Commit 018a17bd authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
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bdi: reimplement bdev_inode_switch_bdi() 



A block_device may be attached to different gendisks and thus
different bdis over time.  bdev_inode_switch_bdi() is used to switch
the associated bdi.  The function assumes that the inode could be
dirty and transfers it between bdis if so.  This is a bit nasty in
that it reaches into bdi internals.

This patch reimplements the function so that it writes out the inode
if dirty.  This is a lot simpler and can be implemented without
exposing bdi internals.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 1a1e4530

fs/block_dev.c

+11 −21
Original line number Diff line number Diff line
@@ -50,32 +50,22 @@ inline struct block_device *I_BDEV(struct inode *inode) 
EXPORT_SYMBOL(I_BDEV);



/*

 * Move the inode from its current bdi to a new bdi. If the inode is dirty we

 * need to move it onto the dirty list of @dst so that the inode is always on

 * the right list.

 * 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.

 */

static void bdev_inode_switch_bdi(struct inode *inode,

			struct backing_dev_info *dst)

{

	struct backing_dev_info *old = inode->i_data.backing_dev_info;

	bool wakeup_bdi = false;



	if (unlikely(dst == old))		/* deadlock avoidance */

		return;

	bdi_lock_two(&old->wb, &dst->wb);

	while (true) {

		spin_lock(&inode->i_lock);

		if (!(inode->i_state & I_DIRTY)) {

			inode->i_data.backing_dev_info = dst;

	if (inode->i_state & I_DIRTY) {

		if (bdi_cap_writeback_dirty(dst) && !wb_has_dirty_io(&dst->wb))

			wakeup_bdi = true;

		list_move(&inode->i_wb_list, &dst->wb.b_dirty);

			spin_unlock(&inode->i_lock);

			return;

		}

		spin_unlock(&inode->i_lock);

	spin_unlock(&old->wb.list_lock);

	spin_unlock(&dst->wb.list_lock);



	if (wakeup_bdi)

		bdi_wakeup_thread_delayed(dst);

		WARN_ON_ONCE(write_inode_now(inode, true));

	}

}



/* Kill _all_ buffers and pagecache , dirty or not.. */

include/linux/backing-dev.h

+0 −1
Original line number Diff line number Diff line
@@ -121,7 +121,6 @@ void bdi_start_background_writeback(struct backing_dev_info *bdi); 
void bdi_writeback_workfn(struct work_struct *work);

int bdi_has_dirty_io(struct backing_dev_info *bdi);

void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);

void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2);



extern spinlock_t bdi_lock;

extern struct list_head bdi_list;

mm/backing-dev.c

+1 −1
Original line number Diff line number Diff line
@@ -40,7 +40,7 @@ LIST_HEAD(bdi_list); 
/* bdi_wq serves all asynchronous writeback tasks */

struct workqueue_struct *bdi_wq;



void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2)

static void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2)

{

	if (wb1 < wb2) {

		spin_lock(&wb1->list_lock);

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