[bug report] dax: Add dax_operations for use by fs-dax on fsdev dax

[bug report] dax: Add dax_operations for use by fs-dax on fsdev dax

[Dan Carpenter]

Hello John Groves,

This email is a free service from the Smatch-CI project
(smatch.sf.net).

Commit 099c81a1f0ab ("dax: Add dax_operations for use by fs-dax on
fsdev dax") from Mar 27, 2026 (linux-next), leads to the following
Smatch static checker warning:

	drivers/dax/fsdev.c:86 fsdev_dax_zero_page_range()
	error: uninitialized symbol 'kaddr'.

drivers/dax/fsdev.c
    79 static int fsdev_dax_zero_page_range(struct dax_device *dax_dev,
    80                         pgoff_t pgoff, size_t nr_pages)
    81 {
    82         void *kaddr;
    83 
    84         WARN_ONCE(nr_pages > 1, "%s: nr_pages > 1\n", __func__);
    85         __fsdev_dax_direct_access(dax_dev, pgoff, 1, DAX_ACCESS, &kaddr, NULL);

The checker thinks __fsdev_dax_direct_access() can return -1.

--> 86         fsdev_write_dax(kaddr, ZERO_PAGE(0), 0, PAGE_SIZE);
                               ^^^^^
which means kaddr is uninitialized

    87         return 0;
    88 }

regards,
dan carpenter