Rather than 'select dax', let the fact that BLK_DEV_PMEM selects dax act as a gate for the device-mapper dax support. Given that all the dax core routines compile to nops when CONFIG_DAX=n, we can simply handle the alloc_dax() error as expected and ifdef out the other dax support code.
Cc: Alasdair Kergon <[email protected]> Cc: Mike Snitzer <[email protected]> Reported-by: Bart Van Assche <[email protected]> Signed-off-by: Dan Williams <[email protected]> --- drivers/md/Kconfig | 1 - drivers/md/dm-linear.c | 6 ++++++ drivers/md/dm-stripe.c | 6 ++++++ drivers/md/dm.c | 10 ++++++---- include/linux/dax.h | 19 +++++++++++++++---- 5 files changed, 33 insertions(+), 9 deletions(-) diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig index 4a249ee86364..8ed48ff351cc 100644 --- a/drivers/md/Kconfig +++ b/drivers/md/Kconfig @@ -200,7 +200,6 @@ config BLK_DEV_DM_BUILTIN config BLK_DEV_DM tristate "Device mapper support" select BLK_DEV_DM_BUILTIN - select DAX ---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 41971a090e34..8804e278e834 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) { @@ -197,6 +198,11 @@ static void linear_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr, return; dax_flush(dax_dev, pgoff, addr, size); } +#else +#define linear_dax_direct_access NULL +#define linear_dax_copy_from_iter NULL +#define linear_dax_flush NULL +#endif static struct target_type linear_target = { .name = "linear", diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c index a0375530b07f..eeb6c784dc4f 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) { @@ -369,6 +370,11 @@ static void stripe_dax_flush(struct dm_target *ti, pgoff_t pgoff, void *addr, return; dax_flush(dax_dev, pgoff, addr, size); } +#else +#define stripe_dax_direct_access NULL +#define stripe_dax_copy_from_iter NULL +#define stripe_dax_flush NULL +#endif /* * Stripe status: diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 2edbcc2d7d3f..70fa48f4d3a3 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1713,7 +1713,7 @@ 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; @@ -1779,9 +1779,11 @@ 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 794811875732..5d51c5ef678b 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -27,16 +27,30 @@ 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); #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) +{ +} #endif int bdev_dax_pgoff(struct block_device *, sector_t, size_t, pgoff_t *pgoff); @@ -75,10 +89,7 @@ static inline void fs_put_dax(struct dax_device *dax_dev) 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); -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
