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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()
This commit is contained in:
Linus Torvalds 2014-08-16 08:56:27 -06:00
commit da06df548e
1 changed files with 30 additions and 56 deletions
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86
fs/aio.c
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@ -192,7 +192,6 @@ static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
} }
file->f_flags = O_RDWR; file->f_flags = O_RDWR;
file->private_data = ctx;
return file; return file;
} }
@ -202,7 +201,7 @@ static struct dentry *aio_mount(struct file_system_type *fs_type,
static const struct dentry_operations ops = { static const struct dentry_operations ops = {
.d_dname = simple_dname, .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 /* aio_setup
@ -556,8 +555,7 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
struct aio_ring *ring; struct aio_ring *ring;
spin_lock(&mm->ioctx_lock); spin_lock(&mm->ioctx_lock);
rcu_read_lock(); table = rcu_dereference_raw(mm->ioctx_table);
table = rcu_dereference(mm->ioctx_table);
while (1) { while (1) {
if (table) if (table)
@ -565,7 +563,6 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
if (!table->table[i]) { if (!table->table[i]) {
ctx->id = i; ctx->id = i;
table->table[i] = ctx; table->table[i] = ctx;
rcu_read_unlock();
spin_unlock(&mm->ioctx_lock); spin_unlock(&mm->ioctx_lock);
/* While kioctx setup is in progress, /* While kioctx setup is in progress,
@ -579,8 +576,6 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
} }
new_nr = (table ? table->nr : 1) * 4; new_nr = (table ? table->nr : 1) * 4;
rcu_read_unlock();
spin_unlock(&mm->ioctx_lock); spin_unlock(&mm->ioctx_lock);
table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) * table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) *
@ -591,8 +586,7 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
table->nr = new_nr; table->nr = new_nr;
spin_lock(&mm->ioctx_lock); spin_lock(&mm->ioctx_lock);
rcu_read_lock(); old = rcu_dereference_raw(mm->ioctx_table);
old = rcu_dereference(mm->ioctx_table);
if (!old) { if (!old) {
rcu_assign_pointer(mm->ioctx_table, table); rcu_assign_pointer(mm->ioctx_table, table);
@ -739,12 +733,9 @@ static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
spin_lock(&mm->ioctx_lock); spin_lock(&mm->ioctx_lock);
rcu_read_lock(); table = rcu_dereference_raw(mm->ioctx_table);
table = rcu_dereference(mm->ioctx_table);
WARN_ON(ctx != table->table[ctx->id]); WARN_ON(ctx != table->table[ctx->id]);
table->table[ctx->id] = NULL; table->table[ctx->id] = NULL;
rcu_read_unlock();
spin_unlock(&mm->ioctx_lock); spin_unlock(&mm->ioctx_lock);
/* percpu_ref_kill() will do the necessary call_rcu() */ /* percpu_ref_kill() will do the necessary call_rcu() */
@ -793,40 +784,30 @@ EXPORT_SYMBOL(wait_on_sync_kiocb);
*/ */
void exit_aio(struct mm_struct *mm) void exit_aio(struct mm_struct *mm)
{ {
struct kioctx_table *table; struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
struct kioctx *ctx; int i;
unsigned i = 0;
while (1) { if (!table)
rcu_read_lock(); return;
table = rcu_dereference(mm->ioctx_table);
do { for (i = 0; i < table->nr; ++i) {
if (!table || i >= table->nr) { struct kioctx *ctx = table->table[i];
rcu_read_unlock();
rcu_assign_pointer(mm->ioctx_table, NULL);
if (table)
kfree(table);
return;
}
ctx = table->table[i++];
} while (!ctx);
rcu_read_unlock();
if (!ctx)
continue;
/* /*
* We don't need to bother with munmap() here - * We don't need to bother with munmap() here - exit_mmap(mm)
* exit_mmap(mm) is coming and it'll unmap everything. * is coming and it'll unmap everything. And we simply can't,
* Since aio_free_ring() uses non-zero ->mmap_size * this is not necessarily our ->mm.
* as indicator that it needs to unmap the area, * Since kill_ioctx() uses non-zero ->mmap_size as indicator
* just set it to 0; aio_free_ring() is the only * that it needs to unmap the area, just set it to 0.
* place that uses ->mmap_size, so it's safe.
*/ */
ctx->mmap_size = 0; ctx->mmap_size = 0;
kill_ioctx(mm, ctx, NULL); kill_ioctx(mm, ctx, NULL);
} }
RCU_INIT_POINTER(mm->ioctx_table, NULL);
kfree(table);
} }
static void put_reqs_available(struct kioctx *ctx, unsigned nr) static void put_reqs_available(struct kioctx *ctx, unsigned nr)
@ -834,10 +815,8 @@ static void put_reqs_available(struct kioctx *ctx, unsigned nr)
struct kioctx_cpu *kcpu; struct kioctx_cpu *kcpu;
unsigned long flags; unsigned long flags;
preempt_disable();
kcpu = this_cpu_ptr(ctx->cpu);
local_irq_save(flags); local_irq_save(flags);
kcpu = this_cpu_ptr(ctx->cpu);
kcpu->reqs_available += nr; kcpu->reqs_available += nr;
while (kcpu->reqs_available >= ctx->req_batch * 2) { while (kcpu->reqs_available >= ctx->req_batch * 2) {
@ -846,7 +825,6 @@ static void put_reqs_available(struct kioctx *ctx, unsigned nr)
} }
local_irq_restore(flags); local_irq_restore(flags);
preempt_enable();
} }
static bool get_reqs_available(struct kioctx *ctx) static bool get_reqs_available(struct kioctx *ctx)
@ -855,10 +833,8 @@ static bool get_reqs_available(struct kioctx *ctx)
bool ret = false; bool ret = false;
unsigned long flags; unsigned long flags;
preempt_disable();
kcpu = this_cpu_ptr(ctx->cpu);
local_irq_save(flags); local_irq_save(flags);
kcpu = this_cpu_ptr(ctx->cpu);
if (!kcpu->reqs_available) { if (!kcpu->reqs_available) {
int old, avail = atomic_read(&ctx->reqs_available); int old, avail = atomic_read(&ctx->reqs_available);
@ -878,7 +854,6 @@ static bool get_reqs_available(struct kioctx *ctx)
kcpu->reqs_available--; kcpu->reqs_available--;
out: out:
local_irq_restore(flags); local_irq_restore(flags);
preempt_enable();
return ret; return ret;
} }
@ -1047,7 +1022,7 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
} }
EXPORT_SYMBOL(aio_complete); 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 * Pull an event off of the ioctx's event ring. Returns the number of
* events fetched * events fetched
*/ */
@ -1270,12 +1245,12 @@ static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
if (compat) if (compat)
ret = compat_rw_copy_check_uvector(rw, ret = compat_rw_copy_check_uvector(rw,
(struct compat_iovec __user *)buf, (struct compat_iovec __user *)buf,
*nr_segs, 1, *iovec, iovec); *nr_segs, UIO_FASTIOV, *iovec, iovec);
else else
#endif #endif
ret = rw_copy_check_uvector(rw, ret = rw_copy_check_uvector(rw,
(struct iovec __user *)buf, (struct iovec __user *)buf,
*nr_segs, 1, *iovec, iovec); *nr_segs, UIO_FASTIOV, *iovec, iovec);
if (ret < 0) if (ret < 0)
return ret; return ret;
@ -1299,9 +1274,8 @@ static ssize_t aio_setup_single_vector(struct kiocb *kiocb,
} }
/* /*
* aio_setup_iocb: * aio_run_iocb:
* Performs the initial checks and aio retry method * Performs the initial checks and io submission.
* setup for the kiocb at the time of io submission.
*/ */
static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode, static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
char __user *buf, bool compat) char __user *buf, bool compat)
@ -1313,7 +1287,7 @@ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
fmode_t mode; fmode_t mode;
aio_rw_op *rw_op; aio_rw_op *rw_op;
rw_iter_op *iter_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; struct iov_iter iter;
switch (opcode) { switch (opcode) {
@ -1348,7 +1322,7 @@ rw_common:
if (!ret) if (!ret)
ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes); ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
if (ret < 0) { if (ret < 0) {
if (iovec != &inline_vec) if (iovec != inline_vecs)
kfree(iovec); kfree(iovec);
return ret; return ret;
} }
@ -1395,7 +1369,7 @@ rw_common:
return -EINVAL; return -EINVAL;
} }
if (iovec != &inline_vec) if (iovec != inline_vecs)
kfree(iovec); kfree(iovec);
if (ret != -EIOCBQUEUED) { if (ret != -EIOCBQUEUED) {