On Mon, Jan 11, 2016 at 02:35:23PM -0500, Matthew Wilcox wrote:
> I would rather see the memory.c code move in the direction of the
> huge_memory.c code. How about something like this?
Whoops, missed some bits in the DAX conversion where we'd return an -errno instead of VM_FAULT flags. Take two.
diff --git a/fs/dax.c b/fs/dax.c
index a610cbe..deff70f 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -498,6 +498,7 @@ EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);
static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
struct vm_area_struct *vma, struct vm_fault *vmf)
{
+ const bool write = vmf->flags & FAULT_FLAG_WRITE;
unsigned long vaddr = (unsigned long)vmf->virtual_address;
struct address_space *mapping = inode->i_mapping;
struct block_device *bdev = bh->b_bdev;
@@ -506,7 +507,7 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
.size = bh->b_size,
};
pgoff_t size;
- int error;
+ int result;
i_mmap_lock_read(mapping);
@@ -518,15 +519,11 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
* allocated past the end of the file.
*/
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
- if (unlikely(vmf->pgoff >= size)) {
- error = -EIO;
- goto out;
- }
+ if (unlikely(vmf->pgoff >= size))
+ goto sigbus;
- if (dax_map_atomic(bdev, &dax) < 0) {
- error = PTR_ERR(dax.addr);
- goto out;
- }
+ if (dax_map_atomic(bdev, &dax) < 0)
+ goto sigbus;
if (buffer_unwritten(bh) || buffer_new(bh)) {
clear_pmem(dax.addr, PAGE_SIZE);
@@ -534,17 +531,19 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
}
dax_unmap_atomic(bdev, &dax);
- error = dax_radix_entry(mapping, vmf->pgoff, dax.sector, false,
- vmf->flags & FAULT_FLAG_WRITE);
- if (error)
- goto out;
+ if (dax_radix_entry(mapping, vmf->pgoff, dax.sector, false, write))
+ goto sigbus;
- error = vm_insert_mixed(vma, vaddr, dax.pfn);
+ result = vmf_insert_pfn(vma, vaddr, dax.pfn, write);
out:
i_mmap_unlock_read(mapping);
- return error;
+ return result;
+
+ sigbus:
+ result = VM_FAULT_SIGBUS;
+ goto out;
}
static int dax_pte_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
@@ -559,7 +558,7 @@ static int dax_pte_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
unsigned blkbits = inode->i_blkbits;
sector_t block;
pgoff_t size;
- int error;
+ int result, error;
int major = 0;
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
@@ -660,13 +659,14 @@ static int dax_pte_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
* indicate what the callback should do via the uptodate variable, same
* as for normal BH based IO completions.
*/
- error = dax_insert_mapping(inode, &bh, vma, vmf);
+ result = dax_insert_mapping(inode, &bh, vma, vmf);
if (buffer_unwritten(&bh)) {
if (complete_unwritten)
- complete_unwritten(&bh, !error);
+ complete_unwritten(&bh, !(result & VM_FAULT_ERROR));
else
WARN_ON_ONCE(!(vmf->flags & FAULT_FLAG_WRITE));
}
+ return result | major;
out:
if (error == -ENOMEM)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 27dbd1b..a95242c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2170,8 +2170,10 @@ struct vm_area_struct *find_extend_vma(struct mm_struct *, unsigned long addr);
int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
unsigned long pfn, unsigned long size, pgprot_t);
int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);
-int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
+int vm_insert_pfn(struct vm_area_struct *, unsigned long addr,
unsigned long pfn);
+int vmf_insert_pfn(struct vm_area_struct *, unsigned long addr,
+ pfn_t pfn, bool write);
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
pfn_t pfn);
int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
diff --git a/mm/memory.c b/mm/memory.c
index 708a0c7c..b93bcba 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1505,8 +1505,15 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
}
EXPORT_SYMBOL(vm_insert_page);
+static pte_t maybe_pte_mkwrite(pte_t pte, struct vm_area_struct *vma)
+{
+ if (likely(vma->vm_flags & VM_WRITE))
+ pte = pte_mkwrite(pte);
+ return pte;
+}
+
static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
- pfn_t pfn, pgprot_t prot)
+ pfn_t pfn, pgprot_t prot, bool write)
{
struct mm_struct *mm = vma->vm_mm;
int retval;
@@ -1526,6 +1533,10 @@ static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
else
entry = pte_mkspecial(pfn_t_pte(pfn, prot));
+ if (write) {
+ entry = pte_mkyoung(pte_mkdirty(entry));
+ entry = maybe_pte_mkwrite(entry, vma);
+ }
set_pte_at(mm, addr, pte, entry);
update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
@@ -1537,26 +1548,28 @@ out:
}
/**
- * vm_insert_pfn - insert single pfn into user vma
+ * vmf_insert_pfn - insert single pfn into user vma
* @vma: user vma to map to
* @addr: target user address of this page
* @pfn: source kernel pfn
+ * @write: Whether to insert a writable entry
*
* Similar to vm_insert_page, this allows drivers to insert individual pages
* they've allocated into a user vma. Same comments apply.
*
* This function should only be called from a vm_ops->fault handler, and
- * in that case the handler should return NULL.
+ * the return value from this function is suitable for returning from that
+ * handler.
*
* vma cannot be a COW mapping.
*
* As this is called only for pages that do not currently exist, we
* do not need to flush old virtual caches or the TLB.
*/
-int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
- unsigned long pfn)
+int vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
+ pfn_t pfn, bool write)
{
- int ret;
+ int error;
pgprot_t pgprot = vma->vm_page_prot;
/*
* Technically, architectures with pte_special can avoid all these
@@ -1568,16 +1581,29 @@ int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
(VM_PFNMAP|VM_MIXEDMAP));
BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
- BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
+ BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_t_valid(pfn));
if (addr < vma->vm_start || addr >= vma->vm_end)
- return -EFAULT;
- if (track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)))
- return -EINVAL;
+ return VM_FAULT_SIGBUS;
+ if (track_pfn_insert(vma, &pgprot, pfn))
+ return VM_FAULT_SIGBUS;
- ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot);
+ error = insert_pfn(vma, addr, pfn, pgprot, write);
+ if (error == -EBUSY || !error)
+ return VM_FAULT_NOPAGE;
+ return VM_FAULT_SIGBUS;
+}
+EXPORT_SYMBOL(vmf_insert_pfn);
- return ret;
+/* TODO: Convert users to vmf_insert_pfn */
+int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
+ unsigned long pfn)
+{
+ int result = vmf_insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV),
+ false);
+ if (result & VM_FAULT_ERROR)
+ return -EFAULT;
+ return 0;
}
EXPORT_SYMBOL(vm_insert_pfn);
@@ -1602,7 +1628,7 @@ int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
page = pfn_t_to_page(pfn);
return insert_page(vma, addr, page, vma->vm_page_prot);
}
- return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
+ return insert_pfn(vma, addr, pfn, vma->vm_page_prot, false);
}
EXPORT_SYMBOL(vm_insert_mixed);
--
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