Change device-mapper's 'select DAX' dependency to be dependent on the
presence of at least one DAX_DRIVER. This allows device-mapper to be
built without bringing the DAX core along which is especially wasteful
when there are no DAX drivers, like BLK_DEV_PMEM, configured.
Cc: Alasdair Kergon <agk@xxxxxxxxxx>
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Reported-by: Bart Van Assche <Bart.VanAssche@xxxxxxx>
Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/md/Kconfig | 2 +-
drivers/md/dm-linear.c | 6 ++++++
drivers/md/dm-stripe.c | 6 ++++++
drivers/md/dm.c | 10 ++++++----
include/linux/dax.h | 30 ++++++++++++++++++++++++------
5 files changed, 43 insertions(+), 11 deletions(-)
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 4a249ee86364..baeea31dc858 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -200,7 +200,7 @@ config BLK_DEV_DM_BUILTIN
config BLK_DEV_DM
tristate "Device mapper support"
select BLK_DEV_DM_BUILTIN
- select DAX
+ select DAX if DAX_DRIVER
---help---
Device-mapper is a low level volume manager. It works by allowing
people to specify mappings for ranges of logical sectors. Various
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index d5f8eff7c11d..df4b6f0489aa 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -154,6 +154,7 @@ static int linear_iterate_devices(struct dm_target *ti,
return fn(ti, lc->dev, lc->start, ti->len, data);
}
+#if IS_ENABLED(CONFIG_DAX)
static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
long nr_pages, void **kaddr, pfn_t *pfn)
{
@@ -184,6 +185,11 @@ static size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
}
+#else
+#define linear_dax_direct_access NULL
+#define linear_dax_copy_from_iter NULL
+#endif
+
static struct target_type linear_target = {
.name = "linear",
.version = {1, 4, 0},
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index b5e892149c54..8cb98ee2c9db 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -311,6 +311,7 @@ static int stripe_map(struct dm_target *ti, struct bio *bio)
return DM_MAPIO_REMAPPED;
}
+#if IS_ENABLED(CONFIG_DAX)
static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
long nr_pages, void **kaddr, pfn_t *pfn)
{
@@ -351,6 +352,11 @@ static size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
}
+#else
+#define stripe_dax_direct_access NULL
+#define stripe_dax_copy_from_iter NULL
+#endif
+
/*
* Stripe status:
*
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 6e54145969c5..e364c584a676 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1685,7 +1685,7 @@ static void cleanup_mapped_device(struct mapped_device *md)
static struct mapped_device *alloc_dev(int minor)
{
int r, numa_node_id = dm_get_numa_node();
- struct dax_device *dax_dev;
+ struct dax_device *dax_dev = NULL;
struct mapped_device *md;
void *old_md;
@@ -1751,9 +1751,11 @@ static struct mapped_device *alloc_dev(int minor)
md->disk->private_data = md;
sprintf(md->disk->disk_name, "dm-%d", minor);
- dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops);
- if (!dax_dev)
- goto bad;
+ if (IS_ENABLED(CONFIG_DAX)) {
+ dax_dev = alloc_dax(md, md->disk->disk_name, &dm_dax_ops);
+ if (!dax_dev)
+ goto bad;
+ }
md->dax_dev = dax_dev;
add_disk(md->disk);
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 122197124b9d..898403da0458 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -25,16 +25,39 @@ extern struct attribute_group dax_attribute_group;
#if IS_ENABLED(CONFIG_DAX)
struct dax_device *dax_get_by_host(const char *host);
+struct dax_device *alloc_dax(void *private, const char *host,
+ const struct dax_operations *ops);
void put_dax(struct dax_device *dax_dev);
+void kill_dax(struct dax_device *dax_dev);
+void dax_write_cache(struct dax_device *dax_dev, bool wc);
+bool dax_write_cache_enabled(struct dax_device *dax_dev);
#else
static inline struct dax_device *dax_get_by_host(const char *host)
{
return NULL;
}
-
+static inline struct dax_device *alloc_dax(void *private, const char *host,
+ const struct dax_operations *ops)
+{
+ /*
+ * Callers should check IS_ENABLED(CONFIG_DAX) to know if this
+ * NULL is an error or expected.
+ */
+ return NULL;
+}
static inline void put_dax(struct dax_device *dax_dev)
{
}
+static inline void kill_dax(struct dax_device *dax_dev)
+{
+}
+static inline void dax_write_cache(struct dax_device *dax_dev, bool wc)
+{
+}
+static inline bool dax_write_cache_enabled(struct dax_device *dax_dev)
+{
+ return false;
+}
#endif
int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff);
@@ -79,18 +102,13 @@ static inline struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
int dax_read_lock(void);
void dax_read_unlock(int id);
-struct dax_device *alloc_dax(void *private, const char *host,
- const struct dax_operations *ops);
bool dax_alive(struct dax_device *dax_dev);
-void kill_dax(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);
size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
size_t bytes, struct iov_iter *i);
void dax_flush(struct dax_device *dax_dev, void *addr, size_t size);
-void dax_write_cache(struct dax_device *dax_dev, bool wc);
-bool dax_write_cache_enabled(struct dax_device *dax_dev);
ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops);
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
