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* bdi: reimplement bdev_inode_switch_bdi()Tejun Heo2016-09-131-1/+1
| | | | | | | | | | | | | | | | | 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 <tj@kernel.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
* bdi: explain the dirty list transferring in bdi_destroy()Tejun Heo2016-09-131-2/+11
| | | | | | | | | | | | | | | | | | bdi_destroy() has code to transfer the remaining dirty inodes to the default_backing_dev_info; however, given the shutdown sequence, it isn't clear how such condition would happen. Also, it isn't a full solution as the transferred inodes stlil point to the bdi which is being destroyed. Operations on those inodes can end up accessing already released fields such as the percpu stat fields. Digging through the history, it seems that the code was added as a quick workaround for a bug report without fully root-causing the issue. We probably want to remove the code in time but for now let's add a comment noting that it is a quick workaround. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
* bdi: make backing_dev_info->wb.dwork canceling stricterTejun Heo2016-09-131-13/+2
| | | | | | | | | | | | | | | | | | | | | Canceling of bdi->wb.dwork is currently a bit mushy. bdi_wb_shutdown() performs cancel_delayed_work_sync() at the end after shutting down and flushing the delayed_work and bdi_destroy() tries yet again after bdi_unregister(). bdi->wb.dwork is queued only after checking BDI_registered while holding bdi->wb_lock and bdi_wb_shutdown() clears the flag while holding the same lock and then flushes the delayed_work. There's no way the delayed_work can be queued again after that. Replace the two unnecessary cancel_delayed_work_sync() invocations with WARNs on pending. This simplifies and clarifies the code a bit and will help future changes in further isolating bdi_writeback handling. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
* bdi: remove bdi->wb_lock locking around bdi->dev clearing in bdi_unregister()Tejun Heo2016-09-131-8/+2
| | | | | | | | | | | | | | | The only places where NULL test on bdi->dev is used are bdi_[un]register(). The functions can't be called in parallel anyway and there's no point in protecting bdi->dev clearing with a lock. Remove bdi->wb_lock grabbing around bdi->dev clearing and move it after device_unregister() call so that bdi->dev doesn't have to be cached in a local variable. This patch shouldn't introduce any behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
* first commitMeizu OpenSource2016-08-151-0/+676