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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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* 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 0struct 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[] __counted_by(nr);};
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 kioctx_cpu __percpu *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 folio **ring_folios; 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 folio *internal_folios[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;};
struct aio_inode_info { struct inode vfs_inode; spinlock_t migrate_lock; struct kioctx *ctx;};
static inline struct aio_inode_info *AIO_I(struct inode *inode){ return container_of(inode, struct aio_inode_info, vfs_inode);}
/*------ 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_SYSCTLstatic const 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 kmem_cache *aio_inode_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; AIO_I(inode)->ctx = 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 struct inode *aio_alloc_inode(struct super_block *sb){ struct aio_inode_info *ai;
ai = alloc_inode_sb(sb, aio_inode_cachep, GFP_KERNEL); if (!ai) return NULL; ai->ctx = NULL;
return &ai->vfs_inode;}
static void aio_free_inode(struct inode *inode){ kmem_cache_free(aio_inode_cachep, AIO_I(inode));}
static const struct super_operations aio_super_operations = { .alloc_inode = aio_alloc_inode, .free_inode = aio_free_inode, .statfs = simple_statfs,};
static int aio_init_fs_context(struct fs_context *fc){ struct pseudo_fs_context *pfc;
pfc = init_pseudo(fc, AIO_RING_MAGIC); if (!pfc) return -ENOMEM; pfc->ops = &aio_super_operations; return 0;}
static void init_once(void *obj){ struct aio_inode_info *ai = obj;
inode_init_once(&ai->vfs_inode); spin_lock_init(&ai->migrate_lock);}
/* 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_inode_cachep = kmem_cache_create("aio_inode_cache", sizeof(struct aio_inode_info), 0, (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_ACCOUNT), init_once); 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;
if (aio_ring_file) { struct inode *inode = file_inode(aio_ring_file);
truncate_setsize(inode, 0);
/* Prevent further access to the kioctx from migratepages */ spin_lock(&AIO_I(inode)->migrate_lock); AIO_I(inode)->ctx = NULL; ctx->aio_ring_file = NULL; spin_unlock(&AIO_I(inode)->migrate_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 folio *folio = ctx->ring_folios[i];
if (!folio) continue;
pr_debug("pid(%d) [%d] folio->count=%d\n", current->pid, i, folio_ref_count(folio)); ctx->ring_folios[i] = NULL; folio_put(folio); }
if (ctx->ring_folios && ctx->ring_folios != ctx->internal_folios) { kfree(ctx->ring_folios); ctx->ring_folios = 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->mmap_size == (vma->vm_end - vma->vm_start))) { 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_prepare(struct vm_area_desc *desc){ vma_desc_set_flags(desc, VMA_DONTEXPAND_BIT, VMA_DONTCOPY_BIT); desc->vm_ops = &aio_ring_vm_ops; return 0;}
static const struct file_operations aio_ring_fops = { .mmap_prepare = aio_ring_mmap_prepare,};
#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; struct aio_inode_info *ai = AIO_I(mapping->host); unsigned long flags; pgoff_t idx; int rc = 0;
/* ai->migrate_lock here protects against the kioctx teardown. */ spin_lock(&ai->migrate_lock); ctx = ai->ctx; 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_folios[idx] != src) 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) { 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_copy(dst, src); folio_migrate_flags(dst, src); BUG_ON(ctx->ring_folios[idx] != src); ctx->ring_folios[idx] = dst; 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(&ai->migrate_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_folios = ctx->internal_folios; if (nr_pages > AIO_RING_PAGES) { ctx->ring_folios = kzalloc_objs(struct folio *, nr_pages); if (!ctx->ring_folios) { put_aio_ring_file(ctx); return -ENOMEM; } }
for (i = 0; i < nr_pages; i++) { struct folio *folio;
folio = __filemap_get_folio(file->f_mapping, i, FGP_LOCK | FGP_ACCESSED | FGP_CREAT, GFP_USER | __GFP_ZERO); if (IS_ERR(folio)) break;
pr_debug("pid(%d) [%d] folio->count=%d\n", current->pid, i, folio_ref_count(folio)); folio_end_read(folio, true);
ctx->ring_folios[i] = folio; } 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, 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 = folio_address(ctx->ring_folios[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); flush_dcache_folio(ctx->ring_folios[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; struct kioctx *ctx; unsigned long flags;
/* * kiocb didn't come from aio or is neither a read nor a write, hence * ignore it. */ if (!(iocb->ki_flags & IOCB_AIO_RW)) return;
req = container_of(iocb, struct aio_kiocb, rw);
if (WARN_ON_ONCE(!list_empty(&req->ki_list))) return;
ctx = req->ki_ctx;
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_percpu_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_folios by ->ring_lock. */ ring = folio_address(ctx->ring_folios[0]); ring->id = ctx->id; return 0; }
new_nr = (table ? table->nr : 1) * 4; spin_unlock(&mm->ioctx_lock);
table = kzalloc_flex(*table, table, new_nr); 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 = folio_address(ctx->ring_folios[0]); head = ring->head;
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);}
struct aio_waiter { struct wait_queue_entry w; size_t min_nr;};
/* 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, avail; 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 = folio_address(ctx->ring_folios[pos / AIO_EVENTS_PER_PAGE]); event = ev_page + pos % AIO_EVENTS_PER_PAGE;
*event = iocb->ki_res;
flush_dcache_folio(ctx->ring_folios[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 = folio_address(ctx->ring_folios[0]); head = ring->head; ring->tail = tail; flush_dcache_folio(ctx->ring_folios[0]);
ctx->completed_events++; if (ctx->completed_events > 1) refill_reqs_available(ctx, head, tail);
avail = tail > head ? tail - head : tail + ctx->nr_events - head; 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);
/* * 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)) { struct aio_waiter *curr, *next; unsigned long flags;
spin_lock_irqsave(&ctx->wait.lock, flags); list_for_each_entry_safe(curr, next, &ctx->wait.head, w.entry) if (avail >= curr->min_nr) { wake_up_process(curr->w.private); list_del_init_careful(&curr->w.entry); } spin_unlock_irqrestore(&ctx->wait.lock, flags); }}
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_folios here is protected by ctx->ring_lock. */ ring = folio_address(ctx->ring_folios[0]); head = ring->head; tail = ring->tail;
/* * 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 folio *folio;
avail = (head <= tail ? tail : ctx->nr_events) - head; if (head == tail) break;
pos = head + AIO_EVENTS_OFFSET; folio = ctx->ring_folios[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 = folio_address(folio); copy_ret = copy_to_user(event + ret, ev + pos, sizeof(*ev) * avail);
if (unlikely(copy_ret)) { ret = -EFAULT; goto out; }
ret += avail; head += avail; head %= ctx->nr_events; }
ring = folio_address(ctx->ring_folios[0]); ring->head = head; flush_dcache_folio(ctx->ring_folios[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){ struct hrtimer_sleeper t; struct aio_waiter w; long ret = 0, ret2 = 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. */ aio_read_events(ctx, min_nr, nr, event, &ret); if (until == 0 || ret < 0 || ret >= min_nr) return ret;
hrtimer_setup_sleeper_on_stack(&t, CLOCK_MONOTONIC, HRTIMER_MODE_REL); if (until != KTIME_MAX) { hrtimer_set_expires_range_ns(&t.timer, until, current->timer_slack_ns); hrtimer_sleeper_start_expires(&t, HRTIMER_MODE_REL); }
init_wait(&w.w);
while (1) { unsigned long nr_got = ret;
w.min_nr = min_nr - ret;
ret2 = prepare_to_wait_event(&ctx->wait, &w.w, TASK_INTERRUPTIBLE); if (!ret2 && !t.task) ret2 = -ETIME;
if (aio_read_events(ctx, min_nr, nr, event, &ret) || ret2) break;
if (nr_got == ret) schedule(); }
finish_wait(&ctx->wait, &w.w); hrtimer_cancel(&t.timer); destroy_hrtimer_on_stack(&t.timer);
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_COMPATCOMPAT_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);
if (S_ISREG(inode->i_mode)) kiocb_end_write(kiocb); }
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 rw_type){ int ret;
req->ki_write_stream = 0; req->ki_complete = aio_complete_rw; req->private = NULL; req->ki_pos = iocb->aio_offset; req->ki_flags = req->ki_filp->f_iocb_flags | IOCB_AIO_RW; 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, rw_type); 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_ubuf(rw, buf, len, 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, READ); 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, file->f_op->read_iter(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, WRITE); 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) { if (S_ISREG(file_inode(file)->i_mode)) kiocb_start_write(req); req->ki_flags |= IOCB_WRITE; aio_rw_done(req, file->f_op->write_iter(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);
scoped_with_creds(iocb->fsync.creds) iocb->ki_res.res = vfs_fsync(iocb->fsync.file, iocb->fsync.datasync);
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 voidaio_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_COMPATCOMPAT_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); 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