Re: [RFC PATCH 3/3] fuse: add per-file DAX flag
On 7/16/21 9:32 AM, Vivek Goyal wrote: > On Fri, Jul 16, 2021 at 09:18:34AM +0800, JeffleXu wrote: >> >> >> On 7/16/21 8:51 AM, Vivek Goyal wrote: >>> On Fri, Jul 16, 2021 at 08:40:29AM +0800, Liu Bo wrote: On Thu, Jul 15, 2021 at 05:30:31PM +0800, Jeffle Xu wrote: > Add one flag for fuse_attr.flags indicating if DAX shall be enabled for > this file. > > When the per-file DAX flag changes for an *opened* file, the state of > the file won't be updated until this file is closed and reopened later. > > Currently it is not implemented yet to change per-file DAX flag inside > guest kernel, e.g., by chattr(1). Thanks for the patch, it looks good to me. I think it's a good starting point, what I'd like to discuss here is whether we're going to let chattr to toggle the dax flag. >>> >>> I have the same question. Why not take chattr approach as taken >>> by ext4/xfs as well. >>> >>> Vivek >> >> Thanks. >> >> We can implement the chattr approach as ext4/xfs do, if we have this use >> scenario. It's an RFC patch, and I want to collect more feedback as soon >> as possible. > > I guess chattr approach will allow client (as well as server) to control > which files should be DAX. While this approach allows only server to > specify which files should use DAX. Given currently we let client > control whether to use dax or not (-o dax), it probably will make > sense to use chattr based approach? Yes, changing the per-file DAX flag from guest side, such as by chattr, may be needed for completeness. I will include this in the next version. > > I will look at the patches. Do you have a corresponding user space > implementation somewhere so that I can test it? Thanks. I have sent the corresponding patch in-reply-to your mail. -- Thanks, Jeffle ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [RFC PATCH 3/3] fuse: add per-file DAX flag
On Fri, Jul 16, 2021 at 09:18:34AM +0800, JeffleXu wrote: > > > On 7/16/21 8:51 AM, Vivek Goyal wrote: > > On Fri, Jul 16, 2021 at 08:40:29AM +0800, Liu Bo wrote: > >> On Thu, Jul 15, 2021 at 05:30:31PM +0800, Jeffle Xu wrote: > >>> Add one flag for fuse_attr.flags indicating if DAX shall be enabled for > >>> this file. > >>> > >>> When the per-file DAX flag changes for an *opened* file, the state of > >>> the file won't be updated until this file is closed and reopened later. > >>> > >>> Currently it is not implemented yet to change per-file DAX flag inside > >>> guest kernel, e.g., by chattr(1). > >> > >> Thanks for the patch, it looks good to me. > >> > >> I think it's a good starting point, what I'd like to discuss here is > >> whether we're going to let chattr to toggle the dax flag. > > > > I have the same question. Why not take chattr approach as taken > > by ext4/xfs as well. > > > > Vivek > > Thanks. > > We can implement the chattr approach as ext4/xfs do, if we have this use > scenario. It's an RFC patch, and I want to collect more feedback as soon > as possible. I guess chattr approach will allow client (as well as server) to control which files should be DAX. While this approach allows only server to specify which files should use DAX. Given currently we let client control whether to use dax or not (-o dax), it probably will make sense to use chattr based approach? I will look at the patches. Do you have a corresponding user space implementation somewhere so that I can test it? Vivek ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [RFC PATCH 3/3] fuse: add per-file DAX flag
On 7/16/21 8:51 AM, Vivek Goyal wrote: > On Fri, Jul 16, 2021 at 08:40:29AM +0800, Liu Bo wrote: >> On Thu, Jul 15, 2021 at 05:30:31PM +0800, Jeffle Xu wrote: >>> Add one flag for fuse_attr.flags indicating if DAX shall be enabled for >>> this file. >>> >>> When the per-file DAX flag changes for an *opened* file, the state of >>> the file won't be updated until this file is closed and reopened later. >>> >>> Currently it is not implemented yet to change per-file DAX flag inside >>> guest kernel, e.g., by chattr(1). >> >> Thanks for the patch, it looks good to me. >> >> I think it's a good starting point, what I'd like to discuss here is >> whether we're going to let chattr to toggle the dax flag. > > I have the same question. Why not take chattr approach as taken > by ext4/xfs as well. > > Vivek Thanks. We can implement the chattr approach as ext4/xfs do, if we have this use scenario. It's an RFC patch, and I want to collect more feedback as soon as possible. -- Thanks, Jeffle ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [RFC PATCH 3/3] fuse: add per-file DAX flag
On Fri, Jul 16, 2021 at 08:40:29AM +0800, Liu Bo wrote:
> On Thu, Jul 15, 2021 at 05:30:31PM +0800, Jeffle Xu wrote:
> > Add one flag for fuse_attr.flags indicating if DAX shall be enabled for
> > this file.
> >
> > When the per-file DAX flag changes for an *opened* file, the state of
> > the file won't be updated until this file is closed and reopened later.
> >
> > Currently it is not implemented yet to change per-file DAX flag inside
> > guest kernel, e.g., by chattr(1).
>
> Thanks for the patch, it looks good to me.
>
> I think it's a good starting point, what I'd like to discuss here is
> whether we're going to let chattr to toggle the dax flag.
I have the same question. Why not take chattr approach as taken
by ext4/xfs as well.
Vivek
>
> My usecase is like, on the fuse server side, if a file is marked as
> DAX, then it won't change any more. So this 'fuse_attr.flags' works
> for me at least.
>
> thanks,
> liubo
>
> >
> > Signed-off-by: Jeffle Xu
> > ---
> > fs/fuse/dax.c | 28
> > fs/fuse/file.c| 4 ++--
> > fs/fuse/fuse_i.h | 5 +++--
> > fs/fuse/inode.c | 4 +++-
> > include/uapi/linux/fuse.h | 5 +
> > 5 files changed, 37 insertions(+), 9 deletions(-)
> >
> > diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
> > index 4873d764cb66..ed5a430364bb 100644
> > --- a/fs/fuse/dax.c
> > +++ b/fs/fuse/dax.c
> > @@ -1341,7 +1341,7 @@ static const struct address_space_operations
> > fuse_dax_file_aops = {
> > .invalidatepage = noop_invalidatepage,
> > };
> >
> > -static bool fuse_should_enable_dax(struct inode *inode)
> > +static bool fuse_should_enable_dax(struct inode *inode, unsigned int flags)
> > {
> > struct fuse_conn *fc = get_fuse_conn(inode);
> > unsigned int mode;
> > @@ -1354,18 +1354,38 @@ static bool fuse_should_enable_dax(struct inode
> > *inode)
> > if (mode == FUSE_DAX_MOUNT_NEVER)
> > return false;
> >
> > - return true;
> > + if (mode == FUSE_DAX_MOUNT_ALWAYS)
> > + return true;
> > +
> > + WARN_ON(mode != FUSE_DAX_MOUNT_INODE);
> > + return flags & FUSE_ATTR_DAX;
> > }
> >
> > -void fuse_dax_inode_init(struct inode *inode)
> > +void fuse_dax_inode_init(struct inode *inode, unsigned int flags)
> > {
> > - if (!fuse_should_enable_dax(inode))
> > + if (!fuse_should_enable_dax(inode, flags))
> > return;
> >
> > inode->i_flags |= S_DAX;
> > inode->i_data.a_ops = _dax_file_aops;
> > }
> >
> > +void fuse_update_dax(struct inode *inode, unsigned int flags)
> > +{
> > + bool oldstate, newstate;
> > + struct fuse_conn *fc = get_fuse_conn(inode);
> > +
> > + if (!IS_ENABLED(CONFIG_FUSE_DAX) || !fc->dax ||
> > + fc->dax->mode != FUSE_DAX_MOUNT_INODE)
> > + return;
> > +
> > + oldstate = IS_DAX(inode);
> > + newstate = flags & FUSE_ATTR_DAX;
> > +
> > + if (oldstate != newstate)
> > + d_mark_dontcache(inode);
> > +}
> > +
> > bool fuse_dax_check_alignment(struct fuse_conn *fc, unsigned int
> > map_alignment)
> > {
> > if (fc->dax && (map_alignment > FUSE_DAX_SHIFT)) {
> > diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> > index 97f860cfc195..cf42af492146 100644
> > --- a/fs/fuse/file.c
> > +++ b/fs/fuse/file.c
> > @@ -3142,7 +3142,7 @@ static const struct address_space_operations
> > fuse_file_aops = {
> > .write_end = fuse_write_end,
> > };
> >
> > -void fuse_init_file_inode(struct inode *inode)
> > +void fuse_init_file_inode(struct inode *inode, struct fuse_attr *attr)
> > {
> > struct fuse_inode *fi = get_fuse_inode(inode);
> >
> > @@ -3156,5 +3156,5 @@ void fuse_init_file_inode(struct inode *inode)
> > fi->writepages = RB_ROOT;
> >
> > if (IS_ENABLED(CONFIG_FUSE_DAX))
> > - fuse_dax_inode_init(inode);
> > + fuse_dax_inode_init(inode, attr->flags);
> > }
> > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> > index f29018323845..b0ecfffd0c7d 100644
> > --- a/fs/fuse/fuse_i.h
> > +++ b/fs/fuse/fuse_i.h
> > @@ -1000,7 +1000,7 @@ int fuse_notify_poll_wakeup(struct fuse_conn *fc,
> > /**
> > * Initialize file operations on a regular file
> > */
> > -void fuse_init_file_inode(struct inode *inode);
> > +void fuse_init_file_inode(struct inode *inode, struct fuse_attr *attr);
> >
> > /**
> > * Initialize inode operations on regular files and special files
> > @@ -1252,8 +1252,9 @@ int fuse_dax_conn_alloc(struct fuse_conn *fc,
> > unsigned int mode,
> > struct dax_device *dax_dev);
> > void fuse_dax_conn_free(struct fuse_conn *fc);
> > bool fuse_dax_inode_alloc(struct super_block *sb, struct fuse_inode *fi);
> > -void fuse_dax_inode_init(struct inode *inode);
> > +void fuse_dax_inode_init(struct inode *inode, unsigned int flags);
> > void fuse_dax_inode_cleanup(struct inode *inode);
> > +void fuse_update_dax(struct inode *inode, unsigned int flags);
> > bool fuse_dax_check_alignment(struct fuse_conn *fc,
