On Thu 04-04-19 05:09:10, Pankaj Gupta wrote: > > > > On Thu, Apr 04, 2019 at 09:09:12AM +1100, Dave Chinner wrote: > > > > On Wed, Apr 03, 2019 at 04:10:18PM +0530, Pankaj Gupta wrote: > > > > > Virtio pmem provides asynchronous host page cache flush > > > > > mechanism. we don't support 'MAP_SYNC' with virtio pmem > > > > > and xfs. > > > > > > > > > > Signed-off-by: Pankaj Gupta <pagupta@xxxxxxxxxx> > > > > > --- > > > > > fs/xfs/xfs_file.c | 8 ++++++++ > > > > > 1 file changed, 8 insertions(+) > > > > > > > > > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > > > > > index 1f2e2845eb76..dced2eb8c91a 100644 > > > > > --- a/fs/xfs/xfs_file.c > > > > > +++ b/fs/xfs/xfs_file.c > > > > > @@ -1203,6 +1203,14 @@ xfs_file_mmap( > > > > > if (!IS_DAX(file_inode(filp)) && (vma->vm_flags & VM_SYNC)) > > > > > return -EOPNOTSUPP; > > > > > > > > > > + /* We don't support synchronous mappings with DAX files if > > > > > + * dax_device is not synchronous. > > > > > + */ > > > > > + if (IS_DAX(file_inode(filp)) && !dax_synchronous( > > > > > + xfs_find_daxdev_for_inode(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))) > > > > > > > > All this ad hoc IS_DAX conditional logic is getting pretty nasty. > > > > > > > > xfs_file_mmap( > > > > .... > > > > { > > > > struct inode *inode = file_inode(filp); > > > > > > > > if (vma->vm_flags & VM_SYNC) { > > > > if (!IS_DAX(inode)) > > > > return -EOPNOTSUPP; > > > > if (!dax_synchronous(xfs_find_daxdev_for_inode(inode)) > > > > return -EOPNOTSUPP; > > > > } > > > > > > > > file_accessed(filp); > > > > vma->vm_ops = &xfs_file_vm_ops; > > > > if (IS_DAX(inode)) > > > > vma->vm_flags |= VM_HUGEPAGE; > > > > return 0; > > > > } > > > > > > > > > > > > Even better, factor out all the "MAP_SYNC supported" checks into a > > > > helper so that the filesystem code just doesn't have to care about > > > > the details of checking for DAX+MAP_SYNC support.... > > > > > > Seconded, since ext4 has nearly the same flag validation logic. > > > > Only issue with this I see is we need the helper function only for supported > filesystems ext4 & xfs (right now). If I create the function in "fs.h" it > will be compiled for every filesystem, even for those don't need it. > > Sample patch below, does below patch is near to what you have in mind? So I would put the helper in include/linux/dax.h and have it like: bool daxdev_mapping_supported(struct vm_area_struct *vma, struct dax_device *dax_dev) { if (!(vma->vm_flags & VM_SYNC)) return true; if (!IS_DAX(file_inode(vma->vm_file))) return false; return dax_synchronous(dax_dev); } Honza > > ================= > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index 1f2e2845eb76..614995170cac 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -1196,12 +1196,17 @@ xfs_file_mmap( > struct file *filp, > struct vm_area_struct *vma) > { > + struct dax_device *dax_dev = xfs_find_daxdev_for_inode(file_inode(filp)); > + > /* > - * We don't support synchronous mappings for non-DAX files. At least > - * until someone comes with a sensible use case. > + * We don't support synchronous mappings for non-DAX files and > + * for DAX files if underneath dax_device is not synchronous. > */ > - if (!IS_DAX(file_inode(filp)) && (vma->vm_flags & VM_SYNC)) > - return -EOPNOTSUPP; > + if (vma->vm_flags & VM_SYNC) { > + int err = is_synchronous(filp, dax_dev); > + if (err) > + return err; > + } > > file_accessed(filp); > vma->vm_ops = &xfs_file_vm_ops; > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 8b42df09b04c..add017de3dd7 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -2162,6 +2162,20 @@ static inline void file_accessed(struct file *file) > touch_atime(&file->f_path); > } > > +struct dax_device; > +extern bool dax_synchronous(struct dax_device *dax_dev); > +static inline int is_synchronous(struct file *filp, struct dax_device *dax_dev) > +{ > + struct inode *inode = file_inode(filp); > + > + if (!IS_DAX(inode)) > + return -EOPNOTSUPP; > + if (!dax_synchronous(dax_dev)) > + return -EOPNOTSUPP; > + > + return 0; > +} > + > int sync_inode(struct inode *inode, struct writeback_control *wbc); > int sync_inode_metadata(struct inode *inode, int wait); > > --------- > > Thanks, > Pankaj > > > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization