This is useful for people who want to use aio in kernel, e.g. vhost-blk.

Cc: Benjamin LaHaise <b...@kvack.org>
Cc: Alexander Viro <v...@zeniv.linux.org.uk>
Cc: Jeff Moyer <jmo...@redhat.com>
Cc: James Bottomley <james.bottom...@hansenpartnership.com>
Cc: Michael S. Tsirkin <m...@redhat.com>
Cc: linux-...@kvack.org
Cc: linux-fsde...@vger.kernel.org
Cc: linux-ker...@vger.kernel.org
Cc: kvm@vger.kernel.org
Cc: virtualizat...@lists.linux-foundation.org
Signed-off-by: Asias He <as...@redhat.com>
---
 fs/aio.c            |   37 ++++++++++++++++++-------------------
 include/linux/aio.h |   21 +++++++++++++++++++++
 2 files changed, 39 insertions(+), 19 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 55c4c76..93dfbdd 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -224,22 +224,24 @@ static void __put_ioctx(struct kioctx *ctx)
        call_rcu(&ctx->rcu_head, ctx_rcu_free);
 }
 
-static inline int try_get_ioctx(struct kioctx *kioctx)
+inline int try_get_ioctx(struct kioctx *kioctx)
 {
        return atomic_inc_not_zero(&kioctx->users);
 }
+EXPORT_SYMBOL(try_get_ioctx);
 
-static inline void put_ioctx(struct kioctx *kioctx)
+inline void put_ioctx(struct kioctx *kioctx)
 {
        BUG_ON(atomic_read(&kioctx->users) <= 0);
        if (unlikely(atomic_dec_and_test(&kioctx->users)))
                __put_ioctx(kioctx);
 }
+EXPORT_SYMBOL(put_ioctx);
 
 /* ioctx_alloc
  *     Allocates and initializes an ioctx.  Returns an ERR_PTR if it failed.
  */
-static struct kioctx *ioctx_alloc(unsigned nr_events)
+struct kioctx *ioctx_alloc(unsigned nr_events)
 {
        struct mm_struct *mm;
        struct kioctx *ctx;
@@ -303,6 +305,7 @@ out_freectx:
        dprintk("aio: error allocating ioctx %d\n", err);
        return ERR_PTR(err);
 }
+EXPORT_SYMBOL(ioctx_alloc);
 
 /* kill_ctx
  *     Cancels all outstanding aio requests on an aio context.  Used 
@@ -436,23 +439,14 @@ static struct kiocb *__aio_get_req(struct kioctx *ctx)
        return req;
 }
 
-/*
- * struct kiocb's are allocated in batches to reduce the number of
- * times the ctx lock is acquired and released.
- */
-#define KIOCB_BATCH_SIZE       32L
-struct kiocb_batch {
-       struct list_head head;
-       long count; /* number of requests left to allocate */
-};
-
-static void kiocb_batch_init(struct kiocb_batch *batch, long total)
+void kiocb_batch_init(struct kiocb_batch *batch, long total)
 {
        INIT_LIST_HEAD(&batch->head);
        batch->count = total;
 }
+EXPORT_SYMBOL(kiocb_batch_init);
 
-static void kiocb_batch_free(struct kioctx *ctx, struct kiocb_batch *batch)
+void kiocb_batch_free(struct kioctx *ctx, struct kiocb_batch *batch)
 {
        struct kiocb *req, *n;
 
@@ -470,6 +464,7 @@ static void kiocb_batch_free(struct kioctx *ctx, struct 
kiocb_batch *batch)
                wake_up_all(&ctx->wait);
        spin_unlock_irq(&ctx->ctx_lock);
 }
+EXPORT_SYMBOL(kiocb_batch_free);
 
 /*
  * Allocate a batch of kiocbs.  This avoids taking and dropping the
@@ -540,7 +535,7 @@ out:
        return allocated;
 }
 
-static inline struct kiocb *aio_get_req(struct kioctx *ctx,
+inline struct kiocb *aio_get_req(struct kioctx *ctx,
                                        struct kiocb_batch *batch)
 {
        struct kiocb *req;
@@ -552,6 +547,7 @@ static inline struct kiocb *aio_get_req(struct kioctx *ctx,
        list_del(&req->ki_batch);
        return req;
 }
+EXPORT_SYMBOL(aio_get_req);
 
 static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
 {
@@ -721,7 +717,7 @@ static inline int __queue_kicked_iocb(struct kiocb *iocb)
  * simplifies the coding of individual aio operations as
  * it avoids various potential races.
  */
-static ssize_t aio_run_iocb(struct kiocb *iocb)
+ssize_t aio_run_iocb(struct kiocb *iocb)
 {
        struct kioctx   *ctx = iocb->ki_ctx;
        ssize_t (*retry)(struct kiocb *);
@@ -815,6 +811,7 @@ out:
        }
        return ret;
 }
+EXPORT_SYMBOL(aio_run_iocb);
 
 /*
  * __aio_run_iocbs:
@@ -1136,7 +1133,7 @@ static inline void clear_timeout(struct aio_timeout *to)
        del_singleshot_timer_sync(&to->timer);
 }
 
-static int read_events(struct kioctx *ctx,
+int read_events(struct kioctx *ctx,
                        long min_nr, long nr,
                        struct io_event __user *event,
                        struct timespec __user *timeout)
@@ -1252,6 +1249,7 @@ out:
        destroy_timer_on_stack(&to.timer);
        return i ? i : ret;
 }
+EXPORT_SYMBOL(read_events);
 
 /* Take an ioctx and remove it from the list of ioctx's.  Protects 
  * against races with itself via ->dead.
@@ -1492,7 +1490,7 @@ static ssize_t aio_setup_single_vector(int type, struct 
file * file, struct kioc
  *     Performs the initial checks and aio retry method
  *     setup for the kiocb at the time of io submission.
  */
-static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
+ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
 {
        struct file *file = kiocb->ki_filp;
        ssize_t ret = 0;
@@ -1570,6 +1568,7 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool 
compat)
 
        return 0;
 }
+EXPORT_SYMBOL(aio_setup_iocb);
 
 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
                         struct iocb *iocb, struct kiocb_batch *batch,
diff --git a/include/linux/aio.h b/include/linux/aio.h
index b1a520e..4731da5 100644
--- a/include/linux/aio.h
+++ b/include/linux/aio.h
@@ -126,6 +126,16 @@ struct kiocb {
        struct eventfd_ctx      *ki_eventfd;
 };
 
+/*
+ * struct kiocb's are allocated in batches to reduce the number of
+ * times the ctx lock is acquired and released.
+ */
+#define KIOCB_BATCH_SIZE       32L
+struct kiocb_batch {
+       struct list_head head;
+       long count; /* number of requests left to allocate */
+};
+
 #define is_sync_kiocb(iocb)    ((iocb)->ki_key == KIOCB_SYNC_KEY)
 #define init_sync_kiocb(x, filp)                       \
        do {                                            \
@@ -216,6 +226,17 @@ struct mm_struct;
 extern void exit_aio(struct mm_struct *mm);
 extern long do_io_submit(aio_context_t ctx_id, long nr,
                         struct iocb __user *__user *iocbpp, bool compat);
+extern struct kioctx *ioctx_alloc(unsigned nr_events);
+extern ssize_t aio_run_iocb(struct kiocb *iocb);
+extern int read_events(struct kioctx *ctx, long min_nr, long nr,
+                      struct io_event __user *event,
+                      struct timespec __user *timeout);
+extern ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat);
+extern void kiocb_batch_init(struct kiocb_batch *batch, long total);
+extern void kiocb_batch_free(struct kioctx *ctx, struct kiocb_batch *batch);
+extern struct kiocb *aio_get_req(struct kioctx *ctx, struct kiocb_batch 
*batch);
+extern int try_get_ioctx(struct kioctx *kioctx);
+extern void put_ioctx(struct kioctx *kioctx);
 #else
 static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }
 static inline int aio_put_req(struct kiocb *iocb) { return 0; }
-- 
1.7.10.4

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