/* * Copyright (C) 2018 Red Hat, Inc. All rights reserved. * * This file is part of LVM2. * * This copyrighted material is made available to anyone wishing to use, * modify, copy, or redistribute it subject to the terms and conditions * of the GNU Lesser General Public License v.2.1. * * You should have received a copy of the GNU Lesser General Public License * along with this program; if not, write to the Free Software Foundation, * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #define _GNU_SOURCE #include "lib/device/bcache.h" #include "base/data-struct/radix-tree.h" #include "lib/log/lvm-logging.h" #include "lib/log/log.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #define SECTOR_SHIFT 9L //---------------------------------------------------------------- static void log_sys_warn(const char *call) { log_warn("%s failed: %s", call, strerror(errno)); } // Assumes the list is not empty. static inline struct dm_list *_list_pop(struct dm_list *head) { struct dm_list *l; l = head->n; dm_list_del(l); return l; } //---------------------------------------------------------------- struct control_block { struct dm_list list; void *context; struct iocb cb; }; struct cb_set { struct dm_list free; struct dm_list allocated; struct control_block *vec; } control_block_set; static struct cb_set *_cb_set_create(unsigned nr) { int i; struct cb_set *cbs = dm_malloc(sizeof(*cbs)); if (!cbs) return NULL; cbs->vec = dm_malloc(nr * sizeof(*cbs->vec)); if (!cbs->vec) { dm_free(cbs); return NULL; } dm_list_init(&cbs->free); dm_list_init(&cbs->allocated); for (i = 0; i < nr; i++) dm_list_add(&cbs->free, &cbs->vec[i].list); return cbs; } static void _cb_set_destroy(struct cb_set *cbs) { // We know this is always called after a wait_all. So there should // never be in flight IO. if (!dm_list_empty(&cbs->allocated)) { // bail out log_error("async io still in flight"); return; } dm_free(cbs->vec); dm_free(cbs); } static struct control_block *_cb_alloc(struct cb_set *cbs, void *context) { struct control_block *cb; if (dm_list_empty(&cbs->free)) return NULL; cb = dm_list_item(_list_pop(&cbs->free), struct control_block); cb->context = context; dm_list_add(&cbs->allocated, &cb->list); return cb; } static void _cb_free(struct cb_set *cbs, struct control_block *cb) { dm_list_del(&cb->list); dm_list_add_h(&cbs->free, &cb->list); } static struct control_block *_iocb_to_cb(struct iocb *icb) { return dm_list_struct_base(icb, struct control_block, cb); } //---------------------------------------------------------------- struct async_engine { struct io_engine e; io_context_t aio_context; struct cb_set *cbs; unsigned page_mask; }; static struct async_engine *_to_async(struct io_engine *e) { return container_of(e, struct async_engine, e); } static void _async_destroy(struct io_engine *ioe) { int r; struct async_engine *e = _to_async(ioe); _cb_set_destroy(e->cbs); // io_destroy is really slow r = io_destroy(e->aio_context); if (r) log_sys_warn("io_destroy"); dm_free(e); } static bool _async_issue(struct io_engine *ioe, enum dir d, int fd, sector_t sb, sector_t se, void *data, void *context) { int r; struct iocb *cb_array[1]; struct control_block *cb; struct async_engine *e = _to_async(ioe); if (((uintptr_t) data) & e->page_mask) { log_warn("misaligned data buffer"); return false; } cb = _cb_alloc(e->cbs, context); if (!cb) { log_warn("couldn't allocate control block"); return false; } memset(&cb->cb, 0, sizeof(cb->cb)); cb->cb.aio_fildes = (int) fd; cb->cb.u.c.buf = data; cb->cb.u.c.offset = sb << SECTOR_SHIFT; cb->cb.u.c.nbytes = (se - sb) << SECTOR_SHIFT; cb->cb.aio_lio_opcode = (d == DIR_READ) ? IO_CMD_PREAD : IO_CMD_PWRITE; cb_array[0] = &cb->cb; do { r = io_submit(e->aio_context, 1, cb_array); } while (r == -EAGAIN); if (r < 0) { log_sys_warn("io_submit"); _cb_free(e->cbs, cb); return false; } return true; } #define MAX_IO 1024 #define MAX_EVENT 64 static bool _async_wait(struct io_engine *ioe, io_complete_fn fn) { int i, r; struct io_event event[MAX_EVENT]; struct control_block *cb; struct async_engine *e = _to_async(ioe); memset(&event, 0, sizeof(event)); do { r = io_getevents(e->aio_context, 1, MAX_EVENT, event, NULL); } while (r == -EINTR); if (r < 0) { log_sys_warn("io_getevents"); return false; } for (i = 0; i < r; i++) { struct io_event *ev = event + i; cb = _iocb_to_cb((struct iocb *) ev->obj); if (ev->res == cb->cb.u.c.nbytes) fn((void *) cb->context, 0); else if ((int) ev->res < 0) fn(cb->context, (int) ev->res); // FIXME: dct added this. a short read is ok?! else if (ev->res >= (1 << SECTOR_SHIFT)) { /* minimum acceptable read is 1 sector */ fn((void *) cb->context, 0); } else { fn(cb->context, -ENODATA); } _cb_free(e->cbs, cb); } return true; } static unsigned _async_max_io(struct io_engine *e) { return MAX_IO; } struct io_engine *create_async_io_engine(void) { int r; struct async_engine *e = dm_malloc(sizeof(*e)); if (!e) return NULL; e->e.destroy = _async_destroy; e->e.issue = _async_issue; e->e.wait = _async_wait; e->e.max_io = _async_max_io; e->aio_context = 0; r = io_setup(MAX_IO, &e->aio_context); if (r < 0) { log_warn("io_setup failed"); dm_free(e); return NULL; } e->cbs = _cb_set_create(MAX_IO); if (!e->cbs) { log_warn("couldn't create control block set"); dm_free(e); return NULL; } e->page_mask = sysconf(_SC_PAGESIZE) - 1; return &e->e; } //---------------------------------------------------------------- struct sync_io { struct dm_list list; void *context; }; struct sync_engine { struct io_engine e; struct dm_list complete; }; static struct sync_engine *_to_sync(struct io_engine *e) { return container_of(e, struct sync_engine, e); } static void _sync_destroy(struct io_engine *ioe) { struct sync_engine *e = _to_sync(ioe); dm_free(e); } static bool _sync_issue(struct io_engine *ioe, enum dir d, int fd, sector_t sb, sector_t se, void *data, void *context) { int r; uint64_t len = (se - sb) * 512, where; struct sync_engine *e = _to_sync(ioe); struct sync_io *io = malloc(sizeof(*io)); if (!io) { log_warn("unable to allocate sync_io"); return false; } where = sb * 512; r = lseek(fd, where, SEEK_SET); if (r < 0) { log_warn("unable to seek to position %llu", (unsigned long long) where); return false; } while (len) { do { if (d == DIR_READ) r = read(fd, data, len); else r = write(fd, data, len); } while ((r < 0) && ((r == EINTR) || (r == EAGAIN))); if (r < 0) { log_warn("io failed %d", r); return false; } len -= r; } if (len) { log_warn("short io %u bytes remaining", (unsigned) len); return false; } dm_list_add(&e->complete, &io->list); io->context = context; return true; } static bool _sync_wait(struct io_engine *ioe, io_complete_fn fn) { struct sync_io *io, *tmp; struct sync_engine *e = _to_sync(ioe); dm_list_iterate_items_safe(io, tmp, &e->complete) { fn(io->context, 0); dm_list_del(&io->list); dm_free(io); } return true; } static unsigned _sync_max_io(struct io_engine *e) { return 1; } struct io_engine *create_sync_io_engine(void) { struct sync_engine *e = dm_malloc(sizeof(*e)); if (!e) return NULL; e->e.destroy = _sync_destroy; e->e.issue = _sync_issue; e->e.wait = _sync_wait; e->e.max_io = _sync_max_io; dm_list_init(&e->complete); return &e->e; } //---------------------------------------------------------------- #define MIN_BLOCKS 16 #define WRITEBACK_LOW_THRESHOLD_PERCENT 33 #define WRITEBACK_HIGH_THRESHOLD_PERCENT 66 //---------------------------------------------------------------- static void *_alloc_aligned(size_t len, size_t alignment) { void *result = NULL; int r = posix_memalign(&result, alignment, len); if (r) return NULL; return result; } //---------------------------------------------------------------- static bool _test_flags(struct block *b, unsigned bits) { return (b->flags & bits) != 0; } static void _set_flags(struct block *b, unsigned bits) { b->flags |= bits; } static void _clear_flags(struct block *b, unsigned bits) { b->flags &= ~bits; } //---------------------------------------------------------------- enum block_flags { BF_IO_PENDING = (1 << 0), BF_DIRTY = (1 << 1), }; struct bcache { sector_t block_sectors; uint64_t nr_data_blocks; uint64_t nr_cache_blocks; unsigned max_io; struct io_engine *engine; void *raw_data; struct block *raw_blocks; /* * Lists that categorise the blocks. */ unsigned nr_locked; 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_data = data; cache->raw_blocks = dm_malloc(count * sizeof(*cache->raw_blocks)); if (!cache->raw_blocks) dm_free(cache->raw_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) { dm_free(cache->raw_data); dm_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) { log_warn("bcache io error %d fd %d", b->error, b->fd); 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); dm_list_init(&b->hash); 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 (!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 = dm_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); dm_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); dm_free(cache); return NULL; } return cache; } void bcache_destroy(struct bcache *cache) { if (cache->nr_locked) log_warn("some blocks are still locked"); bcache_flush(cache); _wait_all(cache); _exit_free_list(cache); radix_tree_destroy(cache->rtree); cache->engine->destroy(cache->engine); dm_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; } //----------------------------------------------------------------