xfs: add DAX file operations support
Add the initial support for DAX file operations to XFS. This
includes the necessary block allocation and mmap page fault hooks
for DAX to function.
Note that there are changes to the splice interfaces to ensure that
for DAX splice avoids direct page cache manipulations and instead
takes the DAX IO paths for read/write operations.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 0b4e79f..a629dce 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -284,7 +284,7 @@
if (file->f_mode & FMODE_NOCMTIME)
ioflags |= XFS_IO_INVIS;
- if (unlikely(ioflags & XFS_IO_ISDIRECT)) {
+ if ((ioflags & XFS_IO_ISDIRECT) && !IS_DAX(inode)) {
xfs_buftarg_t *target =
XFS_IS_REALTIME_INODE(ip) ?
mp->m_rtdev_targp : mp->m_ddev_targp;
@@ -378,7 +378,11 @@
trace_xfs_file_splice_read(ip, count, *ppos, ioflags);
- ret = generic_file_splice_read(infilp, ppos, pipe, count, flags);
+ /* for dax, we need to avoid the page cache */
+ if (IS_DAX(VFS_I(ip)))
+ ret = default_file_splice_read(infilp, ppos, pipe, count, flags);
+ else
+ ret = generic_file_splice_read(infilp, ppos, pipe, count, flags);
if (ret > 0)
XFS_STATS_ADD(xs_read_bytes, ret);
@@ -672,7 +676,7 @@
mp->m_rtdev_targp : mp->m_ddev_targp;
/* DIO must be aligned to device logical sector size */
- if ((pos | count) & target->bt_logical_sectormask)
+ if (!IS_DAX(inode) && ((pos | count) & target->bt_logical_sectormask))
return -EINVAL;
/* "unaligned" here means not aligned to a filesystem block */
@@ -758,8 +762,11 @@
out:
xfs_rw_iunlock(ip, iolock);
- /* No fallback to buffered IO on errors for XFS. */
- ASSERT(ret < 0 || ret == count);
+ /*
+ * No fallback to buffered IO on errors for XFS. DAX can result in
+ * partial writes, but direct IO will either complete fully or fail.
+ */
+ ASSERT(ret < 0 || ret == count || IS_DAX(VFS_I(ip)));
return ret;
}
@@ -842,7 +849,7 @@
if (XFS_FORCED_SHUTDOWN(ip->i_mount))
return -EIO;
- if (unlikely(iocb->ki_flags & IOCB_DIRECT))
+ if ((iocb->ki_flags & IOCB_DIRECT) || IS_DAX(inode))
ret = xfs_file_dio_aio_write(iocb, from);
else
ret = xfs_file_buffered_aio_write(iocb, from);
@@ -1063,17 +1070,6 @@
return xfs_readdir(ip, ctx, bufsize);
}
-STATIC int
-xfs_file_mmap(
- struct file *filp,
- struct vm_area_struct *vma)
-{
- vma->vm_ops = &xfs_file_vm_ops;
-
- file_accessed(filp);
- return 0;
-}
-
/*
* This type is designed to indicate the type of offset we would like
* to search from page cache for xfs_seek_hole_data().
@@ -1454,26 +1450,11 @@
* ordering of:
*
* mmap_sem (MM)
- * i_mmap_lock (XFS - truncate serialisation)
- * page_lock (MM)
- * i_lock (XFS - extent map serialisation)
+ * sb_start_pagefault(vfs, freeze)
+ * i_mmap_lock (XFS - truncate serialisation)
+ * page_lock (MM)
+ * i_lock (XFS - extent map serialisation)
*/
-STATIC int
-xfs_filemap_fault(
- struct vm_area_struct *vma,
- struct vm_fault *vmf)
-{
- struct xfs_inode *ip = XFS_I(vma->vm_file->f_mapping->host);
- int error;
-
- trace_xfs_filemap_fault(ip);
-
- xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
- error = filemap_fault(vma, vmf);
- xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
-
- return error;
-}
/*
* mmap()d file has taken write protection fault and is being made writable. We
@@ -1486,21 +1467,66 @@
struct vm_area_struct *vma,
struct vm_fault *vmf)
{
- struct xfs_inode *ip = XFS_I(vma->vm_file->f_mapping->host);
+ struct inode *inode = file_inode(vma->vm_file);
int ret;
- trace_xfs_filemap_page_mkwrite(ip);
+ trace_xfs_filemap_page_mkwrite(XFS_I(inode));
- sb_start_pagefault(VFS_I(ip)->i_sb);
+ sb_start_pagefault(inode->i_sb);
file_update_time(vma->vm_file);
+ xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
+
+ if (IS_DAX(inode)) {
+ ret = __dax_mkwrite(vma, vmf, xfs_get_blocks_direct,
+ xfs_end_io_dax_write);
+ } else {
+ ret = __block_page_mkwrite(vma, vmf, xfs_get_blocks);
+ ret = block_page_mkwrite_return(ret);
+ }
+
+ xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
+ sb_end_pagefault(inode->i_sb);
+
+ return ret;
+}
+
+STATIC int
+xfs_filemap_fault(
+ struct vm_area_struct *vma,
+ struct vm_fault *vmf)
+{
+ struct xfs_inode *ip = XFS_I(file_inode(vma->vm_file));
+ int ret;
+
+ trace_xfs_filemap_fault(ip);
+
+ /* DAX can shortcut the normal fault path on write faults! */
+ if ((vmf->flags & FAULT_FLAG_WRITE) && IS_DAX(VFS_I(ip)))
+ return xfs_filemap_page_mkwrite(vma, vmf);
+
xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
-
- ret = __block_page_mkwrite(vma, vmf, xfs_get_blocks);
-
+ ret = filemap_fault(vma, vmf);
xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
- sb_end_pagefault(VFS_I(ip)->i_sb);
- return block_page_mkwrite_return(ret);
+ return ret;
+}
+
+static const struct vm_operations_struct xfs_file_vm_ops = {
+ .fault = xfs_filemap_fault,
+ .map_pages = filemap_map_pages,
+ .page_mkwrite = xfs_filemap_page_mkwrite,
+};
+
+STATIC int
+xfs_file_mmap(
+ struct file *filp,
+ struct vm_area_struct *vma)
+{
+ file_accessed(filp);
+ vma->vm_ops = &xfs_file_vm_ops;
+ if (IS_DAX(file_inode(filp)))
+ vma->vm_flags |= VM_MIXEDMAP;
+ return 0;
}
const struct file_operations xfs_file_operations = {
@@ -1531,9 +1557,3 @@
#endif
.fsync = xfs_dir_fsync,
};
-
-static const struct vm_operations_struct xfs_file_vm_ops = {
- .fault = xfs_filemap_fault,
- .map_pages = filemap_map_pages,
- .page_mkwrite = xfs_filemap_page_mkwrite,
-};