From 7bf7eac8d648057519adb6fce1e31458c902212c Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Thu, 16 May 2019 13:26:29 -0700 Subject: dax: Arrange for dax_supported check to span multiple devices Pankaj reports that starting with commit ad428cdb525a "dax: Check the end of the block-device capacity with dax_direct_access()" device-mapper no longer allows dax operation. This results from the stricter checks in __bdev_dax_supported() that validate that the start and end of a block-device map to the same 'pagemap' instance. Teach the dax-core and device-mapper to validate the 'pagemap' on a per-target basis. This is accomplished by refactoring the bdev_dax_supported() internals into generic_fsdax_supported() which takes a sector range to validate. Consequently generic_fsdax_supported() is suitable to be used in a device-mapper ->iterate_devices() callback. A new ->dax_supported() operation is added to allow composite devices to split and route upper-level bdev_dax_supported() requests. Fixes: ad428cdb525a ("dax: Check the end of the block-device...") Cc: Cc: Ira Weiny Cc: Dave Jiang Cc: Keith Busch Cc: Matthew Wilcox Cc: Vishal Verma Cc: Heiko Carstens Cc: Martin Schwidefsky Reviewed-by: Jan Kara Reported-by: Pankaj Gupta Reviewed-by: Pankaj Gupta Tested-by: Pankaj Gupta Tested-by: Vaibhav Jain Reviewed-by: Mike Snitzer Signed-off-by: Dan Williams --- include/linux/dax.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'include') diff --git a/include/linux/dax.h b/include/linux/dax.h index 0dd316a74a29..becaea5f4488 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -19,6 +19,12 @@ struct dax_operations { */ long (*direct_access)(struct dax_device *, pgoff_t, long, void **, pfn_t *); + /* + * Validate whether this device is usable as an fsdax backing + * device. + */ + bool (*dax_supported)(struct dax_device *, struct block_device *, int, + sector_t, sector_t); /* copy_from_iter: required operation for fs-dax direct-i/o */ size_t (*copy_from_iter)(struct dax_device *, pgoff_t, void *, size_t, struct iov_iter *); @@ -75,6 +81,17 @@ static inline bool bdev_dax_supported(struct block_device *bdev, int blocksize) return __bdev_dax_supported(bdev, blocksize); } +bool __generic_fsdax_supported(struct dax_device *dax_dev, + struct block_device *bdev, int blocksize, sector_t start, + sector_t sectors); +static inline bool generic_fsdax_supported(struct dax_device *dax_dev, + struct block_device *bdev, int blocksize, sector_t start, + sector_t sectors) +{ + return __generic_fsdax_supported(dax_dev, bdev, blocksize, start, + sectors); +} + static inline struct dax_device *fs_dax_get_by_host(const char *host) { return dax_get_by_host(host); @@ -99,6 +116,13 @@ static inline bool bdev_dax_supported(struct block_device *bdev, return false; } +static inline bool generic_fsdax_supported(struct dax_device *dax_dev, + struct block_device *bdev, int blocksize, sector_t start, + sector_t sectors) +{ + return false; +} + static inline struct dax_device *fs_dax_get_by_host(const char *host) { return NULL; @@ -142,6 +166,8 @@ bool dax_alive(struct dax_device *dax_dev); void *dax_get_private(struct dax_device *dax_dev); long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn); +bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev, + int blocksize, sector_t start, sector_t len); size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i); size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr, -- cgit