Messages in this thread | | | Date | Mon, 14 Mar 2016 18:42:58 +0100 | From | Rabin Vincent <> | Subject | Re: [PATCH] block: protect iterate_bdevs() against concurrent close |
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(fixed Jens' address)
On Thu, Mar 10, 2016 at 06:37:27PM +0100, Jan Kara wrote: > On Thu 10-03-16 13:26:03, Rabin Vincent wrote: > > If a block device is closed while iterate_bdevs() is handling it, the > > following NULL pointer dereference occurs because bdev->b_disk is NULL > > in bdev_get_queue(), which is called from blk_get_backing_dev_info() (in > > turn called by the mapping_cap_writeback_dirty() call in > > __filemap_fdatawrite_range()): > > Thanks for spotting the problem. The patch will fix the problem you > found. But what prevents e.g. flusher thread from trying to writeback > the block device inode while that gets invalidated at the same moment?
Don't the sync_block_dev() / bdev_write_inode() calls in __blkdev_put() prevent this?
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