aio: kill struct aio_ring_info

struct aio_ring_info was kind of odd, the only place it's used is where
it's embedded in struct kioctx - there's no real need for it.

The next patch rearranges struct kioctx and puts various things on their
own cachelines - getting rid of struct aio_ring_info now makes that
reordering a bit clearer.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
Cc: Zach Brown <zab@redhat.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: Selvan Mani <smani@micron.com>
Cc: Sam Bradshaw <sbradshaw@micron.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Reviewed-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 74 insertions, 81 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 263ebce940c0..16239fbd6458 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -58,18 +58,6 @@ struct aio_ring {
 }; /* 128 bytes + ring size */
 
 #define AIO_RING_PAGES  8
-struct aio_ring_info {
-        unsigned long           mmap_base;
-        unsigned long           mmap_size;
-
-        struct page             **ring_pages;
-        struct mutex            ring_lock;
-        long                    nr_pages;
-
-        unsigned                nr, tail;
-
-        struct page             *internal_pages[AIO_RING_PAGES];
-};
 
 struct kioctx {
         atomic_t                users;
@@ -90,14 +78,30 @@ struct kioctx {
          * 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 ring->nr - 1, which will be larger (see
+         * The real limit is nr_events - 1, which will be larger (see
          * aio_setup_ring())
          */
         unsigned                max_reqs;
 
-        struct aio_ring_info    ring_info;
+        /* Size of ringbuffer, in units of struct io_event */
+        unsigned                nr_events;
 
-        spinlock_t              completion_lock;
+        unsigned long           mmap_base;
+        unsigned long           mmap_size;
+
+        struct page             **ring_pages;
+        long                    nr_pages;
+
+        struct {
+                struct mutex    ring_lock;
+        } ____cacheline_aligned;
+
+        struct {
+                unsigned        tail;
+                spinlock_t      completion_lock;
+        } ____cacheline_aligned;
+
+        struct page             *internal_pages[AIO_RING_PAGES];
 
         struct rcu_head         rcu_head;
         struct work_struct      rcu_work;
@@ -129,26 +133,21 @@ __initcall(aio_setup);
 
 static void aio_free_ring(struct kioctx *ctx)
 {
-        struct aio_ring_info *info = &ctx->ring_info;
         long i;
 
-        for (i=0; i<info->nr_pages; i++)
-                put_page(info->ring_pages[i]);
+        for (i = 0; i < ctx->nr_pages; i++)
+                put_page(ctx->ring_pages[i]);
 
-        if (info->mmap_size) {
-                vm_munmap(info->mmap_base, info->mmap_size);
-        }
+        if (ctx->mmap_size)
+                vm_munmap(ctx->mmap_base, ctx->mmap_size);
 
-        if (info->ring_pages && info->ring_pages != info->internal_pages)
-                kfree(info->ring_pages);
-        info->ring_pages = NULL;
-        info->nr = 0;
+        if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
+                kfree(ctx->ring_pages);
 }
 
 static int aio_setup_ring(struct kioctx *ctx)
 {
         struct aio_ring *ring;
-        struct aio_ring_info *info = &ctx->ring_info;
         unsigned nr_events = ctx->max_reqs;
         struct mm_struct *mm = current->mm;
         unsigned long size, populate;
@@ -166,45 +165,44 @@ static int aio_setup_ring(struct kioctx *ctx)
 
         nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);
 
-        info->nr = 0;
-        info->ring_pages = info->internal_pages;
+        ctx->nr_events = 0;
+        ctx->ring_pages = ctx->internal_pages;
         if (nr_pages > AIO_RING_PAGES) {
-                info->ring_pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
-                if (!info->ring_pages)
+                ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
+                                          GFP_KERNEL);
+                if (!ctx->ring_pages)
                         return -ENOMEM;
         }
 
-        info->mmap_size = nr_pages * PAGE_SIZE;
-        pr_debug("attempting mmap of %lu bytes\n", info->mmap_size);
+        ctx->mmap_size = nr_pages * PAGE_SIZE;
+        pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
         down_write(&mm->mmap_sem);
-        info->mmap_base = do_mmap_pgoff(NULL, 0, info->mmap_size, 
-                                        PROT_READ|PROT_WRITE,
-                                        MAP_ANONYMOUS|MAP_PRIVATE, 0,
-                                        &populate);
-        if (IS_ERR((void *)info->mmap_base)) {
+        ctx->mmap_base = do_mmap_pgoff(NULL, 0, ctx->mmap_size,
+                                       PROT_READ|PROT_WRITE,
+                                       MAP_ANONYMOUS|MAP_PRIVATE, 0, &populate);
+        if (IS_ERR((void *)ctx->mmap_base)) {
                 up_write(&mm->mmap_sem);
-                info->mmap_size = 0;
+                ctx->mmap_size = 0;
                 aio_free_ring(ctx);
                 return -EAGAIN;
         }
 
-        pr_debug("mmap address: 0x%08lx\n", info->mmap_base);
-        info->nr_pages = get_user_pages(current, mm, info->mmap_base, nr_pages,
-                                        1, 0, info->ring_pages, NULL);
+        pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
+        ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages,
+                                       1, 0, ctx->ring_pages, NULL);
         up_write(&mm->mmap_sem);
 
-        if (unlikely(info->nr_pages != nr_pages)) {
+        if (unlikely(ctx->nr_pages != nr_pages)) {
                 aio_free_ring(ctx);
                 return -EAGAIN;
         }
         if (populate)
-                mm_populate(info->mmap_base, populate);
+                mm_populate(ctx->mmap_base, populate);
 
-        ctx->user_id = info->mmap_base;
+        ctx->user_id = ctx->mmap_base;
+        ctx->nr_events = nr_events; /* trusted copy */
 
-        info->nr = nr_events;           /* trusted copy */
-
-        ring = kmap_atomic(info->ring_pages[0]);
+        ring = kmap_atomic(ctx->ring_pages[0]);
         ring->nr = nr_events;   /* user copy */
         ring->id = ctx->user_id;
         ring->head = ring->tail = 0;
@@ -213,7 +211,7 @@ static int aio_setup_ring(struct kioctx *ctx)
         ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
         ring->header_length = sizeof(struct aio_ring);
         kunmap_atomic(ring);
-        flush_dcache_page(info->ring_pages[0]);
+        flush_dcache_page(ctx->ring_pages[0]);
 
         return 0;
 }
@@ -284,7 +282,6 @@ static void free_ioctx_rcu(struct rcu_head *head)
  */
 static void free_ioctx(struct kioctx *ctx)
 {
-        struct aio_ring_info *info = &ctx->ring_info;
         struct aio_ring *ring;
         struct io_event res;
         struct kiocb *req;
@@ -302,18 +299,18 @@ static void free_ioctx(struct kioctx *ctx)
 
         spin_unlock_irq(&ctx->ctx_lock);
 
-        ring = kmap_atomic(info->ring_pages[0]);
+        ring = kmap_atomic(ctx->ring_pages[0]);
         head = ring->head;
         kunmap_atomic(ring);
 
         while (atomic_read(&ctx->reqs_active) > 0) {
-                wait_event(ctx->wait, head != info->tail);
+                wait_event(ctx->wait, head != ctx->tail);
 
-                avail = (head <= info->tail ? info->tail : info->nr) - head;
+                avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
 
                 atomic_sub(avail, &ctx->reqs_active);
                 head += avail;
-                head %= info->nr;
+                head %= ctx->nr_events;
         }
 
         WARN_ON(atomic_read(&ctx->reqs_active) < 0);
@@ -372,7 +369,7 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
         atomic_set(&ctx->dead, 0);
         spin_lock_init(&ctx->ctx_lock);
         spin_lock_init(&ctx->completion_lock);
-        mutex_init(&ctx->ring_info.ring_lock);
+        mutex_init(&ctx->ring_lock);
         init_waitqueue_head(&ctx->wait);
 
         INIT_LIST_HEAD(&ctx->active_reqs);
@@ -396,7 +393,7 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
         spin_unlock(&mm->ioctx_lock);
 
         pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
-                ctx, ctx->user_id, mm, ctx->ring_info.nr);
+                 ctx, ctx->user_id, mm, ctx->nr_events);
         return ctx;
 
 out_cleanup:
@@ -491,7 +488,7 @@ void exit_aio(struct mm_struct *mm)
                  * just set it to 0; aio_free_ring() is the only
                  * place that uses ->mmap_size, so it's safe.
                  */
-                ctx->ring_info.mmap_size = 0;
+                ctx->mmap_size = 0;
 
                 if (!atomic_xchg(&ctx->dead, 1)) {
                         hlist_del_rcu(&ctx->list);
@@ -514,10 +511,10 @@ static inline struct kiocb *aio_get_req(struct kioctx *ctx)
 {
         struct kiocb *req;
 
-        if (atomic_read(&ctx->reqs_active) >= ctx->ring_info.nr)
+        if (atomic_read(&ctx->reqs_active) >= ctx->nr_events)
                 return NULL;
 
-        if (atomic_inc_return(&ctx->reqs_active) > ctx->ring_info.nr - 1)
+        if (atomic_inc_return(&ctx->reqs_active) > ctx->nr_events - 1)
                 goto out_put;
 
         req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
@@ -578,7 +575,6 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id)
 void aio_complete(struct kiocb *iocb, long res, long res2)
 {
         struct kioctx   *ctx = iocb->ki_ctx;
-        struct aio_ring_info    *info;
         struct aio_ring *ring;
         struct io_event *ev_page, *event;
         unsigned long   flags;
@@ -599,8 +595,6 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
                 return;
         }
 
-        info = &ctx->ring_info;
-
         /*
          * Take rcu_read_lock() in case the kioctx is being destroyed, as we
          * need to issue a wakeup after decrementing reqs_active.
@@ -633,13 +627,13 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
          */
         spin_lock_irqsave(&ctx->completion_lock, flags);
 
-        tail = info->tail;
+        tail = ctx->tail;
         pos = tail + AIO_EVENTS_OFFSET;
 
-        if (++tail >= info->nr)
+        if (++tail >= ctx->nr_events)
                 tail = 0;
 
-        ev_page = kmap_atomic(info->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
+        ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
         event = ev_page + pos % AIO_EVENTS_PER_PAGE;
 
         event->obj = (u64)(unsigned long)iocb->ki_obj.user;
@@ -648,7 +642,7 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
         event->res2 = res2;
 
         kunmap_atomic(ev_page);
-        flush_dcache_page(info->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
+        flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
 
         pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
                  ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
@@ -659,12 +653,12 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
          */
         smp_wmb();      /* make event visible before updating tail */
 
-        info->tail = tail;
+        ctx->tail = tail;
 
-        ring = kmap_atomic(info->ring_pages[0]);
+        ring = kmap_atomic(ctx->ring_pages[0]);
         ring->tail = tail;
         kunmap_atomic(ring);
-        flush_dcache_page(info->ring_pages[0]);
+        flush_dcache_page(ctx->ring_pages[0]);
 
         spin_unlock_irqrestore(&ctx->completion_lock, flags);
 
@@ -704,21 +698,20 @@ EXPORT_SYMBOL(aio_complete);
 static long aio_read_events_ring(struct kioctx *ctx,
                                  struct io_event __user *event, long nr)
 {
-        struct aio_ring_info *info = &ctx->ring_info;
         struct aio_ring *ring;
         unsigned head, pos;
         long ret = 0;
         int copy_ret;
 
-        mutex_lock(&info->ring_lock);
+        mutex_lock(&ctx->ring_lock);
 
-        ring = kmap_atomic(info->ring_pages[0]);
+        ring = kmap_atomic(ctx->ring_pages[0]);
         head = ring->head;
         kunmap_atomic(ring);
 
-        pr_debug("h%u t%u m%u\n", head, info->tail, info->nr);
+        pr_debug("h%u t%u m%u\n", head, ctx->tail, ctx->nr_events);
 
-        if (head == info->tail)
+        if (head == ctx->tail)
                 goto out;
 
         while (ret < nr) {
@@ -726,8 +719,8 @@ static long aio_read_events_ring(struct kioctx *ctx,
                 struct io_event *ev;
                 struct page *page;
 
-                avail = (head <= info->tail ? info->tail : info->nr) - head;
-                if (head == info->tail)
+                avail = (head <= ctx->tail ? ctx->tail : ctx->nr_events) - head;
+                if (head == ctx->tail)
                         break;
 
                 avail = min(avail, nr - ret);
@@ -735,7 +728,7 @@ static long aio_read_events_ring(struct kioctx *ctx,
                             ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
 
                 pos = head + AIO_EVENTS_OFFSET;
-                page = info->ring_pages[pos / AIO_EVENTS_PER_PAGE];
+                page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
                 pos %= AIO_EVENTS_PER_PAGE;
 
                 ev = kmap(page);
@@ -750,19 +743,19 @@ static long aio_read_events_ring(struct kioctx *ctx,
 
                 ret += avail;
                 head += avail;
-                head %= info->nr;
+                head %= ctx->nr_events;
         }
 
-        ring = kmap_atomic(info->ring_pages[0]);
+        ring = kmap_atomic(ctx->ring_pages[0]);
         ring->head = head;
         kunmap_atomic(ring);
-        flush_dcache_page(info->ring_pages[0]);
+        flush_dcache_page(ctx->ring_pages[0]);
 
-        pr_debug("%li  h%u t%u\n", ret, head, info->tail);
+        pr_debug("%li  h%u t%u\n", ret, head, ctx->tail);
 
         atomic_sub(ret, &ctx->reqs_active);
 out:
-        mutex_unlock(&info->ring_lock);
+        mutex_unlock(&ctx->ring_lock);
 
         return ret;
 }