linux-kernel - [PATCH 2/3] btrfs: pass in DIO_SKIP_DIO_COUNT to do_blockdev_direct

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Date:	Wed, 15 Apr 2015 16:01:37 -0600
From:	Jens Axboe <axboe@...com>
To:	<linux-kernel@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>
CC:	Jens Axboe <axboe@...com>, Chris Mason <clm@...com>
Subject: [PATCH 2/3] btrfs: pass in DIO_SKIP_DIO_COUNT to do_blockdev_direct_IO()

btrfs_direct_IO() already holds the inode i_dio_count elevated, so
pass in that do_blockdev_direct_IO() does not need to. If we end
up dropping the inode dio count before calling this function, then
we drop the flag as well.

Cc: Chris Mason <clm@...com>
Signed-off-by: Jens Axboe <axboe@...com>
---
 fs/btrfs/inode.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 6fe341a66ed8..3ecac37f10e0 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8121,8 +8121,7 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
 	struct inode *inode = file->f_mapping->host;
 	u64 outstanding_extents = 0;
 	size_t count = 0;
-	int flags = 0;
-	bool wakeup = true;
+	int flags = DIO_SKIP_DIO_COUNT;
 	bool relock = false;
 	ssize_t ret;
 
@@ -8170,8 +8169,11 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
 	} else if (test_bit(BTRFS_INODE_READDIO_NEED_LOCK,
 				     &BTRFS_I(inode)->runtime_flags)) {
 		inode_dio_dec(inode);
+		/*
+		 * we know need i_dio_count inc/dec, the below overwrites
+		 * the skip inc/dec flag.
+		 */
 		flags = DIO_LOCKING | DIO_SKIP_HOLES;
-		wakeup = false;
 	}
 
 	ret = __blockdev_direct_IO(rw, iocb, inode,
@@ -8187,7 +8189,7 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
 						     count - (size_t)ret);
 	}
 out:
-	if (wakeup)
+	if (flags & DIO_SKIP_DIO_COUNT)
 		inode_dio_dec(inode);
 	if (relock)
 		mutex_lock(&inode->i_mutex);
-- 
1.9.1

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