Commit a39e596b authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Dan Williams
Browse files

xfs: support for synchronous DAX faults 



Return IOMAP_F_DIRTY from xfs_file_iomap_begin() when asked to prepare
blocks for writing and the inode is pinned, and has dirty fields other
than the timestamps.  In __xfs_filemap_fault() we then detect this case
and call dax_finish_sync_fault() to make sure all metadata is committed,
and to insert the page table entry.

Note that this will also dirty corresponding radix tree entry which is
what we want - fsync(2) will still provide data integrity guarantees for
applications not using userspace flushing. And applications using
userspace flushing can avoid calling fsync(2) and thus avoid the
performance overhead.

[JK: Added VM_SYNC flag handling]

Reviewed-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 7b565c9f

fs/xfs/xfs_file.c

+14 −1
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ 
#include <linux/falloc.h>

#include <linux/pagevec.h>

#include <linux/backing-dev.h>

#include <linux/mman.h>



static const struct vm_operations_struct xfs_file_vm_ops;
@@ -1040,7 +1041,11 @@ __xfs_filemap_fault( 


	xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);

	if (IS_DAX(inode)) {

		ret = dax_iomap_fault(vmf, pe_size, NULL, &xfs_iomap_ops);

		pfn_t pfn;



		ret = dax_iomap_fault(vmf, pe_size, &pfn, &xfs_iomap_ops);

		if (ret & VM_FAULT_NEEDDSYNC)

			ret = dax_finish_sync_fault(vmf, pe_size, pfn);

	} else {

		if (write_fault)

			ret = iomap_page_mkwrite(vmf, &xfs_iomap_ops);
@@ -1110,6 +1115,13 @@ xfs_file_mmap( 
	struct file	*filp,

	struct vm_area_struct *vma)

{

	/*

	 * We don't support synchronous mappings for non-DAX files. At least

	 * until someone comes with a sensible use case.

	 */

	if (!IS_DAX(file_inode(filp)) && (vma->vm_flags & VM_SYNC))

		return -EOPNOTSUPP;



	file_accessed(filp);

	vma->vm_ops = &xfs_file_vm_ops;

	if (IS_DAX(file_inode(filp)))
@@ -1128,6 +1140,7 @@ const struct file_operations xfs_file_operations = { 
	.compat_ioctl	= xfs_file_compat_ioctl,

#endif

	.mmap		= xfs_file_mmap,

	.mmap_supported_flags = MAP_SYNC,

	.open		= xfs_file_open,

	.release	= xfs_file_release,

	.fsync		= xfs_file_fsync,

fs/xfs/xfs_iomap.c

+5 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ 
#include "xfs_error.h"

#include "xfs_trans.h"

#include "xfs_trans_space.h"

#include "xfs_inode_item.h"

#include "xfs_iomap.h"

#include "xfs_trace.h"

#include "xfs_icache.h"
@@ -1086,6 +1087,10 @@ xfs_file_iomap_begin( 
		trace_xfs_iomap_found(ip, offset, length, 0, &imap);

	}



	if ((flags & IOMAP_WRITE) && xfs_ipincount(ip) &&

	    (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))

		iomap->flags |= IOMAP_F_DIRTY;



	xfs_bmbt_to_iomap(ip, iomap, &imap);



	if (shared)

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