[PATCH v2 09/11] ext2: add support for DAX fsync/msync

[Ross Zwisler <ross.zwisler@linux.intel.com>]

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/ext2/file.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index 11a42c5..6c30ea2 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -102,8 +102,8 @@ static int ext2_dax_pfn_mkwrite(struct vm_area_struct *vma,
 {
 	struct inode *inode = file_inode(vma->vm_file);
 	struct ext2_inode_info *ei = EXT2_I(inode);
-	int ret = VM_FAULT_NOPAGE;
 	loff_t size;
+	int ret;
 
 	sb_start_pagefault(inode->i_sb);
 	file_update_time(vma->vm_file);
@@ -113,6 +113,8 @@ static int ext2_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(&ei->dax_sem);
 	sb_end_pagefault(inode->i_sb);
@@ -161,6 +163,16 @@ int ext2_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 	struct super_block *sb = file->f_mapping->host->i_sb;
 	struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
 
+#ifdef CONFIG_FS_DAX
+	if (dax_mapping(mapping)) {
+		struct ext2_inode_info *ei = EXT2_I(file_inode(file));
+
+		down_read(&ei->dax_sem);
+		dax_fsync(mapping, start, end);
+		up_read(&ei->dax_sem);
+	}
+#endif
+
 	ret = generic_file_fsync(file, start, end, datasync);
 	if (ret == -EIO || test_and_clear_bit(AS_EIO, &mapping->flags)) {
 		/* We don't really know where the IO error happened... */
-- 
2.1.0

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