From: Dan Williams <dan.j.williams@intel.com>
To: linux-nvdimm@lists.01.org
Cc: Jan Kara <jack@suse.cz>, kernel test robot <lkp@intel.com>,
snitzer@redhat.com, linux-kernel@vger.kernel.org,
stable@vger.kernel.org, dm-devel@redhat.com,
Adrian Huang <ahuang12@lenovo.com>,
mpatocka@redhat.com, ira.weiny@intel.com
Subject: [PATCH v4] dm: Call proper helper to determine dax support
Date: Sun, 20 Sep 2020 08:54:42 -0700
Message-ID: <160061715195.13131.5503173247632041975.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)
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.
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>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
Changes since v3 [1]:
- One more kbuild-robot report on dax_read_lock() needing to be guarded
by "#if IS_ENABLED(CONFIG_DAX)" instead of "#ifdef CONFIG_DAX" since
the latter does not handle the "=m" case.
[2]: http://lore.kernel.org/r/160046028990.22670.15271558589864899328.stgit@dwillia2-desk3.amr.corp.intel.com
drivers/dax/super.c | 4 ++++
drivers/md/dm-table.c | 10 +++++++---
include/linux/dax.h | 22 ++++++++++++++++++++--
3 files changed, 31 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..497031392e0a 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)
{
}
@@ -189,14 +198,23 @@ static inline void dax_unlock_page(struct page *page, dax_entry_t cookie)
}
#endif
+#if IS_ENABLED(CONFIG_DAX)
int dax_read_lock(void);
void dax_read_unlock(int id);
+#else
+static inline int dax_read_lock(void)
+{
+ return 0;
+}
+
+static inline void dax_read_unlock(int id)
+{
+}
+#endif /* CONFIG_DAX */
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,
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