aio: now fput() is OK from interrupt context; get rid of manual delayed __fput()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 3 insertions, 70 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 55c4c7656053..71f613cf4a85 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -56,13 +56,6 @@ static struct kmem_cache	*kioctx_cachep;
 
 static struct workqueue_struct *aio_wq;
 
-/* Used for rare fput completion. */
-static void aio_fput_routine(struct work_struct *);
-static DECLARE_WORK(fput_work, aio_fput_routine);
-
-static DEFINE_SPINLOCK(fput_lock);
-static LIST_HEAD(fput_head);
-
 static void aio_kick_handler(struct work_struct *);
 static void aio_queue_work(struct kioctx *);
 
@@ -479,7 +472,6 @@ static int kiocb_batch_refill(struct kioctx *ctx, struct kiocb_batch *batch)
 {
         unsigned short allocated, to_alloc;
         long avail;
-        bool called_fput = false;
         struct kiocb *req, *n;
         struct aio_ring *ring;
 
@@ -495,28 +487,11 @@ static int kiocb_batch_refill(struct kioctx *ctx, struct kiocb_batch *batch)
         if (allocated == 0)
                 goto out;
 
-retry:
         spin_lock_irq(&ctx->ctx_lock);
         ring = kmap_atomic(ctx->ring_info.ring_pages[0]);
 
         avail = aio_ring_avail(&ctx->ring_info, ring) - ctx->reqs_active;
         BUG_ON(avail < 0);
-        if (avail == 0 && !called_fput) {
-                /*
-                 * Handle a potential starvation case.  It is possible that
-                 * we hold the last reference on a struct file, causing us
-                 * to delay the final fput to non-irq context.  In this case,
-                 * ctx->reqs_active is artificially high.  Calling the fput
-                 * routine here may free up a slot in the event completion
-                 * ring, allowing this allocation to succeed.
-                 */
-                kunmap_atomic(ring);
-                spin_unlock_irq(&ctx->ctx_lock);
-                aio_fput_routine(NULL);
-                called_fput = true;
-                goto retry;
-        }
-
         if (avail < allocated) {
                 /* Trim back the number of requests. */
                 list_for_each_entry_safe(req, n, &batch->head, ki_batch) {
@@ -570,36 +545,6 @@ static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
                 wake_up_all(&ctx->wait);
 }
 
-static void aio_fput_routine(struct work_struct *data)
-{
-        spin_lock_irq(&fput_lock);
-        while (likely(!list_empty(&fput_head))) {
-                struct kiocb *req = list_kiocb(fput_head.next);
-                struct kioctx *ctx = req->ki_ctx;
-
-                list_del(&req->ki_list);
-                spin_unlock_irq(&fput_lock);
-
-                /* Complete the fput(s) */
-                if (req->ki_filp != NULL)
-                        fput(req->ki_filp);
-
-                /* Link the iocb into the context's free list */
-                rcu_read_lock();
-                spin_lock_irq(&ctx->ctx_lock);
-                really_put_req(ctx, req);
-                /*
-                 * at that point ctx might've been killed, but actual
-                 * freeing is RCU'd
-                 */
-                spin_unlock_irq(&ctx->ctx_lock);
-                rcu_read_unlock();
-
-                spin_lock_irq(&fput_lock);
-        }
-        spin_unlock_irq(&fput_lock);
-}
-
 /* __aio_put_req
  *      Returns true if this put was the last user of the request.
  */
@@ -618,21 +563,9 @@ static int __aio_put_req(struct kioctx *ctx, struct kiocb *req)
         req->ki_cancel = NULL;
         req->ki_retry = NULL;
 
-        /*
-         * Try to optimize the aio and eventfd file* puts, by avoiding to
-         * schedule work in case it is not final fput() time. In normal cases,
-         * we would not be holding the last reference to the file*, so
-         * this function will be executed w/out any aio kthread wakeup.
-         */
-        if (unlikely(!fput_atomic(req->ki_filp))) {
-                spin_lock(&fput_lock);
-                list_add(&req->ki_list, &fput_head);
-                spin_unlock(&fput_lock);
-                schedule_work(&fput_work);
-        } else {
-                req->ki_filp = NULL;
-                really_put_req(ctx, req);
-        }
+        fput(req->ki_filp);
+        req->ki_filp = NULL;
+        really_put_req(ctx, req);
         return 1;
 }