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@@ -0,0 +1,77 @@
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+/*
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+ * Functions related to io context handling
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+ */
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+#include <linux/kernel.h>
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+#include <linux/module.h>
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+#include <linux/init.h>
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+#include <linux/bio.h>
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+#include <linux/blkdev.h>
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+#include <linux/bootmem.h> /* for max_pfn/max_low_pfn */
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+#include <linux/slab.h>
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+
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+#include "blk.h"
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+
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+/*
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+ * For io context allocations
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+ */
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+static struct kmem_cache *iocontext_cachep;
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+
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+/**
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+ * get_io_context - increment reference count to io_context
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+ * @ioc: io_context to get
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+ *
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+ * Increment reference count to @ioc.
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+ */
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+void get_io_context(struct io_context *ioc)
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+{
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+ BUG_ON(atomic_long_read(&ioc->refcount) <= 0);
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+ atomic_long_inc(&ioc->refcount);
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+}
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+EXPORT_SYMBOL(get_io_context);
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+
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+static void icq_free_icq_rcu(struct rcu_head *head)
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+{
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+ struct io_cq *icq = container_of(head, struct io_cq, __rcu_head);
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+
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+ kmem_cache_free(icq->__rcu_icq_cache, icq);
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+}
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+
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+/* Exit an icq. Called with both ioc and q locked. */
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+static void ioc_exit_icq(struct io_cq *icq)
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+{
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+ struct elevator_type *et = icq->q->elevator->type;
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+
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+ if (icq->flags & ICQ_EXITED)
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+ return;
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+
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+ if (et->ops.elevator_exit_icq_fn)
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+ et->ops.elevator_exit_icq_fn(icq);
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+
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+ icq->flags |= ICQ_EXITED;
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+}
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+
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+/* Release an icq. Called with both ioc and q locked. */
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+static void ioc_destroy_icq(struct io_cq *icq)
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+{
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+ struct io_context *ioc = icq->ioc;
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+ struct request_queue *q = icq->q;
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+ struct elevator_type *et = q->elevator->type;
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+
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+ lockdep_assert_held(&ioc->lock);
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+ lockdep_assert_held(q->queue_lock);
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+
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+ radix_tree_delete(&ioc->icq_tree, icq->q->id);
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+ hlist_del_init(&icq->ioc_node);
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+ list_del_init(&icq->q_node);
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+
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+ /*
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+ * Both setting lookup hint to and clearing it from @icq are done
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+ * under queue_lock. If it's not pointing to @icq now, it never
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+ * will. Hint assignment itself can race safely.
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+ */
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+ if (rcu_dereference_raw(ioc->icq_hint) == icq)
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+ rcu_assign_pointer(ioc->icq_hint, NULL);
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+
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+ ioc_exit_icq(icq);
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+
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+ /*
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韩正义