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-rw-r--r--fs/aio.c1732
1 files changed, 1732 insertions, 0 deletions
diff --git a/fs/aio.c b/fs/aio.c
new file mode 100644
index 000000000..480440f47
--- /dev/null
+++ b/fs/aio.c
@@ -0,0 +1,1732 @@
+/*
+ * 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.
+ */
+#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/uio.h>
+
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/mmu_context.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 <asm/kmap_types.h>
+#include <asm/uaccess.h>
+
+#include "internal.h"
+
+#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[0];
+}; /* 128 bytes + ring size */
+
+#define AIO_RING_PAGES 8
+
+struct kioctx_table {
+ struct rcu_head rcu;
+ unsigned nr;
+ struct kioctx *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 work_struct free_work;
+
+ /*
+ * 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;
+};
+
+/*
+ * We use ki_cancel == KIOCB_CANCELLED to indicate that a kiocb has been either
+ * cancelled or completed (this makes a certain amount of sense because
+ * successful cancellation - io_cancel() - does deliver the completion to
+ * userspace).
+ *
+ * And since most things don't implement kiocb cancellation and we'd really like
+ * kiocb completion to be lockless when possible, we use ki_cancel to
+ * synchronize cancellation and completion - we only set it to KIOCB_CANCELLED
+ * with xchg() or cmpxchg(), see batch_complete_aio() and kiocb_cancel().
+ */
+#define KIOCB_CANCELLED ((void *) (~0ULL))
+
+struct aio_kiocb {
+ struct kiocb common;
+
+ struct kioctx *ki_ctx;
+ kiocb_cancel_fn *ki_cancel;
+
+ struct iocb __user *ki_user_iocb; /* user's aiocb */
+ __u64 ki_user_data; /* user's data for completion */
+
+ struct list_head ki_list; /* the aio core uses this
+ * for cancellation */
+
+ /*
+ * 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);
+unsigned long aio_nr; /* current system wide number of aio requests */
+unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
+/*----end sysctl variables---*/
+
+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 qstr this = QSTR_INIT("[aio]", 5);
+ struct file *file;
+ struct path path;
+ 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;
+
+ path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this);
+ if (!path.dentry) {
+ iput(inode);
+ return ERR_PTR(-ENOMEM);
+ }
+ path.mnt = mntget(aio_mnt);
+
+ d_instantiate(path.dentry, inode);
+ file = alloc_file(&path, FMODE_READ | FMODE_WRITE, &aio_ring_fops);
+ if (IS_ERR(file)) {
+ path_put(&path);
+ return file;
+ }
+
+ file->f_flags = O_RDWR;
+ return file;
+}
+
+static struct dentry *aio_mount(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
+{
+ static const struct dentry_operations ops = {
+ .d_dname = simple_dname,
+ };
+ return mount_pseudo(fs_type, "aio:", NULL, &ops, AIO_RING_MAGIC);
+}
+
+/* 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",
+ .mount = aio_mount,
+ .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);
+
+ pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
+
+ return 0;
+}
+__initcall(aio_setup);
+
+static void put_aio_ring_file(struct kioctx *ctx)
+{
+ struct file *aio_ring_file = ctx->aio_ring_file;
+ if (aio_ring_file) {
+ truncate_setsize(aio_ring_file->f_inode, 0);
+
+ /* Prevent further access to the kioctx from migratepages */
+ spin_lock(&aio_ring_file->f_inode->i_mapping->private_lock);
+ aio_ring_file->f_inode->i_mapping->private_data = NULL;
+ ctx->aio_ring_file = NULL;
+ spin_unlock(&aio_ring_file->f_inode->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_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ vma->vm_flags |= VM_DONTEXPAND;
+ vma->vm_ops = &generic_file_vm_ops;
+ return 0;
+}
+
+static int aio_ring_remap(struct file *file, struct vm_area_struct *vma)
+{
+ 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);
+ for (i = 0; i < table->nr; i++) {
+ struct kioctx *ctx;
+
+ ctx = 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;
+ }
+ }
+
+ rcu_read_unlock();
+ spin_unlock(&mm->ioctx_lock);
+ return res;
+}
+
+static const struct file_operations aio_ring_fops = {
+ .mmap = aio_ring_mmap,
+ .mremap = aio_ring_remap,
+};
+
+#if IS_ENABLED(CONFIG_MIGRATION)
+static int aio_migratepage(struct address_space *mapping, struct page *new,
+ struct page *old, enum migrate_mode mode)
+{
+ struct kioctx *ctx;
+ unsigned long flags;
+ pgoff_t idx;
+ int rc;
+
+ 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 = old->index;
+ if (idx < (pgoff_t)ctx->nr_pages) {
+ /* Make sure the old page hasn't already been changed */
+ if (ctx->ring_pages[idx] != old)
+ rc = -EAGAIN;
+ } else
+ rc = -EINVAL;
+
+ if (rc != 0)
+ goto out_unlock;
+
+ /* Writeback must be complete */
+ BUG_ON(PageWriteback(old));
+ get_page(new);
+
+ rc = migrate_page_move_mapping(mapping, new, old, NULL, mode, 1);
+ if (rc != MIGRATEPAGE_SUCCESS) {
+ put_page(new);
+ goto out_unlock;
+ }
+
+ /* Take completion_lock to prevent other writes to the ring buffer
+ * while the old page is copied to the new. This prevents new
+ * events from being lost.
+ */
+ spin_lock_irqsave(&ctx->completion_lock, flags);
+ migrate_page_copy(new, old);
+ BUG_ON(ctx->ring_pages[idx] != old);
+ ctx->ring_pages[idx] = new;
+ spin_unlock_irqrestore(&ctx->completion_lock, flags);
+
+ /* The old page is no longer accessible. */
+ put_page(old);
+
+out_unlock:
+ mutex_unlock(&ctx->ring_lock);
+out:
+ spin_unlock(&mapping->private_lock);
+ return rc;
+}
+#endif
+
+static const struct address_space_operations aio_ctx_aops = {
+ .set_page_dirty = __set_page_dirty_no_writeback,
+#if IS_ENABLED(CONFIG_MIGRATION)
+ .migratepage = aio_migratepage,
+#endif
+};
+
+static int aio_setup_ring(struct kioctx *ctx)
+{
+ struct aio_ring *ring;
+ unsigned nr_events = ctx->max_reqs;
+ 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_inode->i_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);
+
+ down_write(&mm->mmap_sem);
+ ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
+ PROT_READ | PROT_WRITE,
+ MAP_SHARED, 0, &unused);
+ up_write(&mm->mmap_sem);
+ 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, common);
+ struct kioctx *ctx = req->ki_ctx;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ctx->ctx_lock, flags);
+
+ if (!req->ki_list.next)
+ list_add(&req->ki_list, &ctx->active_reqs);
+
+ req->ki_cancel = cancel;
+
+ spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+}
+EXPORT_SYMBOL(kiocb_set_cancel_fn);
+
+static int kiocb_cancel(struct aio_kiocb *kiocb)
+{
+ kiocb_cancel_fn *old, *cancel;
+
+ /*
+ * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
+ * actually has a cancel function, hence the cmpxchg()
+ */
+
+ cancel = ACCESS_ONCE(kiocb->ki_cancel);
+ do {
+ if (!cancel || cancel == KIOCB_CANCELLED)
+ return -EINVAL;
+
+ old = cancel;
+ cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
+ } while (cancel != old);
+
+ return cancel(&kiocb->common);
+}
+
+static void free_ioctx(struct work_struct *work)
+{
+ struct kioctx *ctx = container_of(work, struct kioctx, free_work);
+
+ 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);
+
+ INIT_WORK(&ctx->free_work, free_ioctx);
+ schedule_work(&ctx->free_work);
+}
+
+/*
+ * 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);
+
+ list_del_init(&req->ki_list);
+ kiocb_cancel(req);
+ }
+
+ 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 (!table->table[i]) {
+ ctx->id = i;
+ 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(sizeof(*table) + sizeof(struct kioctx *) *
+ 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;
+
+ /*
+ * 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)nr_events > (aio_max_nr * 2UL))
+ return ERR_PTR(-EAGAIN);
+
+ ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
+ if (!ctx)
+ return ERR_PTR(-ENOMEM);
+
+ ctx->max_reqs = nr_events;
+
+ 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);
+ 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 + nr_events > (aio_max_nr * 2UL) ||
+ aio_nr + nr_events < 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 != table->table[ctx->id]);
+ table->table[ctx->id] = NULL;
+ spin_unlock(&mm->ioctx_lock);
+
+ /* percpu_ref_kill() will do the necessary call_rcu() */
+ 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 = table->table[i];
+
+ 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 old, avail = atomic_read(&ctx->reqs_available);
+
+ do {
+ if (avail < ctx->req_batch)
+ goto out;
+
+ old = avail;
+ avail = atomic_cmpxchg(&ctx->reqs_available,
+ avail, avail - ctx->req_batch);
+ } while (avail != old);
+
+ 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);
+}
+
+/* aio_get_req
+ * Allocate a slot for an aio request.
+ * Returns NULL if no requests are free.
+ */
+static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
+{
+ struct aio_kiocb *req;
+
+ if (!get_reqs_available(ctx)) {
+ user_refill_reqs_available(ctx);
+ if (!get_reqs_available(ctx))
+ return NULL;
+ }
+
+ req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
+ if (unlikely(!req))
+ goto out_put;
+
+ percpu_ref_get(&ctx->reqs);
+
+ req->ki_ctx = ctx;
+ return req;
+out_put:
+ put_reqs_available(ctx, 1);
+ return NULL;
+}
+
+static void kiocb_free(struct aio_kiocb *req)
+{
+ if (req->common.ki_filp)
+ fput(req->common.ki_filp);
+ if (req->ki_eventfd != NULL)
+ eventfd_ctx_put(req->ki_eventfd);
+ kmem_cache_free(kiocb_cachep, 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;
+
+ ctx = table->table[id];
+ if (ctx && ctx->user_id == ctx_id) {
+ percpu_ref_get(&ctx->users);
+ ret = ctx;
+ }
+out:
+ rcu_read_unlock();
+ return ret;
+}
+
+/* aio_complete
+ * Called when the io request on the given iocb is complete.
+ */
+static void aio_complete(struct kiocb *kiocb, long res, long res2)
+{
+ struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, common);
+ struct kioctx *ctx = iocb->ki_ctx;
+ struct aio_ring *ring;
+ struct io_event *ev_page, *event;
+ unsigned tail, pos, head;
+ unsigned long flags;
+
+ /*
+ * Special case handling for sync iocbs:
+ * - events go directly into the iocb for fast handling
+ * - the sync task with the iocb in its stack holds the single iocb
+ * ref, no other paths have a way to get another ref
+ * - the sync task helpfully left a reference to itself in the iocb
+ */
+ BUG_ON(is_sync_kiocb(kiocb));
+
+ if (iocb->ki_list.next) {
+ unsigned long flags;
+
+ spin_lock_irqsave(&ctx->ctx_lock, flags);
+ list_del(&iocb->ki_list);
+ spin_unlock_irqrestore(&ctx->ctx_lock, 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->obj = (u64)(unsigned long)iocb->ki_user_iocb;
+ event->data = iocb->ki_user_data;
+ event->res = res;
+ event->res2 = res2;
+
+ 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, iocb->ki_user_iocb, 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 */
+
+ 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 != NULL)
+ eventfd_signal(iocb->ki_eventfd, 1);
+
+ /* everything turned out well, dispose of the aiocb. */
+ kiocb_free(iocb);
+
+ /*
+ * 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);
+
+ percpu_ref_put(&ctx->reqs);
+}
+
+/* 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;
+
+ avail = min(avail, nr - ret);
+ avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
+ ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
+
+ pos = head + AIO_EVENTS_OFFSET;
+ page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
+ pos %= AIO_EVENTS_PER_PAGE;
+
+ 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,
+ struct timespec __user *timeout)
+{
+ ktime_t until = { .tv64 = KTIME_MAX };
+ long ret = 0;
+
+ if (timeout) {
+ struct timespec ts;
+
+ if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
+ return -EFAULT;
+
+ until = timespec_to_ktime(ts);
+ }
+
+ /*
+ * 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.tv64 == 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);
+
+ if (!ret && signal_pending(current))
+ ret = -EINTR;
+
+ 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;
+}
+
+/* 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;
+}
+
+typedef ssize_t (rw_iter_op)(struct kiocb *, struct iov_iter *);
+
+static int aio_setup_vectored_rw(int rw, char __user *buf, size_t len,
+ struct iovec **iovec,
+ bool compat,
+ struct iov_iter *iter)
+{
+#ifdef CONFIG_COMPAT
+ if (compat)
+ return compat_import_iovec(rw,
+ (struct compat_iovec __user *)buf,
+ len, UIO_FASTIOV, iovec, iter);
+#endif
+ return import_iovec(rw, (struct iovec __user *)buf,
+ len, UIO_FASTIOV, iovec, iter);
+}
+
+/*
+ * aio_run_iocb:
+ * Performs the initial checks and io submission.
+ */
+static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
+ char __user *buf, size_t len, bool compat)
+{
+ struct file *file = req->ki_filp;
+ ssize_t ret;
+ int rw;
+ fmode_t mode;
+ rw_iter_op *iter_op;
+ struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+ struct iov_iter iter;
+
+ switch (opcode) {
+ case IOCB_CMD_PREAD:
+ case IOCB_CMD_PREADV:
+ mode = FMODE_READ;
+ rw = READ;
+ iter_op = file->f_op->read_iter;
+ goto rw_common;
+
+ case IOCB_CMD_PWRITE:
+ case IOCB_CMD_PWRITEV:
+ mode = FMODE_WRITE;
+ rw = WRITE;
+ iter_op = file->f_op->write_iter;
+ goto rw_common;
+rw_common:
+ if (unlikely(!(file->f_mode & mode)))
+ return -EBADF;
+
+ if (!iter_op)
+ return -EINVAL;
+
+ if (opcode == IOCB_CMD_PREADV || opcode == IOCB_CMD_PWRITEV)
+ ret = aio_setup_vectored_rw(rw, buf, len,
+ &iovec, compat, &iter);
+ else {
+ ret = import_single_range(rw, buf, len, iovec, &iter);
+ iovec = NULL;
+ }
+ if (!ret)
+ ret = rw_verify_area(rw, file, &req->ki_pos,
+ iov_iter_count(&iter));
+ if (ret < 0) {
+ kfree(iovec);
+ return ret;
+ }
+
+ len = ret;
+
+ if (rw == WRITE)
+ file_start_write(file);
+
+ ret = iter_op(req, &iter);
+
+ if (rw == WRITE)
+ file_end_write(file);
+ kfree(iovec);
+ break;
+
+ case IOCB_CMD_FDSYNC:
+ if (!file->f_op->aio_fsync)
+ return -EINVAL;
+
+ ret = file->f_op->aio_fsync(req, 1);
+ break;
+
+ case IOCB_CMD_FSYNC:
+ if (!file->f_op->aio_fsync)
+ return -EINVAL;
+
+ ret = file->f_op->aio_fsync(req, 0);
+ break;
+
+ default:
+ pr_debug("EINVAL: no operation provided\n");
+ return -EINVAL;
+ }
+
+ if (ret != -EIOCBQUEUED) {
+ /*
+ * There's no easy way to restart the syscall since other AIO's
+ * may be already running. Just fail this IO with EINTR.
+ */
+ if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
+ ret == -ERESTARTNOHAND ||
+ ret == -ERESTART_RESTARTBLOCK))
+ ret = -EINTR;
+ aio_complete(req, ret, 0);
+ }
+
+ return 0;
+}
+
+static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
+ struct iocb *iocb, bool compat)
+{
+ struct aio_kiocb *req;
+ ssize_t ret;
+
+ /* enforce forwards compatibility on users */
+ if (unlikely(iocb->aio_reserved1 || 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;
+
+ req->common.ki_filp = fget(iocb->aio_fildes);
+ if (unlikely(!req->common.ki_filp)) {
+ ret = -EBADF;
+ goto out_put_req;
+ }
+ req->common.ki_pos = iocb->aio_offset;
+ req->common.ki_complete = aio_complete;
+ req->common.ki_flags = iocb_flags(req->common.ki_filp);
+
+ if (iocb->aio_flags & IOCB_FLAG_RESFD) {
+ /*
+ * 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.
+ */
+ req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
+ if (IS_ERR(req->ki_eventfd)) {
+ ret = PTR_ERR(req->ki_eventfd);
+ req->ki_eventfd = NULL;
+ goto out_put_req;
+ }
+
+ req->common.ki_flags |= IOCB_EVENTFD;
+ }
+
+ ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
+ if (unlikely(ret)) {
+ pr_debug("EFAULT: aio_key\n");
+ goto out_put_req;
+ }
+
+ req->ki_user_iocb = user_iocb;
+ req->ki_user_data = iocb->aio_data;
+
+ ret = aio_run_iocb(&req->common, iocb->aio_lio_opcode,
+ (char __user *)(unsigned long)iocb->aio_buf,
+ iocb->aio_nbytes,
+ compat);
+ if (ret)
+ goto out_put_req;
+
+ return 0;
+out_put_req:
+ put_reqs_available(ctx, 1);
+ percpu_ref_put(&ctx->reqs);
+ kiocb_free(req);
+ return ret;
+}
+
+long do_io_submit(aio_context_t ctx_id, long nr,
+ struct iocb __user *__user *iocbpp, bool compat)
+{
+ struct kioctx *ctx;
+ long ret = 0;
+ int i = 0;
+ struct blk_plug plug;
+
+ if (unlikely(nr < 0))
+ return -EINVAL;
+
+ if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
+ nr = LONG_MAX/sizeof(*iocbpp);
+
+ if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
+ return -EFAULT;
+
+ ctx = lookup_ioctx(ctx_id);
+ if (unlikely(!ctx)) {
+ pr_debug("EINVAL: invalid context id\n");
+ return -EINVAL;
+ }
+
+ blk_start_plug(&plug);
+
+ /*
+ * 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, compat);
+ if (ret)
+ break;
+ }
+ blk_finish_plug(&plug);
+
+ percpu_ref_put(&ctx->users);
+ return i ? i : 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.
+ */
+SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
+ struct iocb __user * __user *, iocbpp)
+{
+ return do_io_submit(ctx_id, nr, iocbpp, 0);
+}
+
+/* lookup_kiocb
+ * Finds a given iocb for cancellation.
+ */
+static struct aio_kiocb *
+lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, u32 key)
+{
+ struct aio_kiocb *kiocb;
+
+ assert_spin_locked(&ctx->ctx_lock);
+
+ if (key != KIOCB_KEY)
+ return NULL;
+
+ /* TODO: use a hash or array, this sucks. */
+ list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
+ if (kiocb->ki_user_iocb == iocb)
+ 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.
+ */
+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;
+ 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);
+
+ kiocb = lookup_kiocb(ctx, iocb, key);
+ if (kiocb)
+ ret = kiocb_cancel(kiocb);
+ else
+ ret = -EINVAL;
+
+ 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;
+}
+
+/* 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.
+ */
+SYSCALL_DEFINE5(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))
+ ret = read_events(ioctx, min_nr, nr, events, timeout);
+ percpu_ref_put(&ioctx->users);
+ }
+ return ret;
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-18 04:05:52 +0000