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Merge git://git.kvack.org/~bcrl/aio-next
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Pull aio updates from Ben LaHaise.

* git://git.kvack.org/~bcrl/aio-next:
  aio: use iovec array rather than the single one
  aio: fix some comments
  aio: use the macro rather than the inline magic number
  aio: remove the needless registration of ring file's private_data
  aio: remove no longer needed preempt_disable()
  aio: kill the misleading rcu read locks in ioctx_add_table() and kill_ioctx()
  aio: change exit_aio() to load mm->ioctx_table once and avoid rcu_read_lock()
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@torvalds
torvalds committed Aug 16, 2014
2 parents 88ec63d + 00fefb9 commit da06df5
Showing 1 changed file with 30 additions and 56 deletions.
86 changes: 30 additions & 56 deletions fs/aio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -192,7 +192,6 @@ static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
}

file->f_flags = O_RDWR;
file->private_data = ctx;
return file;
}

Expand All @@ -202,7 +201,7 @@ static struct dentry *aio_mount(struct file_system_type *fs_type,
static const struct dentry_operations ops = {
.d_dname = simple_dname,
};
return mount_pseudo(fs_type, "aio:", NULL, &ops, 0xa10a10a1);
return mount_pseudo(fs_type, "aio:", NULL, &ops, AIO_RING_MAGIC);
}

/* aio_setup
Expand Down Expand Up @@ -556,16 +555,14 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
struct aio_ring *ring;

spin_lock(&mm->ioctx_lock);
rcu_read_lock();
table = rcu_dereference(mm->ioctx_table);
table = rcu_dereference_raw(mm->ioctx_table);

while (1) {
if (table)
for (i = 0; i < table->nr; i++)
if (!table->table[i]) {
ctx->id = i;
table->table[i] = ctx;
rcu_read_unlock();
spin_unlock(&mm->ioctx_lock);

/* While kioctx setup is in progress,
Expand All @@ -579,8 +576,6 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
}

new_nr = (table ? table->nr : 1) * 4;

rcu_read_unlock();
spin_unlock(&mm->ioctx_lock);

table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) *
Expand All @@ -591,8 +586,7 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
table->nr = new_nr;

spin_lock(&mm->ioctx_lock);
rcu_read_lock();
old = rcu_dereference(mm->ioctx_table);
old = rcu_dereference_raw(mm->ioctx_table);

if (!old) {
rcu_assign_pointer(mm->ioctx_table, table);
Expand Down Expand Up @@ -739,12 +733,9 @@ static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,


spin_lock(&mm->ioctx_lock);
rcu_read_lock();
table = rcu_dereference(mm->ioctx_table);

table = rcu_dereference_raw(mm->ioctx_table);
WARN_ON(ctx != table->table[ctx->id]);
table->table[ctx->id] = NULL;
rcu_read_unlock();
spin_unlock(&mm->ioctx_lock);

/* percpu_ref_kill() will do the necessary call_rcu() */
Expand Down Expand Up @@ -793,51 +784,39 @@ EXPORT_SYMBOL(wait_on_sync_kiocb);
*/
void exit_aio(struct mm_struct *mm)
{
struct kioctx_table *table;
struct kioctx *ctx;
unsigned i = 0;

while (1) {
rcu_read_lock();
table = rcu_dereference(mm->ioctx_table);

do {
if (!table || i >= table->nr) {
rcu_read_unlock();
rcu_assign_pointer(mm->ioctx_table, NULL);
if (table)
kfree(table);
return;
}
struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
int i;

ctx = table->table[i++];
} while (!ctx);
if (!table)
return;

rcu_read_unlock();
for (i = 0; i < table->nr; ++i) {
struct kioctx *ctx = table->table[i];

if (!ctx)
continue;
/*
* We don't need to bother with munmap() here -
* exit_mmap(mm) is coming and it'll unmap everything.
* Since aio_free_ring() uses non-zero ->mmap_size
* as indicator that it needs to unmap the area,
* just set it to 0; aio_free_ring() is the only
* place that uses ->mmap_size, so it's safe.
* We don't need to bother with munmap() here - exit_mmap(mm)
* is coming and it'll unmap everything. And we simply can't,
* this is not necessarily our ->mm.
* Since kill_ioctx() uses non-zero ->mmap_size as indicator
* that it needs to unmap the area, just set it to 0.
*/
ctx->mmap_size = 0;

kill_ioctx(mm, ctx, NULL);
}

RCU_INIT_POINTER(mm->ioctx_table, NULL);
kfree(table);
}

static void put_reqs_available(struct kioctx *ctx, unsigned nr)
{
struct kioctx_cpu *kcpu;
unsigned long flags;

preempt_disable();
kcpu = this_cpu_ptr(ctx->cpu);

local_irq_save(flags);
kcpu = this_cpu_ptr(ctx->cpu);
kcpu->reqs_available += nr;

while (kcpu->reqs_available >= ctx->req_batch * 2) {
Expand All @@ -846,7 +825,6 @@ static void put_reqs_available(struct kioctx *ctx, unsigned nr)
}

local_irq_restore(flags);
preempt_enable();
}

static bool get_reqs_available(struct kioctx *ctx)
Expand All @@ -855,10 +833,8 @@ static bool get_reqs_available(struct kioctx *ctx)
bool ret = false;
unsigned long flags;

preempt_disable();
kcpu = this_cpu_ptr(ctx->cpu);

local_irq_save(flags);
kcpu = this_cpu_ptr(ctx->cpu);
if (!kcpu->reqs_available) {
int old, avail = atomic_read(&ctx->reqs_available);

Expand All @@ -878,7 +854,6 @@ static bool get_reqs_available(struct kioctx *ctx)
kcpu->reqs_available--;
out:
local_irq_restore(flags);
preempt_enable();
return ret;
}

Expand Down Expand Up @@ -1047,7 +1022,7 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
}
EXPORT_SYMBOL(aio_complete);

/* aio_read_events
/* aio_read_events_ring
* Pull an event off of the ioctx's event ring. Returns the number of
* events fetched
*/
Expand Down Expand Up @@ -1270,12 +1245,12 @@ static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
if (compat)
ret = compat_rw_copy_check_uvector(rw,
(struct compat_iovec __user *)buf,
*nr_segs, 1, *iovec, iovec);
*nr_segs, UIO_FASTIOV, *iovec, iovec);
else
#endif
ret = rw_copy_check_uvector(rw,
(struct iovec __user *)buf,
*nr_segs, 1, *iovec, iovec);
*nr_segs, UIO_FASTIOV, *iovec, iovec);
if (ret < 0)
return ret;

Expand All @@ -1299,9 +1274,8 @@ static ssize_t aio_setup_single_vector(struct kiocb *kiocb,
}

/*
* aio_setup_iocb:
* Performs the initial checks and aio retry method
* setup for the kiocb at the time of io submission.
* aio_run_iocb:
* Performs the initial checks and io submission.
*/
static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
char __user *buf, bool compat)
Expand All @@ -1313,7 +1287,7 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
fmode_t mode;
aio_rw_op *rw_op;
rw_iter_op *iter_op;
struct iovec inline_vec, *iovec = &inline_vec;
struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
struct iov_iter iter;

switch (opcode) {
Expand Down Expand Up @@ -1348,7 +1322,7 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
if (!ret)
ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
if (ret < 0) {
if (iovec != &inline_vec)
if (iovec != inline_vecs)
kfree(iovec);
return ret;
}
Expand Down Expand Up @@ -1395,7 +1369,7 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
return -EINVAL;
}

if (iovec != &inline_vec)
if (iovec != inline_vecs)
kfree(iovec);

if (ret != -EIOCBQUEUED) {
Expand Down

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