9:26 a.m.
From: Goldwyn Rodrigues <rgoldwyn(a)suse.com>
Change dax_iomap_pfn to return the address as well in order to
use it for performing a memcpy in case the type is IOMAP_DAX_COW.
We don't handle PMD because btrfs does not support hugepages.
Question:
The sequence of bdev_dax_pgoff() and dax_direct_access() is
used multiple times to calculate address and pfn's. Would it make
sense to call it while calculating address as well to reduce code?
Signed-off-by: Goldwyn Rodrigues <rgoldwyn(a)suse.com>
---
fs/dax.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 610bfa861a28..718b1632a39d 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -984,7 +984,7 @@ static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
}
static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size,
- pfn_t *pfnp)
+ pfn_t *pfnp, void **addr)
{
const sector_t sector = dax_iomap_sector(iomap, pos);
pgoff_t pgoff;
@@ -996,7 +996,7 @@ static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t
size,
return rc;
id = dax_read_lock();
length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
- NULL, pfnp);
+ addr, pfnp);
if (length < 0) {
rc = length;
goto out;
@@ -1286,6 +1286,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t
*pfnp,
XA_STATE(xas, &mapping->i_pages, vmf->pgoff);
struct inode *inode = mapping->host;
unsigned long vaddr = vmf->address;
+ void *addr;
loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
struct iomap iomap = { 0 };
unsigned flags = IOMAP_FAULT;
@@ -1375,16 +1376,26 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t
*pfnp,
sync = dax_fault_is_synchronous(flags, vma, &iomap);
switch (iomap.type) {
+ case IOMAP_DAX_COW:
case IOMAP_MAPPED:
if (iomap.flags & IOMAP_F_NEW) {
count_vm_event(PGMAJFAULT);
count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
major = VM_FAULT_MAJOR;
}
- error = dax_iomap_pfn(&iomap, pos, PAGE_SIZE, &pfn);
+ error = dax_iomap_pfn(&iomap, pos, PAGE_SIZE, &pfn, &addr);
if (error < 0)
goto error_finish_iomap;
+ if (iomap.type == IOMAP_DAX_COW) {
+ if (iomap.inline_data) {
+ error = memcpy_mcsafe(addr, iomap.inline_data,
+ PAGE_SIZE);
+ if (error < 0)
+ goto error_finish_iomap;
+ } else
+ memset(addr, 0, PAGE_SIZE);
+ }
entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn,
0, write && !sync);
@@ -1597,7 +1608,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t
*pfnp,
switch (iomap.type) {
case IOMAP_MAPPED:
- error = dax_iomap_pfn(&iomap, pos, PMD_SIZE, &pfn);
+ error = dax_iomap_pfn(&iomap, pos, PMD_SIZE, &pfn, NULL);
if (error < 0)
goto finish_iomap;
--
2.16.4