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block_dev: only write bdev inode on close 

Since 018a17bdc8 ("bdi: reimplement bdev_inode_switch_bdi()") the
block device code writes out all dirty data whenever switching the
backing_dev_info for a block device inode.  But a block device inode can
only be dirtied when it is in use, which means we only have to write it
out on the final blkdev_put, but not when doing a blkdev_get.

Factoring out the write out from the bdi list switch prepares from
removing the list switch later in the series.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
hifive-unleashed-5.1
Christoph Hellwig 2015-01-14 10:42:33 +01:00 committed by Jens Axboe
parent b4caecd480
commit 564f00f6c0
1 changed files with 19 additions and 12 deletions
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31
fs/block_dev.c
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@ -49,6 +49,17 @@ inline struct block_device *I_BDEV(struct inode *inode)
}
EXPORT_SYMBOL(I_BDEV);
static void bdev_write_inode(struct inode *inode)
{
spin_lock(&inode->i_lock);
while (inode->i_state & I_DIRTY) {
spin_unlock(&inode->i_lock);
WARN_ON_ONCE(write_inode_now(inode, true));
spin_lock(&inode->i_lock);
}
spin_unlock(&inode->i_lock);
}
/*
* Move the inode from its current bdi to a new bdi. Make sure the inode
* is clean before moving so that it doesn't linger on the old bdi.
@ -56,16 +67,10 @@ EXPORT_SYMBOL(I_BDEV);
static void bdev_inode_switch_bdi(struct inode *inode,
struct backing_dev_info *dst)
{
while (true) {
spin_lock(&inode->i_lock);
if (!(inode->i_state & I_DIRTY)) {
inode->i_data.backing_dev_info = dst;
spin_unlock(&inode->i_lock);
return;
}
spin_unlock(&inode->i_lock);
WARN_ON_ONCE(write_inode_now(inode, true));
}
spin_lock(&inode->i_lock);
WARN_ON_ONCE(inode->i_state & I_DIRTY);
inode->i_data.backing_dev_info = dst;
spin_unlock(&inode->i_lock);
}
/* Kill _all_ buffers and pagecache , dirty or not.. */
@ -1464,9 +1469,11 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
WARN_ON_ONCE(bdev->bd_holders);
sync_blockdev(bdev);
kill_bdev(bdev);
/* ->release can cause the old bdi to disappear,
* so must switch it out first
/*
* ->release can cause the queue to disappear, so flush all
* dirty data before.
*/
bdev_write_inode(bdev->bd_inode);
bdev_inode_switch_bdi(bdev->bd_inode,
&default_backing_dev_info);
}