linux-kernel - [PATCH 1/9] writeback: Move clearing of I_SYNC into inode_sync

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Date:	Thu,  3 May 2012 14:47:55 +0200
From:	Jan Kara <jack@...e.cz>
To:	linux-fsdevel@...r.kernel.org
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Al Viro <viro@...IV.linux.org.uk>,
	Christoph Hellwig <hch@...radead.org>, dchinner@...hat.com,
	Wu Fengguang <fengguang.wu@...el.com>, Jan Kara <jack@...e.cz>
Subject: [PATCH 1/9] writeback: Move clearing of I_SYNC into inode_sync_complete()

Move clearing of I_SYNC into inode_sync_complete().  It is more logical to have
clearing of I_SYNC bit and waking of waiters in one place. Also later we will
have two places needing to clear I_SYNC and wake up waiters so this allows them
to use the common helper. Moving of I_SYNC clearing to a later stage of
writeback_single_inode() is safe since we hold i_lock all the time.

Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Jan Kara <jack@...e.cz>
---
 fs/fs-writeback.c |    8 ++------
 1 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 539f36c..dd41437 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -231,11 +231,8 @@ static void requeue_io(struct inode *inode, struct bdi_writeback *wb)
 
 static void inode_sync_complete(struct inode *inode)
 {
-	/*
-	 * Prevent speculative execution through
-	 * spin_unlock(&wb->list_lock);
-	 */
-
+	inode->i_state &= ~I_SYNC;
+	/* Waiters must see I_SYNC cleared before being woken up */
 	smp_mb();
 	wake_up_bit(&inode->i_state, __I_SYNC);
 }
@@ -436,7 +433,6 @@ writeback_single_inode(struct inode *inode, struct bdi_writeback *wb,
 
 	spin_lock(&wb->list_lock);
 	spin_lock(&inode->i_lock);
-	inode->i_state &= ~I_SYNC;
 	if (!(inode->i_state & I_FREEING)) {
 		/*
 		 * Sync livelock prevention. Each inode is tagged and synced in
-- 
1.7.1

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