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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /fs/aio.c
downloadlinux-stericsson-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'fs/aio.c')
-rw-r--r--fs/aio.c1729
1 files changed, 1729 insertions, 0 deletions
diff --git a/fs/aio.c b/fs/aio.c
new file mode 100644
index 000000000000..d06a266769bc
--- /dev/null
+++ b/fs/aio.c
@@ -0,0 +1,1729 @@
+/*
+ * An async IO implementation for Linux
+ * Written by Benjamin LaHaise <bcrl@kvack.org>
+ *
+ * Implements an efficient asynchronous io interface.
+ *
+ * Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved.
+ *
+ * See ../COPYING for licensing terms.
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/time.h>
+#include <linux/aio_abi.h>
+#include <linux/module.h>
+#include <linux/syscalls.h>
+
+#define DEBUG 0
+
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/slab.h>
+#include <linux/timer.h>
+#include <linux/aio.h>
+#include <linux/highmem.h>
+#include <linux/workqueue.h>
+#include <linux/security.h>
+
+#include <asm/kmap_types.h>
+#include <asm/uaccess.h>
+#include <asm/mmu_context.h>
+
+#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 DEFINE_SPINLOCK(fput_lock);
+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; i<info->nr_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;
+
+ 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;
+
+ /* 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);
+
+ if (aio_setup_ring(ctx) < 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(-ENOMEM);
+
+ 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();
+
+ cancel_delayed_work(&ctx->wq);
+ flush_workqueue(aio_wq);
+ 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_obj.user = NULL;
+ req->ki_dtor = NULL;
+ req->private = 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)
+{
+ if (req->ki_dtor)
+ req->ki_dtor(req);
+ req->ki_ctx = NULL;
+ req->ki_filp = NULL;
+ req->ki_obj.user = NULL;
+ req->ki_dtor = NULL;
+ req->private = 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;
+}
+
+/*
+ * 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)
+ */
+static void use_mm(struct mm_struct *mm)
+{
+ struct mm_struct *active_mm;
+ struct task_struct *tsk = current;
+
+ task_lock(tsk);
+ tsk->flags |= PF_BORROWED_MM;
+ active_mm = tsk->active_mm;
+ atomic_inc(&mm->mm_count);
+ tsk->mm = mm;
+ tsk->active_mm = mm;
+ activate_mm(active_mm, mm);
+ task_unlock(tsk);
+
+ mmdrop(active_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)
+{
+ struct task_struct *tsk = current;
+
+ task_lock(tsk);
+ tsk->flags &= ~PF_BORROWED_MM;
+ tsk->mm = NULL;
+ /* active_mm is still 'mm' */
+ enter_lazy_tlb(mm, tsk);
+ task_unlock(tsk);
+}
+
+/*
+ * 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 inline int __queue_kicked_iocb(struct kiocb *iocb)
+{
+ struct kioctx *ctx = iocb->ki_ctx;
+
+ if (list_empty(&iocb->ki_run_list)) {
+ list_add_tail(&iocb->ki_run_list,
+ &ctx->run_list);
+ iocb->ki_queued++;
+ return 1;
+ }
+ return 0;
+}
+
+/* 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;
+
+ 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;
+ }
+
+ /*
+ * 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);
+ /* 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);
+
+ 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 int __aio_run_iocbs(struct kioctx *ctx)
+{
+ struct kiocb *iocb;
+ int count = 0;
+ LIST_HEAD(run_list);
+
+ list_splice_init(&ctx->run_list, &run_list);
+ while (!list_empty(&run_list)) {
+ iocb = list_entry(run_list.next, struct kiocb,
+ ki_run_list);
+ list_del(&iocb->ki_run_list);
+ /*
+ * Hold an extra reference while retrying i/o.
+ */
+ iocb->ki_users++; /* grab extra reference */
+ aio_run_iocb(iocb);
+ if (__aio_put_req(ctx, iocb)) /* drop extra ref */
+ put_ioctx(ctx);
+ count++;
+ }
+ aio_run++;
+ if (!list_empty(&ctx->run_list))
+ return 1;
+ return 0;
+}
+
+static void aio_queue_work(struct kioctx * ctx)
+{
+ unsigned long timeout;
+ /*
+ * if someone is waiting, get the work started right
+ * away, otherwise, use a longer delay
+ */
+ smp_mb();
+ if (waitqueue_active(&ctx->wait))
+ timeout = 1;
+ else
+ timeout = HZ/10;
+ queue_delayed_work(aio_wq, &ctx->wq, timeout);
+}
+
+
+/*
+ * 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)
+{
+ int requeue;
+
+ spin_lock_irq(&ctx->ctx_lock);
+
+ requeue = __aio_run_iocbs(ctx);
+ spin_unlock_irq(&ctx->ctx_lock);
+ if (requeue)
+ aio_queue_work(ctx);
+}
+
+/*
+ * just like aio_run_iocbs, but keeps running them until
+ * the list stays empty
+ */
+static inline void aio_run_all_iocbs(struct kioctx *ctx)
+{
+ spin_lock_irq(&ctx->ctx_lock);
+ while (__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, so that
+ * copy_xxx_user operates on the issuer's address
+ * space.
+ * Run on aiod's context.
+ */
+static void aio_kick_handler(void *data)
+{
+ struct kioctx *ctx = data;
+ mm_segment_t oldfs = get_fs();
+ int requeue;
+
+ set_fs(USER_DS);
+ use_mm(ctx->mm);
+ spin_lock_irq(&ctx->ctx_lock);
+ requeue =__aio_run_iocbs(ctx);
+ unuse_mm(ctx->mm);
+ spin_unlock_irq(&ctx->ctx_lock);
+ set_fs(oldfs);
+ /*
+ * we're in a worker thread already, don't use queue_delayed_work,
+ */
+ if (requeue)
+ queue_work(aio_wq, &ctx->wq);
+}
+
+
+/*
+ * 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) {
+ aio_queue_work(ctx);
+ 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)) {
+ kiocbSetKicked(iocb);
+ wake_up_process(iocb->ki_obj.tsk);
+ return;
+ }
+
+ iocb->ki_kicked++;
+ /* If its already kicked we shouldn't queue it again */
+ if (!kiocbTryKick(iocb)) {
+ queue_kicked_iocb(iocb);
+ }
+}
+EXPORT_SYMBOL(kick_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_obj.tsk);
+ 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);
+
+ /*
+ * cancelled requests don't get events, userland was given one
+ * when the event got cancelled.
+ */
+ if (kiocbIsCancelled(iocb))
+ goto put_rq;
+
+ 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_obj.user;
+ 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_obj.user, 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);
+put_rq:
+ /* 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 aio_timeout {
+ struct timer_list timer;
+ int timed_out;
+ struct task_struct *p;
+};
+
+static void timeout_func(unsigned long data)
+{
+ struct aio_timeout *to = (struct aio_timeout *)data;
+
+ to->timed_out = 1;
+ wake_up_process(to->p);
+}
+
+static inline void init_timeout(struct aio_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 aio_timeout *to,
+ const struct timespec *ts)
+{
+ to->timer.expires = start_jiffies + timespec_to_jiffies(ts);
+ if (time_after(to->timer.expires, jiffies))
+ add_timer(&to->timer);
+ else
+ to->timed_out = 1;
+}
+
+static inline void clear_timeout(struct aio_timeout *to)
+{
+ del_singleshot_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 aio_timeout to;
+ int event_loop = 0; /* testing only */
+ int retry = 0;
+
+ /* needed to zero any padding within an entry (there shouldn't be
+ * any, but C is fun!
+ */
+ memset(&ent, 0, sizeof(ent));
+retry:
+ 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 */
+
+ /* racey check, but it gets redone */
+ if (!retry && unlikely(!list_empty(&ctx->run_list))) {
+ retry = 1;
+ aio_run_all_iocbs(ctx);
+ goto retry;
+ }
+
+ 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);
+ 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 __user *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;
+
+ get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */
+ 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;
+}
+
+/*
+ * Default 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;
+ struct address_space *mapping = file->f_mapping;
+ struct inode *inode = mapping->host;
+ 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;
+ /*
+ * For pipes and sockets we return once we have
+ * some data; for regular files we retry till we
+ * complete the entire read or find that we can't
+ * read any more data (e.g short reads).
+ */
+ if (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))
+ 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;
+}
+
+/*
+ * Default 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);
+
+ 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;
+}
+
+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, void *key)
+{
+ 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_obj.user = user_iocb;
+ req->ki_user_data = iocb->aio_data;
+ req->ki_pos = iocb->aio_offset;
+
+ req->ki_buf = (char __user *)(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);
+ list_add_tail(&req->ki_run_list, &ctx->run_list);
+ /* drain the run list */
+ while (__aio_run_iocbs(ctx))
+ ;
+ spin_unlock_irq(&ctx->ctx_lock);
+ 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 * __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; i<nr; i++) {
+ struct iocb __user *user_iocb;
+ struct iocb tmp;
+
+ if (unlikely(__get_user(user_iocb, iocbpp + i))) {
+ ret = -EFAULT;
+ break;
+ }
+
+ if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
+ ret = -EFAULT;
+ break;
+ }
+
+ ret = io_submit_one(ctx, user_iocb, &tmp);
+ if (ret)
+ break;
+ }
+
+ put_ioctx(ctx);
+ return i ? i : ret;
+}
+
+/* lookup_kiocb
+ * Finds a given iocb for cancellation.
+ * MUST be called with ctx->ctx_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_obj.user == 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 ++;
+ kiocbSetCancelled(kiocb);
+ } 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_obj.user;
+ 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);