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Subject[PATCH 8/8] aio: move sanity checks and request allocation to io_submit_one()
Date
From: Al Viro <viro@zeniv.linux.org.uk>

makes for somewhat cleaner control flow in __io_submit_one()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/aio.c | 86 +++++++++++++++++++++++++++++++---------------------------------
1 file changed, 42 insertions(+), 44 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index af51b1360305..6993581b77b2 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1788,36 +1788,15 @@ static int aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
}

static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
- struct iocb __user *user_iocb, bool compat)
+ struct iocb __user *user_iocb, struct aio_kiocb *req,
+ bool compat)
{
- struct aio_kiocb *req;
struct file *file;
int ret;

- /* enforce forwards compatibility on users */
- if (unlikely(iocb->aio_reserved2)) {
- pr_debug("EINVAL: reserve field set\n");
- return -EINVAL;
- }
-
- /* prevent overflows */
- if (unlikely(
- (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
- (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
- ((ssize_t)iocb->aio_nbytes < 0)
- )) {
- pr_debug("EINVAL: overflow check\n");
- return -EINVAL;
- }
-
- req = aio_get_req(ctx);
- if (unlikely(!req))
- return -EAGAIN;
-
req->ki_filp = fget(iocb->aio_fildes);
- ret = -EBADF;
if (unlikely(!req->ki_filp))
- goto out_put_req;
+ return -EBADF;

if (iocb->aio_flags & IOCB_FLAG_RESFD) {
struct eventfd_ctx *eventfd;
@@ -1828,17 +1807,15 @@ static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
* event using the eventfd_signal() function.
*/
eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
- if (IS_ERR(eventfd)) {
- ret = PTR_ERR(eventfd);
- goto out_put_req;
- }
+ if (IS_ERR(eventfd))
+ return PTR_ERR(req->ki_eventfd);
+
req->ki_eventfd = eventfd;
}

- ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
- if (unlikely(ret)) {
+ if (unlikely(put_user(KIOCB_KEY, &user_iocb->aio_key))) {
pr_debug("EFAULT: aio_key\n");
- goto out_put_req;
+ return -EFAULT;
}

req->ki_user_iocb = user_iocb;
@@ -1873,30 +1850,51 @@ static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
break;
}
fput(file);
-
- /*
- * If ret is 0, we'd either done aio_complete() ourselves or have
- * arranged for that to be done asynchronously. Anything non-zero
- * means that we need to destroy req ourselves.
- */
- if (ret)
- goto out_put_req;
- return 0;
-out_put_req:
- iocb_put(req);
- put_reqs_available(ctx, 1);
return ret;
}

static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
bool compat)
{
+ struct aio_kiocb *req;
struct iocb iocb;
+ int err;

if (unlikely(copy_from_user(&iocb, user_iocb, sizeof(iocb))))
return -EFAULT;

- return __io_submit_one(ctx, &iocb, user_iocb, compat);
+ /* enforce forwards compatibility on users */
+ if (unlikely(iocb.aio_reserved2)) {
+ pr_debug("EINVAL: reserve field set\n");
+ return -EINVAL;
+ }
+
+ /* prevent overflows */
+ if (unlikely(
+ (iocb.aio_buf != (unsigned long)iocb.aio_buf) ||
+ (iocb.aio_nbytes != (size_t)iocb.aio_nbytes) ||
+ ((ssize_t)iocb.aio_nbytes < 0)
+ )) {
+ pr_debug("EINVAL: overflow check\n");
+ return -EINVAL;
+ }
+
+ req = aio_get_req(ctx);
+ if (unlikely(!req))
+ return -EAGAIN;
+
+ err = __io_submit_one(ctx, &iocb, user_iocb, req, compat);
+
+ /*
+ * If err is 0, we'd either done aio_complete() ourselves or have
+ * arranged for that to be done asynchronously. Anything non-zero
+ * means that we need to destroy req ourselves.
+ */
+ if (unlikely(err)) {
+ iocb_put(req);
+ put_reqs_available(ctx, 1);
+ }
+ return err;
}

/* sys_io_submit:
--
2.11.0
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