Re: [RFC PATCH v4] ceph: use 'copy-from2' operation in copy_file_range

From: Luis Henriques
Date: Thu Jan 09 2020 - 09:30:56 EST

On Thu, Jan 09, 2020 at 08:06:17AM -0500, Jeff Layton 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@xxxxxxxx>
> > ---
> > 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@xxxxxxxx/
> > [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.

I was going to drop the RFC, but then at the last minute decided to leave.

> 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.

Hmm... TBH I didn't thought about that, but since the libceph patch would
be changing its API (ceph_osdc_copy_from would have 2 extra parameters), I
don't think that's a good idea. Bisection would be broken between these 2
patches.

>
> 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:
>
> copy_from
> copy_from
> copy_from
> ...
> wait
> wait
> wait

Ah! It looks like you've been looking into my TODO list :-)

In fact I was discussing copy_file_range performance with some colleagues
just before the EOY break and one of the things I had decided to
experiment was to parallelize the 'copy-from' requests. I haven't looked
yet at the details, but I expect to be looking into that soon(ish).

Thanks for your review and suggestion.

Cheers,
--
Luís

>
> > 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@xxxxxxxxxx>
>