forked from vitalif/vitastor
361 lines
14 KiB
C++
361 lines
14 KiB
C++
#include "osd.h"
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#include "xor.h"
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// read: read directly or read paired stripe(s), reconstruct, return
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// write: read paired stripe(s), modify, write
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//
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// nuance: take care to read the same version from paired stripes!
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// to do so, we remember "last readable" version until a write request completes
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// and we postpone other write requests to the same stripe until completion of previous ones
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//
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// sync: sync peers, get unstable versions from somewhere, stabilize them
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struct off_len_t
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{
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uint64_t offset, len;
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};
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struct osd_read_stripe_t
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{
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uint64_t pos;
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uint32_t start, end;
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uint32_t real_start, real_end;
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};
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struct osd_primary_read_t
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{
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pg_num_t pg_num;
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object_id oid;
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uint64_t target_ver;
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int n_subops = 0, done = 0, errors = 0;
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int degraded = 0, pg_size, pg_minsize;
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osd_read_stripe_t *stripes;
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osd_op_t *subops = NULL;
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};
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void osd_t::finish_primary_op(osd_op_t *cur_op, int retval)
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{
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// FIXME add separate magics
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cur_op->reply.hdr.magic = SECONDARY_OSD_REPLY_MAGIC;
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cur_op->reply.hdr.id = cur_op->op.hdr.id;
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cur_op->reply.hdr.opcode = cur_op->op.hdr.opcode;
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cur_op->reply.hdr.retval = retval;
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outbox_push(this->clients[cur_op->peer_fd], cur_op);
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}
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inline void split_stripes(uint64_t pg_minsize, uint32_t bs_block_size, uint64_t start, uint64_t end, osd_read_stripe_t *stripes)
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{
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for (int role = 0; role < pg_minsize; role++)
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{
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if (start < (1+role)*bs_block_size && end > role*bs_block_size)
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{
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stripes[role].real_start = stripes[role].start
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= start < role*bs_block_size ? 0 : start-role*bs_block_size;
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stripes[role].real_end = stripes[role].end
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= end > (role+1)*bs_block_size ? bs_block_size : end-role*bs_block_size;
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}
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}
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}
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void osd_t::exec_primary_read(osd_op_t *cur_op)
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{
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// PG number is calculated from the offset
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// Our EC scheme stores data in fixed chunks equal to (K*block size)
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// But we must not use K in the process of calculating the PG number
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// So we calculate the PG number using a separate setting which should be per-inode (FIXME)
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uint64_t start = cur_op->op.rw.offset;
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uint64_t end = cur_op->op.rw.offset + cur_op->op.rw.len;
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// FIXME Real pg_num should equal the below expression + 1
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pg_num_t pg_num = (cur_op->op.rw.inode + cur_op->op.rw.offset / parity_block_size) % pg_count;
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// FIXME: Postpone operations in inactive PGs
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if (pg_num > pgs.size() || !(pgs[pg_num].state & PG_ACTIVE))
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{
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finish_primary_op(cur_op, -EINVAL);
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return;
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}
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uint64_t pg_parity_size = bs_block_size * pgs[pg_num].pg_minsize;
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object_id oid = {
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.inode = cur_op->op.rw.inode,
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// oid.stripe = starting offset of the parity stripe, so it can be mapped back to the PG
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.stripe = (cur_op->op.rw.offset / parity_block_size) * parity_block_size +
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((cur_op->op.rw.offset % parity_block_size) / pg_parity_size) * pg_parity_size
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};
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if (end > (oid.stripe + pg_parity_size) ||
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(start % bs_disk_alignment) != 0 ||
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(end % bs_disk_alignment) != 0)
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{
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finish_primary_op(cur_op, -EINVAL);
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return;
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}
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osd_primary_read_t *op_data = (osd_primary_read_t*)calloc(
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sizeof(osd_primary_read_t) + sizeof(osd_read_stripe_t) * pgs[pg_num].pg_size, 1
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);
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op_data->oid = oid;
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op_data->stripes = ((osd_read_stripe_t*)(op_data+1));
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cur_op->op_data = op_data;
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split_stripes(pgs[pg_num].pg_minsize, bs_block_size, start, end, op_data->stripes);
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// Determine version
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{
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auto vo_it = pgs[pg_num].ver_override.find(oid);
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op_data->target_ver = vo_it != pgs[pg_num].ver_override.end() ? vo_it->second : UINT64_MAX;
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}
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if (pgs[pg_num].state == PG_ACTIVE)
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{
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// Fast happy-path
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submit_read_subops(pgs[pg_num].pg_minsize, pgs[pg_num].cur_set.data(), cur_op);
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cur_op->send_list.push_back(cur_op->buf, cur_op->op.rw.len);
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}
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else
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{
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// PG may be degraded or have misplaced objects
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spp::sparse_hash_map<object_id, pg_osd_set_state_t*> obj_states;
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auto st_it = pgs[pg_num].obj_states.find(oid);
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uint64_t* cur_set = (st_it != pgs[pg_num].obj_states.end()
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? st_it->second->read_target.data()
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: pgs[pg_num].cur_set.data());
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if (extend_missing_stripes(op_data->stripes, cur_set, pgs[pg_num].pg_minsize, pgs[pg_num].pg_size) < 0)
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{
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free(op_data);
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finish_primary_op(cur_op, -EIO);
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return;
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}
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// Submit reads
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submit_read_subops(pgs[pg_num].pg_size, cur_set, cur_op);
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op_data->pg_minsize = pgs[pg_num].pg_minsize;
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op_data->pg_size = pgs[pg_num].pg_size;
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op_data->degraded = 1;
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}
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}
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void osd_t::handle_primary_read_subop(osd_op_t *cur_op, int ok)
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{
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osd_primary_read_t *op_data = (osd_primary_read_t*)cur_op->op_data;
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if (!ok)
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op_data->errors++;
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else
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op_data->done++;
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if ((op_data->errors + op_data->done) >= op_data->n_subops)
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{
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delete[] op_data->subops;
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op_data->subops = NULL;
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if (op_data->errors > 0)
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{
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free(op_data);
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cur_op->op_data = NULL;
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finish_primary_op(cur_op, -EIO);
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return;
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}
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if (op_data->degraded)
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{
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// Reconstruct missing stripes
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// FIXME: Always EC(k+1) by now. Add different coding schemes
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osd_read_stripe_t *stripes = op_data->stripes;
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for (int role = 0; role < op_data->pg_minsize; role++)
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{
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if (stripes[role].end != 0 && stripes[role].real_end == 0)
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{
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int prev = -2;
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for (int other = 0; other < op_data->pg_size; other++)
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{
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if (other != role)
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{
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if (prev == -2)
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{
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prev = other;
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}
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else if (prev >= 0)
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{
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memxor(
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cur_op->buf + stripes[prev].pos + (stripes[prev].real_start - stripes[role].start),
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cur_op->buf + stripes[other].pos + (stripes[other].real_start - stripes[other].start),
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cur_op->buf + stripes[role].pos, stripes[role].end - stripes[role].start
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);
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prev = -1;
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}
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else
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{
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memxor(
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cur_op->buf + stripes[role].pos,
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cur_op->buf + stripes[other].pos + (stripes[other].real_start - stripes[role].start),
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cur_op->buf + stripes[role].pos, stripes[role].end - stripes[role].start
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);
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}
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}
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}
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}
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if (stripes[role].end != 0)
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{
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// Send buffer in parts to avoid copying
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cur_op->send_list.push_back(
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cur_op->buf + stripes[role].pos + (stripes[role].real_start - stripes[role].start), stripes[role].end
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);
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}
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}
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}
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free(op_data);
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cur_op->op_data = NULL;
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finish_primary_op(cur_op, cur_op->op.rw.len);
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}
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}
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int osd_t::extend_missing_stripes(osd_read_stripe_t *stripes, osd_num_t *osd_set, int minsize, int size)
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{
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for (int role = 0; role < minsize; role++)
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{
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if (stripes[role].end != 0 && osd_set[role] == 0)
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{
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stripes[role].real_start = stripes[role].real_end = 0;
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// Stripe is missing. Extend read to other stripes.
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// We need at least pg_minsize stripes to recover the lost part.
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int exist = 0;
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for (int j = 0; j < size; j++)
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{
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if (osd_set[j] != 0)
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{
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if (stripes[j].real_end == 0 || j >= minsize)
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{
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stripes[j].real_start = stripes[role].start;
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stripes[j].real_end = stripes[role].end;
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}
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else
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{
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stripes[j].real_start = stripes[j].start < stripes[role].start ? stripes[j].start : stripes[role].start;
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stripes[j].real_end = stripes[j].end > stripes[role].end ? stripes[j].end : stripes[role].end;
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}
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exist++;
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if (exist >= minsize)
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{
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break;
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}
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}
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}
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if (exist < minsize)
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{
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// Less than minsize stripes are available for this object
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return -1;
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}
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}
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}
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return 0;
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}
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void osd_t::submit_read_subops(int read_pg_size, const uint64_t* osd_set, osd_op_t *cur_op)
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{
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osd_primary_read_t *op_data = (osd_primary_read_t*)cur_op->op_data;
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osd_read_stripe_t *stripes = op_data->stripes;
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uint64_t buf_size = 0;
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int n_subops = 0;
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for (int role = 0; role < read_pg_size; role++)
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{
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if (stripes[role].real_end != 0)
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{
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n_subops++;
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stripes[role].pos = buf_size;
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buf_size += stripes[role].real_end - stripes[role].real_start;
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}
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else if (stripes[role].end != 0)
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{
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stripes[role].pos = buf_size;
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buf_size += stripes[role].end - stripes[role].start;
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}
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}
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osd_op_t *subops = new osd_op_t[n_subops];
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cur_op->buf = memalign(MEM_ALIGNMENT, buf_size);
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op_data->n_subops = n_subops;
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op_data->subops = subops;
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int subop = 0;
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for (int role = 0; role < read_pg_size; role++)
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{
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if (stripes[role].real_end == 0)
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{
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continue;
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}
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auto role_osd_num = osd_set[role];
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if (role_osd_num != 0)
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{
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if (role_osd_num == this->osd_num)
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{
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subops[subop].bs_op = {
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.opcode = BS_OP_READ,
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.callback = [this, cur_op](blockstore_op_t *subop)
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{
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handle_primary_read_subop(cur_op, subop->retval == subop->len);
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},
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.oid = {
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.inode = op_data->oid.inode,
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.stripe = op_data->oid.stripe | role,
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},
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.version = op_data->target_ver,
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.offset = stripes[role].real_start,
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.len = stripes[role].real_end - stripes[role].real_start,
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.buf = cur_op->buf + stripes[role].pos,
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};
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bs->enqueue_op(&subops[subop].bs_op);
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}
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else
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{
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subops[subop].op_type = OSD_OP_OUT;
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subops[subop].peer_fd = this->osd_peer_fds.at(role_osd_num);
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subops[subop].op.sec_rw = {
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.header = {
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.magic = SECONDARY_OSD_OP_MAGIC,
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.id = this->next_subop_id++,
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.opcode = OSD_OP_SECONDARY_READ,
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},
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.oid = {
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.inode = op_data->oid.inode,
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.stripe = op_data->oid.stripe | role,
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},
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.version = op_data->target_ver,
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.offset = stripes[role].real_start,
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.len = stripes[role].real_end - stripes[role].real_start,
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};
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subops[subop].buf = cur_op->buf + stripes[role].pos;
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subops[subop].callback = [this, cur_op](osd_op_t *subop)
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{
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// so it doesn't get freed. FIXME: do it better
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subop->buf = NULL;
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handle_primary_read_subop(cur_op, subop->reply.hdr.retval == subop->op.sec_rw.len);
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};
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outbox_push(clients[subops[subop].peer_fd], &subops[subop]);
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}
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subop++;
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}
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}
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}
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void osd_t::exec_primary_write(osd_op_t *cur_op)
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{
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// "RAID5" EC(k+1) parity modification variants (Px = previous, Nx = new):
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// 1,2,3 write N1 -> read P2 -> write N3 = N1^P2
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// _,2,3 write N1 -> read P2 -> write N3 = N1^P2
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// 1,_,3 write N1 -> read P1,P3 -> write N3 = N1^P3^P1
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// 1,2,_ write N1 -> read nothing
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// 1,2,3,4 write N1 -> read P2,P3 -> write N4 = N1^P2^P3
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// (or read P1,P4 -> write N4 = N1^P4^P1)
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// 1,_,3,4 write N1 -> read P1,P4 -> write N4 = N1^P4^P1
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// _,2,3,4 write N1 -> read P2,P3 -> write N4 = N1^P3^P2
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// 1,2,3,4,5 write N1 -> read P1,P5 -> write N5 = N1^P5^P1
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// 1,_,3,4,5 write N1 -> read P1,P5 -> write N5 = N1^P5^P1
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// _,2,3,4,5 write N1 -> read P2,P3,P4 -> write N5 = N1^P2^P3^P4
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//
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// I.e, when we write a part:
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// 1) If parity is missing and all other parts are available:
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// just overwrite the part
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// 2) If the modified part is missing and all other parts are available:
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// read all other parts except parity, xor them all with the new data
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// 3) If all parts are available and size=3:
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// read the paired data stripe, xor it with the new data
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// 4) Otherwise:
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// read old parity and old data of the modified part, xor them both with the new data
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// Ouсh. Scary. But faster than the generic variant.
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//
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// Generic variant for jerasure is a simple RMW process: read all -> decode -> modify -> encode -> write
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}
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void osd_t::exec_primary_sync(osd_op_t *cur_op)
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{
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}
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