FAILED: patch "[PATCH] dax: use pfn_mkwrite to update c/mtime + freeze protection" failed to apply to 4.0-stable tree

From 0e3b210ce1722168227cb3bc7746256d0c0afece Mon Sep 17 00:00:00 2001

The patch below does not apply to the 4.0-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0e3b210ce1722168227cb3bc7746256d0c0afece Mon Sep 17 00:00:00 2001
From: Boaz Harrosh <[email protected]>
Date: Wed, 15 Apr 2015 16:15:14 -0700
Subject: [PATCH] dax: use pfn_mkwrite to update c/mtime + freeze protection

From: Yigal Korman <[email protected]>

[v1]
Without this patch, c/mtime is not updated correctly when mmap'ed page is first read from and then written to.

A new xfstest is submitted for testing this (generic/080)

[v2]
Jan Kara has pointed out that if we add the sb_start/end_pagefault pair in the new pfn_mkwrite we are then fixing another bug where: A user could start writing to the page while filesystem is frozen.

Signed-off-by Yigal Korman <[email protected]>

Signed-off-by Boaz Harrosh <[email protected]>

Reviewed-by Jan Kara <[email protected]>

Cc Matthew Wilcox <[email protected]>

Cc Dave Chinner <[email protected]>

Cc Hugh Dickins <[email protected]>

Cc Mel Gorman <[email protected]>

Cc Kirill A. Shutemov <[email protected]>

Cc <[email protected]>

Signed-off-by Andrew Morton <[email protected]>

Signed-off-by Linus Torvalds <[email protected]>

fs/dax.c +17 -0

index ed1619ec6537..d0bd1f4f81b3 100644
@@ -464,6 +464,23 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 EXPORT_SYMBOL_GPL(dax_fault);
 
 /**
+ * dax_pfn_mkwrite - handle first write to DAX page
+ * @vma: The virtual memory area where the fault occurred
+ * @vmf: The description of the fault
+ *
+ */
+int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct super_block *sb = file_inode(vma->vm_file)->i_sb;
+
+	sb_start_pagefault(sb);
+	file_update_time(vma->vm_file);
+	sb_end_pagefault(sb);
+	return VM_FAULT_NOPAGE;
+}
+EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
+
+/**
  * dax_zero_page_range - zero a range within a page of a DAX file
  * @inode: The file being truncated
  * @from: The file offset that is being truncated to

fs/ext2/file.c +1 -0

index e31701713516..866a3ce3f864 100644
@@ -39,6 +39,7 @@ static int ext2_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 static const struct vm_operations_struct ext2_dax_vm_ops = {
 	.fault		= ext2_dax_fault,
 	.page_mkwrite	= ext2_dax_mkwrite,
+	.pfn_mkwrite	= dax_pfn_mkwrite,
 };
 
 static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)

fs/ext4/file.c +1 -0

index 598abbbe6786..aa78c70553f4 100644
@@ -206,6 +206,7 @@ static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 static const struct vm_operations_struct ext4_dax_vm_ops = {
 	.fault		= ext4_dax_fault,
 	.page_mkwrite	= ext4_dax_mkwrite,
+	.pfn_mkwrite	= dax_pfn_mkwrite,
 };
 #else
 #define ext4_dax_vm_ops	ext4_file_vm_ops

include/linux/fs.h +1 -0

index 60733bdc74b4..0f696328f218 100644
@@ -2620,6 +2620,7 @@ int dax_clear_blocks(struct inode *, sector_t block, long size);
 int dax_zero_page_range(struct inode *, loff_t from, unsigned len, get_block_t);
 int dax_truncate_page(struct inode *, loff_t from, get_block_t);
 int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t);
+int dax_pfn_mkwrite(struct vm_area_struct *, struct vm_fault *);
 #define dax_mkwrite(vma, vmf, gb)	dax_fault(vma, vmf, gb)
 
 #ifdef CONFIG_BLOCK