From ff9ea323816dc1c8ac7144afd4eab3ac97704430 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 8 Sep 2014 08:03:56 +0900 Subject: block, bdi: an active gendisk always has a request_queue associated with it bdev_get_queue() returns the request_queue associated with the specified block_device. blk_get_backing_dev_info() makes use of bdev_get_queue() to determine the associated bdi given a block_device. All the callers of bdev_get_queue() including blk_get_backing_dev_info() assume that bdev_get_queue() may return NULL and implement NULL handling; however, bdev_get_queue() requires the passed in block_device is opened and attached to its gendisk. Because an active gendisk always has a valid request_queue associated with it, bdev_get_queue() can never return NULL and neither can blk_get_backing_dev_info(). Make it clear that neither of the two functions can return NULL and remove NULL handling from all the callers. Signed-off-by: Tejun Heo Cc: Chris Mason Cc: Dave Chinner Signed-off-by: Jens Axboe --- fs/block_dev.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'fs/block_dev.c') diff --git a/fs/block_dev.c b/fs/block_dev.c index 6d7274619bf9..d3251eca6429 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1173,8 +1173,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) if (!ret) { bd_set_size(bdev,(loff_t)get_capacity(disk)<<9); bdi = blk_get_backing_dev_info(bdev); - if (bdi == NULL) - bdi = &default_backing_dev_info; bdev_inode_switch_bdi(bdev->bd_inode, bdi); } -- cgit v1.2.3 From 018a17bdc8658ad448497c84d4ba21b6985820ec Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 8 Sep 2014 08:04:01 +0900 Subject: 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: Tejun Heo Cc: Alexander Viro Signed-off-by: Jens Axboe --- fs/block_dev.c | 32 +++++++++++--------------------- include/linux/backing-dev.h | 1 - mm/backing-dev.c | 2 +- 3 files changed, 12 insertions(+), 23 deletions(-) (limited to 'fs/block_dev.c') diff --git a/fs/block_dev.c b/fs/block_dev.c index d3251eca6429..cc8d68ac29aa 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -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); - spin_lock(&inode->i_lock); - 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); + 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_unlock(&inode->i_lock); - spin_unlock(&old->wb.list_lock); - spin_unlock(&dst->wb.list_lock); - - if (wakeup_bdi) - bdi_wakeup_thread_delayed(dst); } /* Kill _all_ buffers and pagecache , dirty or not.. */ diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 2103a7fa3fd8..5da6012b7a14 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -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; diff --git a/mm/backing-dev.c b/mm/backing-dev.c index b65fe93ad612..7d63d5e9d3de 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -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); -- cgit v1.2.3