diff options
Diffstat (limited to 'fs/btrfs/reada.c')
| -rw-r--r-- | fs/btrfs/reada.c | 1086 |
1 files changed, 0 insertions, 1086 deletions
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c deleted file mode 100644 index eb96fdc3be25..000000000000 --- a/fs/btrfs/reada.c +++ /dev/null @@ -1,1086 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * Copyright (C) 2011 STRATO. All rights reserved. - */ - -#include <linux/sched.h> -#include <linux/pagemap.h> -#include <linux/writeback.h> -#include <linux/blkdev.h> -#include <linux/slab.h> -#include <linux/workqueue.h> -#include "ctree.h" -#include "volumes.h" -#include "disk-io.h" -#include "transaction.h" -#include "dev-replace.h" -#include "block-group.h" - -#undef DEBUG - -/* - * This is the implementation for the generic read ahead framework. - * - * To trigger a readahead, btrfs_reada_add must be called. It will start - * a read ahead for the given range [start, end) on tree root. The returned - * handle can either be used to wait on the readahead to finish - * (btrfs_reada_wait), or to send it to the background (btrfs_reada_detach). - * - * The read ahead works as follows: - * On btrfs_reada_add, the root of the tree is inserted into a radix_tree. - * reada_start_machine will then search for extents to prefetch and trigger - * some reads. When a read finishes for a node, all contained node/leaf - * pointers that lie in the given range will also be enqueued. The reads will - * be triggered in sequential order, thus giving a big win over a naive - * enumeration. It will also make use of multi-device layouts. Each disk - * will have its on read pointer and all disks will by utilized in parallel. - * Also will no two disks read both sides of a mirror simultaneously, as this - * would waste seeking capacity. Instead both disks will read different parts - * of the filesystem. - * Any number of readaheads can be started in parallel. The read order will be - * determined globally, i.e. 2 parallel readaheads will normally finish faster - * than the 2 started one after another. - */ - -#define MAX_IN_FLIGHT 6 - -struct reada_extctl { - struct list_head list; - struct reada_control *rc; - u64 generation; -}; - -struct reada_extent { - u64 logical; - u64 owner_root; - struct btrfs_key top; - struct list_head extctl; - int refcnt; - spinlock_t lock; - struct reada_zone *zones[BTRFS_MAX_MIRRORS]; - int nzones; - int scheduled; - int level; -}; - -struct reada_zone { - u64 start; - u64 end; - u64 elems; - struct list_head list; - spinlock_t lock; - int locked; - struct btrfs_device *device; - struct btrfs_device *devs[BTRFS_MAX_MIRRORS]; /* full list, incl - * self */ - int ndevs; - struct kref refcnt; -}; - -struct reada_machine_work { - struct btrfs_work work; - struct btrfs_fs_info *fs_info; -}; - -static void reada_extent_put(struct btrfs_fs_info *, struct reada_extent *); -static void reada_control_release(struct kref *kref); -static void reada_zone_release(struct kref *kref); -static void reada_start_machine(struct btrfs_fs_info *fs_info); -static void __reada_start_machine(struct btrfs_fs_info *fs_info); - -static int reada_add_block(struct reada_control *rc, u64 logical, - struct btrfs_key *top, u64 owner_root, - u64 generation, int level); - -/* recurses */ -/* in case of err, eb might be NULL */ -static void __readahead_hook(struct btrfs_fs_info *fs_info, - struct reada_extent *re, struct extent_buffer *eb, - int err) -{ - int nritems; - int i; - u64 bytenr; - u64 generation; - struct list_head list; - - spin_lock(&re->lock); - /* - * just take the full list from the extent. afterwards we - * don't need the lock anymore - */ - list_replace_init(&re->extctl, &list); - re->scheduled = 0; - spin_unlock(&re->lock); - - /* - * this is the error case, the extent buffer has not been - * read correctly. We won't access anything from it and - * just cleanup our data structures. Effectively this will - * cut the branch below this node from read ahead. - */ - if (err) - goto cleanup; - - /* - * FIXME: currently we just set nritems to 0 if this is a leaf, - * effectively ignoring the content. In a next step we could - * trigger more readahead depending from the content, e.g. - * fetch the checksums for the extents in the leaf. - */ - if (!btrfs_header_level(eb)) - goto cleanup; - - nritems = btrfs_header_nritems(eb); - generation = btrfs_header_generation(eb); - for (i = 0; i < nritems; i++) { - struct reada_extctl *rec; - u64 n_gen; - struct btrfs_key key; - struct btrfs_key next_key; - - btrfs_node_key_to_cpu(eb, &key, i); - if (i + 1 < nritems) - btrfs_node_key_to_cpu(eb, &next_key, i + 1); - else - next_key = re->top; - bytenr = btrfs_node_blockptr(eb, i); - n_gen = btrfs_node_ptr_generation(eb, i); - - list_for_each_entry(rec, &list, list) { - struct reada_control *rc = rec->rc; - - /* - * if the generation doesn't match, just ignore this - * extctl. This will probably cut off a branch from - * prefetch. Alternatively one could start a new (sub-) - * prefetch for this branch, starting again from root. - * FIXME: move the generation check out of this loop - */ -#ifdef DEBUG - if (rec->generation != generation) { - btrfs_debug(fs_info, - "generation mismatch for (%llu,%d,%llu) %llu != %llu", - key.objectid, key.type, key.offset, - rec->generation, generation); - } -#endif - if (rec->generation == generation && - btrfs_comp_cpu_keys(&key, &rc->key_end) < 0 && - btrfs_comp_cpu_keys(&next_key, &rc->key_start) > 0) - reada_add_block(rc, bytenr, &next_key, - btrfs_header_owner(eb), n_gen, - btrfs_header_level(eb) - 1); - } - } - -cleanup: - /* - * free extctl records - */ - while (!list_empty(&list)) { - struct reada_control *rc; - struct reada_extctl *rec; - - rec = list_first_entry(&list, struct reada_extctl, list); - list_del(&rec->list); - rc = rec->rc; - kfree(rec); - - kref_get(&rc->refcnt); - if (atomic_dec_and_test(&rc->elems)) { - kref_put(&rc->refcnt, reada_control_release); - wake_up(&rc->wait); - } - kref_put(&rc->refcnt, reada_control_release); - - reada_extent_put(fs_info, re); /* one ref for each entry */ - } - - return; -} - -int btree_readahead_hook(struct extent_buffer *eb, int err) -{ - struct btrfs_fs_info *fs_info = eb->fs_info; - int ret = 0; - struct reada_extent *re; - - /* find extent */ - spin_lock(&fs_info->reada_lock); - re = radix_tree_lookup(&fs_info->reada_tree, - eb->start >> fs_info->sectorsize_bits); - if (re) - re->refcnt++; - spin_unlock(&fs_info->reada_lock); - if (!re) { - ret = -1; - goto start_machine; - } - - __readahead_hook(fs_info, re, eb, err); - reada_extent_put(fs_info, re); /* our ref */ - -start_machine: - reada_start_machine(fs_info); - return ret; -} - -static struct reada_zone *reada_find_zone(struct btrfs_device *dev, u64 logical, - struct btrfs_io_context *bioc) -{ - struct btrfs_fs_info *fs_info = dev->fs_info; - int ret; - struct reada_zone *zone; - struct btrfs_block_group *cache = NULL; - u64 start; - u64 end; - int i; - - zone = NULL; - spin_lock(&fs_info->reada_lock); - ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone, - logical >> fs_info->sectorsize_bits, 1); - if (ret == 1 && logical >= zone->start && logical <= zone->end) { - kref_get(&zone->refcnt); - spin_unlock(&fs_info->reada_lock); - return zone; - } - - spin_unlock(&fs_info->reada_lock); - - cache = btrfs_lookup_block_group(fs_info, logical); - if (!cache) - return NULL; - - start = cache->start; - end = start + cache->length - 1; - btrfs_put_block_group(cache); - - zone = kzalloc(sizeof(*zone), GFP_KERNEL); - if (!zone) - return NULL; - - ret = radix_tree_preload(GFP_KERNEL); - if (ret) { - kfree(zone); - return NULL; - } - - zone->start = start; - zone->end = end; - INIT_LIST_HEAD(&zone->list); - spin_lock_init(&zone->lock); - zone->locked = 0; - kref_init(&zone->refcnt); - zone->elems = 0; - zone->device = dev; /* our device always sits at index 0 */ - for (i = 0; i < bioc->num_stripes; ++i) { - /* bounds have already been checked */ - zone->devs[i] = bioc->stripes[i].dev; - } - zone->ndevs = bioc->num_stripes; - - spin_lock(&fs_info->reada_lock); - ret = radix_tree_insert(&dev->reada_zones, - (unsigned long)(zone->end >> fs_info->sectorsize_bits), - zone); - - if (ret == -EEXIST) { - kfree(zone); - ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone, - logical >> fs_info->sectorsize_bits, 1); - if (ret == 1 && logical >= zone->start && logical <= zone->end) - kref_get(&zone->refcnt); - else - zone = NULL; - } - spin_unlock(&fs_info->reada_lock); - radix_tree_preload_end(); - - return zone; -} - -static struct reada_extent *reada_find_extent(struct btrfs_fs_info *fs_info, - u64 logical, - struct btrfs_key *top, - u64 owner_root, int level) -{ - int ret; - struct reada_extent *re = NULL; - struct reada_extent *re_exist = NULL; - struct btrfs_io_context *bioc = NULL; - struct btrfs_device *dev; - struct btrfs_device *prev_dev; - u64 length; - int real_stripes; - int nzones = 0; - unsigned long index = logical >> fs_info->sectorsize_bits; - int dev_replace_is_ongoing; - int have_zone = 0; - - spin_lock(&fs_info->reada_lock); - re = radix_tree_lookup(&fs_info->reada_tree, index); - if (re) - re->refcnt++; - spin_unlock(&fs_info->reada_lock); - - if (re) - return re; - - re = kzalloc(sizeof(*re), GFP_KERNEL); - if (!re) - return NULL; - - re->logical = logical; - re->top = *top; - INIT_LIST_HEAD(&re->extctl); - spin_lock_init(&re->lock); - re->refcnt = 1; - re->owner_root = owner_root; - re->level = level; - - /* - * map block - */ - length = fs_info->nodesize; - ret = btrfs_map_block(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical, - &length, &bioc, 0); - if (ret || !bioc || length < fs_info->nodesize) - goto error; - - if (bioc->num_stripes > BTRFS_MAX_MIRRORS) { - btrfs_err(fs_info, - "readahead: more than %d copies not supported", - BTRFS_MAX_MIRRORS); - goto error; - } - - real_stripes = bioc->num_stripes - bioc->num_tgtdevs; - for (nzones = 0; nzones < real_stripes; ++nzones) { - struct reada_zone *zone; - - dev = bioc->stripes[nzones].dev; - - /* cannot read ahead on missing device. */ - if (!dev->bdev) - continue; - - zone = reada_find_zone(dev, logical, bioc); - if (!zone) - continue; - - re->zones[re->nzones++] = zone; - spin_lock(&zone->lock); - if (!zone->elems) - kref_get(&zone->refcnt); - ++zone->elems; - spin_unlock(&zone->lock); - spin_lock(&fs_info->reada_lock); - kref_put(&zone->refcnt, reada_zone_release); - spin_unlock(&fs_info->reada_lock); - } - if (re->nzones == 0) { - /* not a single zone found, error and out */ - goto error; - } - - /* Insert extent in reada tree + all per-device trees, all or nothing */ - down_read(&fs_info->dev_replace.rwsem); - ret = radix_tree_preload(GFP_KERNEL); - if (ret) { - up_read(&fs_info->dev_replace.rwsem); - goto error; - } - - spin_lock(&fs_info->reada_lock); - ret = radix_tree_insert(&fs_info->reada_tree, index, re); - if (ret == -EEXIST) { - re_exist = radix_tree_lookup(&fs_info->reada_tree, index); - re_exist->refcnt++; - spin_unlock(&fs_info->reada_lock); - radix_tree_preload_end(); - up_read(&fs_info->dev_replace.rwsem); - goto error; - } - if (ret) { - spin_unlock(&fs_info->reada_lock); - radix_tree_preload_end(); - up_read(&fs_info->dev_replace.rwsem); - goto error; - } - radix_tree_preload_end(); - prev_dev = NULL; - dev_replace_is_ongoing = btrfs_dev_replace_is_ongoing( - &fs_info->dev_replace); - for (nzones = 0; nzones < re->nzones; ++nzones) { - dev = re->zones[nzones]->device; - - if (dev == prev_dev) { - /* - * in case of DUP, just add the first zone. As both - * are on the same device, there's nothing to gain - * from adding both. - * Also, it wouldn't work, as the tree is per device - * and adding would fail with EEXIST - */ - continue; - } - if (!dev->bdev) - continue; - - if (test_bit(BTRFS_DEV_STATE_NO_READA, &dev->dev_state)) - continue; - - if (dev_replace_is_ongoing && - dev == fs_info->dev_replace.tgtdev) { - /* - * as this device is selected for reading only as - * a last resort, skip it for read ahead. - */ - continue; - } - prev_dev = dev; - ret = radix_tree_insert(&dev->reada_extents, index, re); - if (ret) { - while (--nzones >= 0) { - dev = re->zones[nzones]->device; - BUG_ON(dev == NULL); - /* ignore whether the entry was inserted */ - radix_tree_delete(&dev->reada_extents, index); - } - radix_tree_delete(&fs_info->reada_tree, index); - spin_unlock(&fs_info->reada_lock); - up_read(&fs_info->dev_replace.rwsem); - goto error; - } - have_zone = 1; - } - if (!have_zone) - radix_tree_delete(&fs_info->reada_tree, index); - spin_unlock(&fs_info->reada_lock); - up_read(&fs_info->dev_replace.rwsem); - - if (!have_zone) - goto error; - - btrfs_put_bioc(bioc); - return re; - -error: - for (nzones = 0; nzones < re->nzones; ++nzones) { - struct reada_zone *zone; - - zone = re->zones[nzones]; - kref_get(&zone->refcnt); - spin_lock(&zone->lock); - --zone->elems; - if (zone->elems == 0) { - /* - * no fs_info->reada_lock needed, as this can't be - * the last ref - */ - kref_put(&zone->refcnt, reada_zone_release); - } - spin_unlock(&zone->lock); - - spin_lock(&fs_info->reada_lock); - kref_put(&zone->refcnt, reada_zone_release); - spin_unlock(&fs_info->reada_lock); - } - btrfs_put_bioc(bioc); - kfree(re); - return re_exist; -} - -static void reada_extent_put(struct btrfs_fs_info *fs_info, - struct reada_extent *re) -{ - int i; - unsigned long index = re->logical >> fs_info->sectorsize_bits; - - spin_lock(&fs_info->reada_lock); - if (--re->refcnt) { - spin_unlock(&fs_info->reada_lock); - return; - } - - radix_tree_delete(&fs_info->reada_tree, index); - for (i = 0; i < re->nzones; ++i) { - struct reada_zone *zone = re->zones[i]; - - radix_tree_delete(&zone->device->reada_extents, index); - } - - spin_unlock(&fs_info->reada_lock); - - for (i = 0; i < re->nzones; ++i) { - struct reada_zone *zone = re->zones[i]; - - kref_get(&zone->refcnt); - spin_lock(&zone->lock); - --zone->elems; - if (zone->elems == 0) { - /* no fs_info->reada_lock needed, as this can't be - * the last ref */ - kref_put(&zone->refcnt, reada_zone_release); - } - spin_unlock(&zone->lock); - - spin_lock(&fs_info->reada_lock); - kref_put(&zone->refcnt, reada_zone_release); - spin_unlock(&fs_info->reada_lock); - } - - kfree(re); -} - -static void reada_zone_release(struct kref *kref) -{ - struct reada_zone *zone = container_of(kref, struct reada_zone, refcnt); - struct btrfs_fs_info *fs_info = zone->device->fs_info; - - lockdep_assert_held(&fs_info->reada_lock); - - radix_tree_delete(&zone->device->reada_zones, - zone->end >> fs_info->sectorsize_bits); - - kfree(zone); -} - -static void reada_control_release(struct kref *kref) -{ - struct reada_control *rc = container_of(kref, struct reada_control, - refcnt); - - kfree(rc); -} - -static int reada_add_block(struct reada_control *rc, u64 logical, - struct btrfs_key *top, u64 owner_root, - u64 generation, int level) -{ - struct btrfs_fs_info *fs_info = rc->fs_info; - struct reada_extent *re; - struct reada_extctl *rec; - - /* takes one ref */ - re = reada_find_extent(fs_info, logical, top, owner_root, level); - if (!re) - return -1; - - rec = kzalloc(sizeof(*rec), GFP_KERNEL); - if (!rec) { - reada_extent_put(fs_info, re); - return -ENOMEM; - } - - rec->rc = rc; - rec->generation = generation; - atomic_inc(&rc->elems); - - spin_lock(&re->lock); - list_add_tail(&rec->list, &re->extctl); - spin_unlock(&re->lock); - - /* leave the ref on the extent */ - - return 0; -} - -/* - * called with fs_info->reada_lock held - */ -static void reada_peer_zones_set_lock(struct reada_zone *zone, int lock) -{ - int i; - unsigned long index = zone->end >> zone->device->fs_info->sectorsize_bits; - - for (i = 0; i < zone->ndevs; ++i) { - struct reada_zone *peer; - peer = radix_tree_lookup(&zone->devs[i]->reada_zones, index); - if (peer && peer->device != zone->device) - peer->locked = lock; - } -} - -/* - * called with fs_info->reada_lock held - */ -static int reada_pick_zone(struct btrfs_device *dev) -{ - struct reada_zone *top_zone = NULL; - struct reada_zone *top_locked_zone = NULL; - u64 top_elems = 0; - u64 top_locked_elems = 0; - unsigned long index = 0; - int ret; - - if (dev->reada_curr_zone) { - reada_peer_zones_set_lock(dev->reada_curr_zone, 0); - kref_put(&dev->reada_curr_zone->refcnt, reada_zone_release); - dev->reada_curr_zone = NULL; - } - /* pick the zone with the most elements */ - while (1) { - struct reada_zone *zone; - - ret = radix_tree_gang_lookup(&dev->reada_zones, - (void **)&zone, index, 1); - if (ret == 0) - break; - index = (zone->end >> dev->fs_info->sectorsize_bits) + 1; - if (zone->locked) { - if (zone->elems > top_locked_elems) { - top_locked_elems = zone->elems; - top_locked_zone = zone; - } - } else { - if (zone->elems > top_elems) { - top_elems = zone->elems; - top_zone = zone; - } - } - } - if (top_zone) - dev->reada_curr_zone = top_zone; - else if (top_locked_zone) - dev->reada_curr_zone = top_locked_zone; - else - return 0; - - dev->reada_next = dev->reada_curr_zone->start; - kref_get(&dev->reada_curr_zone->refcnt); - reada_peer_zones_set_lock(dev->reada_curr_zone, 1); - - return 1; -} - -static int reada_tree_block_flagged(struct btrfs_fs_info *fs_info, u64 bytenr, - u64 owner_root, int level, int mirror_num, - struct extent_buffer **eb) -{ - struct extent_buffer *buf = NULL; - int ret; - - buf = btrfs_find_create_tree_block(fs_info, bytenr, owner_root, level); - if (IS_ERR(buf)) - return 0; - - set_bit(EXTENT_BUFFER_READAHEAD, &buf->bflags); - - ret = read_extent_buffer_pages(buf, WAIT_PAGE_LOCK, mirror_num); - if (ret) { - free_extent_buffer_stale(buf); - return ret; - } - - if (test_bit(EXTENT_BUFFER_CORRUPT, &buf->bflags)) { - free_extent_buffer_stale(buf); - return -EIO; - } else if (extent_buffer_uptodate(buf)) { - *eb = buf; - } else { - free_extent_buffer(buf); - } - return 0; -} - -static int reada_start_machine_dev(struct btrfs_device *dev) -{ - struct btrfs_fs_info *fs_info = dev->fs_info; - struct reada_extent *re = NULL; - int mirror_num = 0; - struct extent_buffer *eb = NULL; - u64 logical; - int ret; - int i; - - spin_lock(&fs_info->reada_lock); - if (dev->reada_curr_zone == NULL) { - ret = reada_pick_zone(dev); - if (!ret) { - spin_unlock(&fs_info->reada_lock); - return 0; - } - } - /* - * FIXME currently we issue the reads one extent at a time. If we have - * a contiguous block of extents, we could also coagulate them or use - * plugging to speed things up - */ - ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re, - dev->reada_next >> fs_info->sectorsize_bits, 1); - if (ret == 0 || re->logical > dev->reada_curr_zone->end) { - ret = reada_pick_zone(dev); - if (!ret) { - spin_unlock(&fs_info->reada_lock); - return 0; - } - re = NULL; - ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re, - dev->reada_next >> fs_info->sectorsize_bits, 1); - } - if (ret == 0) { - spin_unlock(&fs_info->reada_lock); - return 0; - } - dev->reada_next = re->logical + fs_info->nodesize; - re->refcnt++; - - spin_unlock(&fs_info->reada_lock); - - spin_lock(&re->lock); - if (re->scheduled || list_empty(&re->extctl)) { - spin_unlock(&re->lock); - reada_extent_put(fs_info, re); - return 0; - } - re->scheduled = 1; - spin_unlock(&re->lock); - - /* - * find mirror num - */ - for (i = 0; i < re->nzones; ++i) { - if (re->zones[i]->device == dev) { - mirror_num = i + 1; - break; - } - } - logical = re->logical; - - atomic_inc(&dev->reada_in_flight); - ret = reada_tree_block_flagged(fs_info, logical, re->owner_root, - re->level, mirror_num, &eb); - if (ret) - __readahead_hook(fs_info, re, NULL, ret); - else if (eb) - __readahead_hook(fs_info, re, eb, ret); - - if (eb) - free_extent_buffer(eb); - - atomic_dec(&dev->reada_in_flight); - reada_extent_put(fs_info, re); - - return 1; - -} - -static void reada_start_machine_worker(struct btrfs_work *work) -{ - struct reada_machine_work *rmw; - int old_ioprio; - - rmw = container_of(work, struct reada_machine_work, work); - - old_ioprio = IOPRIO_PRIO_VALUE(task_nice_ioclass(current), - task_nice_ioprio(current)); - set_task_ioprio(current, BTRFS_IOPRIO_READA); - __reada_start_machine(rmw->fs_info); - set_task_ioprio(current, old_ioprio); - - atomic_dec(&rmw->fs_info->reada_works_cnt); - - kfree(rmw); -} - -/* Try to start up to 10k READA requests for a group of devices */ -static int reada_start_for_fsdevs(struct btrfs_fs_devices *fs_devices) -{ - u64 enqueued; - u64 total = 0; - struct btrfs_device *device; - - do { - enqueued = 0; - list_for_each_entry(device, &fs_devices->devices, dev_list) { - if (atomic_read(&device->reada_in_flight) < - MAX_IN_FLIGHT) - enqueued += reada_start_machine_dev(device); - } - total += enqueued; - } while (enqueued && total < 10000); - - return total; -} - -static void __reada_start_machine(struct btrfs_fs_info *fs_info) -{ - struct btrfs_fs_devices *fs_devices = fs_info->fs_devices, *seed_devs; - int i; - u64 enqueued = 0; - - mutex_lock(&fs_devices->device_list_mutex); - - enqueued += reada_start_for_fsdevs(fs_devices); - list_for_each_entry(seed_devs, &fs_devices->seed_list, seed_list) - enqueued += reada_start_for_fsdevs(seed_devs); - - mutex_unlock(&fs_devices->device_list_mutex); - if (enqueued == 0) - return; - - /* - * If everything is already in the cache, this is effectively single - * threaded. To a) not hold the caller for too long and b) to utilize - * more cores, we broke the loop above after 10000 iterations and now - * enqueue to workers to finish it. This will distribute the load to - * the cores. - */ - for (i = 0; i < 2; ++i) { - reada_start_machine(fs_info); - if (atomic_read(&fs_info->reada_works_cnt) > - BTRFS_MAX_MIRRORS * 2) - break; - } -} - -static void reada_start_machine(struct btrfs_fs_info *fs_info) -{ - struct reada_machine_work *rmw; - - rmw = kzalloc(sizeof(*rmw), GFP_KERNEL); - if (!rmw) { - /* FIXME we cannot handle this properly right now */ - BUG(); - } - btrfs_init_work(&rmw->work, reada_start_machine_worker, NULL, NULL); - rmw->fs_info = fs_info; - - btrfs_queue_work(fs_info->readahead_workers, &rmw->work); - atomic_inc(&fs_info->reada_works_cnt); -} - -#ifdef DEBUG -static void dump_devs(struct btrfs_fs_info *fs_info, int all) -{ - struct btrfs_device *device; - struct btrfs_fs_devices *fs_devices = fs_info->fs_devices; - unsigned long index; - int ret; - int i; - int j; - int cnt; - - spin_lock(&fs_info->reada_lock); - list_for_each_entry(device, &fs_devices->devices, dev_list) { - btrfs_debug(fs_info, "dev %lld has %d in flight", device->devid, - atomic_read(&device->reada_in_flight)); - index = 0; - while (1) { - struct reada_zone *zone; - ret = radix_tree_gang_lookup(&device->reada_zones, - (void **)&zone, index, 1); - if (ret == 0) - break; - pr_debug(" zone %llu-%llu elems %llu locked %d devs", - zone->start, zone->end, zone->elems, - zone->locked); - for (j = 0; j < zone->ndevs; ++j) { - pr_cont(" %lld", - zone->devs[j]->devid); - } - if (device->reada_curr_zone == zone) - pr_cont(" curr off %llu", - device->reada_next - zone->start); - pr_cont("\n"); - index = (zone->end >> fs_info->sectorsize_bits) + 1; - } - cnt = 0; - index = 0; - while (all) { - struct reada_extent *re = NULL; - - ret = radix_tree_gang_lookup(&device->reada_extents, - (void **)&re, index, 1); - if (ret == 0) - break; - pr_debug(" re: logical %llu size %u empty %d scheduled %d", - re->logical, fs_info->nodesize, - list_empty(&re->extctl), re->scheduled); - - for (i = 0; i < re->nzones; ++i) { - pr_cont(" zone %llu-%llu devs", - re->zones[i]->start, - re->zones[i]->end); - for (j = 0; j < re->zones[i]->ndevs; ++j) { - pr_cont(" %lld", - re->zones[i]->devs[j]->devid); - } - } - pr_cont("\n"); - index = (re->logical >> fs_info->sectorsize_bits) + 1; - if (++cnt > 15) - break; - } - } - - index = 0; - cnt = 0; - while (all) { - struct reada_extent *re = NULL; - - ret = radix_tree_gang_lookup(&fs_info->reada_tree, (void **)&re, - index, 1); - if (ret == 0) - break; - if (!re->scheduled) { - index = (re->logical >> fs_info->sectorsize_bits) + 1; - continue; - } - pr_debug("re: logical %llu size %u list empty %d scheduled %d", - re->logical, fs_info->nodesize, - list_empty(&re->extctl), re->scheduled); - for (i = 0; i < re->nzones; ++i) { - pr_cont(" zone %llu-%llu devs", - re->zones[i]->start, - re->zones[i]->end); - for (j = 0; j < re->zones[i]->ndevs; ++j) { - pr_cont(" %lld", - re->zones[i]->devs[j]->devid); - } - } - pr_cont("\n"); - index = (re->logical >> fs_info->sectorsize_bits) + 1; - } - spin_unlock(&fs_info->reada_lock); -} -#endif - -/* - * interface - */ -struct reada_control *btrfs_reada_add(struct btrfs_root *root, - struct btrfs_key *key_start, struct btrfs_key *key_end) -{ - struct reada_control *rc; - u64 start; - u64 generation; - int ret; - int level; - struct extent_buffer *node; - static struct btrfs_key max_key = { - .objectid = (u64)-1, - .type = (u8)-1, - .offset = (u64)-1 - }; - - rc = kzalloc(sizeof(*rc), GFP_KERNEL); - if (!rc) - return ERR_PTR(-ENOMEM); - - rc->fs_info = root->fs_info; - rc->key_start = *key_start; - rc->key_end = *key_end; - atomic_set(&rc->elems, 0); - init_waitqueue_head(&rc->wait); - kref_init(&rc->refcnt); - kref_get(&rc->refcnt); /* one ref for having elements */ - - node = btrfs_root_node(root); - start = node->start; - generation = btrfs_header_generation(node); - level = btrfs_header_level(node); - free_extent_buffer(node); - - ret = reada_add_block(rc, start, &max_key, root->root_key.objectid, - generation, level); - if (ret) { - kfree(rc); - return ERR_PTR(ret); - } - - reada_start_machine(root->fs_info); - - return rc; -} - -#ifdef DEBUG -int btrfs_reada_wait(void *handle) -{ - struct reada_control *rc = handle; - struct btrfs_fs_info *fs_info = rc->fs_info; - - while (atomic_read(&rc->elems)) { - if (!atomic_read(&fs_info->reada_works_cnt)) - reada_start_machine(fs_info); - wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0, - 5 * HZ); - dump_devs(fs_info, atomic_read(&rc->elems) < 10 ? 1 : 0); - } - - dump_devs(fs_info, atomic_read(&rc->elems) < 10 ? 1 : 0); - - kref_put(&rc->refcnt, reada_control_release); - - return 0; -} -#else -int btrfs_reada_wait(void *handle) -{ - struct reada_control *rc = handle; - struct btrfs_fs_info *fs_info = rc->fs_info; - - while (atomic_read(&rc->elems)) { - if (!atomic_read(&fs_info->reada_works_cnt)) - reada_start_machine(fs_info); - wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0, - (HZ + 9) / 10); - } - - kref_put(&rc->refcnt, reada_control_release); - - return 0; -} -#endif - -void btrfs_reada_detach(void *handle) -{ - struct reada_control *rc = handle; - - kref_put(&rc->refcnt, reada_control_release); -} - -/* - * Before removing a device (device replace or device remove ioctls), call this - * function to wait for all existing readahead requests on the device and to - * make sure no one queues more readahead requests for the device. - * - * Must be called without holding neither the device list mutex nor the device - * replace semaphore, otherwise it will deadlock. - */ -void btrfs_reada_remove_dev(struct btrfs_device *dev) -{ - struct btrfs_fs_info *fs_info = dev->fs_info; - - /* Serialize with readahead extent creation at reada_find_extent(). */ - spin_lock(&fs_info->reada_lock); - set_bit(BTRFS_DEV_STATE_NO_READA, &dev->dev_state); - spin_unlock(&fs_info->reada_lock); - - /* - * There might be readahead requests added to the radix trees which - * were not yet added to the readahead work queue. We need to start - * them and wait for their completion, otherwise we can end up with - * use-after-free problems when dropping the last reference on the - * readahead extents and their zones, as they need to access the - * device structure. - */ - reada_start_machine(fs_info); - btrfs_flush_workqueue(fs_info->readahead_workers); -} - -/* - * If when removing a device (device replace or device remove ioctls) an error - * happens after calling btrfs_reada_remove_dev(), call this to undo what that - * function did. This is safe to call even if btrfs_reada_remove_dev() was not - * called before. - */ -void btrfs_reada_undo_remove_dev(struct btrfs_device *dev) -{ - spin_lock(&dev->fs_info->reada_lock); - clear_bit(BTRFS_DEV_STATE_NO_READA, &dev->dev_state); - spin_unlock(&dev->fs_info->reada_lock); -} |