On Wed, May 29, 2019 at 11:09 PM Olga Kornievskaia
<olga.kornievskaia@xxxxxxxxx> wrote:
>
> On Wed, May 29, 2019 at 1:43 PM Amir Goldstein <amir73il@xxxxxxxxx> wrote:
> >
> > We want to enable cross-filesystem copy_file_range functionality
> > where possible, so push the "same superblock only" checks down to
> > the individual filesystem callouts so they can make their own
> > decisions about cross-superblock copy offload and fallack to
> > generic_copy_file_range() for cross-superblock copy.
> >
> > [Amir] We do not call ->remap_file_range() in case the inodes are not
> > on the same sb and do not call ->copy_file_range() in case the inodes
> > are not on the same filesystem type.
> >
> > This changes behavior of the copy_file_range(2) syscall, which will
> > now allow cross filesystem in-kernel copy. CIFS already supports
> > cross-superblock copy, between two shares to the same server. This
> > functionality will now be available via the copy_file_range(2) syscall.
> >
> > Cc: Steve French <stfrench@xxxxxxxxxxxxx>
> > Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> > Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> > Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> > ---
> > fs/ceph/file.c | 4 +++-
> > fs/cifs/cifsfs.c | 2 +-
> > fs/fuse/file.c | 5 ++++-
> > fs/nfs/nfs4file.c | 5 ++++-
> > fs/read_write.c | 20 ++++++++++++++------
> > 5 files changed, 26 insertions(+), 10 deletions(-)
> >
> > diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> > index 8a70708e1aca..e9614d686301 100644
> > --- a/fs/ceph/file.c
> > +++ b/fs/ceph/file.c
> > @@ -1909,6 +1909,8 @@ static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
> >
> > if (src_inode == dst_inode)
> > return -EINVAL;
> > + if (src_inode->i_sb != dst_inode->i_sb)
> > + return -EXDEV;
> > if (ceph_snap(dst_inode) != CEPH_NOSNAP)
> > return -EROFS;
> >
> > @@ -2126,7 +2128,7 @@ static ssize_t ceph_copy_file_range(struct file *src_file, loff_t src_off,
> > ret = __ceph_copy_file_range(src_file, src_off, dst_file, dst_off,
> > len, flags);
> >
> > - if (ret == -EOPNOTSUPP)
> > + if (ret == -EOPNOTSUPP || ret == -EXDEV)
> > ret = generic_copy_file_range(src_file, src_off, dst_file,
> > dst_off, len, flags);
> > return ret;
> > diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> > index ab6c5c24146d..83956452c108 100644
> > --- a/fs/cifs/cifsfs.c
> > +++ b/fs/cifs/cifsfs.c
> > @@ -1154,7 +1154,7 @@ static ssize_t cifs_copy_file_range(struct file *src_file, loff_t off,
> > len, flags);
> > free_xid(xid);
> >
> > - if (rc == -EOPNOTSUPP)
> > + if (rc == -EOPNOTSUPP || rc == -EXDEV)
> > rc = generic_copy_file_range(src_file, off, dst_file,
> > destoff, len, flags);
> > return rc;
> > diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> > index 7f33d68f66d9..eab00cd089e8 100644
> > --- a/fs/fuse/file.c
> > +++ b/fs/fuse/file.c
> > @@ -3126,6 +3126,9 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
> > if (fc->no_copy_file_range)
> > return -EOPNOTSUPP;
> >
> > + if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
> > + return -EXDEV;
> > +
> > inode_lock(inode_out);
> >
> > err = file_modified(file_out);
> > @@ -3187,7 +3190,7 @@ static ssize_t fuse_copy_file_range(struct file *src_file, loff_t src_off,
> > ret = __fuse_copy_file_range(src_file, src_off, dst_file, dst_off,
> > len, flags);
> >
> > - if (ret == -EOPNOTSUPP)
> > + if (ret == -EOPNOTSUPP || ret == -EXDEV)
> > ret = generic_copy_file_range(src_file, src_off, dst_file,
> > dst_off, len, flags);
> > return ret;
> > diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
> > index 4842f3ab3161..f4157eb1f69d 100644
> > --- a/fs/nfs/nfs4file.c
> > +++ b/fs/nfs/nfs4file.c
> > @@ -133,6 +133,9 @@ static ssize_t __nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
> > struct file *file_out, loff_t pos_out,
> > size_t count, unsigned int flags)
> > {
> > + /* Only offload copy if superblock is the same */
> > + if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
> > + return -EXDEV;
> > if (!nfs_server_capable(file_inode(file_out), NFS_CAP_COPY))
> > return -EOPNOTSUPP;
> > if (file_inode(file_in) == file_inode(file_out))
> > @@ -148,7 +151,7 @@ static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
> >
> > ret = __nfs4_copy_file_range(file_in, pos_in, file_out, pos_out, count,
> > flags);
> > - if (ret == -EOPNOTSUPP)
> > + if (ret == -EOPNOTSUPP || ret == -EXDEV)
> > ret = generic_copy_file_range(file_in, pos_in, file_out,
> > pos_out, count, flags);
> > return ret;
> > diff --git a/fs/read_write.c b/fs/read_write.c
> > index 706ea5f276a7..d8930bb735cb 100644
> > --- a/fs/read_write.c
> > +++ b/fs/read_write.c
> > @@ -1618,7 +1618,18 @@ static ssize_t do_copy_file_range(struct file *file_in, loff_t pos_in,
> > struct file *file_out, loff_t pos_out,
> > size_t len, unsigned int flags)
> > {
> > - if (file_out->f_op->copy_file_range)
> > + /*
> > + * Although we now allow filesystems to handle cross sb copy, passing
> > + * an inode of the wrong filesystem type to filesystem operation can
> > + * often result in an attempt to dereference the wrong concrete inode
> > + * struct, so avoid doing that until we really have a good reason.
> > + * The incentive for passing inode from different sb to filesystem is
> > + * NFS cross server copy and for that use case, enforcing same
> > + * filesystem type is acceptable.
> > + */
> > + if (file_out->f_op->copy_file_range &&
> > + file_inode(file_in)->i_sb->s_type ==
> > + file_inode(file_out)->i_sb->s_type)
>
> While I'm not sure how much I care (vs wanting at least this much of
> cross device copy available) but in NFS there are several NFS
> file_system_type defined which would disallow a copy between them
> (like nfs4_remote_fs_type, nfs4_remote_referral_fs_type, and good old
> nfs4_fs_type).
>
> One idea would be to push the check into the filesystems themselves.
>
That will require more delicate patches to filesystems.
Are you saying there is a *good* reason to do that now?
Is nfs copy offload expected to be between different types of nfs
file_system_type?
Thanks,
Amir.
