fsdax: output address in dax_iomap_pfn() and rename it

Add address output in dax_iomap_pfn() in order to perform a memcpy() in
CoW case.  Since this function both output address and pfn, rename it to
dax_iomap_direct_access().

[ruansy.fnst@fujitsu.com: initialize `rc', per Dan]
Link: https://lore.kernel.org/linux-fsdevel/Yp8FUZnO64Qvyx5G@kili/
Link: https://lkml.kernel.org/r/20220607143837.161174-1-ruansy.fnst@fujitsu.com
Link: https://lkml.kernel.org/r/20220603053738.1218681-9-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/dax.c b/fs/dax.c
index b59b864..7a8eb1e 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1026,20 +1026,22 @@ int dax_writeback_mapping_range(struct address_space *mapping,
 }
 EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);
 
-static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
-                        pfn_t *pfnp)
+static int dax_iomap_direct_access(const struct iomap *iomap, loff_t pos,
+               size_t size, void **kaddr, pfn_t *pfnp)
 {
        pgoff_t pgoff = dax_iomap_pgoff(iomap, pos);
-       int id, rc;
+       int id, rc = 0;
        long length;
 
        id = dax_read_lock();
        length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
-                                  DAX_ACCESS, NULL, pfnp);
+                                  DAX_ACCESS, kaddr, pfnp);
        if (length < 0) {
                rc = length;
                goto out;
        }
+       if (!pfnp)
+               goto out_check_addr;
        rc = -EINVAL;
        if (PFN_PHYS(length) < size)
                goto out;
@@ -1049,6 +1051,12 @@ static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
        if (length > 1 && !pfn_t_devmap(*pfnp))
                goto out;
        rc = 0;
+
+out_check_addr:
+       if (!kaddr)
+               goto out;
+       if (!*kaddr)
+               rc = -EFAULT;
 out:
        dax_read_unlock(id);
        return rc;
@@ -1456,7 +1464,7 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf,
                return pmd ? VM_FAULT_FALLBACK : VM_FAULT_SIGBUS;
        }
 
-       err = dax_iomap_pfn(&iter->iomap, pos, size, &pfn);
+       err = dax_iomap_direct_access(&iter->iomap, pos, size, NULL, &pfn);
        if (err)
                return pmd ? VM_FAULT_FALLBACK : dax_fault_return(err);