aio: do fget() after aio_get_req()

aio_get_req() will fail if we have the maximum number of requests
outstanding, which depending on the application may not be uncommon.  So
avoid doing an unnecessary fget().

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/aio.c b/fs/aio.c
index 01a7339e73843a29c86a7c752f0722e728ffa861..5d056a2da4b5cbd83e09d6ba846a098bdf8dae81 100644 (file)
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -587,6 +587,8 @@ static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
 {
        assert_spin_locked(&ctx->ctx_lock);
 
+       if (req->ki_filp)
+               fput(req->ki_filp);
        if (req->ki_eventfd != NULL)
                eventfd_ctx_put(req->ki_eventfd);
        if (req->ki_dtor)
@@ -605,9 +607,6 @@ static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
  */
 static void __aio_put_req(struct kioctx *ctx, struct kiocb *req)
 {
-       pr_debug("(%p): f_count=%ld\n",
-                req, atomic_long_read(&req->ki_filp->f_count));
-
        assert_spin_locked(&ctx->ctx_lock);
 
        req->ki_users--;
@@ -618,8 +617,6 @@ static void __aio_put_req(struct kioctx *ctx, struct kiocb *req)
        req->ki_cancel = NULL;
        req->ki_retry = NULL;
 
-       fput(req->ki_filp);
-       req->ki_filp = NULL;
        really_put_req(ctx, req);
 }
 
@@ -1267,7 +1264,6 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
                         bool compat)
 {
        struct kiocb *req;
-       struct file *file;
        ssize_t ret;
 
        /* enforce forwards compatibility on users */
@@ -1286,16 +1282,16 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
                return -EINVAL;
        }
 
-       file = fget(iocb->aio_fildes);
-       if (unlikely(!file))
-               return -EBADF;
-
        req = aio_get_req(ctx, batch);  /* returns with 2 references to req */
-       if (unlikely(!req)) {
-               fput(file);
+       if (unlikely(!req))
                return -EAGAIN;
+
+       req->ki_filp = fget(iocb->aio_fildes);
+       if (unlikely(!req->ki_filp)) {
+               ret = -EBADF;
+               goto out_put_req;
        }
-       req->ki_filp = file;
+
        if (iocb->aio_flags & IOCB_FLAG_RESFD) {
                /*
                 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an