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Diffstat (limited to 'fs/dax.c')
-rw-r--r--fs/dax.c20
1 files changed, 19 insertions, 1 deletions
diff --git a/fs/dax.c b/fs/dax.c
index a86d3cc2b..43671b682 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -29,6 +29,11 @@
#include <linux/uio.h>
#include <linux/vmstat.h>
+/*
+ * dax_clear_blocks() is called from within transaction context from XFS,
+ * and hence this means the stack from this point must follow GFP_NOFS
+ * semantics for all operations.
+ */
int dax_clear_blocks(struct inode *inode, sector_t block, long size)
{
struct block_device *bdev = inode->i_sb->s_bdev;
@@ -169,8 +174,10 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
else
len = iov_iter_zero(max - pos, iter);
- if (!len)
+ if (!len) {
+ retval = -EFAULT;
break;
+ }
pos += len;
addr += len;
@@ -534,6 +541,10 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
unsigned long pfn;
int result = 0;
+ /* dax pmd mappings are broken wrt gup and fork */
+ if (!IS_ENABLED(CONFIG_FS_DAX_PMD))
+ return VM_FAULT_FALLBACK;
+
/* Fall back to PTEs if we're going to COW */
if (write && !(vma->vm_flags & VM_SHARED))
return VM_FAULT_FALLBACK;
@@ -622,6 +633,13 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR))
goto fallback;
+ /*
+ * TODO: teach vmf_insert_pfn_pmd() to support
+ * 'pte_special' for pmds
+ */
+ if (pfn_valid(pfn))
+ goto fallback;
+
if (buffer_unwritten(&bh) || buffer_new(&bh)) {
int i;
for (i = 0; i < PTRS_PER_PMD; i++)