On Thu, Sep 17, 2020 at 10:30:03PM -0700, Dan Williams wrote:
From: Jan Kara jack@suse.cz
DM was calling generic_fsdax_supported() to determine whether a device referenced in the DM table supports DAX. However this is a helper for "leaf" device drivers so that they don't have to duplicate common generic checks. High level code should call dax_supported() helper which that calls into appropriate helper for the particular device. This problem manifested itself as kernel messages:
dm-3: error: dax access failed (-95)
when lvm2-testsuite run in cases where a DM device was stacked on top of another DM device.
Is there somewhere where it is documented which of:
bdev_dax_supported, generic_fsdax_supported, and dax_supported
one is supposed to use for a given circumstance?
I guess the last two can test a given range w/ blocksize; the first one only does blocksize; and the middle one also checks with whatever fs might be mounted? <shrug>
(I ask because it took me a while to figure out how to revert correctly the brokenness in rc3-5 that broke my nightly dax fstesting.)
--D
Fixes: 7bf7eac8d648 ("dax: Arrange for dax_supported check to span multiple devices") Cc: stable@vger.kernel.org Tested-by: Adrian Huang ahuang12@lenovo.com Signed-off-by: Jan Kara jack@suse.cz Acked-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Dan Williams dan.j.williams@intel.com
Changes since v1 [1]:
- Add missing dax_read_lock() around dax_supported()
drivers/dax/super.c | 4 ++++ drivers/md/dm-table.c | 10 +++++++--- include/linux/dax.h | 11 +++++++++-- 3 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/drivers/dax/super.c b/drivers/dax/super.c index e5767c83ea23..b6284c5cae0a 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -325,11 +325,15 @@ EXPORT_SYMBOL_GPL(dax_direct_access); bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev, int blocksize, sector_t start, sector_t len) {
- if (!dax_dev)
return false;- if (!dax_alive(dax_dev)) return false;
return dax_dev->ops->dax_supported(dax_dev, bdev, blocksize, start, len); } +EXPORT_SYMBOL_GPL(dax_supported); size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i) diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 5edc3079e7c1..229f461e7def 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -860,10 +860,14 @@ EXPORT_SYMBOL_GPL(dm_table_set_type); int device_supports_dax(struct dm_target *ti, struct dm_dev *dev, sector_t start, sector_t len, void *data) {
- int blocksize = *(int *) data;
- int blocksize = *(int *) data, id;
- bool rc;
- return generic_fsdax_supported(dev->dax_dev, dev->bdev, blocksize,
start, len);
- id = dax_read_lock();
- rc = dax_supported(dev->dax_dev, dev->bdev, blocksize, start, len);
- dax_read_unlock(id);
- return rc;
} /* Check devices support synchronous DAX */ diff --git a/include/linux/dax.h b/include/linux/dax.h index 6904d4e0b2e0..9f916326814a 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -130,6 +130,8 @@ static inline bool generic_fsdax_supported(struct dax_device *dax_dev, return __generic_fsdax_supported(dax_dev, bdev, blocksize, start, sectors); } +bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
int blocksize, sector_t start, sector_t len);static inline void fs_put_dax(struct dax_device *dax_dev) { @@ -157,6 +159,13 @@ static inline bool generic_fsdax_supported(struct dax_device *dax_dev, return false; } +static inline bool dax_supported(struct dax_device *dax_dev,
struct block_device *bdev, int blocksize, sector_t start,sector_t len)+{
- return false;
+}
static inline void fs_put_dax(struct dax_device *dax_dev) { } @@ -195,8 +204,6 @@ 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,
-- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel