mm = current->mm; + struct kioctx **tmp; + int was_dead; + + /* delete the entry from the list is someone else hasn't already */ + write_lock(&mm->ioctx_list_lock); + was_dead = ioctx->dead; + ioctx->dead = 1; + for (tmp = &mm->ioctx_list; *tmp && *tmp != ioctx; + tmp = &(*tmp)->next) + ; + if (*tmp) + *tmp = ioctx->next; + write_unlock(&mm->ioctx_list_lock); + + dprintk("aio_release(%p)\n", ioctx); + if (likely(!was_dead)) + put_ioctx(ioctx); /* twice for the list */ + + aio_cancel_all(ioctx); + wait_for_all_aios(ioctx); + /* + * this is an overkill, but ensures we don't leave + * the ctx on the aio_wq + */ + flush_workqueue(aio_wq); + put_ioctx(ioctx); /* once for the lookup */ +} + +/* sys_io_setup: + * Create an aio_context capable of receiving at least nr_events. + * ctxp must not point to an aio_context that already exists, and + * must be initialized to 0 prior to the call. On successful + * creation of the aio_context, *ctxp is filled in with the resulting + * handle. May fail with -EINVAL if *ctxp is not initialized, + * if the specified nr_events exceeds internal limits. May fail + * with -EAGAIN if the specified nr_events exceeds the user's limit + * of available events. May fail with -ENOMEM if insufficient kernel + * resources are available. May fail with -EFAULT if an invalid + * pointer is passed for ctxp. Will fail with -ENOSYS if not + * implemented. + */ +asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t *ctxp) +{ + struct kioctx *ioctx = NULL; + unsigned long ctx; + long ret; + + ret = get_user(ctx, ctxp); + if (unlikely(ret)) + goto out; + + ret = -EINVAL; + if (unlikely(ctx || (int)nr_events <= 0)) { + pr_debug("EINVAL: io_setup: ctx or nr_events > max\n"); + goto out; + } + + ioctx = ioctx_alloc(nr_events); + ret = PTR_ERR(ioctx); + if (!IS_ERR(ioctx)) { + ret = put_user(ioctx->user_id, ctxp); + if (!ret) + return 0; + io_destroy(ioctx); + } + +out: + return ret; +} + +/* sys_io_destroy: + * Destroy the aio_context specified. May cancel any outstanding + * AIOs and block on completion. Will fail with -ENOSYS if not + * implemented. May fail with -EFAULT if the context pointed to + * is invalid. + */ +asmlinkage long sys_io_destroy(aio_context_t ctx) +{ + struct kioctx *ioctx = lookup_ioctx(ctx); + if (likely(NULL != ioctx)) { + io_destroy(ioctx); + return 0; + } + pr_debug("EINVAL: io_destroy: invalid context id\n"); + return -EINVAL; +} + +/* + * Retry method for aio_read (also used for first time submit) + * Responsible for updating iocb state as retries progress + */ +static ssize_t aio_pread(struct kiocb *iocb) +{ + struct file *file = iocb->ki_filp; + ssize_t ret = 0; + + ret = file->f_op->aio_read(iocb, iocb->ki_buf, + iocb->ki_left, iocb->ki_pos); + + /* + * Can't just depend on iocb->ki_left to determine + * whether we are done. This may have been a short read. + */ + if (ret > 0) { + iocb->ki_buf += ret; + iocb->ki_left -= ret; + + ret = -EIOCBRETRY; + } + + /* This means we must have transferred all that we could */ + /* No need to retry anymore */ + if ((ret == 0) || (iocb->ki_left == 0)) + ret = iocb->ki_nbytes - iocb->ki_left; + + return ret; +} + +/* + * Retry method for aio_write (also used for first time submit) + * Responsible for updating iocb state as retries progress + */ +static ssize_t aio_pwrite(struct kiocb *iocb) +{ + struct file *file = iocb->ki_filp; + ssize_t ret = 0; + + ret = file->f_op->aio_write(iocb, iocb->ki_buf, + iocb->ki_left, iocb->ki_pos); + + /* + * TBD: Even if iocb->ki_left = 0, could we need to + * wait for data to be sync'd ? Or can we assume + * that aio_fdsync/aio_fsync would be called explicitly + * as required. + */ + if (ret > 0) { + iocb->ki_buf += ret; + iocb->ki_left -= ret; + + ret = -EIOCBRETRY; + } + + /* This means we must have transferred all that we could */ + /* No need to retry anymore */ + if (ret == 0) + ret = iocb->ki_nbytes - iocb->ki_left; + + return ret; +} + +static ssize_t aio_fdsync(struct kiocb *iocb) +{ + struct file *file = iocb->ki_filp; + ssize_t ret = -EINVAL; + + if (file->f_op->aio_fsync) + ret = file->f_op->aio_fsync(iocb, 1); + return ret; +} + +static ssize_t aio_fsync(struct kiocb *iocb) +{ + struct file *file = iocb->ki_filp; + ssize_t ret = -EINVAL; + + if (file->f_op->aio_fsync) + ret = file->f_op->aio_fsync(iocb, 0); + return ret; +} + +/* + * aio_setup_iocb: + * Performs the initial checks and aio retry method + * setup for the kiocb at the time of io submission. + */ +ssize_t aio_setup_iocb(struct kiocb *kiocb) +{ + struct file *file = kiocb->ki_filp; + ssize_t ret = 0; + + switch (kiocb->ki_opcode) { + case IOCB_CMD_PREAD: + ret = -EBADF; + if (unlikely(!(file->f_mode & FMODE_READ))) + break; + ret = -EFAULT; + if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf, + kiocb->ki_left))) + break; + ret = -EINVAL; + if (file->f_op->aio_read) + kiocb->ki_retry = aio_pread; + break; + case IOCB_CMD_PWRITE: + ret = -EBADF; + if (unlikely(!(file->f_mode & FMODE_WRITE))) + break; + ret = -EFAULT; + if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf, + kiocb->ki_left))) + break; + ret = -EINVAL; + if (file->f_op->aio_write) + kiocb->ki_retry = aio_pwrite; + break; + case IOCB_CMD_FDSYNC: + ret = -EINVAL; + if (file->f_op->aio_fsync) + kiocb->ki_retry = aio_fdsync; + break; + case IOCB_CMD_FSYNC: + ret = -EINVAL; + if (file->f_op->aio_fsync) + kiocb->ki_retry = aio_fsync; + break; + default: + dprintk("EINVAL: io_submit: no operation provided\n"); + ret = -EINVAL; + } + + if (!kiocb->ki_retry) + return ret; + + return 0; +} + +/* + * aio_wake_function: + * wait queue callback function for aio notification, + * Simply triggers a retry of the operation via kick_iocb. + * + * This callback is specified in the wait queue entry in + * a kiocb (current->io_wait points to this wait queue + * entry when an aio operation executes; it is used + * instead of a synchronous wait when an i/o blocking + * condition is encountered during aio). + * + * Note: + * This routine is executed with the wait queue lock held. + * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests + * the ioctx lock inside the wait queue lock. This is safe + * because this callback isn't used for wait queues which + * are nested inside ioctx lock (i.e. ctx->wait) + */ +int aio_wake_function(wait_queue_t *wait, unsigned mode, int sync) +{ + struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait); + + list_del_init(&wait->task_list); + kick_iocb(iocb); + return 1; +} + +int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, + struct iocb *iocb) +{ + struct kiocb *req; + struct file *file; + ssize_t ret; + + /* enforce forwards compatibility on users */ + if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2 || + iocb->aio_reserved3)) { + pr_debug("EINVAL: io_submit: reserve field set\n"); + return -EINVAL; + } + + /* prevent overflows */ + if (unlikely( + (iocb->aio_buf != (unsigned long)iocb->aio_buf) || + (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || + ((ssize_t)iocb->aio_nbytes < 0) + )) { + pr_debug("EINVAL: io_submit: overflow check\n"); + return -EINVAL; + } + + file = fget(iocb->aio_fildes); + if (unlikely(!file)) + return -EBADF; + + req = aio_get_req(ctx); /* returns with 2 references to req */ + if (unlikely(!req)) { + fput(file); + return -EAGAIN; + } + + req->ki_filp = file; + iocb->aio_key = req->ki_key; + ret = put_user(iocb->aio_key, &user_iocb->aio_key); + if (unlikely(ret)) { + dprintk("EFAULT: aio_key\n"); + goto out_put_req; + } + + req->ki_user_obj = user_iocb; + req->ki_user_data = iocb->aio_data; + req->ki_pos = iocb->aio_offset; + + req->ki_buf = (char *)(unsigned long)iocb->aio_buf; + req->ki_left = req->ki_nbytes = iocb->aio_nbytes; + req->ki_opcode = iocb->aio_lio_opcode; + init_waitqueue_func_entry(&req->ki_wait, aio_wake_function); + INIT_LIST_HEAD(&req->ki_wait.task_list); + req->ki_run_list.next = req->ki_run_list.prev = NULL; + req->ki_retry = NULL; + req->ki_retried = 0; + req->ki_kicked = 0; + req->ki_queued = 0; + aio_run = 0; + aio_wakeups = 0; + + ret = aio_setup_iocb(req); + + if (ret) + goto out_put_req; + + spin_lock_irq(&ctx->ctx_lock); + ret = aio_run_iocb(req); + spin_unlock_irq(&ctx->ctx_lock); + + if (-EIOCBRETRY == ret) + queue_work(aio_wq, &ctx->wq); + aio_put_req(req); /* drop extra ref to req */ + return 0; + +out_put_req: + aio_put_req(req); /* drop extra ref to req */ + aio_put_req(req); /* drop i/o ref to req */ + return ret; +} + +/* sys_io_submit: + * Queue the nr iocbs pointed to by iocbpp for processing. Returns + * the number of iocbs queued. May return -EINVAL if the aio_context + * specified by ctx_id is invalid, if nr is < 0, if the iocb at + * *iocbpp[0] is not properly initialized, if the operation specified + * is invalid for the file descriptor in the iocb. May fail with + * -EFAULT if any of the data structures point to invalid data. May + * fail with -EBADF if the file descriptor specified in the first + * iocb is invalid. May fail with -EAGAIN if insufficient resources + * are available to queue any iocbs. Will return 0 if nr is 0. Will + * fail with -ENOSYS if not implemented. + */ +asmlinkage long sys_io_submit(aio_context_t ctx_id, long nr, + struct iocb __user **iocbpp) +{ + struct kioctx *ctx; + long ret = 0; + int i; + + if (unlikely(nr < 0)) + return -EINVAL; + + if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) + return -EFAULT; + + ctx = lookup_ioctx(ctx_id); + if (unlikely(!ctx)) { + pr_debug("EINVAL: io_submit: invalid context id\n"); + return -EINVAL; + } + + /* + * AKPM: should this return a partial result if some of the IOs were + * successfully submitted? + */ + for (i=0; ictx_lock held. + */ +struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, u32 key) +{ + struct list_head *pos; + /* TODO: use a hash or array, this sucks. */ + list_for_each(pos, &ctx->active_reqs) { + struct kiocb *kiocb = list_kiocb(pos); + if (kiocb->ki_user_obj == iocb && kiocb->ki_key == key) + return kiocb; + } + return NULL; +} + +/* sys_io_cancel: + * Attempts to cancel an iocb previously passed to io_submit. If + * the operation is successfully cancelled, the resulting event is + * copied into the memory pointed to by result without being placed + * into the completion queue and 0 is returned. May fail with + * -EFAULT if any of the data structures pointed to are invalid. + * May fail with -EINVAL if aio_context specified by ctx_id is + * invalid. May fail with -EAGAIN if the iocb specified was not + * cancelled. Will fail with -ENOSYS if not implemented. + */ +asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb, + struct io_event __user *result) +{ + int (*cancel)(struct kiocb *iocb, struct io_event *res); + struct kioctx *ctx; + struct kiocb *kiocb; + u32 key; + int ret; + + ret = get_user(key, &iocb->aio_key); + if (unlikely(ret)) + return -EFAULT; + + ctx = lookup_ioctx(ctx_id); + if (unlikely(!ctx)) + return -EINVAL; + + spin_lock_irq(&ctx->ctx_lock); + ret = -EAGAIN; + kiocb = lookup_kiocb(ctx, iocb, key); + if (kiocb && kiocb->ki_cancel) { + cancel = kiocb->ki_cancel; + kiocb->ki_users ++; + } else + cancel = NULL; + spin_unlock_irq(&ctx->ctx_lock); + + if (NULL != cancel) { + struct io_event tmp; + pr_debug("calling cancel\n"); + memset(&tmp, 0, sizeof(tmp)); + tmp.obj = (u64)(unsigned long)kiocb->ki_user_obj; + tmp.data = kiocb->ki_user_data; + ret = cancel(kiocb, &tmp); + if (!ret) { + /* Cancellation succeeded -- copy the result + * into the user's buffer. + */ + if (copy_to_user(result, &tmp, sizeof(tmp))) + ret = -EFAULT; + } + } else + printk(KERN_DEBUG "iocb has no cancel operation\n"); + + put_ioctx(ctx); + + return ret; +} + +/* io_getevents: + * Attempts to read at least min_nr events and up to nr events from + * the completion queue for the aio_context specified by ctx_id. May + * fail with -EINVAL if ctx_id is invalid, if min_nr is out of range, + * if nr is out of range, if when is out of range. May fail with + * -EFAULT if any of the memory specified to is invalid. May return + * 0 or < min_nr if no events are available and the timeout specified + * by when has elapsed, where when == NULL specifies an infinite + * timeout. Note that the timeout pointed to by when is relative and + * will be updated if not NULL and the operation blocks. Will fail + * with -ENOSYS if not implemented. + */ +asmlinkage long sys_io_getevents(aio_context_t ctx_id, + long min_nr, + long nr, + struct io_event __user *events, + struct timespec __user *timeout) +{ + struct kioctx *ioctx = lookup_ioctx(ctx_id); + long ret = -EINVAL; + + if (likely(ioctx)) { + if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0)) + ret = read_events(ioctx, min_nr, nr, events, timeout); + put_ioctx(ioctx); + } + + return ret; +} + +__initcall(aio_setup); + +EXPORT_SYMBOL(aio_complete); +EXPORT_SYMBOL(aio_put_req); +EXPORT_SYMBOL(wait_on_sync_kiocb); diff -upN reference/include/linux/aio.h current/include/linux/aio.h --- reference/include/linux/aio.h 2004-04-07 14:54:36.000000000 -0700 +++ current/include/linux/aio.h 2004-05-09 13:45:18.000000000 -0700 @@ -54,7 +54,7 @@ struct kiocb { struct file *ki_filp; struct kioctx *ki_ctx; /* may be NULL for sync ops */ int (*ki_cancel)(struct kiocb *, struct io_event *); - long (*ki_retry)(struct kiocb *); + ssize_t (*ki_retry)(struct kiocb *); struct list_head ki_list; /* the aio core uses this * for cancellation */ @@ -63,6 +63,16 @@ struct kiocb { __u64 ki_user_data; /* user's data for completion */ loff_t ki_pos; + /* State that we remember to be able to restart/retry */ + unsigned short ki_opcode; + size_t ki_nbytes; /* copy of iocb->aio_nbytes */ + char *ki_buf; /* remaining iocb->aio_buf */ + size_t ki_left; /* remaining bytes */ + wait_queue_t ki_wait; + long ki_retried; /* just for testing */ + long ki_kicked; /* just for testing */ + long ki_queued; /* just for testing */ + char private[KIOCB_PRIVATE_SIZE]; }; @@ -77,6 +87,8 @@ struct kiocb { (x)->ki_ctx = &tsk->active_mm->default_kioctx; \ (x)->ki_cancel = NULL; \ (x)->ki_user_obj = tsk; \ + (x)->ki_user_data = 0; \ + init_wait((&(x)->ki_wait)); \ } while (0) #define AIO_RING_MAGIC 0xa10a10a1 @@ -159,6 +171,17 @@ int FASTCALL(io_submit_one(struct kioctx #define get_ioctx(kioctx) do { if (unlikely(atomic_read(&(kioctx)->users) <= 0)) BUG(); atomic_inc(&(kioctx)->users); } while (0) #define put_ioctx(kioctx) do { if (unlikely(atomic_dec_and_test(&(kioctx)->users))) __put_ioctx(kioctx); else if (unlikely(atomic_read(&(kioctx)->users) < 0)) BUG(); } while (0) +#define in_aio() !is_sync_wait(current->io_wait) +/* may be used for debugging */ +#define warn_if_async() if (in_aio()) {\ + printk(KERN_ERR "%s(%s:%d) called in async context!\n", \ + __FUNCTION__, __FILE__, __LINE__); \ + dump_stack(); \ + } + +#define io_wait_to_kiocb(wait) container_of(wait, struct kiocb, ki_wait) +#define is_retried_kiocb(iocb) ((iocb)->ki_retried > 1) + #include static inline struct kiocb *list_kiocb(struct list_head *h) diff -upN reference/include/linux/errno.h current/include/linux/errno.h --- reference/include/linux/errno.h 2002-12-09 18:46:15.000000000 -0800 +++ current/include/linux/errno.h 2004-05-09 13:45:18.000000000 -0700 @@ -22,6 +22,7 @@ #define EBADTYPE 527 /* Type not supported by server */ #define EJUKEBOX 528 /* Request initiated, but will not complete before timeout */ #define EIOCBQUEUED 529 /* iocb queued, will get completion event */ +#define EIOCBRETRY 530 /* iocb queued, will trigger a retry */ #endif diff -upN reference/include/linux/init_task.h current/include/linux/init_task.h --- reference/include/linux/init_task.h 2004-05-09 13:44:20.000000000 -0700 +++ current/include/linux/init_task.h 2004-05-09 13:45:18.000000000 -0700 @@ -113,6 +113,7 @@ extern struct group_info init_groups; .switch_lock = SPIN_LOCK_UNLOCKED, \ .journal_info = NULL, \ .map_base = __TASK_UNMAPPED_BASE, \ + .io_wait = NULL, \ } diff -upN reference/include/linux/sched.h current/include/linux/sched.h --- reference/include/linux/sched.h 2004-05-09 13:44:24.000000000 -0700 +++ current/include/linux/sched.h 2004-05-09 13:45:18.000000000 -0700 @@ -543,6 +543,13 @@ struct task_struct { struct mempolicy *mempolicy; short il_next; /* could be shared with used_math */ +/* + * current io wait handle: wait queue entry to use for io waits + * If this thread is processing aio, this points at the waitqueue + * inside the currently handled kiocb. It may be NULL (i.e. default + * to a stack based synchronous wait) if its doing sync IO. + */ + wait_queue_t *io_wait; }; static inline pid_t process_group(struct task_struct *tsk) diff -upN reference/include/linux/wait.h current/include/linux/wait.h --- reference/include/linux/wait.h 2003-10-01 11:47:14.000000000 -0700 +++ current/include/linux/wait.h 2004-05-09 13:45:18.000000000 -0700 @@ -80,6 +80,15 @@ static inline int waitqueue_active(wait_ return !list_empty(&q->task_list); } +/* + * Used to distinguish between sync and async io wait context: + * sync i/o typically specifies a NULL wait queue entry or a wait + * queue entry bound to a task (current task) to wake up. + * aio specifies a wait queue entry with an async notification + * callback routine, not associated with any task. + */ +#define is_sync_wait(wait) (!(wait) || ((wait)->task)) + extern void FASTCALL(add_wait_queue(wait_queue_head_t *q, wait_queue_t * wait)); extern void FASTCALL(add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t * wait)); extern void FASTCALL(remove_wait_queue(wait_queue_head_t *q, wait_queue_t * wait)); diff -upN reference/kernel/fork.c current/kernel/fork.c --- reference/kernel/fork.c 2004-05-09 13:44:24.000000000 -0700 +++ current/kernel/fork.c 2004-05-09 13:45:18.000000000 -0700 @@ -149,7 +149,12 @@ void fastcall prepare_to_wait(wait_queue spin_lock_irqsave(&q->lock, flags); if (list_empty(&wait->task_list)) __add_wait_queue(q, wait); - set_current_state(state); + /* + * don't alter the task state if this is just going to + * queue an async wait queue callback + */ + if (is_sync_wait(wait)) + set_current_state(state); spin_unlock_irqrestore(&q->lock, flags); } @@ -164,7 +169,12 @@ prepare_to_wait_exclusive(wait_queue_hea spin_lock_irqsave(&q->lock, flags); if (list_empty(&wait->task_list)) __add_wait_queue_tail(q, wait); - set_current_state(state); + /* + * don't alter the task state if this is just going to + * queue an async wait queue callback + */ + if (is_sync_wait(wait)) + set_current_state(state); spin_unlock_irqrestore(&q->lock, flags); } @@ -970,6 +980,7 @@ struct task_struct *copy_process(unsigne p->start_time = get_jiffies_64(); p->security = NULL; p->io_context = NULL; + p->io_wait = NULL; p->audit_context = NULL; p->mempolicy = mpol_copy(p->mempolicy); if (IS_ERR(p->mempolicy)) {