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Date: Thu, 28 Feb 2013 12:35:39 -0800
From: Kent Overstreet <koverstreet@...gle.com>
To: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-aio@...ck.org
Cc: Kent Overstreet <koverstreet@...gle.com>, tytso@....edu,
axboe@...nel.dk, zab@...hat.com, bcrl@...ck.org, anatol@...gle.com
Subject: [PATCH 2/4] aio: Allow cancellation without a cancel callback
Prep work for bio cancellation. At least initially, we don't want to
implement a callback that has to chase down all the state (multiple
bios/requests) associated with the iocb; a simple flag will suffice.
Signed-off-by: Kent Overstreet <koverstreet@...gle.com>
---
drivers/usb/gadget/inode.c | 7 +----
fs/aio.c | 76 +++++++++++++++++++++-------------------------
include/linux/aio.h | 5 +++
3 files changed, 41 insertions(+), 47 deletions(-)
diff --git a/drivers/usb/gadget/inode.c b/drivers/usb/gadget/inode.c
index fd1bf4a..e5e2210 100644
--- a/drivers/usb/gadget/inode.c
+++ b/drivers/usb/gadget/inode.c
@@ -528,19 +528,14 @@ static void ep_aio_cancel(struct kiocb *iocb)
{
struct kiocb_priv *priv = iocb->private;
struct ep_data *epdata;
- int value;
local_irq_disable();
epdata = priv->epdata;
// spin_lock(&epdata->dev->lock);
if (likely(epdata && epdata->ep && priv->req))
- value = usb_ep_dequeue (epdata->ep, priv->req);
- else
- value = -EINVAL;
+ usb_ep_dequeue (epdata->ep, priv->req);
// spin_unlock(&epdata->dev->lock);
local_irq_enable();
-
- return value;
}
static ssize_t ep_copy_to_user(struct kiocb_priv *priv)
diff --git a/fs/aio.c b/fs/aio.c
index 4b9bfb5..f5f27bd 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -242,48 +242,34 @@ static int aio_setup_ring(struct kioctx *ctx)
void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel)
{
- struct kioctx *ctx = req->ki_ctx;
- unsigned long flags;
-
- spin_lock_irqsave(&ctx->ctx_lock, flags);
+ kiocb_cancel_fn *p, *old = req->ki_cancel;
- if (!req->ki_list.next)
- list_add(&req->ki_list, &ctx->active_reqs);
-
- req->ki_cancel = cancel;
+ do {
+ if (old == KIOCB_CANCELLED) {
+ cancel(req);
+ return;
+ }
- spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+ p = old;
+ old = cmpxchg(&req->ki_cancel, old, cancel);
+ } while (old != p);
}
EXPORT_SYMBOL(kiocb_set_cancel_fn);
-static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb)
+static void kiocb_cancel(struct kioctx *ctx, struct kiocb *req)
{
- kiocb_cancel_fn *old, *cancel;
- int ret = -EINVAL;
-
- /*
- * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
- * actually has a cancel function, hence the cmpxchg()
- */
-
- cancel = ACCESS_ONCE(kiocb->ki_cancel);
- do {
- if (!cancel || cancel == KIOCB_CANCELLED)
- return ret;
-
- old = cancel;
- cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
- } while (cancel != old);
-
- atomic_inc(&kiocb->ki_users);
- spin_unlock_irq(&ctx->ctx_lock);
+ kiocb_cancel_fn *cancel;
- ret = cancel(kiocb);
+ cancel = xchg(&req->ki_cancel, KIOCB_CANCELLED);
+ if (cancel && cancel != KIOCB_CANCELLED) {
+ atomic_inc(&req->ki_users);
+ spin_unlock_irq(&ctx->ctx_lock);
- spin_lock_irq(&ctx->ctx_lock);
- aio_put_req(kiocb);
+ cancel(req);
- return ret;
+ spin_lock_irq(&ctx->ctx_lock);
+ aio_put_req(req);
+ }
}
static void free_ioctx_rcu(struct rcu_head *head)
@@ -1126,6 +1112,10 @@ rw_common:
req->ki_nbytes = ret;
+ spin_lock_irq(&req->ki_ctx->ctx_lock);
+ list_add(&req->ki_list, &req->ki_ctx->active_reqs);
+ spin_unlock_irq(&req->ki_ctx->ctx_lock);
+
/* XXX: move/kill - rw_verify_area()? */
/* This matches the pread()/pwrite() logic */
if (req->ki_pos < 0) {
@@ -1141,6 +1131,10 @@ rw_common:
if (!file->f_op->aio_fsync)
return -EINVAL;
+ spin_lock_irq(&req->ki_ctx->ctx_lock);
+ list_add(&req->ki_list, &req->ki_ctx->active_reqs);
+ spin_unlock_irq(&req->ki_ctx->ctx_lock);
+
ret = file->f_op->aio_fsync(req, 1);
break;
@@ -1148,6 +1142,10 @@ rw_common:
if (!file->f_op->aio_fsync)
return -EINVAL;
+ spin_lock_irq(&req->ki_ctx->ctx_lock);
+ list_add(&req->ki_list, &req->ki_ctx->active_reqs);
+ spin_unlock_irq(&req->ki_ctx->ctx_lock);
+
ret = file->f_op->aio_fsync(req, 0);
break;
@@ -1363,14 +1361,8 @@ SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
spin_lock_irq(&ctx->ctx_lock);
kiocb = lookup_kiocb(ctx, iocb, key);
- if (kiocb)
- ret = kiocb_cancel(ctx, kiocb);
- else
- ret = -EINVAL;
-
- spin_unlock_irq(&ctx->ctx_lock);
-
- if (!ret) {
+ if (kiocb) {
+ kiocb_cancel(ctx, kiocb);
/*
* The result argument is no longer used - the io_event is
* always delivered via the ring buffer. -EINPROGRESS indicates
@@ -1379,6 +1371,8 @@ SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
ret = -EINPROGRESS;
}
+ spin_unlock_irq(&ctx->ctx_lock);
+
put_ioctx(ctx);
return ret;
diff --git a/include/linux/aio.h b/include/linux/aio.h
index 7340f77..d9686f1 100644
--- a/include/linux/aio.h
+++ b/include/linux/aio.h
@@ -65,6 +65,11 @@ struct kiocb {
struct eventfd_ctx *ki_eventfd;
};
+static inline bool kiocb_cancelled(struct kiocb *kiocb)
+{
+ return kiocb->ki_cancel == KIOCB_CANCELLED;
+}
+
static inline bool is_sync_kiocb(struct kiocb *kiocb)
{
return kiocb->ki_ctx == NULL;
--
1.7.12
--
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