Commit 58a9d3d8 authored May 24, 2010 by Richard Kennedy Committed by Linus Torvalds May 25, 2010

fs-writeback: check sync bit earlier in inode_wait_for_writeback



When wb_writeback() hasn't written anything it will re-acquire the inode
lock before calling inode_wait_for_writeback.

This change tests the sync bit first so that is doesn't need to drop &
re-acquire the lock if the inode became available while wb_writeback() was
waiting to get the lock.

Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ec95f53a

fs/fs-writeback.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -409,11 +409,11 @@ static void inode_wait_for_writeback(struct inode *inode)
		wait_queue_head_t *wqh;

		wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
		do {
		while (inode->i_state & I_SYNC) {
		spin_unlock(&inode_lock);
		__wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE);
		spin_lock(&inode_lock);
		} while (inode->i_state & I_SYNC);
		}
		}

		/*

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