mirror of
git://sourceware.org/git/lvm2.git
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ca66d52032
io_setup() for aio may fail if a system has reached the aio request limit. In this case, fall back to using sync io. Also, lvm use of aio can be disabled entirely with config setting global/use_aio=0. The system limit for aio requests can be seen from /proc/sys/fs/aio-max-nr The current usage of aio requests can be seen from /proc/sys/fs/aio-nr The system limit for aio requests can be increased by setting fs.aio-max-nr using sysctl. Also add last-byte limit to the sync io code.
1295 lines
28 KiB
C
1295 lines
28 KiB
C
/*
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* Copyright (C) 2018 Red Hat, Inc. All rights reserved.
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*
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* This file is part of LVM2.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU Lesser General Public License v.2.1.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#define _GNU_SOURCE
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#include "lib/device/bcache.h"
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#include "base/data-struct/radix-tree.h"
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#include "lib/log/lvm-logging.h"
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#include "lib/log/log.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <libaio.h>
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#include <unistd.h>
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#include <linux/fs.h>
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#include <sys/user.h>
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#define SECTOR_SHIFT 9L
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//----------------------------------------------------------------
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static void log_sys_warn(const char *call)
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{
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log_warn("%s failed: %s", call, strerror(errno));
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}
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// Assumes the list is not empty.
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static inline struct dm_list *_list_pop(struct dm_list *head)
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{
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struct dm_list *l;
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l = head->n;
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dm_list_del(l);
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return l;
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}
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//----------------------------------------------------------------
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struct control_block {
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struct dm_list list;
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void *context;
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struct iocb cb;
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};
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struct cb_set {
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struct dm_list free;
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struct dm_list allocated;
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struct control_block *vec;
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} control_block_set;
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static struct cb_set *_cb_set_create(unsigned nr)
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{
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int i;
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struct cb_set *cbs = malloc(sizeof(*cbs));
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if (!cbs)
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return NULL;
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cbs->vec = malloc(nr * sizeof(*cbs->vec));
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if (!cbs->vec) {
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free(cbs);
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return NULL;
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}
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dm_list_init(&cbs->free);
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dm_list_init(&cbs->allocated);
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for (i = 0; i < nr; i++)
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dm_list_add(&cbs->free, &cbs->vec[i].list);
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return cbs;
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}
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static void _cb_set_destroy(struct cb_set *cbs)
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{
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// We know this is always called after a wait_all. So there should
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// never be in flight IO.
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if (!dm_list_empty(&cbs->allocated)) {
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// bail out
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log_error("async io still in flight");
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return;
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}
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free(cbs->vec);
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free(cbs);
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}
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static struct control_block *_cb_alloc(struct cb_set *cbs, void *context)
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{
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struct control_block *cb;
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if (dm_list_empty(&cbs->free))
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return NULL;
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cb = dm_list_item(_list_pop(&cbs->free), struct control_block);
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cb->context = context;
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dm_list_add(&cbs->allocated, &cb->list);
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return cb;
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}
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static void _cb_free(struct cb_set *cbs, struct control_block *cb)
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{
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dm_list_del(&cb->list);
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dm_list_add_h(&cbs->free, &cb->list);
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}
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static struct control_block *_iocb_to_cb(struct iocb *icb)
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{
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return dm_list_struct_base(icb, struct control_block, cb);
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}
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//----------------------------------------------------------------
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struct async_engine {
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struct io_engine e;
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io_context_t aio_context;
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struct cb_set *cbs;
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unsigned page_mask;
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};
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static struct async_engine *_to_async(struct io_engine *e)
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{
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return container_of(e, struct async_engine, e);
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}
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static void _async_destroy(struct io_engine *ioe)
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{
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int r;
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struct async_engine *e = _to_async(ioe);
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_cb_set_destroy(e->cbs);
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// io_destroy is really slow
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r = io_destroy(e->aio_context);
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if (r)
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log_sys_warn("io_destroy");
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free(e);
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}
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static int _last_byte_fd;
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static uint64_t _last_byte_offset;
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static int _last_byte_sector_size;
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static bool _async_issue(struct io_engine *ioe, enum dir d, int fd,
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sector_t sb, sector_t se, void *data, void *context)
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{
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int r;
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struct iocb *cb_array[1];
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struct control_block *cb;
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struct async_engine *e = _to_async(ioe);
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sector_t offset;
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sector_t nbytes;
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sector_t limit_nbytes;
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sector_t extra_nbytes = 0;
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if (((uintptr_t) data) & e->page_mask) {
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log_warn("misaligned data buffer");
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return false;
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}
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offset = sb << SECTOR_SHIFT;
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nbytes = (se - sb) << SECTOR_SHIFT;
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/*
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* If bcache block goes past where lvm wants to write, then clamp it.
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*/
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if ((d == DIR_WRITE) && _last_byte_offset && (fd == _last_byte_fd)) {
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if (offset > _last_byte_offset) {
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log_error("Limit write at %llu len %llu beyond last byte %llu",
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(unsigned long long)offset,
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(unsigned long long)nbytes,
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(unsigned long long)_last_byte_offset);
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return false;
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}
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if (offset + nbytes > _last_byte_offset) {
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limit_nbytes = _last_byte_offset - offset;
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if (limit_nbytes % _last_byte_sector_size)
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extra_nbytes = _last_byte_sector_size - (limit_nbytes % _last_byte_sector_size);
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if (extra_nbytes) {
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log_debug("Limit write at %llu len %llu to len %llu rounded to %llu",
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(unsigned long long)offset,
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(unsigned long long)nbytes,
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(unsigned long long)limit_nbytes,
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(unsigned long long)(limit_nbytes + extra_nbytes));
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nbytes = limit_nbytes + extra_nbytes;
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} else {
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log_debug("Limit write at %llu len %llu to len %llu",
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(unsigned long long)offset,
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(unsigned long long)nbytes,
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(unsigned long long)limit_nbytes);
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nbytes = limit_nbytes;
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}
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}
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}
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cb = _cb_alloc(e->cbs, context);
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if (!cb) {
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log_warn("couldn't allocate control block");
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return false;
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}
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memset(&cb->cb, 0, sizeof(cb->cb));
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cb->cb.aio_fildes = (int) fd;
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cb->cb.u.c.buf = data;
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cb->cb.u.c.offset = offset;
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cb->cb.u.c.nbytes = nbytes;
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cb->cb.aio_lio_opcode = (d == DIR_READ) ? IO_CMD_PREAD : IO_CMD_PWRITE;
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#if 0
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if (d == DIR_READ) {
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log_debug("io R off %llu bytes %llu",
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(unsigned long long)cb->cb.u.c.offset,
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(unsigned long long)cb->cb.u.c.nbytes);
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} else {
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log_debug("io W off %llu bytes %llu",
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(unsigned long long)cb->cb.u.c.offset,
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(unsigned long long)cb->cb.u.c.nbytes);
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}
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#endif
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cb_array[0] = &cb->cb;
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do {
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r = io_submit(e->aio_context, 1, cb_array);
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} while (r == -EAGAIN);
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if (r < 0) {
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_cb_free(e->cbs, cb);
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return false;
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}
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return true;
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}
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/*
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* MAX_IO is returned to the layer above via bcache_max_prefetches() which
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* tells the caller how many devices to submit io for concurrently. There will
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* be an open file descriptor for each of these, so keep it low enough to avoid
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* reaching the default max open file limit (1024) when there are over 1024
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* devices being scanned.
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*/
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#define MAX_IO 256
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#define MAX_EVENT 64
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static bool _async_wait(struct io_engine *ioe, io_complete_fn fn)
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{
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int i, r;
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struct io_event event[MAX_EVENT];
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struct control_block *cb;
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struct async_engine *e = _to_async(ioe);
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memset(&event, 0, sizeof(event));
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do {
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r = io_getevents(e->aio_context, 1, MAX_EVENT, event, NULL);
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} while (r == -EINTR);
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if (r < 0) {
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log_sys_warn("io_getevents");
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return false;
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}
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for (i = 0; i < r; i++) {
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struct io_event *ev = event + i;
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cb = _iocb_to_cb((struct iocb *) ev->obj);
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if (ev->res == cb->cb.u.c.nbytes)
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fn((void *) cb->context, 0);
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else if ((int) ev->res < 0)
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fn(cb->context, (int) ev->res);
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// FIXME: dct added this. a short read is ok?!
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else if (ev->res >= (1 << SECTOR_SHIFT)) {
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/* minimum acceptable read is 1 sector */
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fn((void *) cb->context, 0);
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} else {
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fn(cb->context, -ENODATA);
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}
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_cb_free(e->cbs, cb);
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}
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return true;
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}
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static unsigned _async_max_io(struct io_engine *e)
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{
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return MAX_IO;
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}
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struct io_engine *create_async_io_engine(void)
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{
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int r;
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struct async_engine *e = malloc(sizeof(*e));
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if (!e)
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return NULL;
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e->e.destroy = _async_destroy;
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e->e.issue = _async_issue;
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e->e.wait = _async_wait;
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e->e.max_io = _async_max_io;
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e->aio_context = 0;
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r = io_setup(MAX_IO, &e->aio_context);
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if (r < 0) {
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log_warn("io_setup failed");
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free(e);
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return NULL;
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}
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e->cbs = _cb_set_create(MAX_IO);
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if (!e->cbs) {
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log_warn("couldn't create control block set");
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free(e);
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return NULL;
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}
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e->page_mask = sysconf(_SC_PAGESIZE) - 1;
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return &e->e;
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}
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//----------------------------------------------------------------
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struct sync_io {
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struct dm_list list;
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void *context;
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};
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struct sync_engine {
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struct io_engine e;
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struct dm_list complete;
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};
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static struct sync_engine *_to_sync(struct io_engine *e)
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{
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return container_of(e, struct sync_engine, e);
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}
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static void _sync_destroy(struct io_engine *ioe)
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{
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struct sync_engine *e = _to_sync(ioe);
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free(e);
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}
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static bool _sync_issue(struct io_engine *ioe, enum dir d, int fd,
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sector_t sb, sector_t se, void *data, void *context)
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{
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int r;
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uint64_t len = (se - sb) * 512, where;
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struct sync_engine *e = _to_sync(ioe);
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struct sync_io *io = malloc(sizeof(*io));
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if (!io) {
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log_warn("unable to allocate sync_io");
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return false;
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}
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where = sb * 512;
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r = lseek(fd, where, SEEK_SET);
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if (r < 0) {
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log_warn("unable to seek to position %llu", (unsigned long long) where);
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free(io);
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return false;
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}
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/*
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* If bcache block goes past where lvm wants to write, then clamp it.
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*/
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if ((d == DIR_WRITE) && _last_byte_offset && (fd == _last_byte_fd)) {
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uint64_t offset = where;
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uint64_t nbytes = len;
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sector_t limit_nbytes = 0;
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sector_t extra_nbytes = 0;
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if (offset > _last_byte_offset) {
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log_error("Limit write at %llu len %llu beyond last byte %llu",
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(unsigned long long)offset,
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(unsigned long long)nbytes,
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(unsigned long long)_last_byte_offset);
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return false;
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}
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if (offset + nbytes > _last_byte_offset) {
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limit_nbytes = _last_byte_offset - offset;
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if (limit_nbytes % _last_byte_sector_size)
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extra_nbytes = _last_byte_sector_size - (limit_nbytes % _last_byte_sector_size);
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if (extra_nbytes) {
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log_debug("Limit write at %llu len %llu to len %llu rounded to %llu",
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(unsigned long long)offset,
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(unsigned long long)nbytes,
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(unsigned long long)limit_nbytes,
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(unsigned long long)(limit_nbytes + extra_nbytes));
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nbytes = limit_nbytes + extra_nbytes;
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} else {
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log_debug("Limit write at %llu len %llu to len %llu",
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(unsigned long long)offset,
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(unsigned long long)nbytes,
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(unsigned long long)limit_nbytes);
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nbytes = limit_nbytes;
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}
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}
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where = offset;
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len = nbytes;
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}
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while (len) {
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do {
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if (d == DIR_READ)
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r = read(fd, data, len);
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else
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r = write(fd, data, len);
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} while ((r < 0) && ((r == EINTR) || (r == EAGAIN)));
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if (r < 0) {
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log_warn("io failed %d", r);
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free(io);
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return false;
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}
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len -= r;
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}
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if (len) {
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log_warn("short io %u bytes remaining", (unsigned) len);
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free(io);
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return false;
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}
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dm_list_add(&e->complete, &io->list);
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io->context = context;
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return true;
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}
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static bool _sync_wait(struct io_engine *ioe, io_complete_fn fn)
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{
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struct sync_io *io, *tmp;
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struct sync_engine *e = _to_sync(ioe);
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dm_list_iterate_items_safe(io, tmp, &e->complete) {
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fn(io->context, 0);
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dm_list_del(&io->list);
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free(io);
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}
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return true;
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}
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static unsigned _sync_max_io(struct io_engine *e)
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{
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return 1;
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}
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struct io_engine *create_sync_io_engine(void)
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{
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struct sync_engine *e = malloc(sizeof(*e));
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if (!e)
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return NULL;
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e->e.destroy = _sync_destroy;
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e->e.issue = _sync_issue;
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e->e.wait = _sync_wait;
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e->e.max_io = _sync_max_io;
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dm_list_init(&e->complete);
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return &e->e;
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}
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//----------------------------------------------------------------
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#define MIN_BLOCKS 16
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#define WRITEBACK_LOW_THRESHOLD_PERCENT 33
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#define WRITEBACK_HIGH_THRESHOLD_PERCENT 66
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//----------------------------------------------------------------
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static void *_alloc_aligned(size_t len, size_t alignment)
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{
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void *result = NULL;
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int r = posix_memalign(&result, alignment, len);
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if (r)
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return NULL;
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return result;
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}
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//----------------------------------------------------------------
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static bool _test_flags(struct block *b, unsigned bits)
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{
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return (b->flags & bits) != 0;
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}
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static void _set_flags(struct block *b, unsigned bits)
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{
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b->flags |= bits;
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}
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static void _clear_flags(struct block *b, unsigned bits)
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{
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b->flags &= ~bits;
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}
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|
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//----------------------------------------------------------------
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enum block_flags {
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BF_IO_PENDING = (1 << 0),
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BF_DIRTY = (1 << 1),
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};
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|
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struct bcache {
|
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sector_t block_sectors;
|
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uint64_t nr_data_blocks;
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uint64_t nr_cache_blocks;
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unsigned max_io;
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|
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struct io_engine *engine;
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void *raw_data;
|
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struct block *raw_blocks;
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|
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/*
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* Lists that categorise the blocks.
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|
*/
|
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unsigned nr_locked;
|
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unsigned nr_dirty;
|
|
unsigned nr_io_pending;
|
|
|
|
struct dm_list free;
|
|
struct dm_list errored;
|
|
struct dm_list dirty;
|
|
struct dm_list clean;
|
|
struct dm_list io_pending;
|
|
|
|
struct radix_tree *rtree;
|
|
|
|
/*
|
|
* Statistics
|
|
*/
|
|
unsigned read_hits;
|
|
unsigned read_misses;
|
|
unsigned write_zeroes;
|
|
unsigned write_hits;
|
|
unsigned write_misses;
|
|
unsigned prefetches;
|
|
};
|
|
|
|
//----------------------------------------------------------------
|
|
|
|
struct key_parts {
|
|
uint32_t fd;
|
|
uint64_t b;
|
|
} __attribute__ ((packed));
|
|
|
|
union key {
|
|
struct key_parts parts;
|
|
uint8_t bytes[12];
|
|
};
|
|
|
|
static struct block *_block_lookup(struct bcache *cache, int fd, uint64_t i)
|
|
{
|
|
union key k;
|
|
union radix_value v;
|
|
|
|
k.parts.fd = fd;
|
|
k.parts.b = i;
|
|
|
|
if (radix_tree_lookup(cache->rtree, k.bytes, k.bytes + sizeof(k.bytes), &v))
|
|
return v.ptr;
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static bool _block_insert(struct block *b)
|
|
{
|
|
union key k;
|
|
union radix_value v;
|
|
|
|
k.parts.fd = b->fd;
|
|
k.parts.b = b->index;
|
|
v.ptr = b;
|
|
|
|
return radix_tree_insert(b->cache->rtree, k.bytes, k.bytes + sizeof(k.bytes), v);
|
|
}
|
|
|
|
static void _block_remove(struct block *b)
|
|
{
|
|
union key k;
|
|
|
|
k.parts.fd = b->fd;
|
|
k.parts.b = b->index;
|
|
|
|
radix_tree_remove(b->cache->rtree, k.bytes, k.bytes + sizeof(k.bytes));
|
|
}
|
|
|
|
//----------------------------------------------------------------
|
|
|
|
static bool _init_free_list(struct bcache *cache, unsigned count, unsigned pgsize)
|
|
{
|
|
unsigned i;
|
|
size_t block_size = cache->block_sectors << SECTOR_SHIFT;
|
|
unsigned char *data =
|
|
(unsigned char *) _alloc_aligned(count * block_size, pgsize);
|
|
|
|
/* Allocate the data for each block. We page align the data. */
|
|
if (!data)
|
|
return false;
|
|
|
|
cache->raw_blocks = malloc(count * sizeof(*cache->raw_blocks));
|
|
if (!cache->raw_blocks) {
|
|
free(data);
|
|
return false;
|
|
}
|
|
|
|
cache->raw_data = data;
|
|
|
|
for (i = 0; i < count; i++) {
|
|
struct block *b = cache->raw_blocks + i;
|
|
b->cache = cache;
|
|
b->data = data + (block_size * i);
|
|
dm_list_add(&cache->free, &b->list);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static void _exit_free_list(struct bcache *cache)
|
|
{
|
|
free(cache->raw_data);
|
|
free(cache->raw_blocks);
|
|
}
|
|
|
|
static struct block *_alloc_block(struct bcache *cache)
|
|
{
|
|
if (dm_list_empty(&cache->free))
|
|
return NULL;
|
|
|
|
return dm_list_struct_base(_list_pop(&cache->free), struct block, list);
|
|
}
|
|
|
|
static void _free_block(struct block *b)
|
|
{
|
|
dm_list_add(&b->cache->free, &b->list);
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* Clean/dirty list management.
|
|
* Always use these methods to ensure nr_dirty_ is correct.
|
|
*--------------------------------------------------------------*/
|
|
|
|
static void _unlink_block(struct block *b)
|
|
{
|
|
if (_test_flags(b, BF_DIRTY))
|
|
b->cache->nr_dirty--;
|
|
|
|
dm_list_del(&b->list);
|
|
}
|
|
|
|
static void _link_block(struct block *b)
|
|
{
|
|
struct bcache *cache = b->cache;
|
|
|
|
if (_test_flags(b, BF_DIRTY)) {
|
|
dm_list_add(&cache->dirty, &b->list);
|
|
cache->nr_dirty++;
|
|
} else
|
|
dm_list_add(&cache->clean, &b->list);
|
|
}
|
|
|
|
static void _relink(struct block *b)
|
|
{
|
|
_unlink_block(b);
|
|
_link_block(b);
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* Low level IO handling
|
|
*
|
|
* We cannot have two concurrent writes on the same block.
|
|
* eg, background writeback, put with dirty, flush?
|
|
*
|
|
* To avoid this we introduce some restrictions:
|
|
*
|
|
* i) A held block can never be written back.
|
|
* ii) You cannot get a block until writeback has completed.
|
|
*
|
|
*--------------------------------------------------------------*/
|
|
|
|
static void _complete_io(void *context, int err)
|
|
{
|
|
struct block *b = context;
|
|
struct bcache *cache = b->cache;
|
|
|
|
b->error = err;
|
|
_clear_flags(b, BF_IO_PENDING);
|
|
cache->nr_io_pending--;
|
|
|
|
/*
|
|
* b is on the io_pending list, so we don't want to use unlink_block.
|
|
* Which would incorrectly adjust nr_dirty.
|
|
*/
|
|
dm_list_del(&b->list);
|
|
|
|
if (b->error) {
|
|
dm_list_add(&cache->errored, &b->list);
|
|
|
|
} else {
|
|
_clear_flags(b, BF_DIRTY);
|
|
_link_block(b);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* |b->list| should be valid (either pointing to itself, on one of the other
|
|
* lists.
|
|
*/
|
|
static void _issue_low_level(struct block *b, enum dir d)
|
|
{
|
|
struct bcache *cache = b->cache;
|
|
sector_t sb = b->index * cache->block_sectors;
|
|
sector_t se = sb + cache->block_sectors;
|
|
|
|
if (_test_flags(b, BF_IO_PENDING))
|
|
return;
|
|
|
|
b->io_dir = d;
|
|
_set_flags(b, BF_IO_PENDING);
|
|
cache->nr_io_pending++;
|
|
|
|
dm_list_move(&cache->io_pending, &b->list);
|
|
|
|
if (!cache->engine->issue(cache->engine, d, b->fd, sb, se, b->data, b)) {
|
|
/* FIXME: if io_submit() set an errno, return that instead of EIO? */
|
|
_complete_io(b, -EIO);
|
|
return;
|
|
}
|
|
}
|
|
|
|
static inline void _issue_read(struct block *b)
|
|
{
|
|
_issue_low_level(b, DIR_READ);
|
|
}
|
|
|
|
static inline void _issue_write(struct block *b)
|
|
{
|
|
_issue_low_level(b, DIR_WRITE);
|
|
}
|
|
|
|
static bool _wait_io(struct bcache *cache)
|
|
{
|
|
return cache->engine->wait(cache->engine, _complete_io);
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* High level IO handling
|
|
*--------------------------------------------------------------*/
|
|
|
|
static void _wait_all(struct bcache *cache)
|
|
{
|
|
while (!dm_list_empty(&cache->io_pending))
|
|
_wait_io(cache);
|
|
}
|
|
|
|
static void _wait_specific(struct block *b)
|
|
{
|
|
while (_test_flags(b, BF_IO_PENDING))
|
|
_wait_io(b->cache);
|
|
}
|
|
|
|
static unsigned _writeback(struct bcache *cache, unsigned count)
|
|
{
|
|
unsigned actual = 0;
|
|
struct block *b, *tmp;
|
|
|
|
dm_list_iterate_items_gen_safe (b, tmp, &cache->dirty, list) {
|
|
if (actual == count)
|
|
break;
|
|
|
|
// We can't writeback anything that's still in use.
|
|
if (!b->ref_count) {
|
|
_issue_write(b);
|
|
actual++;
|
|
}
|
|
}
|
|
|
|
return actual;
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* High level allocation
|
|
*--------------------------------------------------------------*/
|
|
|
|
static struct block *_find_unused_clean_block(struct bcache *cache)
|
|
{
|
|
struct block *b;
|
|
|
|
dm_list_iterate_items (b, &cache->clean) {
|
|
if (!b->ref_count) {
|
|
_unlink_block(b);
|
|
_block_remove(b);
|
|
return b;
|
|
}
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static struct block *_new_block(struct bcache *cache, int fd, block_address i, bool can_wait)
|
|
{
|
|
struct block *b;
|
|
|
|
b = _alloc_block(cache);
|
|
while (!b && !dm_list_empty(&cache->clean)) {
|
|
b = _find_unused_clean_block(cache);
|
|
if (!b) {
|
|
if (can_wait) {
|
|
if (dm_list_empty(&cache->io_pending))
|
|
_writeback(cache, 16); // FIXME: magic number
|
|
_wait_io(cache);
|
|
} else {
|
|
log_error("bcache no new blocks for fd %d index %u",
|
|
fd, (uint32_t) i);
|
|
return NULL;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (b) {
|
|
dm_list_init(&b->list);
|
|
b->flags = 0;
|
|
b->fd = fd;
|
|
b->index = i;
|
|
b->ref_count = 0;
|
|
b->error = 0;
|
|
|
|
if (!_block_insert(b)) {
|
|
log_error("bcache unable to insert block in radix tree (OOM?)");
|
|
_free_block(b);
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
return b;
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* Block reference counting
|
|
*--------------------------------------------------------------*/
|
|
static void _zero_block(struct block *b)
|
|
{
|
|
b->cache->write_zeroes++;
|
|
memset(b->data, 0, b->cache->block_sectors << SECTOR_SHIFT);
|
|
_set_flags(b, BF_DIRTY);
|
|
}
|
|
|
|
static void _hit(struct block *b, unsigned flags)
|
|
{
|
|
struct bcache *cache = b->cache;
|
|
|
|
if (flags & (GF_ZERO | GF_DIRTY))
|
|
cache->write_hits++;
|
|
else
|
|
cache->read_hits++;
|
|
|
|
_relink(b);
|
|
}
|
|
|
|
static void _miss(struct bcache *cache, unsigned flags)
|
|
{
|
|
if (flags & (GF_ZERO | GF_DIRTY))
|
|
cache->write_misses++;
|
|
else
|
|
cache->read_misses++;
|
|
}
|
|
|
|
static struct block *_lookup_or_read_block(struct bcache *cache,
|
|
int fd, block_address i,
|
|
unsigned flags)
|
|
{
|
|
struct block *b = _block_lookup(cache, fd, i);
|
|
|
|
if (b) {
|
|
// FIXME: this is insufficient. We need to also catch a read
|
|
// lock of a write locked block. Ref count needs to distinguish.
|
|
if (b->ref_count && (flags & (GF_DIRTY | GF_ZERO))) {
|
|
log_warn("concurrent write lock attempted");
|
|
return NULL;
|
|
}
|
|
|
|
if (_test_flags(b, BF_IO_PENDING)) {
|
|
_miss(cache, flags);
|
|
_wait_specific(b);
|
|
|
|
} else
|
|
_hit(b, flags);
|
|
|
|
_unlink_block(b);
|
|
|
|
if (flags & GF_ZERO)
|
|
_zero_block(b);
|
|
|
|
} else {
|
|
_miss(cache, flags);
|
|
|
|
b = _new_block(cache, fd, i, true);
|
|
if (b) {
|
|
if (flags & GF_ZERO)
|
|
_zero_block(b);
|
|
|
|
else {
|
|
_issue_read(b);
|
|
_wait_specific(b);
|
|
|
|
// we know the block is clean and unerrored.
|
|
_unlink_block(b);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (b) {
|
|
if (flags & (GF_DIRTY | GF_ZERO))
|
|
_set_flags(b, BF_DIRTY);
|
|
|
|
_link_block(b);
|
|
return b;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void _preemptive_writeback(struct bcache *cache)
|
|
{
|
|
// FIXME: this ignores those blocks that are in the error state. Track
|
|
// nr_clean instead?
|
|
unsigned nr_available = cache->nr_cache_blocks - (cache->nr_dirty - cache->nr_io_pending);
|
|
if (nr_available < (WRITEBACK_LOW_THRESHOLD_PERCENT * cache->nr_cache_blocks / 100))
|
|
_writeback(cache, (WRITEBACK_HIGH_THRESHOLD_PERCENT * cache->nr_cache_blocks / 100) - nr_available);
|
|
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* Public interface
|
|
*--------------------------------------------------------------*/
|
|
struct bcache *bcache_create(sector_t block_sectors, unsigned nr_cache_blocks,
|
|
struct io_engine *engine)
|
|
{
|
|
struct bcache *cache;
|
|
unsigned max_io = engine->max_io(engine);
|
|
long pgsize = sysconf(_SC_PAGESIZE);
|
|
|
|
if (pgsize < 0) {
|
|
log_warn("WARNING: _SC_PAGESIZE returns negative value.");
|
|
return NULL;
|
|
}
|
|
|
|
if (!nr_cache_blocks) {
|
|
log_warn("bcache must have at least one cache block");
|
|
return NULL;
|
|
}
|
|
|
|
if (!block_sectors) {
|
|
log_warn("bcache must have a non zero block size");
|
|
return NULL;
|
|
}
|
|
|
|
if (block_sectors & ((pgsize >> SECTOR_SHIFT) - 1)) {
|
|
log_warn("bcache block size must be a multiple of page size");
|
|
return NULL;
|
|
}
|
|
|
|
cache = malloc(sizeof(*cache));
|
|
if (!cache)
|
|
return NULL;
|
|
|
|
cache->block_sectors = block_sectors;
|
|
cache->nr_cache_blocks = nr_cache_blocks;
|
|
cache->max_io = nr_cache_blocks < max_io ? nr_cache_blocks : max_io;
|
|
cache->engine = engine;
|
|
cache->nr_locked = 0;
|
|
cache->nr_dirty = 0;
|
|
cache->nr_io_pending = 0;
|
|
|
|
dm_list_init(&cache->free);
|
|
dm_list_init(&cache->errored);
|
|
dm_list_init(&cache->dirty);
|
|
dm_list_init(&cache->clean);
|
|
dm_list_init(&cache->io_pending);
|
|
|
|
cache->rtree = radix_tree_create(NULL, NULL);
|
|
if (!cache->rtree) {
|
|
cache->engine->destroy(cache->engine);
|
|
free(cache);
|
|
return NULL;
|
|
}
|
|
|
|
cache->read_hits = 0;
|
|
cache->read_misses = 0;
|
|
cache->write_zeroes = 0;
|
|
cache->write_hits = 0;
|
|
cache->write_misses = 0;
|
|
cache->prefetches = 0;
|
|
|
|
if (!_init_free_list(cache, nr_cache_blocks, pgsize)) {
|
|
cache->engine->destroy(cache->engine);
|
|
radix_tree_destroy(cache->rtree);
|
|
free(cache);
|
|
return NULL;
|
|
}
|
|
|
|
return cache;
|
|
}
|
|
|
|
void bcache_destroy(struct bcache *cache)
|
|
{
|
|
if (cache->nr_locked)
|
|
log_warn("some blocks are still locked");
|
|
|
|
if (!bcache_flush(cache))
|
|
stack;
|
|
_wait_all(cache);
|
|
_exit_free_list(cache);
|
|
radix_tree_destroy(cache->rtree);
|
|
cache->engine->destroy(cache->engine);
|
|
free(cache);
|
|
}
|
|
|
|
sector_t bcache_block_sectors(struct bcache *cache)
|
|
{
|
|
return cache->block_sectors;
|
|
}
|
|
|
|
unsigned bcache_nr_cache_blocks(struct bcache *cache)
|
|
{
|
|
return cache->nr_cache_blocks;
|
|
}
|
|
|
|
unsigned bcache_max_prefetches(struct bcache *cache)
|
|
{
|
|
return cache->max_io;
|
|
}
|
|
|
|
void bcache_prefetch(struct bcache *cache, int fd, block_address i)
|
|
{
|
|
struct block *b = _block_lookup(cache, fd, i);
|
|
|
|
if (!b) {
|
|
if (cache->nr_io_pending < cache->max_io) {
|
|
b = _new_block(cache, fd, i, false);
|
|
if (b) {
|
|
cache->prefetches++;
|
|
_issue_read(b);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
//----------------------------------------------------------------
|
|
|
|
static void _recycle_block(struct bcache *cache, struct block *b)
|
|
{
|
|
_unlink_block(b);
|
|
_block_remove(b);
|
|
_free_block(b);
|
|
}
|
|
|
|
bool bcache_get(struct bcache *cache, int fd, block_address i,
|
|
unsigned flags, struct block **result)
|
|
{
|
|
struct block *b;
|
|
|
|
b = _lookup_or_read_block(cache, fd, i, flags);
|
|
if (b) {
|
|
if (b->error) {
|
|
if (b->io_dir == DIR_READ) {
|
|
// Now we know the read failed we can just forget
|
|
// about this block, since there's no dirty data to
|
|
// be written back.
|
|
_recycle_block(cache, b);
|
|
}
|
|
return false;
|
|
}
|
|
|
|
if (!b->ref_count)
|
|
cache->nr_locked++;
|
|
b->ref_count++;
|
|
|
|
*result = b;
|
|
return true;
|
|
}
|
|
|
|
*result = NULL;
|
|
|
|
log_error("bcache failed to get block %u fd %d", (uint32_t) i, fd);
|
|
return false;
|
|
}
|
|
|
|
//----------------------------------------------------------------
|
|
|
|
static void _put_ref(struct block *b)
|
|
{
|
|
if (!b->ref_count) {
|
|
log_warn("ref count on bcache block already zero");
|
|
return;
|
|
}
|
|
|
|
b->ref_count--;
|
|
if (!b->ref_count)
|
|
b->cache->nr_locked--;
|
|
}
|
|
|
|
void bcache_put(struct block *b)
|
|
{
|
|
_put_ref(b);
|
|
|
|
if (_test_flags(b, BF_DIRTY))
|
|
_preemptive_writeback(b->cache);
|
|
}
|
|
|
|
//----------------------------------------------------------------
|
|
|
|
bool bcache_flush(struct bcache *cache)
|
|
{
|
|
// Only dirty data is on the errored list, since bad read blocks get
|
|
// recycled straight away. So we put these back on the dirty list, and
|
|
// try and rewrite everything.
|
|
dm_list_splice(&cache->dirty, &cache->errored);
|
|
|
|
while (!dm_list_empty(&cache->dirty)) {
|
|
struct block *b = dm_list_item(_list_pop(&cache->dirty), struct block);
|
|
if (b->ref_count || _test_flags(b, BF_IO_PENDING)) {
|
|
// The superblock may well be still locked.
|
|
continue;
|
|
}
|
|
|
|
_issue_write(b);
|
|
}
|
|
|
|
_wait_all(cache);
|
|
|
|
return dm_list_empty(&cache->errored);
|
|
}
|
|
|
|
//----------------------------------------------------------------
|
|
/*
|
|
* You can safely call this with a NULL block.
|
|
*/
|
|
static bool _invalidate_block(struct bcache *cache, struct block *b)
|
|
{
|
|
if (!b)
|
|
return true;
|
|
|
|
if (_test_flags(b, BF_IO_PENDING))
|
|
_wait_specific(b);
|
|
|
|
if (b->ref_count) {
|
|
log_warn("bcache_invalidate: block (%d, %llu) still held",
|
|
b->fd, (unsigned long long) b->index);
|
|
return false;
|
|
}
|
|
|
|
if (_test_flags(b, BF_DIRTY)) {
|
|
_issue_write(b);
|
|
_wait_specific(b);
|
|
|
|
if (b->error)
|
|
return false;
|
|
}
|
|
|
|
_recycle_block(cache, b);
|
|
|
|
return true;
|
|
}
|
|
|
|
bool bcache_invalidate(struct bcache *cache, int fd, block_address i)
|
|
{
|
|
return _invalidate_block(cache, _block_lookup(cache, fd, i));
|
|
}
|
|
|
|
//----------------------------------------------------------------
|
|
|
|
struct invalidate_iterator {
|
|
bool success;
|
|
struct radix_tree_iterator it;
|
|
};
|
|
|
|
static bool _writeback_v(struct radix_tree_iterator *it,
|
|
uint8_t *kb, uint8_t *ke, union radix_value v)
|
|
{
|
|
struct block *b = v.ptr;
|
|
|
|
if (_test_flags(b, BF_DIRTY))
|
|
_issue_write(b);
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool _invalidate_v(struct radix_tree_iterator *it,
|
|
uint8_t *kb, uint8_t *ke, union radix_value v)
|
|
{
|
|
struct block *b = v.ptr;
|
|
struct invalidate_iterator *iit = container_of(it, struct invalidate_iterator, it);
|
|
|
|
if (b->error || _test_flags(b, BF_DIRTY)) {
|
|
log_warn("bcache_invalidate: block (%d, %llu) still dirty",
|
|
b->fd, (unsigned long long) b->index);
|
|
iit->success = false;
|
|
return true;
|
|
}
|
|
|
|
if (b->ref_count) {
|
|
log_warn("bcache_invalidate: block (%d, %llu) still held",
|
|
b->fd, (unsigned long long) b->index);
|
|
iit->success = false;
|
|
return true;
|
|
}
|
|
|
|
_unlink_block(b);
|
|
_free_block(b);
|
|
|
|
// We can't remove the block from the radix tree yet because
|
|
// we're in the middle of an iteration.
|
|
return true;
|
|
}
|
|
|
|
bool bcache_invalidate_fd(struct bcache *cache, int fd)
|
|
{
|
|
union key k;
|
|
struct invalidate_iterator it;
|
|
|
|
k.parts.fd = fd;
|
|
|
|
it.it.visit = _writeback_v;
|
|
radix_tree_iterate(cache->rtree, k.bytes, k.bytes + sizeof(k.parts.fd), &it.it);
|
|
|
|
_wait_all(cache);
|
|
|
|
it.success = true;
|
|
it.it.visit = _invalidate_v;
|
|
radix_tree_iterate(cache->rtree, k.bytes, k.bytes + sizeof(k.parts.fd), &it.it);
|
|
radix_tree_remove_prefix(cache->rtree, k.bytes, k.bytes + sizeof(k.parts.fd));
|
|
return it.success;
|
|
}
|
|
|
|
//----------------------------------------------------------------
|
|
|
|
void bcache_set_last_byte(struct bcache *cache, int fd, uint64_t offset, int sector_size)
|
|
{
|
|
_last_byte_fd = fd;
|
|
_last_byte_offset = offset;
|
|
_last_byte_sector_size = sector_size;
|
|
if (!sector_size)
|
|
_last_byte_sector_size = 512;
|
|
}
|
|
|
|
void bcache_unset_last_byte(struct bcache *cache, int fd)
|
|
{
|
|
if (_last_byte_fd == fd) {
|
|
_last_byte_fd = 0;
|
|
_last_byte_offset = 0;
|
|
_last_byte_sector_size = 0;
|
|
}
|
|
}
|
|
|