On Wed, Oct 24, 2018 at 10:58 PM Olga Kornievskaia <olga.kornievskaia@xxxxxxxxx> wrote: > > From: Olga Kornievskaia <kolga@xxxxxxxxxx> > > This patch removes the check for source and destination files to > come from the same superblock. This feature was of interest to > NFS as well as CIFS communities. > > Specifically, this feature is needed to allow for NFSv4.2 copy offload > to be done between different NFSv4.2 servers. SMBv3 copy offload between > different servers would be able to use this as well. > > Removal of the check implies that passed in source and destination > files can come from different superblocks of the same file system > type or different. It is upto each individual copy_file_range() > file system implementation to decide what type of copy it is > capable of doing and return -EXDEV in cases support is lacking. > > There are 3 known implementator of copy_file_range() f_op: NFS, > CIFS, OverlayFS. NFS and CIFS are interested to support cross-device > copy offload but do not support cross file system types copy offload. > Following patches will add appropriate checks in each of the drivers. > That should be the other way around - first add limitation inside filesystems then relax vfs check. otherwise you leave a bug in the middle of bisect. > If the copy_file_range() errors with EXDEV, the code would fallback > on doing do_splice_direct() copying which in itself is beneficial. > > Adding wording to the vfs.txt and porting documentation about the > new support for cross-device copy offload. > > Signed-off-by: Olga Kornievskaia <kolga@xxxxxxxxxx> > --- > Documentation/filesystems/porting | 7 +++++++ > Documentation/filesystems/vfs.txt | 6 +++++- > fs/read_write.c | 9 +++------ > 3 files changed, 15 insertions(+), 7 deletions(-) > > diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting > index 7b7b845..ebb4954 100644 > --- a/Documentation/filesystems/porting > +++ b/Documentation/filesystems/porting > @@ -622,3 +622,10 @@ in your dentry operations instead. > alloc_file_clone(file, flags, ops) does not affect any caller's references. > On success you get a new struct file sharing the mount/dentry with the > original, on failure - ERR_PTR(). > +-- > +[mandatory] > + ->copy_file_range() may now be passed files which belong to two > + different superblocks of the same file system type or which belong > + to two different filesystems types all together. As before, the > + destination's copy_file_range() is the function which is called. > + If it cannot copy ranges from the source, it should return -EXDEV. > diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt > index a6c6a8a..34c0e8c 100644 > --- a/Documentation/filesystems/vfs.txt > +++ b/Documentation/filesystems/vfs.txt > @@ -1,5 +1,6 @@ > > Overview of the Linux Virtual File System > +- [fs] nfs: Don't let readdirplus revalidate an inode that was marked as stale (Benjamin Coddington) [1429514 1416532] > ??? Thanks, Amir.
