Add support for changing devices alignment.

On kernels that do not support per-device align sysfs property
we set it to 0.

Signed-off-by: Joao Martins <[email protected]>
---
 daxctl/lib/libdaxctl-private.h |  1 +
 daxctl/lib/libdaxctl.c         | 36 ++++++++++++++++++++++++++++++++++++
 daxctl/lib/libdaxctl.sym       |  2 ++
 daxctl/libdaxctl.h             |  2 ++
 4 files changed, 41 insertions(+)

diff --git a/daxctl/lib/libdaxctl-private.h b/daxctl/lib/libdaxctl-private.h
index 9f9c70d6024f..b307a8bc9438 100644
--- a/daxctl/lib/libdaxctl-private.h
+++ b/daxctl/lib/libdaxctl-private.h
@@ -99,6 +99,7 @@ struct daxctl_dev {
        struct list_node list;
        unsigned long long resource;
        unsigned long long size;
+       unsigned long align;
        struct kmod_module *module;
        struct daxctl_region *region;
        struct daxctl_memory *mem;
diff --git a/daxctl/lib/libdaxctl.c b/daxctl/lib/libdaxctl.c
index 9b43b68facfe..39871427c799 100644
--- a/daxctl/lib/libdaxctl.c
+++ b/daxctl/lib/libdaxctl.c
@@ -498,6 +498,13 @@ static void *add_dax_dev(void *parent, int id, const char 
*daxdev_base)
                goto err_read;
        dev->size = strtoull(buf, NULL, 0);
 
+       /* Device align attribute is only available in v5.10 or up */
+       sprintf(path, "%s/align", daxdev_base);
+       if (!sysfs_read_attr(ctx, path, buf))
+               dev->align = strtoull(buf, NULL, 0);
+       else
+               dev->align = 0;
+
        dev->dev_path = strdup(daxdev_base);
        if (!dev->dev_path)
                goto err_read;
@@ -1086,6 +1093,35 @@ DAXCTL_EXPORT int daxctl_dev_set_size(struct daxctl_dev 
*dev, unsigned long long
        return 0;
 }
 
+DAXCTL_EXPORT unsigned long daxctl_dev_get_align(struct daxctl_dev *dev)
+{
+       return dev->align;
+}
+
+DAXCTL_EXPORT int daxctl_dev_set_align(struct daxctl_dev *dev, unsigned long 
align)
+{
+       struct daxctl_ctx *ctx = daxctl_dev_get_ctx(dev);
+       char buf[SYSFS_ATTR_SIZE];
+       char *path = dev->dev_buf;
+       int len = dev->buf_len;
+
+       if (snprintf(path, len, "%s/align", dev->dev_path) >= len) {
+               err(ctx, "%s: buffer too small!\n",
+                               daxctl_dev_get_devname(dev));
+               return -ENXIO;
+       }
+
+       sprintf(buf, "%#lx\n", align);
+       if (sysfs_write_attr(ctx, path, buf) < 0) {
+               err(ctx, "%s: failed to set align\n",
+                               daxctl_dev_get_devname(dev));
+               return -ENXIO;
+       }
+
+       dev->align = align;
+       return 0;
+}
+
 DAXCTL_EXPORT int daxctl_dev_get_target_node(struct daxctl_dev *dev)
 {
        return dev->target_node;
diff --git a/daxctl/lib/libdaxctl.sym b/daxctl/lib/libdaxctl.sym
index 33c926411037..c3d08179c9fd 100644
--- a/daxctl/lib/libdaxctl.sym
+++ b/daxctl/lib/libdaxctl.sym
@@ -81,4 +81,6 @@ global:
        daxctl_dev_set_size;
        daxctl_region_create_dev;
        daxctl_region_destroy_dev;
+       daxctl_dev_get_align;
+       daxctl_dev_set_align;
 } LIBDAXCTL_7;
diff --git a/daxctl/libdaxctl.h b/daxctl/libdaxctl.h
index 2b14faad1895..b0bb5d78d357 100644
--- a/daxctl/libdaxctl.h
+++ b/daxctl/libdaxctl.h
@@ -71,6 +71,8 @@ int daxctl_dev_get_minor(struct daxctl_dev *dev);
 unsigned long long daxctl_dev_get_resource(struct daxctl_dev *dev);
 unsigned long long daxctl_dev_get_size(struct daxctl_dev *dev);
 int daxctl_dev_set_size(struct daxctl_dev *dev, unsigned long long size);
+unsigned long daxctl_dev_get_align(struct daxctl_dev *dev);
+int daxctl_dev_set_align(struct daxctl_dev *dev, unsigned long align);
 struct daxctl_ctx *daxctl_dev_get_ctx(struct daxctl_dev *dev);
 int daxctl_dev_is_enabled(struct daxctl_dev *dev);
 int daxctl_dev_disable(struct daxctl_dev *dev);
-- 
1.8.3.1
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