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-rw-r--r--fs/aio.c2416
1 files changed, 2416 insertions, 0 deletions
diff --git a/fs/aio.c b/fs/aio.c
new file mode 100644
index 000000000..e85ba0b77
--- /dev/null
+++ b/fs/aio.c
@@ -0,0 +1,2416 @@
+/*
+ * 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.
+ * Copyright 2018 Christoph Hellwig.
+ *
+ * See ../COPYING for licensing terms.
+ */
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/time.h>
+#include <linux/aio_abi.h>
+#include <linux/export.h>
+#include <linux/syscalls.h>
+#include <linux/backing-dev.h>
+#include <linux/refcount.h>
+#include <linux/uio.h>
+
+#include <linux/sched/signal.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/percpu.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 <linux/eventfd.h>
+#include <linux/blkdev.h>
+#include <linux/compat.h>
+#include <linux/migrate.h>
+#include <linux/ramfs.h>
+#include <linux/percpu-refcount.h>
+#include <linux/mount.h>
+#include <linux/pseudo_fs.h>
+
+#include <linux/uaccess.h>
+#include <linux/nospec.h>
+
+#include "internal.h"
+
+#define KIOCB_KEY 0
+
+#define AIO_RING_MAGIC 0xa10a10a1
+#define AIO_RING_COMPAT_FEATURES 1
+#define AIO_RING_INCOMPAT_FEATURES 0
+struct aio_ring {
+ unsigned id; /* kernel internal index number */
+ unsigned nr; /* number of io_events */
+ unsigned head; /* Written to by userland or under ring_lock
+ * mutex by aio_read_events_ring(). */
+ unsigned tail;
+
+ unsigned magic;
+ unsigned compat_features;
+ unsigned incompat_features;
+ unsigned header_length; /* size of aio_ring */
+
+
+ struct io_event io_events[];
+}; /* 128 bytes + ring size */
+
+/*
+ * Plugging is meant to work with larger batches of IOs. If we don't
+ * have more than the below, then don't bother setting up a plug.
+ */
+#define AIO_PLUG_THRESHOLD 2
+
+#define AIO_RING_PAGES 8
+
+struct kioctx_table {
+ struct rcu_head rcu;
+ unsigned nr;
+ struct kioctx __rcu *table[];
+};
+
+struct kioctx_cpu {
+ unsigned reqs_available;
+};
+
+struct ctx_rq_wait {
+ struct completion comp;
+ atomic_t count;
+};
+
+struct kioctx {
+ struct percpu_ref users;
+ atomic_t dead;
+
+ struct percpu_ref reqs;
+
+ unsigned long user_id;
+
+ struct __percpu kioctx_cpu *cpu;
+
+ /*
+ * For percpu reqs_available, number of slots we move to/from global
+ * counter at a time:
+ */
+ unsigned req_batch;
+ /*
+ * This is what userspace passed to io_setup(), it's not used for
+ * anything but counting against the global max_reqs quota.
+ *
+ * The real limit is nr_events - 1, which will be larger (see
+ * aio_setup_ring())
+ */
+ unsigned max_reqs;
+
+ /* Size of ringbuffer, in units of struct io_event */
+ unsigned nr_events;
+
+ unsigned long mmap_base;
+ unsigned long mmap_size;
+
+ struct page **ring_pages;
+ long nr_pages;
+
+ struct rcu_work free_rwork; /* see free_ioctx() */
+
+ /*
+ * signals when all in-flight requests are done
+ */
+ struct ctx_rq_wait *rq_wait;
+
+ struct {
+ /*
+ * This counts the number of available slots in the ringbuffer,
+ * so we avoid overflowing it: it's decremented (if positive)
+ * when allocating a kiocb and incremented when the resulting
+ * io_event is pulled off the ringbuffer.
+ *
+ * We batch accesses to it with a percpu version.
+ */
+ atomic_t reqs_available;
+ } ____cacheline_aligned_in_smp;
+
+ struct {
+ spinlock_t ctx_lock;
+ struct list_head active_reqs; /* used for cancellation */
+ } ____cacheline_aligned_in_smp;
+
+ struct {
+ struct mutex ring_lock;
+ wait_queue_head_t wait;
+ } ____cacheline_aligned_in_smp;
+
+ struct {
+ unsigned tail;
+ unsigned completed_events;
+ spinlock_t completion_lock;
+ } ____cacheline_aligned_in_smp;
+
+ struct page *internal_pages[AIO_RING_PAGES];
+ struct file *aio_ring_file;
+
+ unsigned id;
+};
+
+/*
+ * First field must be the file pointer in all the
+ * iocb unions! See also 'struct kiocb' in <linux/fs.h>
+ */
+struct fsync_iocb {
+ struct file *file;
+ struct work_struct work;
+ bool datasync;
+ struct cred *creds;
+};
+
+struct poll_iocb {
+ struct file *file;
+ struct wait_queue_head *head;
+ __poll_t events;
+ bool cancelled;
+ bool work_scheduled;
+ bool work_need_resched;
+ struct wait_queue_entry wait;
+ struct work_struct work;
+};
+
+/*
+ * NOTE! Each of the iocb union members has the file pointer
+ * as the first entry in their struct definition. So you can
+ * access the file pointer through any of the sub-structs,
+ * or directly as just 'ki_filp' in this struct.
+ */
+struct aio_kiocb {
+ union {
+ struct file *ki_filp;
+ struct kiocb rw;
+ struct fsync_iocb fsync;
+ struct poll_iocb poll;
+ };
+
+ struct kioctx *ki_ctx;
+ kiocb_cancel_fn *ki_cancel;
+
+ struct io_event ki_res;
+
+ struct list_head ki_list; /* the aio core uses this
+ * for cancellation */
+ refcount_t ki_refcnt;
+
+ /*
+ * If the aio_resfd field of the userspace iocb is not zero,
+ * this is the underlying eventfd context to deliver events to.
+ */
+ struct eventfd_ctx *ki_eventfd;
+};
+
+/*------ sysctl variables----*/
+static DEFINE_SPINLOCK(aio_nr_lock);
+static unsigned long aio_nr; /* current system wide number of aio requests */
+static unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
+/*----end sysctl variables---*/
+#ifdef CONFIG_SYSCTL
+static struct ctl_table aio_sysctls[] = {
+ {
+ .procname = "aio-nr",
+ .data = &aio_nr,
+ .maxlen = sizeof(aio_nr),
+ .mode = 0444,
+ .proc_handler = proc_doulongvec_minmax,
+ },
+ {
+ .procname = "aio-max-nr",
+ .data = &aio_max_nr,
+ .maxlen = sizeof(aio_max_nr),
+ .mode = 0644,
+ .proc_handler = proc_doulongvec_minmax,
+ },
+ {}
+};
+
+static void __init aio_sysctl_init(void)
+{
+ register_sysctl_init("fs", aio_sysctls);
+}
+#else
+#define aio_sysctl_init() do { } while (0)
+#endif
+
+static struct kmem_cache *kiocb_cachep;
+static struct kmem_cache *kioctx_cachep;
+
+static struct vfsmount *aio_mnt;
+
+static const struct file_operations aio_ring_fops;
+static const struct address_space_operations aio_ctx_aops;
+
+static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
+{
+ struct file *file;
+ struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
+ if (IS_ERR(inode))
+ return ERR_CAST(inode);
+
+ inode->i_mapping->a_ops = &aio_ctx_aops;
+ inode->i_mapping->private_data = ctx;
+ inode->i_size = PAGE_SIZE * nr_pages;
+
+ file = alloc_file_pseudo(inode, aio_mnt, "[aio]",
+ O_RDWR, &aio_ring_fops);
+ if (IS_ERR(file))
+ iput(inode);
+ return file;
+}
+
+static int aio_init_fs_context(struct fs_context *fc)
+{
+ if (!init_pseudo(fc, AIO_RING_MAGIC))
+ return -ENOMEM;
+ fc->s_iflags |= SB_I_NOEXEC;
+ return 0;
+}
+
+/* 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)
+{
+ static struct file_system_type aio_fs = {
+ .name = "aio",
+ .init_fs_context = aio_init_fs_context,
+ .kill_sb = kill_anon_super,
+ };
+ aio_mnt = kern_mount(&aio_fs);
+ if (IS_ERR(aio_mnt))
+ panic("Failed to create aio fs mount.");
+
+ kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
+ kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
+ aio_sysctl_init();
+ return 0;
+}
+__initcall(aio_setup);
+
+static void put_aio_ring_file(struct kioctx *ctx)
+{
+ struct file *aio_ring_file = ctx->aio_ring_file;
+ struct address_space *i_mapping;
+
+ if (aio_ring_file) {
+ truncate_setsize(file_inode(aio_ring_file), 0);
+
+ /* Prevent further access to the kioctx from migratepages */
+ i_mapping = aio_ring_file->f_mapping;
+ spin_lock(&i_mapping->private_lock);
+ i_mapping->private_data = NULL;
+ ctx->aio_ring_file = NULL;
+ spin_unlock(&i_mapping->private_lock);
+
+ fput(aio_ring_file);
+ }
+}
+
+static void aio_free_ring(struct kioctx *ctx)
+{
+ int i;
+
+ /* Disconnect the kiotx from the ring file. This prevents future
+ * accesses to the kioctx from page migration.
+ */
+ put_aio_ring_file(ctx);
+
+ for (i = 0; i < ctx->nr_pages; i++) {
+ struct page *page;
+ pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
+ page_count(ctx->ring_pages[i]));
+ page = ctx->ring_pages[i];
+ if (!page)
+ continue;
+ ctx->ring_pages[i] = NULL;
+ put_page(page);
+ }
+
+ if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
+ kfree(ctx->ring_pages);
+ ctx->ring_pages = NULL;
+ }
+}
+
+static int aio_ring_mremap(struct vm_area_struct *vma)
+{
+ struct file *file = vma->vm_file;
+ struct mm_struct *mm = vma->vm_mm;
+ struct kioctx_table *table;
+ int i, res = -EINVAL;
+
+ spin_lock(&mm->ioctx_lock);
+ rcu_read_lock();
+ table = rcu_dereference(mm->ioctx_table);
+ if (!table)
+ goto out_unlock;
+
+ for (i = 0; i < table->nr; i++) {
+ struct kioctx *ctx;
+
+ ctx = rcu_dereference(table->table[i]);
+ if (ctx && ctx->aio_ring_file == file) {
+ if (!atomic_read(&ctx->dead)) {
+ ctx->user_id = ctx->mmap_base = vma->vm_start;
+ res = 0;
+ }
+ break;
+ }
+ }
+
+out_unlock:
+ rcu_read_unlock();
+ spin_unlock(&mm->ioctx_lock);
+ return res;
+}
+
+static const struct vm_operations_struct aio_ring_vm_ops = {
+ .mremap = aio_ring_mremap,
+#if IS_ENABLED(CONFIG_MMU)
+ .fault = filemap_fault,
+ .map_pages = filemap_map_pages,
+ .page_mkwrite = filemap_page_mkwrite,
+#endif
+};
+
+static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ vma->vm_flags |= VM_DONTEXPAND;
+ vma->vm_ops = &aio_ring_vm_ops;
+ return 0;
+}
+
+static const struct file_operations aio_ring_fops = {
+ .mmap = aio_ring_mmap,
+};
+
+#if IS_ENABLED(CONFIG_MIGRATION)
+static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
+ struct folio *src, enum migrate_mode mode)
+{
+ struct kioctx *ctx;
+ unsigned long flags;
+ pgoff_t idx;
+ int rc;
+
+ /*
+ * We cannot support the _NO_COPY case here, because copy needs to
+ * happen under the ctx->completion_lock. That does not work with the
+ * migration workflow of MIGRATE_SYNC_NO_COPY.
+ */
+ if (mode == MIGRATE_SYNC_NO_COPY)
+ return -EINVAL;
+
+ rc = 0;
+
+ /* mapping->private_lock here protects against the kioctx teardown. */
+ spin_lock(&mapping->private_lock);
+ ctx = mapping->private_data;
+ if (!ctx) {
+ rc = -EINVAL;
+ goto out;
+ }
+
+ /* The ring_lock mutex. The prevents aio_read_events() from writing
+ * to the ring's head, and prevents page migration from mucking in
+ * a partially initialized kiotx.
+ */
+ if (!mutex_trylock(&ctx->ring_lock)) {
+ rc = -EAGAIN;
+ goto out;
+ }
+
+ idx = src->index;
+ if (idx < (pgoff_t)ctx->nr_pages) {
+ /* Make sure the old folio hasn't already been changed */
+ if (ctx->ring_pages[idx] != &src->page)
+ rc = -EAGAIN;
+ } else
+ rc = -EINVAL;
+
+ if (rc != 0)
+ goto out_unlock;
+
+ /* Writeback must be complete */
+ BUG_ON(folio_test_writeback(src));
+ folio_get(dst);
+
+ rc = folio_migrate_mapping(mapping, dst, src, 1);
+ if (rc != MIGRATEPAGE_SUCCESS) {
+ folio_put(dst);
+ goto out_unlock;
+ }
+
+ /* Take completion_lock to prevent other writes to the ring buffer
+ * while the old folio is copied to the new. This prevents new
+ * events from being lost.
+ */
+ spin_lock_irqsave(&ctx->completion_lock, flags);
+ folio_migrate_copy(dst, src);
+ BUG_ON(ctx->ring_pages[idx] != &src->page);
+ ctx->ring_pages[idx] = &dst->page;
+ spin_unlock_irqrestore(&ctx->completion_lock, flags);
+
+ /* The old folio is no longer accessible. */
+ folio_put(src);
+
+out_unlock:
+ mutex_unlock(&ctx->ring_lock);
+out:
+ spin_unlock(&mapping->private_lock);
+ return rc;
+}
+#else
+#define aio_migrate_folio NULL
+#endif
+
+static const struct address_space_operations aio_ctx_aops = {
+ .dirty_folio = noop_dirty_folio,
+ .migrate_folio = aio_migrate_folio,
+};
+
+static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
+{
+ struct aio_ring *ring;
+ struct mm_struct *mm = current->mm;
+ unsigned long size, unused;
+ int nr_pages;
+ int i;
+ struct file *file;
+
+ /* 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 = PFN_UP(size);
+ if (nr_pages < 0)
+ return -EINVAL;
+
+ file = aio_private_file(ctx, nr_pages);
+ if (IS_ERR(file)) {
+ ctx->aio_ring_file = NULL;
+ return -ENOMEM;
+ }
+
+ ctx->aio_ring_file = file;
+ nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
+ / sizeof(struct io_event);
+
+ ctx->ring_pages = ctx->internal_pages;
+ if (nr_pages > AIO_RING_PAGES) {
+ ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
+ GFP_KERNEL);
+ if (!ctx->ring_pages) {
+ put_aio_ring_file(ctx);
+ return -ENOMEM;
+ }
+ }
+
+ for (i = 0; i < nr_pages; i++) {
+ struct page *page;
+ page = find_or_create_page(file->f_mapping,
+ i, GFP_HIGHUSER | __GFP_ZERO);
+ if (!page)
+ break;
+ pr_debug("pid(%d) page[%d]->count=%d\n",
+ current->pid, i, page_count(page));
+ SetPageUptodate(page);
+ unlock_page(page);
+
+ ctx->ring_pages[i] = page;
+ }
+ ctx->nr_pages = i;
+
+ if (unlikely(i != nr_pages)) {
+ aio_free_ring(ctx);
+ return -ENOMEM;
+ }
+
+ ctx->mmap_size = nr_pages * PAGE_SIZE;
+ pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
+
+ if (mmap_write_lock_killable(mm)) {
+ ctx->mmap_size = 0;
+ aio_free_ring(ctx);
+ return -EINTR;
+ }
+
+ ctx->mmap_base = do_mmap(ctx->aio_ring_file, 0, ctx->mmap_size,
+ PROT_READ | PROT_WRITE,
+ MAP_SHARED, 0, &unused, NULL);
+ mmap_write_unlock(mm);
+ if (IS_ERR((void *)ctx->mmap_base)) {
+ ctx->mmap_size = 0;
+ aio_free_ring(ctx);
+ return -ENOMEM;
+ }
+
+ pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
+
+ ctx->user_id = ctx->mmap_base;
+ ctx->nr_events = nr_events; /* trusted copy */
+
+ ring = kmap_atomic(ctx->ring_pages[0]);
+ ring->nr = nr_events; /* user copy */
+ ring->id = ~0U;
+ 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);
+ flush_dcache_page(ctx->ring_pages[0]);
+
+ return 0;
+}
+
+#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)
+
+void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
+{
+ struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, rw);
+ struct kioctx *ctx = req->ki_ctx;
+ unsigned long flags;
+
+ if (WARN_ON_ONCE(!list_empty(&req->ki_list)))
+ return;
+
+ spin_lock_irqsave(&ctx->ctx_lock, flags);
+ list_add_tail(&req->ki_list, &ctx->active_reqs);
+ req->ki_cancel = cancel;
+ spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+}
+EXPORT_SYMBOL(kiocb_set_cancel_fn);
+
+/*
+ * free_ioctx() should be RCU delayed to synchronize against the RCU
+ * protected lookup_ioctx() and also needs process context to call
+ * aio_free_ring(). Use rcu_work.
+ */
+static void free_ioctx(struct work_struct *work)
+{
+ struct kioctx *ctx = container_of(to_rcu_work(work), struct kioctx,
+ free_rwork);
+ pr_debug("freeing %p\n", ctx);
+
+ aio_free_ring(ctx);
+ free_percpu(ctx->cpu);
+ percpu_ref_exit(&ctx->reqs);
+ percpu_ref_exit(&ctx->users);
+ kmem_cache_free(kioctx_cachep, ctx);
+}
+
+static void free_ioctx_reqs(struct percpu_ref *ref)
+{
+ struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
+
+ /* At this point we know that there are no any in-flight requests */
+ if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
+ complete(&ctx->rq_wait->comp);
+
+ /* Synchronize against RCU protected table->table[] dereferences */
+ INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
+ queue_rcu_work(system_wq, &ctx->free_rwork);
+}
+
+/*
+ * When this function runs, the kioctx has been removed from the "hash table"
+ * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
+ * now it's safe to cancel any that need to be.
+ */
+static void free_ioctx_users(struct percpu_ref *ref)
+{
+ struct kioctx *ctx = container_of(ref, struct kioctx, users);
+ struct aio_kiocb *req;
+
+ spin_lock_irq(&ctx->ctx_lock);
+
+ while (!list_empty(&ctx->active_reqs)) {
+ req = list_first_entry(&ctx->active_reqs,
+ struct aio_kiocb, ki_list);
+ req->ki_cancel(&req->rw);
+ list_del_init(&req->ki_list);
+ }
+
+ spin_unlock_irq(&ctx->ctx_lock);
+
+ percpu_ref_kill(&ctx->reqs);
+ percpu_ref_put(&ctx->reqs);
+}
+
+static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
+{
+ unsigned i, new_nr;
+ struct kioctx_table *table, *old;
+ struct aio_ring *ring;
+
+ spin_lock(&mm->ioctx_lock);
+ table = rcu_dereference_raw(mm->ioctx_table);
+
+ while (1) {
+ if (table)
+ for (i = 0; i < table->nr; i++)
+ if (!rcu_access_pointer(table->table[i])) {
+ ctx->id = i;
+ rcu_assign_pointer(table->table[i], ctx);
+ spin_unlock(&mm->ioctx_lock);
+
+ /* While kioctx setup is in progress,
+ * we are protected from page migration
+ * changes ring_pages by ->ring_lock.
+ */
+ ring = kmap_atomic(ctx->ring_pages[0]);
+ ring->id = ctx->id;
+ kunmap_atomic(ring);
+ return 0;
+ }
+
+ new_nr = (table ? table->nr : 1) * 4;
+ spin_unlock(&mm->ioctx_lock);
+
+ table = kzalloc(struct_size(table, table, new_nr), GFP_KERNEL);
+ if (!table)
+ return -ENOMEM;
+
+ table->nr = new_nr;
+
+ spin_lock(&mm->ioctx_lock);
+ old = rcu_dereference_raw(mm->ioctx_table);
+
+ if (!old) {
+ rcu_assign_pointer(mm->ioctx_table, table);
+ } else if (table->nr > old->nr) {
+ memcpy(table->table, old->table,
+ old->nr * sizeof(struct kioctx *));
+
+ rcu_assign_pointer(mm->ioctx_table, table);
+ kfree_rcu(old, rcu);
+ } else {
+ kfree(table);
+ table = old;
+ }
+ }
+}
+
+static void aio_nr_sub(unsigned nr)
+{
+ spin_lock(&aio_nr_lock);
+ if (WARN_ON(aio_nr - nr > aio_nr))
+ aio_nr = 0;
+ else
+ aio_nr -= nr;
+ spin_unlock(&aio_nr_lock);
+}
+
+/* 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 = current->mm;
+ struct kioctx *ctx;
+ int err = -ENOMEM;
+
+ /*
+ * Store the original nr_events -- what userspace passed to io_setup(),
+ * for counting against the global limit -- before it changes.
+ */
+ unsigned int max_reqs = nr_events;
+
+ /*
+ * We keep track of the number of available ringbuffer slots, to prevent
+ * overflow (reqs_available), and we also use percpu counters for this.
+ *
+ * So since up to half the slots might be on other cpu's percpu counters
+ * and unavailable, double nr_events so userspace sees what they
+ * expected: additionally, we move req_batch slots to/from percpu
+ * counters at a time, so make sure that isn't 0:
+ */
+ nr_events = max(nr_events, num_possible_cpus() * 4);
+ nr_events *= 2;
+
+ /* Prevent overflows */
+ if (nr_events > (0x10000000U / sizeof(struct io_event))) {
+ pr_debug("ENOMEM: nr_events too high\n");
+ return ERR_PTR(-EINVAL);
+ }
+
+ if (!nr_events || (unsigned long)max_reqs > aio_max_nr)
+ return ERR_PTR(-EAGAIN);
+
+ ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
+ if (!ctx)
+ return ERR_PTR(-ENOMEM);
+
+ ctx->max_reqs = max_reqs;
+
+ spin_lock_init(&ctx->ctx_lock);
+ spin_lock_init(&ctx->completion_lock);
+ mutex_init(&ctx->ring_lock);
+ /* Protect against page migration throughout kiotx setup by keeping
+ * the ring_lock mutex held until setup is complete. */
+ mutex_lock(&ctx->ring_lock);
+ init_waitqueue_head(&ctx->wait);
+
+ INIT_LIST_HEAD(&ctx->active_reqs);
+
+ if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
+ goto err;
+
+ if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
+ goto err;
+
+ ctx->cpu = alloc_percpu(struct kioctx_cpu);
+ if (!ctx->cpu)
+ goto err;
+
+ err = aio_setup_ring(ctx, nr_events);
+ if (err < 0)
+ goto err;
+
+ atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
+ ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
+ if (ctx->req_batch < 1)
+ ctx->req_batch = 1;
+
+ /* limit the number of system wide aios */
+ spin_lock(&aio_nr_lock);
+ if (aio_nr + ctx->max_reqs > aio_max_nr ||
+ aio_nr + ctx->max_reqs < aio_nr) {
+ spin_unlock(&aio_nr_lock);
+ err = -EAGAIN;
+ goto err_ctx;
+ }
+ aio_nr += ctx->max_reqs;
+ spin_unlock(&aio_nr_lock);
+
+ percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */
+ percpu_ref_get(&ctx->reqs); /* free_ioctx_users() will drop this */
+
+ err = ioctx_add_table(ctx, mm);
+ if (err)
+ goto err_cleanup;
+
+ /* Release the ring_lock mutex now that all setup is complete. */
+ mutex_unlock(&ctx->ring_lock);
+
+ pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
+ ctx, ctx->user_id, mm, ctx->nr_events);
+ return ctx;
+
+err_cleanup:
+ aio_nr_sub(ctx->max_reqs);
+err_ctx:
+ atomic_set(&ctx->dead, 1);
+ if (ctx->mmap_size)
+ vm_munmap(ctx->mmap_base, ctx->mmap_size);
+ aio_free_ring(ctx);
+err:
+ mutex_unlock(&ctx->ring_lock);
+ free_percpu(ctx->cpu);
+ percpu_ref_exit(&ctx->reqs);
+ percpu_ref_exit(&ctx->users);
+ kmem_cache_free(kioctx_cachep, ctx);
+ pr_debug("error allocating ioctx %d\n", err);
+ return ERR_PTR(err);
+}
+
+/* kill_ioctx
+ * 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 int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
+ struct ctx_rq_wait *wait)
+{
+ struct kioctx_table *table;
+
+ spin_lock(&mm->ioctx_lock);
+ if (atomic_xchg(&ctx->dead, 1)) {
+ spin_unlock(&mm->ioctx_lock);
+ return -EINVAL;
+ }
+
+ table = rcu_dereference_raw(mm->ioctx_table);
+ WARN_ON(ctx != rcu_access_pointer(table->table[ctx->id]));
+ RCU_INIT_POINTER(table->table[ctx->id], NULL);
+ spin_unlock(&mm->ioctx_lock);
+
+ /* free_ioctx_reqs() will do the necessary RCU synchronization */
+ wake_up_all(&ctx->wait);
+
+ /*
+ * It'd be more correct to do this in free_ioctx(), after all
+ * the outstanding kiocbs have finished - but by then io_destroy
+ * has already returned, so io_setup() could potentially return
+ * -EAGAIN with no ioctxs actually in use (as far as userspace
+ * could tell).
+ */
+ aio_nr_sub(ctx->max_reqs);
+
+ if (ctx->mmap_size)
+ vm_munmap(ctx->mmap_base, ctx->mmap_size);
+
+ ctx->rq_wait = wait;
+ percpu_ref_kill(&ctx->users);
+ return 0;
+}
+
+/*
+ * 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.
+ *
+ * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
+ * them.
+ */
+void exit_aio(struct mm_struct *mm)
+{
+ struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
+ struct ctx_rq_wait wait;
+ int i, skipped;
+
+ if (!table)
+ return;
+
+ atomic_set(&wait.count, table->nr);
+ init_completion(&wait.comp);
+
+ skipped = 0;
+ for (i = 0; i < table->nr; ++i) {
+ struct kioctx *ctx =
+ rcu_dereference_protected(table->table[i], true);
+
+ if (!ctx) {
+ skipped++;
+ continue;
+ }
+
+ /*
+ * We don't need to bother with munmap() here - exit_mmap(mm)
+ * is coming and it'll unmap everything. And we simply can't,
+ * this is not necessarily our ->mm.
+ * Since kill_ioctx() uses non-zero ->mmap_size as indicator
+ * that it needs to unmap the area, just set it to 0.
+ */
+ ctx->mmap_size = 0;
+ kill_ioctx(mm, ctx, &wait);
+ }
+
+ if (!atomic_sub_and_test(skipped, &wait.count)) {
+ /* Wait until all IO for the context are done. */
+ wait_for_completion(&wait.comp);
+ }
+
+ RCU_INIT_POINTER(mm->ioctx_table, NULL);
+ kfree(table);
+}
+
+static void put_reqs_available(struct kioctx *ctx, unsigned nr)
+{
+ struct kioctx_cpu *kcpu;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ kcpu = this_cpu_ptr(ctx->cpu);
+ kcpu->reqs_available += nr;
+
+ while (kcpu->reqs_available >= ctx->req_batch * 2) {
+ kcpu->reqs_available -= ctx->req_batch;
+ atomic_add(ctx->req_batch, &ctx->reqs_available);
+ }
+
+ local_irq_restore(flags);
+}
+
+static bool __get_reqs_available(struct kioctx *ctx)
+{
+ struct kioctx_cpu *kcpu;
+ bool ret = false;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ kcpu = this_cpu_ptr(ctx->cpu);
+ if (!kcpu->reqs_available) {
+ int avail = atomic_read(&ctx->reqs_available);
+
+ do {
+ if (avail < ctx->req_batch)
+ goto out;
+ } while (!atomic_try_cmpxchg(&ctx->reqs_available,
+ &avail, avail - ctx->req_batch));
+
+ kcpu->reqs_available += ctx->req_batch;
+ }
+
+ ret = true;
+ kcpu->reqs_available--;
+out:
+ local_irq_restore(flags);
+ return ret;
+}
+
+/* refill_reqs_available
+ * Updates the reqs_available reference counts used for tracking the
+ * number of free slots in the completion ring. This can be called
+ * from aio_complete() (to optimistically update reqs_available) or
+ * from aio_get_req() (the we're out of events case). It must be
+ * called holding ctx->completion_lock.
+ */
+static void refill_reqs_available(struct kioctx *ctx, unsigned head,
+ unsigned tail)
+{
+ unsigned events_in_ring, completed;
+
+ /* Clamp head since userland can write to it. */
+ head %= ctx->nr_events;
+ if (head <= tail)
+ events_in_ring = tail - head;
+ else
+ events_in_ring = ctx->nr_events - (head - tail);
+
+ completed = ctx->completed_events;
+ if (events_in_ring < completed)
+ completed -= events_in_ring;
+ else
+ completed = 0;
+
+ if (!completed)
+ return;
+
+ ctx->completed_events -= completed;
+ put_reqs_available(ctx, completed);
+}
+
+/* user_refill_reqs_available
+ * Called to refill reqs_available when aio_get_req() encounters an
+ * out of space in the completion ring.
+ */
+static void user_refill_reqs_available(struct kioctx *ctx)
+{
+ spin_lock_irq(&ctx->completion_lock);
+ if (ctx->completed_events) {
+ struct aio_ring *ring;
+ unsigned head;
+
+ /* Access of ring->head may race with aio_read_events_ring()
+ * here, but that's okay since whether we read the old version
+ * or the new version, and either will be valid. The important
+ * part is that head cannot pass tail since we prevent
+ * aio_complete() from updating tail by holding
+ * ctx->completion_lock. Even if head is invalid, the check
+ * against ctx->completed_events below will make sure we do the
+ * safe/right thing.
+ */
+ ring = kmap_atomic(ctx->ring_pages[0]);
+ head = ring->head;
+ kunmap_atomic(ring);
+
+ refill_reqs_available(ctx, head, ctx->tail);
+ }
+
+ spin_unlock_irq(&ctx->completion_lock);
+}
+
+static bool get_reqs_available(struct kioctx *ctx)
+{
+ if (__get_reqs_available(ctx))
+ return true;
+ user_refill_reqs_available(ctx);
+ return __get_reqs_available(ctx);
+}
+
+/* aio_get_req
+ * Allocate a slot for an aio request.
+ * Returns NULL if no requests are free.
+ *
+ * The refcount is initialized to 2 - one for the async op completion,
+ * one for the synchronous code that does this.
+ */
+static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
+{
+ struct aio_kiocb *req;
+
+ req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
+ if (unlikely(!req))
+ return NULL;
+
+ if (unlikely(!get_reqs_available(ctx))) {
+ kmem_cache_free(kiocb_cachep, req);
+ return NULL;
+ }
+
+ percpu_ref_get(&ctx->reqs);
+ req->ki_ctx = ctx;
+ INIT_LIST_HEAD(&req->ki_list);
+ refcount_set(&req->ki_refcnt, 2);
+ req->ki_eventfd = NULL;
+ return req;
+}
+
+static struct kioctx *lookup_ioctx(unsigned long ctx_id)
+{
+ struct aio_ring __user *ring = (void __user *)ctx_id;
+ struct mm_struct *mm = current->mm;
+ struct kioctx *ctx, *ret = NULL;
+ struct kioctx_table *table;
+ unsigned id;
+
+ if (get_user(id, &ring->id))
+ return NULL;
+
+ rcu_read_lock();
+ table = rcu_dereference(mm->ioctx_table);
+
+ if (!table || id >= table->nr)
+ goto out;
+
+ id = array_index_nospec(id, table->nr);
+ ctx = rcu_dereference(table->table[id]);
+ if (ctx && ctx->user_id == ctx_id) {
+ if (percpu_ref_tryget_live(&ctx->users))
+ ret = ctx;
+ }
+out:
+ rcu_read_unlock();
+ return ret;
+}
+
+static inline void iocb_destroy(struct aio_kiocb *iocb)
+{
+ if (iocb->ki_eventfd)
+ eventfd_ctx_put(iocb->ki_eventfd);
+ if (iocb->ki_filp)
+ fput(iocb->ki_filp);
+ percpu_ref_put(&iocb->ki_ctx->reqs);
+ kmem_cache_free(kiocb_cachep, iocb);
+}
+
+/* aio_complete
+ * Called when the io request on the given iocb is complete.
+ */
+static void aio_complete(struct aio_kiocb *iocb)
+{
+ struct kioctx *ctx = iocb->ki_ctx;
+ struct aio_ring *ring;
+ struct io_event *ev_page, *event;
+ unsigned tail, pos, head;
+ unsigned long flags;
+
+ /*
+ * Add a completion event to the ring buffer. Must be done holding
+ * ctx->completion_lock to prevent other code from messing with the tail
+ * pointer since we might be called from irq context.
+ */
+ spin_lock_irqsave(&ctx->completion_lock, flags);
+
+ tail = ctx->tail;
+ pos = tail + AIO_EVENTS_OFFSET;
+
+ if (++tail >= ctx->nr_events)
+ tail = 0;
+
+ ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
+ event = ev_page + pos % AIO_EVENTS_PER_PAGE;
+
+ *event = iocb->ki_res;
+
+ kunmap_atomic(ev_page);
+ flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
+
+ pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n", ctx, tail, iocb,
+ (void __user *)(unsigned long)iocb->ki_res.obj,
+ iocb->ki_res.data, iocb->ki_res.res, iocb->ki_res.res2);
+
+ /* after flagging the request as done, we
+ * must never even look at it again
+ */
+ smp_wmb(); /* make event visible before updating tail */
+
+ ctx->tail = tail;
+
+ ring = kmap_atomic(ctx->ring_pages[0]);
+ head = ring->head;
+ ring->tail = tail;
+ kunmap_atomic(ring);
+ flush_dcache_page(ctx->ring_pages[0]);
+
+ ctx->completed_events++;
+ if (ctx->completed_events > 1)
+ refill_reqs_available(ctx, head, tail);
+ spin_unlock_irqrestore(&ctx->completion_lock, flags);
+
+ pr_debug("added to ring %p at [%u]\n", iocb, tail);
+
+ /*
+ * Check if the user asked us to deliver the result through an
+ * eventfd. The eventfd_signal() function is safe to be called
+ * from IRQ context.
+ */
+ if (iocb->ki_eventfd)
+ eventfd_signal(iocb->ki_eventfd, 1);
+
+ /*
+ * We have to order our ring_info tail store above and test
+ * of the wait list below outside the wait lock. This is
+ * like in wake_up_bit() where clearing a bit has to be
+ * ordered with the unlocked test.
+ */
+ smp_mb();
+
+ if (waitqueue_active(&ctx->wait))
+ wake_up(&ctx->wait);
+}
+
+static inline void iocb_put(struct aio_kiocb *iocb)
+{
+ if (refcount_dec_and_test(&iocb->ki_refcnt)) {
+ aio_complete(iocb);
+ iocb_destroy(iocb);
+ }
+}
+
+/* aio_read_events_ring
+ * Pull an event off of the ioctx's event ring. Returns the number of
+ * events fetched
+ */
+static long aio_read_events_ring(struct kioctx *ctx,
+ struct io_event __user *event, long nr)
+{
+ struct aio_ring *ring;
+ unsigned head, tail, pos;
+ long ret = 0;
+ int copy_ret;
+
+ /*
+ * The mutex can block and wake us up and that will cause
+ * wait_event_interruptible_hrtimeout() to schedule without sleeping
+ * and repeat. This should be rare enough that it doesn't cause
+ * peformance issues. See the comment in read_events() for more detail.
+ */
+ sched_annotate_sleep();
+ mutex_lock(&ctx->ring_lock);
+
+ /* Access to ->ring_pages here is protected by ctx->ring_lock. */
+ ring = kmap_atomic(ctx->ring_pages[0]);
+ head = ring->head;
+ tail = ring->tail;
+ kunmap_atomic(ring);
+
+ /*
+ * Ensure that once we've read the current tail pointer, that
+ * we also see the events that were stored up to the tail.
+ */
+ smp_rmb();
+
+ pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
+
+ if (head == tail)
+ goto out;
+
+ head %= ctx->nr_events;
+ tail %= ctx->nr_events;
+
+ while (ret < nr) {
+ long avail;
+ struct io_event *ev;
+ struct page *page;
+
+ avail = (head <= tail ? tail : ctx->nr_events) - head;
+ if (head == tail)
+ break;
+
+ pos = head + AIO_EVENTS_OFFSET;
+ page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
+ pos %= AIO_EVENTS_PER_PAGE;
+
+ avail = min(avail, nr - ret);
+ avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
+
+ ev = kmap(page);
+ copy_ret = copy_to_user(event + ret, ev + pos,
+ sizeof(*ev) * avail);
+ kunmap(page);
+
+ if (unlikely(copy_ret)) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ ret += avail;
+ head += avail;
+ head %= ctx->nr_events;
+ }
+
+ ring = kmap_atomic(ctx->ring_pages[0]);
+ ring->head = head;
+ kunmap_atomic(ring);
+ flush_dcache_page(ctx->ring_pages[0]);
+
+ pr_debug("%li h%u t%u\n", ret, head, tail);
+out:
+ mutex_unlock(&ctx->ring_lock);
+
+ return ret;
+}
+
+static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
+ struct io_event __user *event, long *i)
+{
+ long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
+
+ if (ret > 0)
+ *i += ret;
+
+ if (unlikely(atomic_read(&ctx->dead)))
+ ret = -EINVAL;
+
+ if (!*i)
+ *i = ret;
+
+ return ret < 0 || *i >= min_nr;
+}
+
+static long read_events(struct kioctx *ctx, long min_nr, long nr,
+ struct io_event __user *event,
+ ktime_t until)
+{
+ long ret = 0;
+
+ /*
+ * Note that aio_read_events() is being called as the conditional - i.e.
+ * we're calling it after prepare_to_wait() has set task state to
+ * TASK_INTERRUPTIBLE.
+ *
+ * But aio_read_events() can block, and if it blocks it's going to flip
+ * the task state back to TASK_RUNNING.
+ *
+ * This should be ok, provided it doesn't flip the state back to
+ * TASK_RUNNING and return 0 too much - that causes us to spin. That
+ * will only happen if the mutex_lock() call blocks, and we then find
+ * the ringbuffer empty. So in practice we should be ok, but it's
+ * something to be aware of when touching this code.
+ */
+ if (until == 0)
+ aio_read_events(ctx, min_nr, nr, event, &ret);
+ else
+ wait_event_interruptible_hrtimeout(ctx->wait,
+ aio_read_events(ctx, min_nr, nr, event, &ret),
+ until);
+ return ret;
+}
+
+/* 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.
+ */
+SYSCALL_DEFINE2(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 || nr_events == 0)) {
+ pr_debug("EINVAL: ctx %lu nr_events %u\n",
+ ctx, nr_events);
+ goto out;
+ }
+
+ ioctx = ioctx_alloc(nr_events);
+ ret = PTR_ERR(ioctx);
+ if (!IS_ERR(ioctx)) {
+ ret = put_user(ioctx->user_id, ctxp);
+ if (ret)
+ kill_ioctx(current->mm, ioctx, NULL);
+ percpu_ref_put(&ioctx->users);
+ }
+
+out:
+ return ret;
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
+{
+ struct kioctx *ioctx = NULL;
+ unsigned long ctx;
+ long ret;
+
+ ret = get_user(ctx, ctx32p);
+ if (unlikely(ret))
+ goto out;
+
+ ret = -EINVAL;
+ if (unlikely(ctx || nr_events == 0)) {
+ pr_debug("EINVAL: ctx %lu nr_events %u\n",
+ ctx, nr_events);
+ goto out;
+ }
+
+ ioctx = ioctx_alloc(nr_events);
+ ret = PTR_ERR(ioctx);
+ if (!IS_ERR(ioctx)) {
+ /* truncating is ok because it's a user address */
+ ret = put_user((u32)ioctx->user_id, ctx32p);
+ if (ret)
+ kill_ioctx(current->mm, ioctx, NULL);
+ percpu_ref_put(&ioctx->users);
+ }
+
+out:
+ return ret;
+}
+#endif
+
+/* 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 -EINVAL if the context pointed to
+ * is invalid.
+ */
+SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
+{
+ struct kioctx *ioctx = lookup_ioctx(ctx);
+ if (likely(NULL != ioctx)) {
+ struct ctx_rq_wait wait;
+ int ret;
+
+ init_completion(&wait.comp);
+ atomic_set(&wait.count, 1);
+
+ /* Pass requests_done to kill_ioctx() where it can be set
+ * in a thread-safe way. If we try to set it here then we have
+ * a race condition if two io_destroy() called simultaneously.
+ */
+ ret = kill_ioctx(current->mm, ioctx, &wait);
+ percpu_ref_put(&ioctx->users);
+
+ /* Wait until all IO for the context are done. Otherwise kernel
+ * keep using user-space buffers even if user thinks the context
+ * is destroyed.
+ */
+ if (!ret)
+ wait_for_completion(&wait.comp);
+
+ return ret;
+ }
+ pr_debug("EINVAL: invalid context id\n");
+ return -EINVAL;
+}
+
+static void aio_remove_iocb(struct aio_kiocb *iocb)
+{
+ struct kioctx *ctx = iocb->ki_ctx;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ctx->ctx_lock, flags);
+ list_del(&iocb->ki_list);
+ spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+}
+
+static void aio_complete_rw(struct kiocb *kiocb, long res)
+{
+ struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, rw);
+
+ if (!list_empty_careful(&iocb->ki_list))
+ aio_remove_iocb(iocb);
+
+ if (kiocb->ki_flags & IOCB_WRITE) {
+ struct inode *inode = file_inode(kiocb->ki_filp);
+
+ /*
+ * Tell lockdep we inherited freeze protection from submission
+ * thread.
+ */
+ if (S_ISREG(inode->i_mode))
+ __sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
+ file_end_write(kiocb->ki_filp);
+ }
+
+ iocb->ki_res.res = res;
+ iocb->ki_res.res2 = 0;
+ iocb_put(iocb);
+}
+
+static int aio_prep_rw(struct kiocb *req, const struct iocb *iocb)
+{
+ int ret;
+
+ req->ki_complete = aio_complete_rw;
+ req->private = NULL;
+ req->ki_pos = iocb->aio_offset;
+ req->ki_flags = req->ki_filp->f_iocb_flags;
+ if (iocb->aio_flags & IOCB_FLAG_RESFD)
+ req->ki_flags |= IOCB_EVENTFD;
+ if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
+ /*
+ * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
+ * aio_reqprio is interpreted as an I/O scheduling
+ * class and priority.
+ */
+ ret = ioprio_check_cap(iocb->aio_reqprio);
+ if (ret) {
+ pr_debug("aio ioprio check cap error: %d\n", ret);
+ return ret;
+ }
+
+ req->ki_ioprio = iocb->aio_reqprio;
+ } else
+ req->ki_ioprio = get_current_ioprio();
+
+ ret = kiocb_set_rw_flags(req, iocb->aio_rw_flags);
+ if (unlikely(ret))
+ return ret;
+
+ req->ki_flags &= ~IOCB_HIPRI; /* no one is going to poll for this I/O */
+ return 0;
+}
+
+static ssize_t aio_setup_rw(int rw, const struct iocb *iocb,
+ struct iovec **iovec, bool vectored, bool compat,
+ struct iov_iter *iter)
+{
+ void __user *buf = (void __user *)(uintptr_t)iocb->aio_buf;
+ size_t len = iocb->aio_nbytes;
+
+ if (!vectored) {
+ ssize_t ret = import_single_range(rw, buf, len, *iovec, iter);
+ *iovec = NULL;
+ return ret;
+ }
+
+ return __import_iovec(rw, buf, len, UIO_FASTIOV, iovec, iter, compat);
+}
+
+static inline void aio_rw_done(struct kiocb *req, ssize_t ret)
+{
+ switch (ret) {
+ case -EIOCBQUEUED:
+ break;
+ case -ERESTARTSYS:
+ case -ERESTARTNOINTR:
+ case -ERESTARTNOHAND:
+ case -ERESTART_RESTARTBLOCK:
+ /*
+ * There's no easy way to restart the syscall since other AIO's
+ * may be already running. Just fail this IO with EINTR.
+ */
+ ret = -EINTR;
+ fallthrough;
+ default:
+ req->ki_complete(req, ret);
+ }
+}
+
+static int aio_read(struct kiocb *req, const struct iocb *iocb,
+ bool vectored, bool compat)
+{
+ struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+ struct iov_iter iter;
+ struct file *file;
+ int ret;
+
+ ret = aio_prep_rw(req, iocb);
+ if (ret)
+ return ret;
+ file = req->ki_filp;
+ if (unlikely(!(file->f_mode & FMODE_READ)))
+ return -EBADF;
+ if (unlikely(!file->f_op->read_iter))
+ return -EINVAL;
+
+ ret = aio_setup_rw(ITER_DEST, iocb, &iovec, vectored, compat, &iter);
+ if (ret < 0)
+ return ret;
+ ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
+ if (!ret)
+ aio_rw_done(req, call_read_iter(file, req, &iter));
+ kfree(iovec);
+ return ret;
+}
+
+static int aio_write(struct kiocb *req, const struct iocb *iocb,
+ bool vectored, bool compat)
+{
+ struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+ struct iov_iter iter;
+ struct file *file;
+ int ret;
+
+ ret = aio_prep_rw(req, iocb);
+ if (ret)
+ return ret;
+ file = req->ki_filp;
+
+ if (unlikely(!(file->f_mode & FMODE_WRITE)))
+ return -EBADF;
+ if (unlikely(!file->f_op->write_iter))
+ return -EINVAL;
+
+ ret = aio_setup_rw(ITER_SOURCE, iocb, &iovec, vectored, compat, &iter);
+ if (ret < 0)
+ return ret;
+ ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
+ if (!ret) {
+ /*
+ * Open-code file_start_write here to grab freeze protection,
+ * which will be released by another thread in
+ * aio_complete_rw(). Fool lockdep by telling it the lock got
+ * released so that it doesn't complain about the held lock when
+ * we return to userspace.
+ */
+ if (S_ISREG(file_inode(file)->i_mode)) {
+ sb_start_write(file_inode(file)->i_sb);
+ __sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
+ }
+ req->ki_flags |= IOCB_WRITE;
+ aio_rw_done(req, call_write_iter(file, req, &iter));
+ }
+ kfree(iovec);
+ return ret;
+}
+
+static void aio_fsync_work(struct work_struct *work)
+{
+ struct aio_kiocb *iocb = container_of(work, struct aio_kiocb, fsync.work);
+ const struct cred *old_cred = override_creds(iocb->fsync.creds);
+
+ iocb->ki_res.res = vfs_fsync(iocb->fsync.file, iocb->fsync.datasync);
+ revert_creds(old_cred);
+ put_cred(iocb->fsync.creds);
+ iocb_put(iocb);
+}
+
+static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb,
+ bool datasync)
+{
+ if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes ||
+ iocb->aio_rw_flags))
+ return -EINVAL;
+
+ if (unlikely(!req->file->f_op->fsync))
+ return -EINVAL;
+
+ req->creds = prepare_creds();
+ if (!req->creds)
+ return -ENOMEM;
+
+ req->datasync = datasync;
+ INIT_WORK(&req->work, aio_fsync_work);
+ schedule_work(&req->work);
+ return 0;
+}
+
+static void aio_poll_put_work(struct work_struct *work)
+{
+ struct poll_iocb *req = container_of(work, struct poll_iocb, work);
+ struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
+
+ iocb_put(iocb);
+}
+
+/*
+ * Safely lock the waitqueue which the request is on, synchronizing with the
+ * case where the ->poll() provider decides to free its waitqueue early.
+ *
+ * Returns true on success, meaning that req->head->lock was locked, req->wait
+ * is on req->head, and an RCU read lock was taken. Returns false if the
+ * request was already removed from its waitqueue (which might no longer exist).
+ */
+static bool poll_iocb_lock_wq(struct poll_iocb *req)
+{
+ wait_queue_head_t *head;
+
+ /*
+ * While we hold the waitqueue lock and the waitqueue is nonempty,
+ * wake_up_pollfree() will wait for us. However, taking the waitqueue
+ * lock in the first place can race with the waitqueue being freed.
+ *
+ * We solve this as eventpoll does: by taking advantage of the fact that
+ * all users of wake_up_pollfree() will RCU-delay the actual free. If
+ * we enter rcu_read_lock() and see that the pointer to the queue is
+ * non-NULL, we can then lock it without the memory being freed out from
+ * under us, then check whether the request is still on the queue.
+ *
+ * Keep holding rcu_read_lock() as long as we hold the queue lock, in
+ * case the caller deletes the entry from the queue, leaving it empty.
+ * In that case, only RCU prevents the queue memory from being freed.
+ */
+ rcu_read_lock();
+ head = smp_load_acquire(&req->head);
+ if (head) {
+ spin_lock(&head->lock);
+ if (!list_empty(&req->wait.entry))
+ return true;
+ spin_unlock(&head->lock);
+ }
+ rcu_read_unlock();
+ return false;
+}
+
+static void poll_iocb_unlock_wq(struct poll_iocb *req)
+{
+ spin_unlock(&req->head->lock);
+ rcu_read_unlock();
+}
+
+static void aio_poll_complete_work(struct work_struct *work)
+{
+ struct poll_iocb *req = container_of(work, struct poll_iocb, work);
+ struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
+ struct poll_table_struct pt = { ._key = req->events };
+ struct kioctx *ctx = iocb->ki_ctx;
+ __poll_t mask = 0;
+
+ if (!READ_ONCE(req->cancelled))
+ mask = vfs_poll(req->file, &pt) & req->events;
+
+ /*
+ * Note that ->ki_cancel callers also delete iocb from active_reqs after
+ * calling ->ki_cancel. We need the ctx_lock roundtrip here to
+ * synchronize with them. In the cancellation case the list_del_init
+ * itself is not actually needed, but harmless so we keep it in to
+ * avoid further branches in the fast path.
+ */
+ spin_lock_irq(&ctx->ctx_lock);
+ if (poll_iocb_lock_wq(req)) {
+ if (!mask && !READ_ONCE(req->cancelled)) {
+ /*
+ * The request isn't actually ready to be completed yet.
+ * Reschedule completion if another wakeup came in.
+ */
+ if (req->work_need_resched) {
+ schedule_work(&req->work);
+ req->work_need_resched = false;
+ } else {
+ req->work_scheduled = false;
+ }
+ poll_iocb_unlock_wq(req);
+ spin_unlock_irq(&ctx->ctx_lock);
+ return;
+ }
+ list_del_init(&req->wait.entry);
+ poll_iocb_unlock_wq(req);
+ } /* else, POLLFREE has freed the waitqueue, so we must complete */
+ list_del_init(&iocb->ki_list);
+ iocb->ki_res.res = mangle_poll(mask);
+ spin_unlock_irq(&ctx->ctx_lock);
+
+ iocb_put(iocb);
+}
+
+/* assumes we are called with irqs disabled */
+static int aio_poll_cancel(struct kiocb *iocb)
+{
+ struct aio_kiocb *aiocb = container_of(iocb, struct aio_kiocb, rw);
+ struct poll_iocb *req = &aiocb->poll;
+
+ if (poll_iocb_lock_wq(req)) {
+ WRITE_ONCE(req->cancelled, true);
+ if (!req->work_scheduled) {
+ schedule_work(&aiocb->poll.work);
+ req->work_scheduled = true;
+ }
+ poll_iocb_unlock_wq(req);
+ } /* else, the request was force-cancelled by POLLFREE already */
+
+ return 0;
+}
+
+static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
+ void *key)
+{
+ struct poll_iocb *req = container_of(wait, struct poll_iocb, wait);
+ struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
+ __poll_t mask = key_to_poll(key);
+ unsigned long flags;
+
+ /* for instances that support it check for an event match first: */
+ if (mask && !(mask & req->events))
+ return 0;
+
+ /*
+ * Complete the request inline if possible. This requires that three
+ * conditions be met:
+ * 1. An event mask must have been passed. If a plain wakeup was done
+ * instead, then mask == 0 and we have to call vfs_poll() to get
+ * the events, so inline completion isn't possible.
+ * 2. The completion work must not have already been scheduled.
+ * 3. ctx_lock must not be busy. We have to use trylock because we
+ * already hold the waitqueue lock, so this inverts the normal
+ * locking order. Use irqsave/irqrestore because not all
+ * filesystems (e.g. fuse) call this function with IRQs disabled,
+ * yet IRQs have to be disabled before ctx_lock is obtained.
+ */
+ if (mask && !req->work_scheduled &&
+ spin_trylock_irqsave(&iocb->ki_ctx->ctx_lock, flags)) {
+ struct kioctx *ctx = iocb->ki_ctx;
+
+ list_del_init(&req->wait.entry);
+ list_del(&iocb->ki_list);
+ iocb->ki_res.res = mangle_poll(mask);
+ if (iocb->ki_eventfd && !eventfd_signal_allowed()) {
+ iocb = NULL;
+ INIT_WORK(&req->work, aio_poll_put_work);
+ schedule_work(&req->work);
+ }
+ spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+ if (iocb)
+ iocb_put(iocb);
+ } else {
+ /*
+ * Schedule the completion work if needed. If it was already
+ * scheduled, record that another wakeup came in.
+ *
+ * Don't remove the request from the waitqueue here, as it might
+ * not actually be complete yet (we won't know until vfs_poll()
+ * is called), and we must not miss any wakeups. POLLFREE is an
+ * exception to this; see below.
+ */
+ if (req->work_scheduled) {
+ req->work_need_resched = true;
+ } else {
+ schedule_work(&req->work);
+ req->work_scheduled = true;
+ }
+
+ /*
+ * If the waitqueue is being freed early but we can't complete
+ * the request inline, we have to tear down the request as best
+ * we can. That means immediately removing the request from its
+ * waitqueue and preventing all further accesses to the
+ * waitqueue via the request. We also need to schedule the
+ * completion work (done above). Also mark the request as
+ * cancelled, to potentially skip an unneeded call to ->poll().
+ */
+ if (mask & POLLFREE) {
+ WRITE_ONCE(req->cancelled, true);
+ list_del_init(&req->wait.entry);
+
+ /*
+ * Careful: this *must* be the last step, since as soon
+ * as req->head is NULL'ed out, the request can be
+ * completed and freed, since aio_poll_complete_work()
+ * will no longer need to take the waitqueue lock.
+ */
+ smp_store_release(&req->head, NULL);
+ }
+ }
+ return 1;
+}
+
+struct aio_poll_table {
+ struct poll_table_struct pt;
+ struct aio_kiocb *iocb;
+ bool queued;
+ int error;
+};
+
+static void
+aio_poll_queue_proc(struct file *file, struct wait_queue_head *head,
+ struct poll_table_struct *p)
+{
+ struct aio_poll_table *pt = container_of(p, struct aio_poll_table, pt);
+
+ /* multiple wait queues per file are not supported */
+ if (unlikely(pt->queued)) {
+ pt->error = -EINVAL;
+ return;
+ }
+
+ pt->queued = true;
+ pt->error = 0;
+ pt->iocb->poll.head = head;
+ add_wait_queue(head, &pt->iocb->poll.wait);
+}
+
+static int aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
+{
+ struct kioctx *ctx = aiocb->ki_ctx;
+ struct poll_iocb *req = &aiocb->poll;
+ struct aio_poll_table apt;
+ bool cancel = false;
+ __poll_t mask;
+
+ /* reject any unknown events outside the normal event mask. */
+ if ((u16)iocb->aio_buf != iocb->aio_buf)
+ return -EINVAL;
+ /* reject fields that are not defined for poll */
+ if (iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags)
+ return -EINVAL;
+
+ INIT_WORK(&req->work, aio_poll_complete_work);
+ req->events = demangle_poll(iocb->aio_buf) | EPOLLERR | EPOLLHUP;
+
+ req->head = NULL;
+ req->cancelled = false;
+ req->work_scheduled = false;
+ req->work_need_resched = false;
+
+ apt.pt._qproc = aio_poll_queue_proc;
+ apt.pt._key = req->events;
+ apt.iocb = aiocb;
+ apt.queued = false;
+ apt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
+
+ /* initialized the list so that we can do list_empty checks */
+ INIT_LIST_HEAD(&req->wait.entry);
+ init_waitqueue_func_entry(&req->wait, aio_poll_wake);
+
+ mask = vfs_poll(req->file, &apt.pt) & req->events;
+ spin_lock_irq(&ctx->ctx_lock);
+ if (likely(apt.queued)) {
+ bool on_queue = poll_iocb_lock_wq(req);
+
+ if (!on_queue || req->work_scheduled) {
+ /*
+ * aio_poll_wake() already either scheduled the async
+ * completion work, or completed the request inline.
+ */
+ if (apt.error) /* unsupported case: multiple queues */
+ cancel = true;
+ apt.error = 0;
+ mask = 0;
+ }
+ if (mask || apt.error) {
+ /* Steal to complete synchronously. */
+ list_del_init(&req->wait.entry);
+ } else if (cancel) {
+ /* Cancel if possible (may be too late though). */
+ WRITE_ONCE(req->cancelled, true);
+ } else if (on_queue) {
+ /*
+ * Actually waiting for an event, so add the request to
+ * active_reqs so that it can be cancelled if needed.
+ */
+ list_add_tail(&aiocb->ki_list, &ctx->active_reqs);
+ aiocb->ki_cancel = aio_poll_cancel;
+ }
+ if (on_queue)
+ poll_iocb_unlock_wq(req);
+ }
+ if (mask) { /* no async, we'd stolen it */
+ aiocb->ki_res.res = mangle_poll(mask);
+ apt.error = 0;
+ }
+ spin_unlock_irq(&ctx->ctx_lock);
+ if (mask)
+ iocb_put(aiocb);
+ return apt.error;
+}
+
+static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
+ struct iocb __user *user_iocb, struct aio_kiocb *req,
+ bool compat)
+{
+ req->ki_filp = fget(iocb->aio_fildes);
+ if (unlikely(!req->ki_filp))
+ return -EBADF;
+
+ if (iocb->aio_flags & IOCB_FLAG_RESFD) {
+ struct eventfd_ctx *eventfd;
+ /*
+ * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
+ * instance of the file* now. The file descriptor must be
+ * an eventfd() fd, and will be signaled for each completed
+ * event using the eventfd_signal() function.
+ */
+ eventfd = eventfd_ctx_fdget(iocb->aio_resfd);
+ if (IS_ERR(eventfd))
+ return PTR_ERR(eventfd);
+
+ req->ki_eventfd = eventfd;
+ }
+
+ if (unlikely(put_user(KIOCB_KEY, &user_iocb->aio_key))) {
+ pr_debug("EFAULT: aio_key\n");
+ return -EFAULT;
+ }
+
+ req->ki_res.obj = (u64)(unsigned long)user_iocb;
+ req->ki_res.data = iocb->aio_data;
+ req->ki_res.res = 0;
+ req->ki_res.res2 = 0;
+
+ switch (iocb->aio_lio_opcode) {
+ case IOCB_CMD_PREAD:
+ return aio_read(&req->rw, iocb, false, compat);
+ case IOCB_CMD_PWRITE:
+ return aio_write(&req->rw, iocb, false, compat);
+ case IOCB_CMD_PREADV:
+ return aio_read(&req->rw, iocb, true, compat);
+ case IOCB_CMD_PWRITEV:
+ return aio_write(&req->rw, iocb, true, compat);
+ case IOCB_CMD_FSYNC:
+ return aio_fsync(&req->fsync, iocb, false);
+ case IOCB_CMD_FDSYNC:
+ return aio_fsync(&req->fsync, iocb, true);
+ case IOCB_CMD_POLL:
+ return aio_poll(req, iocb);
+ default:
+ pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
+ return -EINVAL;
+ }
+}
+
+static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
+ bool compat)
+{
+ struct aio_kiocb *req;
+ struct iocb iocb;
+ int err;
+
+ if (unlikely(copy_from_user(&iocb, user_iocb, sizeof(iocb))))
+ return -EFAULT;
+
+ /* enforce forwards compatibility on users */
+ if (unlikely(iocb.aio_reserved2)) {
+ pr_debug("EINVAL: 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: overflow check\n");
+ return -EINVAL;
+ }
+
+ req = aio_get_req(ctx);
+ if (unlikely(!req))
+ return -EAGAIN;
+
+ err = __io_submit_one(ctx, &iocb, user_iocb, req, compat);
+
+ /* Done with the synchronous reference */
+ iocb_put(req);
+
+ /*
+ * If err is 0, we'd either done aio_complete() ourselves or have
+ * arranged for that to be done asynchronously. Anything non-zero
+ * means that we need to destroy req ourselves.
+ */
+ if (unlikely(err)) {
+ iocb_destroy(req);
+ put_reqs_available(ctx, 1);
+ }
+ return err;
+}
+
+/* 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.
+ */
+SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
+ struct iocb __user * __user *, iocbpp)
+{
+ struct kioctx *ctx;
+ long ret = 0;
+ int i = 0;
+ struct blk_plug plug;
+
+ if (unlikely(nr < 0))
+ return -EINVAL;
+
+ ctx = lookup_ioctx(ctx_id);
+ if (unlikely(!ctx)) {
+ pr_debug("EINVAL: invalid context id\n");
+ return -EINVAL;
+ }
+
+ if (nr > ctx->nr_events)
+ nr = ctx->nr_events;
+
+ if (nr > AIO_PLUG_THRESHOLD)
+ blk_start_plug(&plug);
+ for (i = 0; i < nr; i++) {
+ struct iocb __user *user_iocb;
+
+ if (unlikely(get_user(user_iocb, iocbpp + i))) {
+ ret = -EFAULT;
+ break;
+ }
+
+ ret = io_submit_one(ctx, user_iocb, false);
+ if (ret)
+ break;
+ }
+ if (nr > AIO_PLUG_THRESHOLD)
+ blk_finish_plug(&plug);
+
+ percpu_ref_put(&ctx->users);
+ return i ? i : ret;
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
+ int, nr, compat_uptr_t __user *, iocbpp)
+{
+ struct kioctx *ctx;
+ long ret = 0;
+ int i = 0;
+ struct blk_plug plug;
+
+ if (unlikely(nr < 0))
+ return -EINVAL;
+
+ ctx = lookup_ioctx(ctx_id);
+ if (unlikely(!ctx)) {
+ pr_debug("EINVAL: invalid context id\n");
+ return -EINVAL;
+ }
+
+ if (nr > ctx->nr_events)
+ nr = ctx->nr_events;
+
+ if (nr > AIO_PLUG_THRESHOLD)
+ blk_start_plug(&plug);
+ for (i = 0; i < nr; i++) {
+ compat_uptr_t user_iocb;
+
+ if (unlikely(get_user(user_iocb, iocbpp + i))) {
+ ret = -EFAULT;
+ break;
+ }
+
+ ret = io_submit_one(ctx, compat_ptr(user_iocb), true);
+ if (ret)
+ break;
+ }
+ if (nr > AIO_PLUG_THRESHOLD)
+ blk_finish_plug(&plug);
+
+ percpu_ref_put(&ctx->users);
+ return i ? i : ret;
+}
+#endif
+
+/* 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.
+ */
+SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
+ struct io_event __user *, result)
+{
+ struct kioctx *ctx;
+ struct aio_kiocb *kiocb;
+ int ret = -EINVAL;
+ u32 key;
+ u64 obj = (u64)(unsigned long)iocb;
+
+ if (unlikely(get_user(key, &iocb->aio_key)))
+ return -EFAULT;
+ if (unlikely(key != KIOCB_KEY))
+ return -EINVAL;
+
+ ctx = lookup_ioctx(ctx_id);
+ if (unlikely(!ctx))
+ return -EINVAL;
+
+ spin_lock_irq(&ctx->ctx_lock);
+ /* TODO: use a hash or array, this sucks. */
+ list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
+ if (kiocb->ki_res.obj == obj) {
+ ret = kiocb->ki_cancel(&kiocb->rw);
+ list_del_init(&kiocb->ki_list);
+ break;
+ }
+ }
+ spin_unlock_irq(&ctx->ctx_lock);
+
+ if (!ret) {
+ /*
+ * The result argument is no longer used - the io_event is
+ * always delivered via the ring buffer. -EINPROGRESS indicates
+ * cancellation is progress:
+ */
+ ret = -EINPROGRESS;
+ }
+
+ percpu_ref_put(&ctx->users);
+
+ return ret;
+}
+
+static long do_io_getevents(aio_context_t ctx_id,
+ long min_nr,
+ long nr,
+ struct io_event __user *events,
+ struct timespec64 *ts)
+{
+ ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
+ struct kioctx *ioctx = lookup_ioctx(ctx_id);
+ long ret = -EINVAL;
+
+ if (likely(ioctx)) {
+ if (likely(min_nr <= nr && min_nr >= 0))
+ ret = read_events(ioctx, min_nr, nr, events, until);
+ percpu_ref_put(&ioctx->users);
+ }
+
+ 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. If
+ * it succeeds, the number of read events is returned. May fail with
+ * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
+ * out of range, if timeout is out of range. May fail with -EFAULT
+ * if any of the memory specified is invalid. May return 0 or
+ * < min_nr if the timeout specified by timeout has elapsed
+ * before sufficient events are available, where timeout == NULL
+ * specifies an infinite timeout. Note that the timeout pointed to by
+ * timeout is relative. Will fail with -ENOSYS if not implemented.
+ */
+#ifdef CONFIG_64BIT
+
+SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
+ long, min_nr,
+ long, nr,
+ struct io_event __user *, events,
+ struct __kernel_timespec __user *, timeout)
+{
+ struct timespec64 ts;
+ int ret;
+
+ if (timeout && unlikely(get_timespec64(&ts, timeout)))
+ return -EFAULT;
+
+ ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
+ if (!ret && signal_pending(current))
+ ret = -EINTR;
+ return ret;
+}
+
+#endif
+
+struct __aio_sigset {
+ const sigset_t __user *sigmask;
+ size_t sigsetsize;
+};
+
+SYSCALL_DEFINE6(io_pgetevents,
+ aio_context_t, ctx_id,
+ long, min_nr,
+ long, nr,
+ struct io_event __user *, events,
+ struct __kernel_timespec __user *, timeout,
+ const struct __aio_sigset __user *, usig)
+{
+ struct __aio_sigset ksig = { NULL, };
+ struct timespec64 ts;
+ bool interrupted;
+ int ret;
+
+ if (timeout && unlikely(get_timespec64(&ts, timeout)))
+ return -EFAULT;
+
+ if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
+ return -EFAULT;
+
+ ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
+ if (ret)
+ return ret;
+
+ ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
+
+ interrupted = signal_pending(current);
+ restore_saved_sigmask_unless(interrupted);
+ if (interrupted && !ret)
+ ret = -ERESTARTNOHAND;
+
+ return ret;
+}
+
+#if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
+
+SYSCALL_DEFINE6(io_pgetevents_time32,
+ aio_context_t, ctx_id,
+ long, min_nr,
+ long, nr,
+ struct io_event __user *, events,
+ struct old_timespec32 __user *, timeout,
+ const struct __aio_sigset __user *, usig)
+{
+ struct __aio_sigset ksig = { NULL, };
+ struct timespec64 ts;
+ bool interrupted;
+ int ret;
+
+ if (timeout && unlikely(get_old_timespec32(&ts, timeout)))
+ return -EFAULT;
+
+ if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
+ return -EFAULT;
+
+
+ ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
+ if (ret)
+ return ret;
+
+ ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
+
+ interrupted = signal_pending(current);
+ restore_saved_sigmask_unless(interrupted);
+ if (interrupted && !ret)
+ ret = -ERESTARTNOHAND;
+
+ return ret;
+}
+
+#endif
+
+#if defined(CONFIG_COMPAT_32BIT_TIME)
+
+SYSCALL_DEFINE5(io_getevents_time32, __u32, ctx_id,
+ __s32, min_nr,
+ __s32, nr,
+ struct io_event __user *, events,
+ struct old_timespec32 __user *, timeout)
+{
+ struct timespec64 t;
+ int ret;
+
+ if (timeout && get_old_timespec32(&t, timeout))
+ return -EFAULT;
+
+ ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
+ if (!ret && signal_pending(current))
+ ret = -EINTR;
+ return ret;
+}
+
+#endif
+
+#ifdef CONFIG_COMPAT
+
+struct __compat_aio_sigset {
+ compat_uptr_t sigmask;
+ compat_size_t sigsetsize;
+};
+
+#if defined(CONFIG_COMPAT_32BIT_TIME)
+
+COMPAT_SYSCALL_DEFINE6(io_pgetevents,
+ compat_aio_context_t, ctx_id,
+ compat_long_t, min_nr,
+ compat_long_t, nr,
+ struct io_event __user *, events,
+ struct old_timespec32 __user *, timeout,
+ const struct __compat_aio_sigset __user *, usig)
+{
+ struct __compat_aio_sigset ksig = { 0, };
+ struct timespec64 t;
+ bool interrupted;
+ int ret;
+
+ if (timeout && get_old_timespec32(&t, timeout))
+ return -EFAULT;
+
+ if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
+ return -EFAULT;
+
+ ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
+ if (ret)
+ return ret;
+
+ ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
+
+ interrupted = signal_pending(current);
+ restore_saved_sigmask_unless(interrupted);
+ if (interrupted && !ret)
+ ret = -ERESTARTNOHAND;
+
+ return ret;
+}
+
+#endif
+
+COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,
+ compat_aio_context_t, ctx_id,
+ compat_long_t, min_nr,
+ compat_long_t, nr,
+ struct io_event __user *, events,
+ struct __kernel_timespec __user *, timeout,
+ const struct __compat_aio_sigset __user *, usig)
+{
+ struct __compat_aio_sigset ksig = { 0, };
+ struct timespec64 t;
+ bool interrupted;
+ int ret;
+
+ if (timeout && get_timespec64(&t, timeout))
+ return -EFAULT;
+
+ if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
+ return -EFAULT;
+
+ ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
+ if (ret)
+ return ret;
+
+ ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
+
+ interrupted = signal_pending(current);
+ restore_saved_sigmask_unless(interrupted);
+ if (interrupted && !ret)
+ ret = -ERESTARTNOHAND;
+
+ return ret;
+}
+#endif