dax: fix lifetime of in-kernel dax mappings with dax_map_atomic()
The DAX implementation needs to protect new calls to ->direct_access()
and usage of its return value against the driver for the underlying
block device being disabled. Use blk_queue_enter()/blk_queue_exit() to
hold off blk_cleanup_queue() from proceeding, or otherwise fail new
mapping requests if the request_queue is being torn down.
This also introduces blk_dax_ctl to simplify the interface from fs/dax.c
through dax_map_atomic() to bdev_direct_access().
[willy@linux.intel.com: fix read() of a hole]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Jan Kara <jack@suse.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index c70e358..88821fa 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1617,6 +1617,20 @@
#endif /* CONFIG_BLK_DEV_INTEGRITY */
+/**
+ * struct blk_dax_ctl - control and output parameters for ->direct_access
+ * @sector: (input) offset relative to a block_device
+ * @addr: (output) kernel virtual address for @sector populated by driver
+ * @pfn: (output) page frame number for @addr populated by driver
+ * @size: (input) number of bytes requested
+ */
+struct blk_dax_ctl {
+ sector_t sector;
+ void __pmem *addr;
+ long size;
+ unsigned long pfn;
+};
+
struct block_device_operations {
int (*open) (struct block_device *, fmode_t);
void (*release) (struct gendisk *, fmode_t);
@@ -1643,8 +1657,7 @@
extern int bdev_read_page(struct block_device *, sector_t, struct page *);
extern int bdev_write_page(struct block_device *, sector_t, struct page *,
struct writeback_control *);
-extern long bdev_direct_access(struct block_device *, sector_t,
- void __pmem **addr, unsigned long *pfn, long size);
+extern long bdev_direct_access(struct block_device *, struct blk_dax_ctl *);
#else /* CONFIG_BLOCK */
struct block_device;