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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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13
fs/block_dev.c
View file

@ -455,10 +455,7 @@ EXPORT_SYMBOL_GPL(bdev_write_page);
/**
* bdev_direct_access() - Get the address for directly-accessibly memory
* @bdev: The device containing the memory
* @sector: The offset within the device
* @addr: Where to put the address of the memory
* @pfn: The Page Frame Number for the memory
* @size: The number of bytes requested
* @dax: control and output parameters for ->direct_access
*
* If a block device is made up of directly addressable memory, this function
* will tell the caller the PFN and the address of the memory. The address
@ -469,10 +466,10 @@ EXPORT_SYMBOL_GPL(bdev_write_page);
* Return: negative errno if an error occurs, otherwise the number of bytes
* accessible at this address.
*/
long bdev_direct_access(struct block_device *bdev, sector_t sector,
void __pmem **addr, unsigned long *pfn, long size)
long bdev_direct_access(struct block_device *bdev, struct blk_dax_ctl *dax)
{
long avail;
sector_t sector = dax->sector;
long avail, size = dax->size;
const struct block_device_operations *ops = bdev->bd_disk->fops;
/*
@ -491,7 +488,7 @@ long bdev_direct_access(struct block_device *bdev, sector_t sector,
sector += get_start_sect(bdev);
if (sector % (PAGE_SIZE / 512))
return -EINVAL;
avail = ops->direct_access(bdev, sector, addr, pfn);
avail = ops->direct_access(bdev, sector, &dax->addr, &dax->pfn);
if (!avail)
return -ERANGE;
if (avail > 0 && avail & ~PAGE_MASK)