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

Ross Zwisler
2015-11-14T00:07:23Z

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/xfs/xfs_file.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 39743ef..2b490a1 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -209,7 +209,8 @@ xfs_file_fsync(
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 xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
int error = 0;
@@ -218,7 +219,13 @@ xfs_file_fsync(

trace_xfs_file_fsync(ip);

- error = filemap_write_and_wait_range(inode->i_mapping, start, end);
+ if (dax_mapping(mapping)) {
+ xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
+ dax_fsync(mapping, start, end);
+ xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
+ }
+
+ error = filemap_write_and_wait_range(mapping, start, end);
if (error)
return error;

@@ -1603,9 +1610,8 @@ xfs_filemap_pmd_fault(
/*
* pfn_mkwrite was originally inteneded to ensure we capture time stamp
* updates on write faults. In reality, it's need to serialise against
- * truncate similar to page_mkwrite. Hence we open-code dax_pfn_mkwrite()
- * here and cycle the XFS_MMAPLOCK_SHARED to ensure we serialise the fault
- * barrier in place.
+ * truncate similar to page_mkwrite. Hence we cycle the XFS_MMAPLOCK_SHARED
+ * to ensure we serialise the fault barrier in place.
*/
static int
xfs_filemap_pfn_mkwrite(
@@ -1628,6 +1634,8 @@ xfs_filemap_pfn_mkwrite(
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (vmf->pgoff >= size)
ret = VM_FAULT_SIGBUS;
+ else if (IS_DAX(inode))
+ ret = dax_pfn_mkwrite(vma, vmf);
xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
sb_end_pagefault(inode->i_sb);
return ret;
--
2.1.0