On Mon, 2022-03-21 at 16:41 +0800, Xiubo Li wrote:
> On 3/18/22 9:50 PM, Jeff Layton wrote:
> > Add a new sparse_read operation for the OSD client, driven by its own
> > state machine. The messenger can repeatedly call the sparse_read
> > operation, and it will pass back the necessary info to set up to read
> > the next extent of data, while zero-filling the sparse regions.
> >
> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > ---
> > include/linux/ceph/osd_client.h | 32 +++++
> > net/ceph/osd_client.c | 238 +++++++++++++++++++++++++++++++-
> > 2 files changed, 266 insertions(+), 4 deletions(-)
> >
> > diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
> > index 00a5b53a6763..2c5f9eb7d888 100644
> > --- a/include/linux/ceph/osd_client.h
> > +++ b/include/linux/ceph/osd_client.h
> > @@ -40,6 +40,36 @@ struct ceph_sparse_extent {
> > u64 len;
> > } __attribute__((packed));
> >
> > +/* Sparse read state machine state values */
> > +enum ceph_sparse_read_state {
> > + CEPH_SPARSE_READ_HDR = 0,
> > + CEPH_SPARSE_READ_EXTENTS,
> > + CEPH_SPARSE_READ_DATA_LEN,
> > + CEPH_SPARSE_READ_DATA,
> > +};
> > +
> > +/*
> > + * A SPARSE_READ reply is a 32-bit count of extents, followed by an array of
> > + * 64-bit offset/length pairs, and then all of the actual file data
> > + * concatenated after it (sans holes).
> > + *
> > + * Unfortunately, we don't know how long the extent array is until we've
> > + * started reading the data section of the reply. The caller should send down
> > + * a destination buffer for the array, but we'll alloc one if it's too small
> > + * or if the caller doesn't.
> > + */
> > +struct ceph_sparse_read {
> > + enum ceph_sparse_read_state sr_state; /* state machine state */
> > + u64 sr_req_off; /* orig request offset */
> > + u64 sr_req_len; /* orig request length */
> > + u64 sr_pos; /* current pos in buffer */
> > + int sr_index; /* current extent index */
> > + __le32 sr_datalen; /* length of actual data */
> > + u32 sr_count; /* extent count in reply */
> > + int sr_ext_len; /* length of extent array */
> > + struct ceph_sparse_extent *sr_extent; /* extent array */
> > +};
> > +
> > /*
> > * A given osd we're communicating with.
> > *
> > @@ -48,6 +78,7 @@ struct ceph_sparse_extent {
> > */
> > struct ceph_osd {
> > refcount_t o_ref;
> > + int o_sparse_op_idx;
> > struct ceph_osd_client *o_osdc;
> > int o_osd;
> > int o_incarnation;
> > @@ -63,6 +94,7 @@ struct ceph_osd {
> > unsigned long lru_ttl;
> > struct list_head o_keepalive_item;
> > struct mutex lock;
> > + struct ceph_sparse_read o_sparse_read;
> > };
> >
> > #define CEPH_OSD_SLAB_OPS 2
> > diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> > index 9fec258e1f8d..3694696c8a31 100644
> > --- a/net/ceph/osd_client.c
> > +++ b/net/ceph/osd_client.c
> > @@ -376,6 +376,7 @@ static void osd_req_op_data_release(struct ceph_osd_request *osd_req,
> >
> > switch (op->op) {
> > case CEPH_OSD_OP_READ:
> > + case CEPH_OSD_OP_SPARSE_READ:
> > case CEPH_OSD_OP_WRITE:
> > case CEPH_OSD_OP_WRITEFULL:
> > kfree(op->extent.sparse_ext);
> > @@ -707,6 +708,7 @@ static void get_num_data_items(struct ceph_osd_request *req,
> > /* reply */
> > case CEPH_OSD_OP_STAT:
> > case CEPH_OSD_OP_READ:
> > + case CEPH_OSD_OP_SPARSE_READ:
> > case CEPH_OSD_OP_LIST_WATCHERS:
> > *num_reply_data_items += 1;
> > break;
> > @@ -776,7 +778,7 @@ void osd_req_op_extent_init(struct ceph_osd_request *osd_req,
> >
> > BUG_ON(opcode != CEPH_OSD_OP_READ && opcode != CEPH_OSD_OP_WRITE &&
> > opcode != CEPH_OSD_OP_WRITEFULL && opcode != CEPH_OSD_OP_ZERO &&
> > - opcode != CEPH_OSD_OP_TRUNCATE);
> > + opcode != CEPH_OSD_OP_TRUNCATE && opcode != CEPH_OSD_OP_SPARSE_READ);
> >
> > op->extent.offset = offset;
> > op->extent.length = length;
> > @@ -985,6 +987,7 @@ static u32 osd_req_encode_op(struct ceph_osd_op *dst,
> > case CEPH_OSD_OP_STAT:
> > break;
> > case CEPH_OSD_OP_READ:
> > + case CEPH_OSD_OP_SPARSE_READ:
> > case CEPH_OSD_OP_WRITE:
> > case CEPH_OSD_OP_WRITEFULL:
> > case CEPH_OSD_OP_ZERO:
> > @@ -1081,7 +1084,8 @@ struct ceph_osd_request *ceph_osdc_new_request(struct ceph_osd_client *osdc,
> >
> > BUG_ON(opcode != CEPH_OSD_OP_READ && opcode != CEPH_OSD_OP_WRITE &&
> > opcode != CEPH_OSD_OP_ZERO && opcode != CEPH_OSD_OP_TRUNCATE &&
> > - opcode != CEPH_OSD_OP_CREATE && opcode != CEPH_OSD_OP_DELETE);
> > + opcode != CEPH_OSD_OP_CREATE && opcode != CEPH_OSD_OP_DELETE &&
> > + opcode != CEPH_OSD_OP_SPARSE_READ);
> >
> > req = ceph_osdc_alloc_request(osdc, snapc, num_ops, use_mempool,
> > GFP_NOFS);
> > @@ -1222,6 +1226,13 @@ static void osd_init(struct ceph_osd *osd)
> > mutex_init(&osd->lock);
> > }
> >
> > +static void ceph_init_sparse_read(struct ceph_sparse_read *sr)
> > +{
> > + kfree(sr->sr_extent);
> > + memset(sr, '\0', sizeof(*sr));
> > + sr->sr_state = CEPH_SPARSE_READ_HDR;
> > +}
> > +
> > static void osd_cleanup(struct ceph_osd *osd)
> > {
> > WARN_ON(!RB_EMPTY_NODE(&osd->o_node));
> > @@ -1232,6 +1243,8 @@ static void osd_cleanup(struct ceph_osd *osd)
> > WARN_ON(!list_empty(&osd->o_osd_lru));
> > WARN_ON(!list_empty(&osd->o_keepalive_item));
> >
> > + ceph_init_sparse_read(&osd->o_sparse_read);
> > +
> > if (osd->o_auth.authorizer) {
> > WARN_ON(osd_homeless(osd));
> > ceph_auth_destroy_authorizer(osd->o_auth.authorizer);
> > @@ -1251,6 +1264,9 @@ static struct ceph_osd *create_osd(struct ceph_osd_client *osdc, int onum)
> > osd_init(osd);
> > osd->o_osdc = osdc;
> > osd->o_osd = onum;
> > + osd->o_sparse_op_idx = -1;
> > +
> > + ceph_init_sparse_read(&osd->o_sparse_read);
> >
> > ceph_con_init(&osd->o_con, osd, &osd_con_ops, &osdc->client->msgr);
> >
> > @@ -2055,6 +2071,7 @@ static void setup_request_data(struct ceph_osd_request *req)
> > &op->raw_data_in);
> > break;
> > case CEPH_OSD_OP_READ:
> > + case CEPH_OSD_OP_SPARSE_READ:
> > ceph_osdc_msg_data_add(reply_msg,
> > &op->extent.osd_data);
> > break;
> > @@ -2470,8 +2487,10 @@ static void finish_request(struct ceph_osd_request *req)
> >
> > req->r_end_latency = ktime_get();
> >
> > - if (req->r_osd)
> > + if (req->r_osd) {
> > + ceph_init_sparse_read(&req->r_osd->o_sparse_read);
> > unlink_request(req->r_osd, req);
> > + }
> > atomic_dec(&osdc->num_requests);
> >
> > /*
> > @@ -5416,6 +5435,24 @@ static void osd_dispatch(struct ceph_connection *con, struct ceph_msg *msg)
> > ceph_msg_put(msg);
> > }
> >
> > +/* How much sparse data was requested? */
> > +static u64 sparse_data_requested(struct ceph_osd_request *req)
> > +{
> > + u64 len = 0;
> > +
> > + if (req->r_flags & CEPH_OSD_FLAG_READ) {
> > + int i;
> > +
> > + for (i = 0; i < req->r_num_ops; ++i) {
> > + struct ceph_osd_req_op *op = &req->r_ops[i];
> > +
> > + if (op->op == CEPH_OSD_OP_SPARSE_READ)
> > + len += op->extent.length;
> > + }
> > + }
> > + return len;
> > +}
> > +
> > /*
> > * Lookup and return message for incoming reply. Don't try to do
> > * anything about a larger than preallocated data portion of the
> > @@ -5432,6 +5469,7 @@ static struct ceph_msg *get_reply(struct ceph_connection *con,
> > int front_len = le32_to_cpu(hdr->front_len);
> > int data_len = le32_to_cpu(hdr->data_len);
> > u64 tid = le64_to_cpu(hdr->tid);
> > + u64 srlen;
> >
> > down_read(&osdc->lock);
> > if (!osd_registered(osd)) {
> > @@ -5464,7 +5502,8 @@ static struct ceph_msg *get_reply(struct ceph_connection *con,
> > req->r_reply = m;
> > }
> >
> > - if (data_len > req->r_reply->data_length) {
> > + srlen = sparse_data_requested(req);
> > + if (!srlen && (data_len > req->r_reply->data_length)) {
> > pr_warn("%s osd%d tid %llu data %d > preallocated %zu, skipping\n",
> > __func__, osd->o_osd, req->r_tid, data_len,
> > req->r_reply->data_length);
> > @@ -5474,6 +5513,8 @@ static struct ceph_msg *get_reply(struct ceph_connection *con,
> > }
> >
> > m = ceph_msg_get(req->r_reply);
> > + m->sparse_read = (bool)srlen;
> > +
> > dout("get_reply tid %lld %p\n", tid, m);
> >
> > out_unlock_session:
> > @@ -5706,9 +5747,198 @@ static int osd_check_message_signature(struct ceph_msg *msg)
> > return ceph_auth_check_message_signature(auth, msg);
> > }
> >
> > +static void advance_cursor(struct ceph_msg_data_cursor *cursor, size_t len, bool zero)
> > +{
> > + while (len) {
> > + struct page *page;
> > + size_t poff, plen;
> > + bool last = false;
> > +
> > + page = ceph_msg_data_next(cursor, &poff, &plen, &last);
> > + if (plen > len)
> > + plen = len;
> > + if (zero)
> > + zero_user_segment(page, poff, poff + plen);
> > + len -= plen;
> > + ceph_msg_data_advance(cursor, plen);
> > + }
> > +}
> > +
> > +static int prep_next_sparse_read(struct ceph_connection *con,
> > + struct ceph_msg_data_cursor *cursor)
> > +{
> > + struct ceph_osd *o = con->private;
> > + struct ceph_sparse_read *sr = &o->o_sparse_read;
> > + struct ceph_osd_request *req;
> > + struct ceph_osd_req_op *op;
> > +
> > + spin_lock(&o->o_requests_lock);
> > + req = lookup_request(&o->o_requests, le64_to_cpu(con->in_msg->hdr.tid));
>
> For the 'o_requests_lock', shouldn't be enough only protecting the
> 'lookup_request()' ? And just unlock it here ?
>
> -- Xiubo
>
No. We're not taking a reference to the req at this point, so once we
drop the lock it could end up being freed. Note that get_reply does
something similar where it just retains the mutex after finding it
without taking a reference to it.
> > + if (!req) {
> > + spin_unlock(&o->o_requests_lock);
> > + return -EBADR;
> > + }
> > +
> > + if (o->o_sparse_op_idx < 0) {
> > + u64 srlen = sparse_data_requested(req);
> > +
> > + dout("%s: [%d] starting new sparse read req. srlen=0x%llx\n",
> > + __func__, o->o_osd, srlen);
> > + ceph_msg_data_cursor_init(cursor, con->in_msg, srlen);
> > + } else {
> > + op = &req->r_ops[o->o_sparse_op_idx];
> > +
> > + WARN_ON_ONCE(op->extent.sparse_ext);
> > +
> > + /* hand back buffer we took earlier */
> > + op->extent.sparse_ext = sr->sr_extent;
> > + sr->sr_extent = NULL;
> > + op->extent.sparse_ext_len = sr->sr_count;
> > + sr->sr_ext_len = 0;
> > + dout("%s: [%d] completed extent array len %d cursor->resid %zd\n",
> > + __func__, o->o_osd, op->extent.sparse_ext_len,
> > + cursor->resid);
> > + /*
> > + * FIXME: Need to advance to the next data item here, in the
> > + * event that there are multiple sparse read requests. Is this
> > + * the right way to do that?
> > + */
> > + if (cursor->resid)
> > + advance_cursor(cursor, cursor->resid, false);
> > + }
> > +
> > + ceph_init_sparse_read(sr);
> > +
> > + /* find next op in this request (if any) */
> > + while (++o->o_sparse_op_idx < req->r_num_ops) {
> > + op = &req->r_ops[o->o_sparse_op_idx];
> > + if (op->op == CEPH_OSD_OP_SPARSE_READ)
> > + goto found;
> > + }
> > +
> > + /* reset for next sparse read request */
> > + spin_unlock(&o->o_requests_lock);
> > + o->o_sparse_op_idx = -1;
> > + return 0;
> > +found:
> > + sr->sr_req_off = op->extent.offset;
> > + sr->sr_req_len = op->extent.length;
> > + sr->sr_pos = sr->sr_req_off;
> > + dout("%s: [%d] new sparse read op at idx %d 0x%llx~0x%llx\n", __func__,
> > + o->o_osd, o->o_sparse_op_idx, sr->sr_req_off, sr->sr_req_len);
> > +
> > + /* hand off request's sparse extent map buffer */
> > + sr->sr_ext_len = op->extent.sparse_ext_len;
> > + op->extent.sparse_ext_len = 0;
> > + sr->sr_extent = op->extent.sparse_ext;
> > + op->extent.sparse_ext = NULL;
> > +
> > + spin_unlock(&o->o_requests_lock);
> > + return 1;
> > +}
> > +
> > +#ifdef __BIG_ENDIAN
> > +static inline void convert_extent_map(struct ceph_sparse_read *sr)
> > +{
> > + int i;
> > +
> > + for (i = 0; i < sr->sr_count; i++) {
> > + struct ceph_sparse_extent *ext = sr->sr_extent[i];
> > +
> > + ext->off = le64_to_cpu((__force __le32)ext->off);
> > + ext->len = le64_to_cpu((__force __le32)ext->len);
> > + }
> > +}
> > +#else
> > +static inline void convert_extent_map(struct ceph_sparse_read *sr)
> > +{
> > +}
> > +#endif
> > +
> > +static int osd_sparse_read(struct ceph_connection *con,
> > + struct ceph_msg_data_cursor *cursor,
> > + u64 *plen, char **pbuf)
> > +{
> > + struct ceph_osd *o = con->private;
> > + struct ceph_sparse_read *sr = &o->o_sparse_read;
> > + u32 count = sr->sr_count;
> > + u64 eoff, elen;
> > + int ret;
> > +
> > + switch (sr->sr_state) {
> > + case CEPH_SPARSE_READ_HDR:
> > +next_op:
> > + ret = prep_next_sparse_read(con, cursor);
> > + if (ret <= 0)
> > + return ret;
> > +
> > + /* number of extents */
> > + *plen = sizeof(sr->sr_count);
> > + *pbuf = (char *)&sr->sr_count;
> > + sr->sr_state = CEPH_SPARSE_READ_EXTENTS;
> > + break;
> > + case CEPH_SPARSE_READ_EXTENTS:
> > + /* Convert sr_count to host-endian */
> > + count = le32_to_cpu((__force __le32)sr->sr_count);
> > + sr->sr_count = count;
> > + dout("[%d] got %u extents\n", o->o_osd, count);
> > +
> > + if (count > 0) {
> > + if (!sr->sr_extent || count > sr->sr_ext_len) {
> > + /* no extent array provided, or too short */
> > + kfree(sr->sr_extent);
> > + sr->sr_extent = kmalloc_array(count, sizeof(*sr->sr_extent),
> > + GFP_NOIO);
> > + if (!sr->sr_extent)
> > + return -ENOMEM;
> > + sr->sr_ext_len = count;
> > + }
> > + *plen = count * sizeof(*sr->sr_extent);
> > + *pbuf = (char *)sr->sr_extent;
> > + sr->sr_state = CEPH_SPARSE_READ_DATA_LEN;
> > + break;
> > + }
> > + /* No extents? Fall through to reading data len */
> > + fallthrough;
> > + case CEPH_SPARSE_READ_DATA_LEN:
> > + convert_extent_map(sr);
> > + *plen = sizeof(sr->sr_datalen);
> > + *pbuf = (char *)&sr->sr_datalen;
> > + sr->sr_state = CEPH_SPARSE_READ_DATA;
> > + break;
> > + case CEPH_SPARSE_READ_DATA:
> > + if (sr->sr_index >= count) {
> > + sr->sr_state = CEPH_SPARSE_READ_HDR;
> > + goto next_op;
> > + }
> > +
> > + eoff = sr->sr_extent[sr->sr_index].off;
> > + elen = sr->sr_extent[sr->sr_index].len;
> > +
> > + dout("[%d] ext %d off 0x%llx len 0x%llx\n",
> > + o->o_osd, sr->sr_index, eoff, elen);
> > +
> > + /* zero out anything from sr_pos to start of extent */
> > + if (sr->sr_pos < eoff)
> > + advance_cursor(cursor, eoff - sr->sr_pos, true);
> > +
> > + /* Set position to end of extent */
> > + sr->sr_pos = eoff + elen;
> > +
> > + /* send back the new length */
> > + *plen = elen;
> > +
> > + /* Bump the array index */
> > + ++sr->sr_index;
> > + break;
> > + }
> > + return 1;
> > +}
> > +
> > static const struct ceph_connection_operations osd_con_ops = {
> > .get = osd_get_con,
> > .put = osd_put_con,
> > + .sparse_read = osd_sparse_read,
> > .alloc_msg = osd_alloc_msg,
> > .dispatch = osd_dispatch,
> > .fault = osd_fault,
>
--
Jeff Layton <jlayton@xxxxxxxxxx>
