From: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
Subject: dax: use pfn_mkwrite to update c/mtime + freeze protection
From: Yigal Korman <yigal@xxxxxxxxxxxxx>
[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 <yigal@xxxxxxxxxxxxx>
Signed-off-by: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Cc: Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/dax.c | 17 +++++++++++++++++
fs/ext2/file.c | 1 +
fs/ext4/file.c | 1 +
include/linux/fs.h | 1 +
4 files changed, 20 insertions(+)
diff -puN fs/dax.c~dax-use-pfn_mkwrite-to-update-c-mtime-freeze-protection fs/dax.c
--- a/fs/dax.c~dax-use-pfn_mkwrite-to-update-c-mtime-freeze-protection
+++ a/fs/dax.c
@@ -464,6 +464,23 @@ int dax_fault(struct vm_area_struct *vma
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
diff -puN fs/ext2/file.c~dax-use-pfn_mkwrite-to-update-c-mtime-freeze-protection fs/ext2/file.c
--- a/fs/ext2/file.c~dax-use-pfn_mkwrite-to-update-c-mtime-freeze-protection
+++ a/fs/ext2/file.c
@@ -39,6 +39,7 @@ static int ext2_dax_mkwrite(struct vm_ar
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)
diff -puN fs/ext4/file.c~dax-use-pfn_mkwrite-to-update-c-mtime-freeze-protection fs/ext4/file.c
--- a/fs/ext4/file.c~dax-use-pfn_mkwrite-to-update-c-mtime-freeze-protection
+++ a/fs/ext4/file.c
@@ -206,6 +206,7 @@ static int ext4_dax_mkwrite(struct vm_ar
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
diff -puN include/linux/fs.h~dax-use-pfn_mkwrite-to-update-c-mtime-freeze-protection include/linux/fs.h
--- a/include/linux/fs.h~dax-use-pfn_mkwrite-to-update-c-mtime-freeze-protection
+++ a/include/linux/fs.h
@@ -2620,6 +2620,7 @@ int dax_clear_blocks(struct inode *, sec
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
_
--
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