[v11,01/07] fsdax: Output address in dax_iomap_pfn() and rename it

Commit Message

Shiyang Ruan May 8, 2022, 2:36 p.m. UTC

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().

Signed-off-by: Shiyang Ruan <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Reviewed-by: Ritesh Harjani <[e-mail]>
Reviewed-by: Dan Williams <[e-mail]>
Reviewed-by: Darrick J. Wong <[e-mail]>
---
 fs/dax.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

Patch

diff --git a/fs/dax.c b/fs/dax.c
index 4d3dfc8bee33..d4f195aeaa12 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1025,8 +1025,8 @@  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;
@@ -1034,11 +1034,13 @@  static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
 
 	id = dax_read_lock();
 	length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
-				   NULL, pfnp);
+				   kaddr, pfnp);
 	if (length < 0) {
 		rc = length;
 		goto out;
 	}
+	if (!pfnp)
+		goto out_check_addr;
 	rc = -EINVAL;
 	if (PFN_PHYS(length) < size)
 		goto out;
@@ -1048,6 +1050,12 @@  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;
@@ -1444,7 +1452,7 @@  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);