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dax: fix lifetime of in-kernel dax mappings with dax_map_atomic()

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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>
This commit is contained in:
Dan Williams
2016-01-15 16:55:59 -08:00
committed by Linus Torvalds
parent fe683adabf
commit b2e0d1625e
3 changed files with 149 additions and 87 deletions
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17
include/linux/blkdev.h
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@@ -1617,6 +1617,20 @@ static inline bool integrity_req_gap_front_merge(struct request *req,
#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 __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,
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;