[PATCH v13 04/59] libceph: add sparse read support to OSD client

Jeff Layton
2022-04-05T20:15:38Z

Have get_reply check for the presence of sparse read ops in the
request and set the sparse_read boolean in the msg. That will queue the
messenger layer to use the sparse read codepath instead of the normal
data receive.

Add a new sparse_read operation for the OSD client, driven by its own
state machine. The messenger will 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.

The state machine will stop at the end of the last extent, and will
attach the extent map buffer to the ceph_osd_req_op so that the caller
can use it.

Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
include/linux/ceph/osd_client.h | 32 ++++
net/ceph/osd_client.c | 256 +++++++++++++++++++++++++++++++-
2 files changed, 284 insertions(+), 4 deletions(-)

diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
index 1dd02240d00d..4088601beacc 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;
} __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 c150683f2a2f..acf6a19b6677 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;
@@ -2474,8 +2491,10 @@ 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);

/*
@@ -5420,6 +5439,24 @@ 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
@@ -5436,6 +5473,7 @@ 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)) {
@@ -5468,7 +5506,8 @@ 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);
@@ -5478,6 +5517,8 @@ 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:
@@ -5710,9 +5751,216 @@ 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));
+ 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 {
+ u64 end;
+
+ 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_cnt = 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_cnt, cursor->resid);
+ /* Advance to end of data for this operation */
+ end = ceph_sparse_ext_map_end(op);
+ if (end < sr->sr_req_len)
+ advance_cursor(cursor, sr->sr_req_len - end, 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_cnt;
+ op->extent.sparse_ext_cnt = 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 __le64)ext->off);
+ ext->len = le64_to_cpu((__force __le64)ext->len);
+ }
+}
+#else
+static inline void convert_extent_map(struct ceph_sparse_read *sr)
+{
+}
+#endif
+
+#define MAX_EXTENTS 4096
+
+static int osd_sparse_read(struct ceph_connection *con,
+ struct ceph_msg_data_cursor *cursor,
+ 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 */
+ ret = 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) {
+ /*
+ * Apply a hard cap to the number of extents.
+ * If we have more, assume something is wrong.
+ */
+ if (count > MAX_EXTENTS) {
+ dout("%s: OSD returned 0x%x extents in a single reply!\n",
+ __func__, count);
+ return -EREMOTEIO;
+ }
+
+ /* 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;
+ }
+ ret = count * sizeof(*sr->sr_extent);
+ *pbuf = (char *)sr->sr_extent;
+ sr->sr_state = CEPH_SPARSE_READ_DATA_LEN;
+ break;
+ }
+ /* No extents? Read data len */
+ fallthrough;
+ case CEPH_SPARSE_READ_DATA_LEN:
+ convert_extent_map(sr);
+ ret = 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);
+
+ if (elen > INT_MAX) {
+ dout("Sparse read extent length too long (0x%llx)\n", elen);
+ return -EREMOTEIO;
+ }
+
+ /* 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 and nullify the ptr */
+ cursor->sr_resid = elen;
+ ret = elen;
+ *pbuf = NULL;
+
+ /* Bump the array index */
+ ++sr->sr_index;
+ break;
+ }
+ return ret;
+}
+
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,
--
2.35.1