Skip to content

Commit

Permalink
aio: kill struct aio_ring_info
Browse files Browse the repository at this point in the history 
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>
  • Loading branch information
Kent Overstreet authored and Linus Torvalds committed May 8, 2013
1 parent a1c8eae commit 58c85dc
Showing 1 changed file with 74 additions and 81 deletions.
155 changes: 74 additions & 81 deletions fs/aio.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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;
Expand Down Expand Up @@ -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;
Expand All @@ -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;
Expand All @@ -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;
}
Expand Down Expand Up @@ -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;
Expand All @@ -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);
Expand Down Expand Up @@ -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);
Expand All @@ -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:
Expand Down Expand Up @@ -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);
Expand All @@ -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);
Expand Down Expand Up @@ -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;
Expand All @@ -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.
Expand Down Expand Up @@ -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;
Expand All @@ -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,
Expand All @@ -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);

Expand Down Expand Up @@ -704,38 +698,37 @@ 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) {
long avail;
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);
avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
((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);
Expand All @@ -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;
}
Expand Down

0 comments on commit 58c85dc

Please sign in to comment.