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-rw-r--r--fs/aio.c180
1 files changed, 118 insertions, 62 deletions
diff --git a/fs/aio.c b/fs/aio.c
index 1c9c5f0a9e2b..733750096b71 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -141,6 +141,7 @@ struct kioctx {
struct {
unsigned tail;
+ unsigned completed_events;
spinlock_t completion_lock;
} ____cacheline_aligned_in_smp;
@@ -192,7 +193,6 @@ static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
}
file->f_flags = O_RDWR;
- file->private_data = ctx;
return file;
}
@@ -202,7 +202,7 @@ static struct dentry *aio_mount(struct file_system_type *fs_type,
static const struct dentry_operations ops = {
.d_dname = simple_dname,
};
- return mount_pseudo(fs_type, "aio:", NULL, &ops, 0xa10a10a1);
+ return mount_pseudo(fs_type, "aio:", NULL, &ops, AIO_RING_MAGIC);
}
/* aio_setup
@@ -506,6 +506,8 @@ static void free_ioctx(struct work_struct *work)
aio_free_ring(ctx);
free_percpu(ctx->cpu);
+ percpu_ref_exit(&ctx->reqs);
+ percpu_ref_exit(&ctx->users);
kmem_cache_free(kioctx_cachep, ctx);
}
@@ -554,8 +556,7 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
struct aio_ring *ring;
spin_lock(&mm->ioctx_lock);
- rcu_read_lock();
- table = rcu_dereference(mm->ioctx_table);
+ table = rcu_dereference_raw(mm->ioctx_table);
while (1) {
if (table)
@@ -563,7 +564,6 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
if (!table->table[i]) {
ctx->id = i;
table->table[i] = ctx;
- rcu_read_unlock();
spin_unlock(&mm->ioctx_lock);
/* While kioctx setup is in progress,
@@ -577,8 +577,6 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
}
new_nr = (table ? table->nr : 1) * 4;
-
- rcu_read_unlock();
spin_unlock(&mm->ioctx_lock);
table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) *
@@ -589,8 +587,7 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
table->nr = new_nr;
spin_lock(&mm->ioctx_lock);
- rcu_read_lock();
- old = rcu_dereference(mm->ioctx_table);
+ old = rcu_dereference_raw(mm->ioctx_table);
if (!old) {
rcu_assign_pointer(mm->ioctx_table, table);
@@ -715,8 +712,8 @@ err_ctx:
err:
mutex_unlock(&ctx->ring_lock);
free_percpu(ctx->cpu);
- free_percpu(ctx->reqs.pcpu_count);
- free_percpu(ctx->users.pcpu_count);
+ 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);
@@ -737,12 +734,9 @@ static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
spin_lock(&mm->ioctx_lock);
- rcu_read_lock();
- table = rcu_dereference(mm->ioctx_table);
-
+ table = rcu_dereference_raw(mm->ioctx_table);
WARN_ON(ctx != table->table[ctx->id]);
table->table[ctx->id] = NULL;
- rcu_read_unlock();
spin_unlock(&mm->ioctx_lock);
/* percpu_ref_kill() will do the necessary call_rcu() */
@@ -791,40 +785,35 @@ EXPORT_SYMBOL(wait_on_sync_kiocb);
*/
void exit_aio(struct mm_struct *mm)
{
- struct kioctx_table *table;
- struct kioctx *ctx;
- unsigned i = 0;
-
- while (1) {
- rcu_read_lock();
- table = rcu_dereference(mm->ioctx_table);
-
- do {
- if (!table || i >= table->nr) {
- rcu_read_unlock();
- rcu_assign_pointer(mm->ioctx_table, NULL);
- if (table)
- kfree(table);
- return;
- }
+ struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
+ int i;
- ctx = table->table[i++];
- } while (!ctx);
+ if (!table)
+ return;
- rcu_read_unlock();
+ for (i = 0; i < table->nr; ++i) {
+ struct kioctx *ctx = table->table[i];
+ struct completion requests_done =
+ COMPLETION_INITIALIZER_ONSTACK(requests_done);
+ if (!ctx)
+ continue;
/*
- * We don't need to bother with munmap() here -
- * exit_mmap(mm) is coming and it'll unmap everything.
- * Since aio_free_ring() uses non-zero ->mmap_size
- * as indicator that it needs to unmap the area,
- * just set it to 0; aio_free_ring() is the only
- * place that uses ->mmap_size, so it's safe.
+ * 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, &requests_done);
- kill_ioctx(mm, ctx, NULL);
+ /* Wait until all IO for the context are done. */
+ wait_for_completion(&requests_done);
}
+
+ RCU_INIT_POINTER(mm->ioctx_table, NULL);
+ kfree(table);
}
static void put_reqs_available(struct kioctx *ctx, unsigned nr)
@@ -832,10 +821,8 @@ static void put_reqs_available(struct kioctx *ctx, unsigned nr)
struct kioctx_cpu *kcpu;
unsigned long flags;
- preempt_disable();
- kcpu = this_cpu_ptr(ctx->cpu);
-
local_irq_save(flags);
+ kcpu = this_cpu_ptr(ctx->cpu);
kcpu->reqs_available += nr;
while (kcpu->reqs_available >= ctx->req_batch * 2) {
@@ -844,7 +831,6 @@ static void put_reqs_available(struct kioctx *ctx, unsigned nr)
}
local_irq_restore(flags);
- preempt_enable();
}
static bool get_reqs_available(struct kioctx *ctx)
@@ -853,10 +839,8 @@ static bool get_reqs_available(struct kioctx *ctx)
bool ret = false;
unsigned long flags;
- preempt_disable();
- kcpu = this_cpu_ptr(ctx->cpu);
-
local_irq_save(flags);
+ kcpu = this_cpu_ptr(ctx->cpu);
if (!kcpu->reqs_available) {
int old, avail = atomic_read(&ctx->reqs_available);
@@ -876,10 +860,71 @@ static bool get_reqs_available(struct kioctx *ctx)
kcpu->reqs_available--;
out:
local_irq_restore(flags);
- preempt_enable();
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.
@@ -888,8 +933,11 @@ static inline struct kiocb *aio_get_req(struct kioctx *ctx)
{
struct kiocb *req;
- if (!get_reqs_available(ctx))
- return NULL;
+ 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))
@@ -948,8 +996,8 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
struct kioctx *ctx = iocb->ki_ctx;
struct aio_ring *ring;
struct io_event *ev_page, *event;
+ unsigned tail, pos, head;
unsigned long flags;
- unsigned tail, pos;
/*
* Special case handling for sync iocbs:
@@ -1010,10 +1058,14 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
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);
@@ -1028,7 +1080,6 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
/* everything turned out well, dispose of the aiocb. */
kiocb_free(iocb);
- put_reqs_available(ctx, 1);
/*
* We have to order our ring_info tail store above and test
@@ -1045,7 +1096,7 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
}
EXPORT_SYMBOL(aio_complete);
-/* aio_read_events
+/* aio_read_events_ring
* Pull an event off of the ioctx's event ring. Returns the number of
* events fetched
*/
@@ -1065,6 +1116,12 @@ static long aio_read_events_ring(struct kioctx *ctx,
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)
@@ -1268,12 +1325,12 @@ static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
if (compat)
ret = compat_rw_copy_check_uvector(rw,
(struct compat_iovec __user *)buf,
- *nr_segs, 1, *iovec, iovec);
+ *nr_segs, UIO_FASTIOV, *iovec, iovec);
else
#endif
ret = rw_copy_check_uvector(rw,
(struct iovec __user *)buf,
- *nr_segs, 1, *iovec, iovec);
+ *nr_segs, UIO_FASTIOV, *iovec, iovec);
if (ret < 0)
return ret;
@@ -1297,9 +1354,8 @@ static ssize_t aio_setup_single_vector(struct kiocb *kiocb,
}
/*
- * aio_setup_iocb:
- * Performs the initial checks and aio retry method
- * setup for the kiocb at the time of io submission.
+ * aio_run_iocb:
+ * Performs the initial checks and io submission.
*/
static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
char __user *buf, bool compat)
@@ -1311,7 +1367,7 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
fmode_t mode;
aio_rw_op *rw_op;
rw_iter_op *iter_op;
- struct iovec inline_vec, *iovec = &inline_vec;
+ struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
struct iov_iter iter;
switch (opcode) {
@@ -1346,7 +1402,7 @@ rw_common:
if (!ret)
ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
if (ret < 0) {
- if (iovec != &inline_vec)
+ if (iovec != inline_vecs)
kfree(iovec);
return ret;
}
@@ -1393,7 +1449,7 @@ rw_common:
return -EINVAL;
}
- if (iovec != &inline_vec)
+ if (iovec != inline_vecs)
kfree(iovec);
if (ret != -EIOCBQUEUED) {
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-12 02:40:50 +0000