+++ /dev/null
-// 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);
-}
projects / linux.git / commitdiff