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path: root/drivers/dax/super.c
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Diffstat (limited to 'drivers/dax/super.c')
-rw-r--r--drivers/dax/super.c81
1 files changed, 73 insertions, 8 deletions
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 465dcd7317d5..ebf43f531ada 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -14,16 +14,13 @@
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/magic.h>
+#include <linux/genhd.h>
#include <linux/cdev.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/dax.h>
#include <linux/fs.h>
-static int nr_dax = CONFIG_NR_DEV_DAX;
-module_param(nr_dax, int, S_IRUGO);
-MODULE_PARM_DESC(nr_dax, "max number of dax device instances");
-
static dev_t dax_devt;
DEFINE_STATIC_SRCU(dax_srcu);
static struct vfsmount *dax_mnt;
@@ -47,6 +44,75 @@ void dax_read_unlock(int id)
}
EXPORT_SYMBOL_GPL(dax_read_unlock);
+int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
+ pgoff_t *pgoff)
+{
+ phys_addr_t phys_off = (get_start_sect(bdev) + sector) * 512;
+
+ if (pgoff)
+ *pgoff = PHYS_PFN(phys_off);
+ if (phys_off % PAGE_SIZE || size % PAGE_SIZE)
+ return -EINVAL;
+ return 0;
+}
+EXPORT_SYMBOL(bdev_dax_pgoff);
+
+/**
+ * __bdev_dax_supported() - Check if the device supports dax for filesystem
+ * @sb: The superblock of the device
+ * @blocksize: The block size of the device
+ *
+ * This is a library function for filesystems to check if the block device
+ * can be mounted with dax option.
+ *
+ * Return: negative errno if unsupported, 0 if supported.
+ */
+int __bdev_dax_supported(struct super_block *sb, int blocksize)
+{
+ struct block_device *bdev = sb->s_bdev;
+ struct dax_device *dax_dev;
+ pgoff_t pgoff;
+ int err, id;
+ void *kaddr;
+ pfn_t pfn;
+ long len;
+
+ if (blocksize != PAGE_SIZE) {
+ pr_err("VFS (%s): error: unsupported blocksize for dax\n",
+ sb->s_id);
+ return -EINVAL;
+ }
+
+ err = bdev_dax_pgoff(bdev, 0, PAGE_SIZE, &pgoff);
+ if (err) {
+ pr_err("VFS (%s): error: unaligned partition for dax\n",
+ sb->s_id);
+ return err;
+ }
+
+ dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
+ if (!dax_dev) {
+ pr_err("VFS (%s): error: device does not support dax\n",
+ sb->s_id);
+ return -EOPNOTSUPP;
+ }
+
+ id = dax_read_lock();
+ len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
+ dax_read_unlock(id);
+
+ put_dax(dax_dev);
+
+ if (len < 1) {
+ pr_err("VFS (%s): error: dax access failed (%ld)",
+ sb->s_id, len);
+ return len < 0 ? len : -EIO;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(__bdev_dax_supported);
+
/**
* struct dax_device - anchor object for dax services
* @inode: core vfs
@@ -261,7 +327,7 @@ struct dax_device *alloc_dax(void *private, const char *__host,
if (__host && !host)
return NULL;
- minor = ida_simple_get(&dax_minor_ida, 0, nr_dax, GFP_KERNEL);
+ minor = ida_simple_get(&dax_minor_ida, 0, MINORMASK+1, GFP_KERNEL);
if (minor < 0)
goto err_minor;
@@ -405,8 +471,7 @@ static int __init dax_fs_init(void)
if (rc)
return rc;
- nr_dax = max(nr_dax, 256);
- rc = alloc_chrdev_region(&dax_devt, 0, nr_dax, "dax");
+ rc = alloc_chrdev_region(&dax_devt, 0, MINORMASK+1, "dax");
if (rc)
__dax_fs_exit();
return rc;
@@ -414,7 +479,7 @@ static int __init dax_fs_init(void)
static void __exit dax_fs_exit(void)
{
- unregister_chrdev_region(dax_devt, nr_dax);
+ unregister_chrdev_region(dax_devt, MINORMASK+1);
ida_destroy(&dax_minor_ida);
__dax_fs_exit();
}