X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=fs%2Fdax.c;h=43671b68220ed968386f5c1ad9067f236fbab67e;hb=45568625feacf13f1450da6b8cec17bf97c5a3fd;hp=a86d3cc2b38941b0e39f23be84e4986d8852ae42;hpb=52e9a33333fc337d03ffb865048f9ccae8552a8d;p=firefly-linux-kernel-4.4.55.git

diff --git a/fs/dax.c b/fs/dax.c
index a86d3cc2b389..43671b68220e 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++)