[PATCH v2 10/11] ext4: add support for DAX fsync/msync

Ross Zwisler
2015-11-14T00:07:22Z

To properly support the new DAX fsync/msync infrastructure filesystems
need to call dax_pfn_mkwrite() so that DAX can properly track when a user
write faults on a previously cleaned address. They also need to call
dax_fsync() in the filesystem fsync() path. This dax_fsync() call uses
addresses retrieved from get_block() so it needs to be ordered with
respect to truncate. This is accomplished by using the same locking that
was set up for DAX page faults.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
fs/ext4/file.c | 4 +++-
fs/ext4/fsync.c | 12 ++++++++++--
2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 749b222..8c8965c 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -291,8 +291,8 @@ static int ext4_dax_pfn_mkwrite(struct vm_area_struct *vma,
{
struct inode *inode = file_inode(vma->vm_file);
struct super_block *sb = inode->i_sb;
- int ret = VM_FAULT_NOPAGE;
loff_t size;
+ int ret;

sb_start_pagefault(sb);
file_update_time(vma->vm_file);
@@ -300,6 +300,8 @@ static int ext4_dax_pfn_mkwrite(struct vm_area_struct *vma,
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (vmf->pgoff >= size)
ret = VM_FAULT_SIGBUS;
+ else
+ ret = dax_pfn_mkwrite(vma, vmf);
up_read(&EXT4_I(inode)->i_mmap_sem);
sb_end_pagefault(sb);

diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
index 8850254..e87c29b 100644
--- a/fs/ext4/fsync.c
+++ b/fs/ext4/fsync.c
@@ -27,6 +27,7 @@
#include <linux/sched.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
+#include <linux/dax.h>

#include "ext4.h"
#include "ext4_jbd2.h"
@@ -86,7 +87,8 @@ static int ext4_sync_parent(struct inode *inode)

int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
{
- struct inode *inode = file->f_mapping->host;
+ struct address_space *mapping = file->f_mapping;
+ struct inode *inode = mapping->host;
struct ext4_inode_info *ei = EXT4_I(inode);
journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
int ret = 0, err;
@@ -112,7 +114,13 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
goto out;
}

- ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
+ if (dax_mapping(mapping)) {
+ down_read(&ei->i_mmap_sem);
+ dax_fsync(mapping, start, end);
+ up_read(&ei->i_mmap_sem);
+ }
+
+ ret = filemap_write_and_wait_range(mapping, start, end);
if (ret)
return ret;
/*
--
2.1.0