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Date:   Tue, 14 Jan 2020 09:55:55 +0000
From:   Luis Henriques <lhenriques@suse.com>
To:     Gregory Farnum <gfarnum@redhat.com>
Cc:     Jeff Layton <jlayton@kernel.org>, Sage Weil <sage@redhat.com>,
        Ilya Dryomov <idryomov@gmail.com>,
        "Yan, Zheng" <zyan@redhat.com>,
        ceph-devel <ceph-devel@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH v4] ceph: use 'copy-from2' operation in
 copy_file_range
Message-ID: <20200114095555.GA17907@brahms.Home>
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On Mon, Jan 13, 2020 at 09:10:01AM -0800, Gregory Farnum wrote:
> On Thu, Jan 9, 2020 at 5:06 AM Jeff Layton <jlayton@kernel.org> wrote:
> >
> > On Wed, 2020-01-08 at 10:03 +0000, Luis Henriques wrote:
> > > Instead of using the 'copy-from' operation, switch copy_file_range to the
> > > new 'copy-from2' operation, which allows to send the truncate_seq and
> > > truncate_size parameters.
> > >
> > > If an OSD does not support the 'copy-from2' operation it will return
> > > -EOPNOTSUPP.  In that case, the kernel client will stop trying to do
> > > remote object copies for this fs client and will always use the generic
> > > VFS copy_file_range.
> > >
> > > Signed-off-by: Luis Henriques <lhenriques@suse.com>
> > > ---
> > > Hi Jeff,
> > >
> > > This is a follow-up to the discussion in [1].  Since PR [2] has been
> > > merged, it's now time to change the kernel client to use the new
> > > 'copy-from2'.  And that's what this patch does.
> > >
> > > [1] https://lore.kernel.org/lkml/20191118120935.7013-1-lhenriques@suse.com/
> > > [2] https://github.com/ceph/ceph/pull/31728
> > >
> > >  fs/ceph/file.c                  | 13 ++++++++++++-
> > >  fs/ceph/super.c                 |  1 +
> > >  fs/ceph/super.h                 |  3 +++
> > >  include/linux/ceph/osd_client.h |  1 +
> > >  include/linux/ceph/rados.h      |  2 ++
> > >  net/ceph/osd_client.c           | 18 ++++++++++++------
> > >  6 files changed, 31 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> > > index 11929d2bb594..1e6cdf2dfe90 100644
> > > --- a/fs/ceph/file.c
> > > +++ b/fs/ceph/file.c
> > > @@ -1974,6 +1974,10 @@ static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
> > >       if (ceph_test_mount_opt(src_fsc, NOCOPYFROM))
> > >               return -EOPNOTSUPP;
> > >
> > > +     /* Do the OSDs support the 'copy-from2' operation? */
> > > +     if (!src_fsc->have_copy_from2)
> > > +             return -EOPNOTSUPP;
> > > +
> > >       /*
> > >        * Striped file layouts require that we copy partial objects, but the
> > >        * OSD copy-from operation only supports full-object copies.  Limit
> > > @@ -2101,8 +2105,15 @@ static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
> > >                       CEPH_OSD_OP_FLAG_FADVISE_NOCACHE,
> > >                       &dst_oid, &dst_oloc,
> > >                       CEPH_OSD_OP_FLAG_FADVISE_SEQUENTIAL |
> > > -                     CEPH_OSD_OP_FLAG_FADVISE_DONTNEED, 0);
> > > +                     CEPH_OSD_OP_FLAG_FADVISE_DONTNEED,
> > > +                     dst_ci->i_truncate_seq, dst_ci->i_truncate_size,
> > > +                     CEPH_OSD_COPY_FROM_FLAG_TRUNCATE_SEQ);
> > >               if (err) {
> > > +                     if (err == -EOPNOTSUPP) {
> > > +                             src_fsc->have_copy_from2 = false;
> > > +                             pr_notice("OSDs don't support 'copy-from2'; "
> > > +                                       "disabling copy_file_range\n");
> > > +                     }
> > >                       dout("ceph_osdc_copy_from returned %d\n", err);
> > >                       if (!ret)
> > >                               ret = err;
> >
> > The patch itself looks fine to me. I'll not merge yet, since you sent it
> > as an RFC, but I don't have any objection to it at first glance. The
> > only other comment I'd make is that you should probably split this into
> > two patches -- one for the libceph changes and one for cephfs.
> >
> > On a related note, I wonder if we'd get better performance out of large
> > copy_file_range calls here if you were to move the wait for all of these
> > osd requests after issuing them all in parallel?
> >
> > Currently we're doing:
> >
> > copy_from
> > wait
> > copy_from
> > wait
> >
> > ...but figure that the second copy_from might very well be between osds
> > that are not involved in the first copy. There's no reason to do them
> > sequentially. It'd be better to issue all of the OSD requests first, and
> > then wait on all of the replies in turn:
> 
> If this is added (good idea in general) it should be throttled — we
> don’t want users accidentally trying to copy a 1TB file and setting
> off 250000 simultaneous copy_from2 requests!

Good point, thanks for the input Greg.  I'll have this in consideration.
That'll probably require another kernel module knob for setting this
throttling value.

Cheers,
--
Luís

> -Greg
> 
> >
> > copy_from
> > copy_from
> > copy_from
> > ...
> > wait
> > wait
> > wait
> >
> > > diff --git a/fs/ceph/super.c b/fs/ceph/super.c
> > > index 29a795f975df..b62c487a53af 100644
> > > --- a/fs/ceph/super.c
> > > +++ b/fs/ceph/super.c
> > > @@ -637,6 +637,7 @@ static struct ceph_fs_client *create_fs_client(struct ceph_mount_options *fsopt,
> > >       fsc->sb = NULL;
> > >       fsc->mount_state = CEPH_MOUNT_MOUNTING;
> > >       fsc->filp_gen = 1;
> > > +     fsc->have_copy_from2 = true;
> > >
> > >       atomic_long_set(&fsc->writeback_count, 0);
> > >
> > > diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> > > index 3bf1a01cd536..b2f86bed5c2c 100644
> > > --- a/fs/ceph/super.h
> > > +++ b/fs/ceph/super.h
> > > @@ -106,6 +106,9 @@ struct ceph_fs_client {
> > >       unsigned long last_auto_reconnect;
> > >       bool blacklisted;
> > >
> > > +     /* Do the OSDs support the 'copy-from2' Op? */
> > > +     bool have_copy_from2;
> > > +
> > >       u32 filp_gen;
> > >       loff_t max_file_size;
> > >
> > > diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
> > > index eaffbdddf89a..5a62dbd3f4c2 100644
> > > --- a/include/linux/ceph/osd_client.h
> > > +++ b/include/linux/ceph/osd_client.h
> > > @@ -534,6 +534,7 @@ int ceph_osdc_copy_from(struct ceph_osd_client *osdc,
> > >                       struct ceph_object_id *dst_oid,
> > >                       struct ceph_object_locator *dst_oloc,
> > >                       u32 dst_fadvise_flags,
> > > +                     u32 truncate_seq, u64 truncate_size,
> > >                       u8 copy_from_flags);
> > >
> > >  /* watch/notify */
> > > diff --git a/include/linux/ceph/rados.h b/include/linux/ceph/rados.h
> > > index 3eb0e55665b4..59bdfd470100 100644
> > > --- a/include/linux/ceph/rados.h
> > > +++ b/include/linux/ceph/rados.h
> > > @@ -256,6 +256,7 @@ extern const char *ceph_osd_state_name(int s);
> > >                                                                           \
> > >       /* tiering */                                                       \
> > >       f(COPY_FROM,    __CEPH_OSD_OP(WR, DATA, 26),    "copy-from")        \
> > > +     f(COPY_FROM2,   __CEPH_OSD_OP(WR, DATA, 45),    "copy-from2")       \
> > >       f(COPY_GET_CLASSIC, __CEPH_OSD_OP(RD, DATA, 27), "copy-get-classic") \
> > >       f(UNDIRTY,      __CEPH_OSD_OP(WR, DATA, 28),    "undirty")          \
> > >       f(ISDIRTY,      __CEPH_OSD_OP(RD, DATA, 29),    "isdirty")          \
> > > @@ -446,6 +447,7 @@ enum {
> > >       CEPH_OSD_COPY_FROM_FLAG_MAP_SNAP_CLONE = 8, /* map snap direct to
> > >                                                    * cloneid */
> > >       CEPH_OSD_COPY_FROM_FLAG_RWORDERED = 16,     /* order with write */
> > > +     CEPH_OSD_COPY_FROM_FLAG_TRUNCATE_SEQ = 32,  /* send truncate_{seq,size} */
> > >  };
> > >
> > >  enum {
> > > diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> > > index ba45b074a362..b68b376d8c2f 100644
> > > --- a/net/ceph/osd_client.c
> > > +++ b/net/ceph/osd_client.c
> > > @@ -402,7 +402,7 @@ static void osd_req_op_data_release(struct ceph_osd_request *osd_req,
> > >       case CEPH_OSD_OP_LIST_WATCHERS:
> > >               ceph_osd_data_release(&op->list_watchers.response_data);
> > >               break;
> > > -     case CEPH_OSD_OP_COPY_FROM:
> > > +     case CEPH_OSD_OP_COPY_FROM2:
> > >               ceph_osd_data_release(&op->copy_from.osd_data);
> > >               break;
> > >       default:
> > > @@ -697,7 +697,7 @@ static void get_num_data_items(struct ceph_osd_request *req,
> > >               case CEPH_OSD_OP_SETXATTR:
> > >               case CEPH_OSD_OP_CMPXATTR:
> > >               case CEPH_OSD_OP_NOTIFY_ACK:
> > > -             case CEPH_OSD_OP_COPY_FROM:
> > > +             case CEPH_OSD_OP_COPY_FROM2:
> > >                       *num_request_data_items += 1;
> > >                       break;
> > >
> > > @@ -1029,7 +1029,7 @@ static u32 osd_req_encode_op(struct ceph_osd_op *dst,
> > >       case CEPH_OSD_OP_CREATE:
> > >       case CEPH_OSD_OP_DELETE:
> > >               break;
> > > -     case CEPH_OSD_OP_COPY_FROM:
> > > +     case CEPH_OSD_OP_COPY_FROM2:
> > >               dst->copy_from.snapid = cpu_to_le64(src->copy_from.snapid);
> > >               dst->copy_from.src_version =
> > >                       cpu_to_le64(src->copy_from.src_version);
> > > @@ -1966,7 +1966,7 @@ static void setup_request_data(struct ceph_osd_request *req)
> > >                       ceph_osdc_msg_data_add(request_msg,
> > >                                              &op->notify_ack.request_data);
> > >                       break;
> > > -             case CEPH_OSD_OP_COPY_FROM:
> > > +             case CEPH_OSD_OP_COPY_FROM2:
> > >                       ceph_osdc_msg_data_add(request_msg,
> > >                                              &op->copy_from.osd_data);
> > >                       break;
> > > @@ -5315,6 +5315,7 @@ static int osd_req_op_copy_from_init(struct ceph_osd_request *req,
> > >                                    struct ceph_object_locator *src_oloc,
> > >                                    u32 src_fadvise_flags,
> > >                                    u32 dst_fadvise_flags,
> > > +                                  u32 truncate_seq, u64 truncate_size,
> > >                                    u8 copy_from_flags)
> > >  {
> > >       struct ceph_osd_req_op *op;
> > > @@ -5325,7 +5326,8 @@ static int osd_req_op_copy_from_init(struct ceph_osd_request *req,
> > >       if (IS_ERR(pages))
> > >               return PTR_ERR(pages);
> > >
> > > -     op = _osd_req_op_init(req, 0, CEPH_OSD_OP_COPY_FROM, dst_fadvise_flags);
> > > +     op = _osd_req_op_init(req, 0, CEPH_OSD_OP_COPY_FROM2,
> > > +                           dst_fadvise_flags);
> > >       op->copy_from.snapid = src_snapid;
> > >       op->copy_from.src_version = src_version;
> > >       op->copy_from.flags = copy_from_flags;
> > > @@ -5335,6 +5337,8 @@ static int osd_req_op_copy_from_init(struct ceph_osd_request *req,
> > >       end = p + PAGE_SIZE;
> > >       ceph_encode_string(&p, end, src_oid->name, src_oid->name_len);
> > >       encode_oloc(&p, end, src_oloc);
> > > +     ceph_encode_32(&p, truncate_seq);
> > > +     ceph_encode_64(&p, truncate_size);
> > >       op->indata_len = PAGE_SIZE - (end - p);
> > >
> > >       ceph_osd_data_pages_init(&op->copy_from.osd_data, pages,
> > > @@ -5350,6 +5354,7 @@ int ceph_osdc_copy_from(struct ceph_osd_client *osdc,
> > >                       struct ceph_object_id *dst_oid,
> > >                       struct ceph_object_locator *dst_oloc,
> > >                       u32 dst_fadvise_flags,
> > > +                     u32 truncate_seq, u64 truncate_size,
> > >                       u8 copy_from_flags)
> > >  {
> > >       struct ceph_osd_request *req;
> > > @@ -5366,7 +5371,8 @@ int ceph_osdc_copy_from(struct ceph_osd_client *osdc,
> > >
> > >       ret = osd_req_op_copy_from_init(req, src_snapid, src_version, src_oid,
> > >                                       src_oloc, src_fadvise_flags,
> > > -                                     dst_fadvise_flags, copy_from_flags);
> > > +                                     dst_fadvise_flags, truncate_seq,
> > > +                                     truncate_size, copy_from_flags);
> > >       if (ret)
> > >               goto out;
> > >
> > --
> > Jeff Layton <jlayton@kernel.org>
> >
>