linux-kernel - [PATCH 10/33] aio: do fget() after aio_get

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Message-Id: <1363883754-27966-11-git-send-email-koverstreet@google.com>
Date:	Thu, 21 Mar 2013 09:35:31 -0700
From:	Kent Overstreet <koverstreet@...gle.com>
To:	linux-kernel@...r.kernel.org, linux-aio@...ck.org,
	akpm@...ux-foundation.org
Cc:	Kent Overstreet <koverstreet@...gle.com>,
	Zach Brown <zab@...hat.com>, Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Mark Fasheh <mfasheh@...e.com>,
	Joel Becker <jlbec@...lplan.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Jens Axboe <axboe@...nel.dk>,
	Asai Thambi S P <asamymuthupa@...ron.com>,
	Selvan Mani <smani@...ron.com>,
	Sam Bradshaw <sbradshaw@...ron.com>,
	Jeff Moyer <jmoyer@...hat.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Benjamin LaHaise <bcrl@...ck.org>,
	Theodore Ts'o <tytso@....edu>
Subject: [PATCH 10/33] 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@...gle.com>
Cc: Zach Brown <zab@...hat.com>
Cc: Felipe Balbi <balbi@...com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Mark Fasheh <mfasheh@...e.com>
Cc: Joel Becker <jlbec@...lplan.org>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Cc: Jens Axboe <axboe@...nel.dk>
Cc: Asai Thambi S P <asamymuthupa@...ron.com>
Cc: Selvan Mani <smani@...ron.com>
Cc: Sam Bradshaw <sbradshaw@...ron.com>
Cc: Jeff Moyer <jmoyer@...hat.com>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: Benjamin LaHaise <bcrl@...ck.org>
Cc: Theodore Ts'o <tytso@....edu>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---
 fs/aio.c | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 2637555..4f23d43 100644
--- 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);
 }
 
@@ -1266,7 +1263,6 @@ 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 */
@@ -1285,16 +1281,16 @@ 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
-- 
1.8.1.3

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