On Wed, Sep 30, 2015 at 4:35 PM, Dave Chinner <[email protected]> wrote: > On Tue, Sep 29, 2015 at 08:41:36PM -0400, Dan Williams wrote: >> The DAX implementation needs to protect new calls to ->direct_access() >> and usage of its return value against unbind of the underlying block >> device. Use blk_queue_enter()/blk_queue_exit() to either prevent >> blk_cleanup_queue() from proceeding, or fail the dax_map_bh() if the >> request_queue is being torn down. >> >> Cc: Jens Axboe <[email protected]> >> Cc: Christoph Hellwig <[email protected]> >> Cc: Boaz Harrosh <[email protected]> >> Cc: Dave Chinner <[email protected]> >> Cc: Ross Zwisler <[email protected]> >> Signed-off-by: Dan Williams <[email protected]> >> --- >> block/blk.h | 2 - >> fs/dax.c | 130 >> +++++++++++++++++++++++++++++++----------------- >> include/linux/blkdev.h | 2 + >> 3 files changed, 85 insertions(+), 49 deletions(-) >> >> diff --git a/block/blk.h b/block/blk.h >> index 5b2cd393afbe..0f8de0dda768 100644 >> --- a/block/blk.h >> +++ b/block/blk.h >> @@ -72,8 +72,6 @@ void blk_dequeue_request(struct request *rq); >> void __blk_queue_free_tags(struct request_queue *q); >> bool __blk_end_bidi_request(struct request *rq, int error, >> unsigned int nr_bytes, unsigned int bidi_bytes); >> -int blk_queue_enter(struct request_queue *q, gfp_t gfp); >> -void blk_queue_exit(struct request_queue *q); >> void blk_freeze_queue(struct request_queue *q); >> >> static inline void blk_queue_enter_live(struct request_queue *q) >> diff --git a/fs/dax.c b/fs/dax.c >> index bcfb14bfc1e4..7ce002bb60d0 100644 >> --- a/fs/dax.c >> +++ b/fs/dax.c >> @@ -63,12 +63,42 @@ int dax_clear_blocks(struct inode *inode, sector_t >> block, long size) >> } >> EXPORT_SYMBOL_GPL(dax_clear_blocks); >> >> -static long dax_get_addr(struct buffer_head *bh, void __pmem **addr, >> - unsigned blkbits) >> +static void __pmem *__dax_map_bh(const struct buffer_head *bh, unsigned >> blkbits, >> + unsigned long *pfn, long *len) > > Please don't use bufferheads for this. Please pass an inode, the > block and length to map, similar to dax_clear_blocks(). > > Why? Because dax_clear_blocks() needs to do this "mapping" too, > and it is called from contexts where there are no bufferheads. > There's a good chance we'll need more mapping contexts like this in > future, so lets not propagate bufferheads deeper into this code > than we absilutely need to. > > We should be trying to limit/remove bufferheads in the DAX code, not > propagating them deeper into the code...
So I gave this a try but ran into the road block that get_block() is performing the inode to bdev conversion and that is filesystem specific. However, I'll at least not pass the bh into this map routine and will call it dax_map_atomic() which is more accurate. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
