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-rw-r--r--drivers/md/bcache/request.c1411
1 files changed, 1411 insertions, 0 deletions
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
new file mode 100644
index 00000000000..e5ff12e52d5
--- /dev/null
+++ b/drivers/md/bcache/request.c
@@ -0,0 +1,1411 @@
+/*
+ * Main bcache entry point - handle a read or a write request and decide what to
+ * do with it; the make_request functions are called by the block layer.
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+#include "debug.h"
+#include "request.h"
+
+#include <linux/cgroup.h>
+#include <linux/module.h>
+#include <linux/hash.h>
+#include <linux/random.h>
+#include "blk-cgroup.h"
+
+#include <trace/events/bcache.h>
+
+#define CUTOFF_CACHE_ADD 95
+#define CUTOFF_CACHE_READA 90
+#define CUTOFF_WRITEBACK 50
+#define CUTOFF_WRITEBACK_SYNC 75
+
+struct kmem_cache *bch_search_cache;
+
+static void check_should_skip(struct cached_dev *, struct search *);
+
+/* Cgroup interface */
+
+#ifdef CONFIG_CGROUP_BCACHE
+static struct bch_cgroup bcache_default_cgroup = { .cache_mode = -1 };
+
+static struct bch_cgroup *cgroup_to_bcache(struct cgroup *cgroup)
+{
+ struct cgroup_subsys_state *css;
+ return cgroup &&
+ (css = cgroup_subsys_state(cgroup, bcache_subsys_id))
+ ? container_of(css, struct bch_cgroup, css)
+ : &bcache_default_cgroup;
+}
+
+struct bch_cgroup *bch_bio_to_cgroup(struct bio *bio)
+{
+ struct cgroup_subsys_state *css = bio->bi_css
+ ? cgroup_subsys_state(bio->bi_css->cgroup, bcache_subsys_id)
+ : task_subsys_state(current, bcache_subsys_id);
+
+ return css
+ ? container_of(css, struct bch_cgroup, css)
+ : &bcache_default_cgroup;
+}
+
+static ssize_t cache_mode_read(struct cgroup *cgrp, struct cftype *cft,
+ struct file *file,
+ char __user *buf, size_t nbytes, loff_t *ppos)
+{
+ char tmp[1024];
+ int len = bch_snprint_string_list(tmp, PAGE_SIZE, bch_cache_modes,
+ cgroup_to_bcache(cgrp)->cache_mode + 1);
+
+ if (len < 0)
+ return len;
+
+ return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);
+}
+
+static int cache_mode_write(struct cgroup *cgrp, struct cftype *cft,
+ const char *buf)
+{
+ int v = bch_read_string_list(buf, bch_cache_modes);
+ if (v < 0)
+ return v;
+
+ cgroup_to_bcache(cgrp)->cache_mode = v - 1;
+ return 0;
+}
+
+static u64 bch_verify_read(struct cgroup *cgrp, struct cftype *cft)
+{
+ return cgroup_to_bcache(cgrp)->verify;
+}
+
+static int bch_verify_write(struct cgroup *cgrp, struct cftype *cft, u64 val)
+{
+ cgroup_to_bcache(cgrp)->verify = val;
+ return 0;
+}
+
+static u64 bch_cache_hits_read(struct cgroup *cgrp, struct cftype *cft)
+{
+ struct bch_cgroup *bcachecg = cgroup_to_bcache(cgrp);
+ return atomic_read(&bcachecg->stats.cache_hits);
+}
+
+static u64 bch_cache_misses_read(struct cgroup *cgrp, struct cftype *cft)
+{
+ struct bch_cgroup *bcachecg = cgroup_to_bcache(cgrp);
+ return atomic_read(&bcachecg->stats.cache_misses);
+}
+
+static u64 bch_cache_bypass_hits_read(struct cgroup *cgrp,
+ struct cftype *cft)
+{
+ struct bch_cgroup *bcachecg = cgroup_to_bcache(cgrp);
+ return atomic_read(&bcachecg->stats.cache_bypass_hits);
+}
+
+static u64 bch_cache_bypass_misses_read(struct cgroup *cgrp,
+ struct cftype *cft)
+{
+ struct bch_cgroup *bcachecg = cgroup_to_bcache(cgrp);
+ return atomic_read(&bcachecg->stats.cache_bypass_misses);
+}
+
+static struct cftype bch_files[] = {
+ {
+ .name = "cache_mode",
+ .read = cache_mode_read,
+ .write_string = cache_mode_write,
+ },
+ {
+ .name = "verify",
+ .read_u64 = bch_verify_read,
+ .write_u64 = bch_verify_write,
+ },
+ {
+ .name = "cache_hits",
+ .read_u64 = bch_cache_hits_read,
+ },
+ {
+ .name = "cache_misses",
+ .read_u64 = bch_cache_misses_read,
+ },
+ {
+ .name = "cache_bypass_hits",
+ .read_u64 = bch_cache_bypass_hits_read,
+ },
+ {
+ .name = "cache_bypass_misses",
+ .read_u64 = bch_cache_bypass_misses_read,
+ },
+ { } /* terminate */
+};
+
+static void init_bch_cgroup(struct bch_cgroup *cg)
+{
+ cg->cache_mode = -1;
+}
+
+static struct cgroup_subsys_state *bcachecg_create(struct cgroup *cgroup)
+{
+ struct bch_cgroup *cg;
+
+ cg = kzalloc(sizeof(*cg), GFP_KERNEL);
+ if (!cg)
+ return ERR_PTR(-ENOMEM);
+ init_bch_cgroup(cg);
+ return &cg->css;
+}
+
+static void bcachecg_destroy(struct cgroup *cgroup)
+{
+ struct bch_cgroup *cg = cgroup_to_bcache(cgroup);
+ free_css_id(&bcache_subsys, &cg->css);
+ kfree(cg);
+}
+
+struct cgroup_subsys bcache_subsys = {
+ .create = bcachecg_create,
+ .destroy = bcachecg_destroy,
+ .subsys_id = bcache_subsys_id,
+ .name = "bcache",
+ .module = THIS_MODULE,
+};
+EXPORT_SYMBOL_GPL(bcache_subsys);
+#endif
+
+static unsigned cache_mode(struct cached_dev *dc, struct bio *bio)
+{
+#ifdef CONFIG_CGROUP_BCACHE
+ int r = bch_bio_to_cgroup(bio)->cache_mode;
+ if (r >= 0)
+ return r;
+#endif
+ return BDEV_CACHE_MODE(&dc->sb);
+}
+
+static bool verify(struct cached_dev *dc, struct bio *bio)
+{
+#ifdef CONFIG_CGROUP_BCACHE
+ if (bch_bio_to_cgroup(bio)->verify)
+ return true;
+#endif
+ return dc->verify;
+}
+
+static void bio_csum(struct bio *bio, struct bkey *k)
+{
+ struct bio_vec *bv;
+ uint64_t csum = 0;
+ int i;
+
+ bio_for_each_segment(bv, bio, i) {
+ void *d = kmap(bv->bv_page) + bv->bv_offset;
+ csum = bch_crc64_update(csum, d, bv->bv_len);
+ kunmap(bv->bv_page);
+ }
+
+ k->ptr[KEY_PTRS(k)] = csum & (~0ULL >> 1);
+}
+
+/* Insert data into cache */
+
+static void bio_invalidate(struct closure *cl)
+{
+ struct btree_op *op = container_of(cl, struct btree_op, cl);
+ struct bio *bio = op->cache_bio;
+
+ pr_debug("invalidating %i sectors from %llu",
+ bio_sectors(bio), (uint64_t) bio->bi_sector);
+
+ while (bio_sectors(bio)) {
+ unsigned len = min(bio_sectors(bio), 1U << 14);
+
+ if (bch_keylist_realloc(&op->keys, 0, op->c))
+ goto out;
+
+ bio->bi_sector += len;
+ bio->bi_size -= len << 9;
+
+ bch_keylist_add(&op->keys,
+ &KEY(op->inode, bio->bi_sector, len));
+ }
+
+ op->insert_data_done = true;
+ bio_put(bio);
+out:
+ continue_at(cl, bch_journal, bcache_wq);
+}
+
+struct open_bucket {
+ struct list_head list;
+ struct task_struct *last;
+ unsigned sectors_free;
+ BKEY_PADDED(key);
+};
+
+void bch_open_buckets_free(struct cache_set *c)
+{
+ struct open_bucket *b;
+
+ while (!list_empty(&c->data_buckets)) {
+ b = list_first_entry(&c->data_buckets,
+ struct open_bucket, list);
+ list_del(&b->list);
+ kfree(b);
+ }
+}
+
+int bch_open_buckets_alloc(struct cache_set *c)
+{
+ int i;
+
+ spin_lock_init(&c->data_bucket_lock);
+
+ for (i = 0; i < 6; i++) {
+ struct open_bucket *b = kzalloc(sizeof(*b), GFP_KERNEL);
+ if (!b)
+ return -ENOMEM;
+
+ list_add(&b->list, &c->data_buckets);
+ }
+
+ return 0;
+}
+
+/*
+ * We keep multiple buckets open for writes, and try to segregate different
+ * write streams for better cache utilization: first we look for a bucket where
+ * the last write to it was sequential with the current write, and failing that
+ * we look for a bucket that was last used by the same task.
+ *
+ * The ideas is if you've got multiple tasks pulling data into the cache at the
+ * same time, you'll get better cache utilization if you try to segregate their
+ * data and preserve locality.
+ *
+ * For example, say you've starting Firefox at the same time you're copying a
+ * bunch of files. Firefox will likely end up being fairly hot and stay in the
+ * cache awhile, but the data you copied might not be; if you wrote all that
+ * data to the same buckets it'd get invalidated at the same time.
+ *
+ * Both of those tasks will be doing fairly random IO so we can't rely on
+ * detecting sequential IO to segregate their data, but going off of the task
+ * should be a sane heuristic.
+ */
+static struct open_bucket *pick_data_bucket(struct cache_set *c,
+ const struct bkey *search,
+ struct task_struct *task,
+ struct bkey *alloc)
+{
+ struct open_bucket *ret, *ret_task = NULL;
+
+ list_for_each_entry_reverse(ret, &c->data_buckets, list)
+ if (!bkey_cmp(&ret->key, search))
+ goto found;
+ else if (ret->last == task)
+ ret_task = ret;
+
+ ret = ret_task ?: list_first_entry(&c->data_buckets,
+ struct open_bucket, list);
+found:
+ if (!ret->sectors_free && KEY_PTRS(alloc)) {
+ ret->sectors_free = c->sb.bucket_size;
+ bkey_copy(&ret->key, alloc);
+ bkey_init(alloc);
+ }
+
+ if (!ret->sectors_free)
+ ret = NULL;
+
+ return ret;
+}
+
+/*
+ * Allocates some space in the cache to write to, and k to point to the newly
+ * allocated space, and updates KEY_SIZE(k) and KEY_OFFSET(k) (to point to the
+ * end of the newly allocated space).
+ *
+ * May allocate fewer sectors than @sectors, KEY_SIZE(k) indicates how many
+ * sectors were actually allocated.
+ *
+ * If s->writeback is true, will not fail.
+ */
+static bool bch_alloc_sectors(struct bkey *k, unsigned sectors,
+ struct search *s)
+{
+ struct cache_set *c = s->op.c;
+ struct open_bucket *b;
+ BKEY_PADDED(key) alloc;
+ struct closure cl, *w = NULL;
+ unsigned i;
+
+ if (s->writeback) {
+ closure_init_stack(&cl);
+ w = &cl;
+ }
+
+ /*
+ * We might have to allocate a new bucket, which we can't do with a
+ * spinlock held. So if we have to allocate, we drop the lock, allocate
+ * and then retry. KEY_PTRS() indicates whether alloc points to
+ * allocated bucket(s).
+ */
+
+ bkey_init(&alloc.key);
+ spin_lock(&c->data_bucket_lock);
+
+ while (!(b = pick_data_bucket(c, k, s->task, &alloc.key))) {
+ unsigned watermark = s->op.write_prio
+ ? WATERMARK_MOVINGGC
+ : WATERMARK_NONE;
+
+ spin_unlock(&c->data_bucket_lock);
+
+ if (bch_bucket_alloc_set(c, watermark, &alloc.key, 1, w))
+ return false;
+
+ spin_lock(&c->data_bucket_lock);
+ }
+
+ /*
+ * If we had to allocate, we might race and not need to allocate the
+ * second time we call find_data_bucket(). If we allocated a bucket but
+ * didn't use it, drop the refcount bch_bucket_alloc_set() took:
+ */
+ if (KEY_PTRS(&alloc.key))
+ __bkey_put(c, &alloc.key);
+
+ for (i = 0; i < KEY_PTRS(&b->key); i++)
+ EBUG_ON(ptr_stale(c, &b->key, i));
+
+ /* Set up the pointer to the space we're allocating: */
+
+ for (i = 0; i < KEY_PTRS(&b->key); i++)
+ k->ptr[i] = b->key.ptr[i];
+
+ sectors = min(sectors, b->sectors_free);
+
+ SET_KEY_OFFSET(k, KEY_OFFSET(k) + sectors);
+ SET_KEY_SIZE(k, sectors);
+ SET_KEY_PTRS(k, KEY_PTRS(&b->key));
+
+ /*
+ * Move b to the end of the lru, and keep track of what this bucket was
+ * last used for:
+ */
+ list_move_tail(&b->list, &c->data_buckets);
+ bkey_copy_key(&b->key, k);
+ b->last = s->task;
+
+ b->sectors_free -= sectors;
+
+ for (i = 0; i < KEY_PTRS(&b->key); i++) {
+ SET_PTR_OFFSET(&b->key, i, PTR_OFFSET(&b->key, i) + sectors);
+
+ atomic_long_add(sectors,
+ &PTR_CACHE(c, &b->key, i)->sectors_written);
+ }
+
+ if (b->sectors_free < c->sb.block_size)
+ b->sectors_free = 0;
+
+ /*
+ * k takes refcounts on the buckets it points to until it's inserted
+ * into the btree, but if we're done with this bucket we just transfer
+ * get_data_bucket()'s refcount.
+ */
+ if (b->sectors_free)
+ for (i = 0; i < KEY_PTRS(&b->key); i++)
+ atomic_inc(&PTR_BUCKET(c, &b->key, i)->pin);
+
+ spin_unlock(&c->data_bucket_lock);
+ return true;
+}
+
+static void bch_insert_data_error(struct closure *cl)
+{
+ struct btree_op *op = container_of(cl, struct btree_op, cl);
+
+ /*
+ * Our data write just errored, which means we've got a bunch of keys to
+ * insert that point to data that wasn't succesfully written.
+ *
+ * We don't have to insert those keys but we still have to invalidate
+ * that region of the cache - so, if we just strip off all the pointers
+ * from the keys we'll accomplish just that.
+ */
+
+ struct bkey *src = op->keys.bottom, *dst = op->keys.bottom;
+
+ while (src != op->keys.top) {
+ struct bkey *n = bkey_next(src);
+
+ SET_KEY_PTRS(src, 0);
+ bkey_copy(dst, src);
+
+ dst = bkey_next(dst);
+ src = n;
+ }
+
+ op->keys.top = dst;
+
+ bch_journal(cl);
+}
+
+static void bch_insert_data_endio(struct bio *bio, int error)
+{
+ struct closure *cl = bio->bi_private;
+ struct btree_op *op = container_of(cl, struct btree_op, cl);
+ struct search *s = container_of(op, struct search, op);
+
+ if (error) {
+ /* TODO: We could try to recover from this. */
+ if (s->writeback)
+ s->error = error;
+ else if (s->write)
+ set_closure_fn(cl, bch_insert_data_error, bcache_wq);
+ else
+ set_closure_fn(cl, NULL, NULL);
+ }
+
+ bch_bbio_endio(op->c, bio, error, "writing data to cache");
+}
+
+static void bch_insert_data_loop(struct closure *cl)
+{
+ struct btree_op *op = container_of(cl, struct btree_op, cl);
+ struct search *s = container_of(op, struct search, op);
+ struct bio *bio = op->cache_bio, *n;
+
+ if (op->skip)
+ return bio_invalidate(cl);
+
+ if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0) {
+ set_gc_sectors(op->c);
+ bch_queue_gc(op->c);
+ }
+
+ do {
+ unsigned i;
+ struct bkey *k;
+ struct bio_set *split = s->d
+ ? s->d->bio_split : op->c->bio_split;
+
+ /* 1 for the device pointer and 1 for the chksum */
+ if (bch_keylist_realloc(&op->keys,
+ 1 + (op->csum ? 1 : 0),
+ op->c))
+ continue_at(cl, bch_journal, bcache_wq);
+
+ k = op->keys.top;
+ bkey_init(k);
+ SET_KEY_INODE(k, op->inode);
+ SET_KEY_OFFSET(k, bio->bi_sector);
+
+ if (!bch_alloc_sectors(k, bio_sectors(bio), s))
+ goto err;
+
+ n = bch_bio_split(bio, KEY_SIZE(k), GFP_NOIO, split);
+ if (!n) {
+ __bkey_put(op->c, k);
+ continue_at(cl, bch_insert_data_loop, bcache_wq);
+ }
+
+ n->bi_end_io = bch_insert_data_endio;
+ n->bi_private = cl;
+
+ if (s->writeback) {
+ SET_KEY_DIRTY(k, true);
+
+ for (i = 0; i < KEY_PTRS(k); i++)
+ SET_GC_MARK(PTR_BUCKET(op->c, k, i),
+ GC_MARK_DIRTY);
+ }
+
+ SET_KEY_CSUM(k, op->csum);
+ if (KEY_CSUM(k))
+ bio_csum(n, k);
+
+ pr_debug("%s", pkey(k));
+ bch_keylist_push(&op->keys);
+
+ trace_bcache_cache_insert(n, n->bi_sector, n->bi_bdev);
+ n->bi_rw |= REQ_WRITE;
+ bch_submit_bbio(n, op->c, k, 0);
+ } while (n != bio);
+
+ op->insert_data_done = true;
+ continue_at(cl, bch_journal, bcache_wq);
+err:
+ /* bch_alloc_sectors() blocks if s->writeback = true */
+ BUG_ON(s->writeback);
+
+ /*
+ * But if it's not a writeback write we'd rather just bail out if
+ * there aren't any buckets ready to write to - it might take awhile and
+ * we might be starving btree writes for gc or something.
+ */
+
+ if (s->write) {
+ /*
+ * Writethrough write: We can't complete the write until we've
+ * updated the index. But we don't want to delay the write while
+ * we wait for buckets to be freed up, so just invalidate the
+ * rest of the write.
+ */
+ op->skip = true;
+ return bio_invalidate(cl);
+ } else {
+ /*
+ * From a cache miss, we can just insert the keys for the data
+ * we have written or bail out if we didn't do anything.
+ */
+ op->insert_data_done = true;
+ bio_put(bio);
+
+ if (!bch_keylist_empty(&op->keys))
+ continue_at(cl, bch_journal, bcache_wq);
+ else
+ closure_return(cl);
+ }
+}
+
+/**
+ * bch_insert_data - stick some data in the cache
+ *
+ * This is the starting point for any data to end up in a cache device; it could
+ * be from a normal write, or a writeback write, or a write to a flash only
+ * volume - it's also used by the moving garbage collector to compact data in
+ * mostly empty buckets.
+ *
+ * It first writes the data to the cache, creating a list of keys to be inserted
+ * (if the data had to be fragmented there will be multiple keys); after the
+ * data is written it calls bch_journal, and after the keys have been added to
+ * the next journal write they're inserted into the btree.
+ *
+ * It inserts the data in op->cache_bio; bi_sector is used for the key offset,
+ * and op->inode is used for the key inode.
+ *
+ * If op->skip is true, instead of inserting the data it invalidates the region
+ * of the cache represented by op->cache_bio and op->inode.
+ */
+void bch_insert_data(struct closure *cl)
+{
+ struct btree_op *op = container_of(cl, struct btree_op, cl);
+
+ bch_keylist_init(&op->keys);
+ bio_get(op->cache_bio);
+ bch_insert_data_loop(cl);
+}
+
+void bch_btree_insert_async(struct closure *cl)
+{
+ struct btree_op *op = container_of(cl, struct btree_op, cl);
+ struct search *s = container_of(op, struct search, op);
+
+ if (bch_btree_insert(op, op->c)) {
+ s->error = -ENOMEM;
+ op->insert_data_done = true;
+ }
+
+ if (op->insert_data_done) {
+ bch_keylist_free(&op->keys);
+ closure_return(cl);
+ } else
+ continue_at(cl, bch_insert_data_loop, bcache_wq);
+}
+
+/* Common code for the make_request functions */
+
+static void request_endio(struct bio *bio, int error)
+{
+ struct closure *cl = bio->bi_private;
+
+ if (error) {
+ struct search *s = container_of(cl, struct search, cl);
+ s->error = error;
+ /* Only cache read errors are recoverable */
+ s->recoverable = false;
+ }
+
+ bio_put(bio);
+ closure_put(cl);
+}
+
+void bch_cache_read_endio(struct bio *bio, int error)
+{
+ struct bbio *b = container_of(bio, struct bbio, bio);
+ struct closure *cl = bio->bi_private;
+ struct search *s = container_of(cl, struct search, cl);
+
+ /*
+ * If the bucket was reused while our bio was in flight, we might have
+ * read the wrong data. Set s->error but not error so it doesn't get
+ * counted against the cache device, but we'll still reread the data
+ * from the backing device.
+ */
+
+ if (error)
+ s->error = error;
+ else if (ptr_stale(s->op.c, &b->key, 0)) {
+ atomic_long_inc(&s->op.c->cache_read_races);
+ s->error = -EINTR;
+ }
+
+ bch_bbio_endio(s->op.c, bio, error, "reading from cache");
+}
+
+static void bio_complete(struct search *s)
+{
+ if (s->orig_bio) {
+ int cpu, rw = bio_data_dir(s->orig_bio);
+ unsigned long duration = jiffies - s->start_time;
+
+ cpu = part_stat_lock();
+ part_round_stats(cpu, &s->d->disk->part0);
+ part_stat_add(cpu, &s->d->disk->part0, ticks[rw], duration);
+ part_stat_unlock();
+
+ trace_bcache_request_end(s, s->orig_bio);
+ bio_endio(s->orig_bio, s->error);
+ s->orig_bio = NULL;
+ }
+}
+
+static void do_bio_hook(struct search *s)
+{
+ struct bio *bio = &s->bio.bio;
+ memcpy(bio, s->orig_bio, sizeof(struct bio));
+
+ bio->bi_end_io = request_endio;
+ bio->bi_private = &s->cl;
+ atomic_set(&bio->bi_cnt, 3);
+}
+
+static void search_free(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ bio_complete(s);
+
+ if (s->op.cache_bio)
+ bio_put(s->op.cache_bio);
+
+ if (s->unaligned_bvec)
+ mempool_free(s->bio.bio.bi_io_vec, s->d->unaligned_bvec);
+
+ closure_debug_destroy(cl);
+ mempool_free(s, s->d->c->search);
+}
+
+static struct search *search_alloc(struct bio *bio, struct bcache_device *d)
+{
+ struct bio_vec *bv;
+ struct search *s = mempool_alloc(d->c->search, GFP_NOIO);
+ memset(s, 0, offsetof(struct search, op.keys));
+
+ __closure_init(&s->cl, NULL);
+
+ s->op.inode = d->id;
+ s->op.c = d->c;
+ s->d = d;
+ s->op.lock = -1;
+ s->task = current;
+ s->orig_bio = bio;
+ s->write = (bio->bi_rw & REQ_WRITE) != 0;
+ s->op.flush_journal = (bio->bi_rw & REQ_FLUSH) != 0;
+ s->op.skip = (bio->bi_rw & REQ_DISCARD) != 0;
+ s->recoverable = 1;
+ s->start_time = jiffies;
+ do_bio_hook(s);
+
+ if (bio->bi_size != bio_segments(bio) * PAGE_SIZE) {
+ bv = mempool_alloc(d->unaligned_bvec, GFP_NOIO);
+ memcpy(bv, bio_iovec(bio),
+ sizeof(struct bio_vec) * bio_segments(bio));
+
+ s->bio.bio.bi_io_vec = bv;
+ s->unaligned_bvec = 1;
+ }
+
+ return s;
+}
+
+static void btree_read_async(struct closure *cl)
+{
+ struct btree_op *op = container_of(cl, struct btree_op, cl);
+
+ int ret = btree_root(search_recurse, op->c, op);
+
+ if (ret == -EAGAIN)
+ continue_at(cl, btree_read_async, bcache_wq);
+
+ closure_return(cl);
+}
+
+/* Cached devices */
+
+static void cached_dev_bio_complete(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+
+ search_free(cl);
+ cached_dev_put(dc);
+}
+
+/* Process reads */
+
+static void cached_dev_read_complete(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+
+ if (s->op.insert_collision)
+ bch_mark_cache_miss_collision(s);
+
+ if (s->op.cache_bio) {
+ int i;
+ struct bio_vec *bv;
+
+ __bio_for_each_segment(bv, s->op.cache_bio, i, 0)
+ __free_page(bv->bv_page);
+ }
+
+ cached_dev_bio_complete(cl);
+}
+
+static void request_read_error(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ struct bio_vec *bv;
+ int i;
+
+ if (s->recoverable) {
+ /* The cache read failed, but we can retry from the backing
+ * device.
+ */
+ pr_debug("recovering at sector %llu",
+ (uint64_t) s->orig_bio->bi_sector);
+
+ s->error = 0;
+ bv = s->bio.bio.bi_io_vec;
+ do_bio_hook(s);
+ s->bio.bio.bi_io_vec = bv;
+
+ if (!s->unaligned_bvec)
+ bio_for_each_segment(bv, s->orig_bio, i)
+ bv->bv_offset = 0, bv->bv_len = PAGE_SIZE;
+ else
+ memcpy(s->bio.bio.bi_io_vec,
+ bio_iovec(s->orig_bio),
+ sizeof(struct bio_vec) *
+ bio_segments(s->orig_bio));
+
+ /* XXX: invalidate cache */
+
+ trace_bcache_read_retry(&s->bio.bio);
+ closure_bio_submit(&s->bio.bio, &s->cl, s->d);
+ }
+
+ continue_at(cl, cached_dev_read_complete, NULL);
+}
+
+static void request_read_done(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+
+ /*
+ * s->cache_bio != NULL implies that we had a cache miss; cache_bio now
+ * contains data ready to be inserted into the cache.
+ *
+ * First, we copy the data we just read from cache_bio's bounce buffers
+ * to the buffers the original bio pointed to:
+ */
+
+ if (s->op.cache_bio) {
+ struct bio_vec *src, *dst;
+ unsigned src_offset, dst_offset, bytes;
+ void *dst_ptr;
+
+ bio_reset(s->op.cache_bio);
+ s->op.cache_bio->bi_sector = s->cache_miss->bi_sector;
+ s->op.cache_bio->bi_bdev = s->cache_miss->bi_bdev;
+ s->op.cache_bio->bi_size = s->cache_bio_sectors << 9;
+ bch_bio_map(s->op.cache_bio, NULL);
+
+ src = bio_iovec(s->op.cache_bio);
+ dst = bio_iovec(s->cache_miss);
+ src_offset = src->bv_offset;
+ dst_offset = dst->bv_offset;
+ dst_ptr = kmap(dst->bv_page);
+
+ while (1) {
+ if (dst_offset == dst->bv_offset + dst->bv_len) {
+ kunmap(dst->bv_page);
+ dst++;
+ if (dst == bio_iovec_idx(s->cache_miss,
+ s->cache_miss->bi_vcnt))
+ break;
+
+ dst_offset = dst->bv_offset;
+ dst_ptr = kmap(dst->bv_page);
+ }
+
+ if (src_offset == src->bv_offset + src->bv_len) {
+ src++;
+ if (src == bio_iovec_idx(s->op.cache_bio,
+ s->op.cache_bio->bi_vcnt))
+ BUG();
+
+ src_offset = src->bv_offset;
+ }
+
+ bytes = min(dst->bv_offset + dst->bv_len - dst_offset,
+ src->bv_offset + src->bv_len - src_offset);
+
+ memcpy(dst_ptr + dst_offset,
+ page_address(src->bv_page) + src_offset,
+ bytes);
+
+ src_offset += bytes;
+ dst_offset += bytes;
+ }
+
+ bio_put(s->cache_miss);
+ s->cache_miss = NULL;
+ }
+
+ if (verify(dc, &s->bio.bio) && s->recoverable)
+ bch_data_verify(s);
+
+ bio_complete(s);
+
+ if (s->op.cache_bio &&
+ !test_bit(CACHE_SET_STOPPING, &s->op.c->flags)) {
+ s->op.type = BTREE_REPLACE;
+ closure_call(&s->op.cl, bch_insert_data, NULL, cl);
+ }
+
+ continue_at(cl, cached_dev_read_complete, NULL);
+}
+
+static void request_read_done_bh(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+
+ bch_mark_cache_accounting(s, !s->cache_miss, s->op.skip);
+
+ if (s->error)
+ continue_at_nobarrier(cl, request_read_error, bcache_wq);
+ else if (s->op.cache_bio || verify(dc, &s->bio.bio))
+ continue_at_nobarrier(cl, request_read_done, bcache_wq);
+ else
+ continue_at_nobarrier(cl, cached_dev_read_complete, NULL);
+}
+
+static int cached_dev_cache_miss(struct btree *b, struct search *s,
+ struct bio *bio, unsigned sectors)
+{
+ int ret = 0;
+ unsigned reada;
+ struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+ struct bio *miss;
+
+ miss = bch_bio_split(bio, sectors, GFP_NOIO, s->d->bio_split);
+ if (!miss)
+ return -EAGAIN;
+
+ if (miss == bio)
+ s->op.lookup_done = true;
+
+ miss->bi_end_io = request_endio;
+ miss->bi_private = &s->cl;
+
+ if (s->cache_miss || s->op.skip)
+ goto out_submit;
+
+ if (miss != bio ||
+ (bio->bi_rw & REQ_RAHEAD) ||
+ (bio->bi_rw & REQ_META) ||
+ s->op.c->gc_stats.in_use >= CUTOFF_CACHE_READA)
+ reada = 0;
+ else {
+ reada = min(dc->readahead >> 9,
+ sectors - bio_sectors(miss));
+
+ if (bio_end(miss) + reada > bdev_sectors(miss->bi_bdev))
+ reada = bdev_sectors(miss->bi_bdev) - bio_end(miss);
+ }
+
+ s->cache_bio_sectors = bio_sectors(miss) + reada;
+ s->op.cache_bio = bio_alloc_bioset(GFP_NOWAIT,
+ DIV_ROUND_UP(s->cache_bio_sectors, PAGE_SECTORS),
+ dc->disk.bio_split);
+
+ if (!s->op.cache_bio)
+ goto out_submit;
+
+ s->op.cache_bio->bi_sector = miss->bi_sector;
+ s->op.cache_bio->bi_bdev = miss->bi_bdev;
+ s->op.cache_bio->bi_size = s->cache_bio_sectors << 9;
+
+ s->op.cache_bio->bi_end_io = request_endio;
+ s->op.cache_bio->bi_private = &s->cl;
+
+ /* btree_search_recurse()'s btree iterator is no good anymore */
+ ret = -EINTR;
+ if (!bch_btree_insert_check_key(b, &s->op, s->op.cache_bio))
+ goto out_put;
+
+ bch_bio_map(s->op.cache_bio, NULL);
+ if (bch_bio_alloc_pages(s->op.cache_bio, __GFP_NOWARN|GFP_NOIO))
+ goto out_put;
+
+ s->cache_miss = miss;
+ bio_get(s->op.cache_bio);
+
+ trace_bcache_cache_miss(s->orig_bio);
+ closure_bio_submit(s->op.cache_bio, &s->cl, s->d);
+
+ return ret;
+out_put:
+ bio_put(s->op.cache_bio);
+ s->op.cache_bio = NULL;
+out_submit:
+ closure_bio_submit(miss, &s->cl, s->d);
+ return ret;
+}
+
+static void request_read(struct cached_dev *dc, struct search *s)
+{
+ struct closure *cl = &s->cl;
+
+ check_should_skip(dc, s);
+ closure_call(&s->op.cl, btree_read_async, NULL, cl);
+
+ continue_at(cl, request_read_done_bh, NULL);
+}
+
+/* Process writes */
+
+static void cached_dev_write_complete(struct closure *cl)
+{
+ struct search *s = container_of(cl, struct search, cl);
+ struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
+
+ up_read_non_owner(&dc->writeback_lock);
+ cached_dev_bio_complete(cl);
+}
+
+static bool should_writeback(struct cached_dev *dc, struct bio *bio)
+{
+ unsigned threshold = (bio->bi_rw & REQ_SYNC)
+ ? CUTOFF_WRITEBACK_SYNC
+ : CUTOFF_WRITEBACK;
+
+ return !atomic_read(&dc->disk.detaching) &&
+ cache_mode(dc, bio) == CACHE_MODE_WRITEBACK &&
+ dc->disk.c->gc_stats.in_use < threshold;
+}
+
+static void request_write(struct cached_dev *dc, struct search *s)
+{
+ struct closure *cl = &s->cl;
+ struct bio *bio = &s->bio.bio;
+ struct bkey start, end;
+ start = KEY(dc->disk.id, bio->bi_sector, 0);
+ end = KEY(dc->disk.id, bio_end(bio), 0);
+
+ bch_keybuf_check_overlapping(&s->op.c->moving_gc_keys, &start, &end);
+
+ check_should_skip(dc, s);
+ down_read_non_owner(&dc->writeback_lock);
+
+ if (bch_keybuf_check_overlapping(&dc->writeback_keys, &start, &end)) {
+ s->op.skip = false;
+ s->writeback = true;
+ }
+
+ if (bio->bi_rw & REQ_DISCARD)
+ goto skip;
+
+ if (s->op.skip)
+ goto skip;
+
+ if (should_writeback(dc, s->orig_bio))
+ s->writeback = true;
+
+ if (!s->writeback) {
+ s->op.cache_bio = bio_clone_bioset(bio, GFP_NOIO,
+ dc->disk.bio_split);
+
+ trace_bcache_writethrough(s->orig_bio);
+ closure_bio_submit(bio, cl, s->d);
+ } else {
+ s->op.cache_bio = bio;
+ trace_bcache_writeback(s->orig_bio);
+ bch_writeback_add(dc, bio_sectors(bio));
+ }
+out:
+ closure_call(&s->op.cl, bch_insert_data, NULL, cl);
+ continue_at(cl, cached_dev_write_complete, NULL);
+skip:
+ s->op.skip = true;
+ s->op.cache_bio = s->orig_bio;
+ bio_get(s->op.cache_bio);
+ trace_bcache_write_skip(s->orig_bio);
+
+ if ((bio->bi_rw & REQ_DISCARD) &&
+ !blk_queue_discard(bdev_get_queue(dc->bdev)))
+ goto out;
+
+ closure_bio_submit(bio, cl, s->d);
+ goto out;
+}
+
+static void request_nodata(struct cached_dev *dc, struct search *s)
+{
+ struct closure *cl = &s->cl;
+ struct bio *bio = &s->bio.bio;
+
+ if (bio->bi_rw & REQ_DISCARD) {
+ request_write(dc, s);
+ return;
+ }
+
+ if (s->op.flush_journal)
+ bch_journal_meta(s->op.c, cl);
+
+ closure_bio_submit(bio, cl, s->d);
+
+ continue_at(cl, cached_dev_bio_complete, NULL);
+}
+
+/* Cached devices - read & write stuff */
+
+int bch_get_congested(struct cache_set *c)
+{
+ int i;
+
+ if (!c->congested_read_threshold_us &&
+ !c->congested_write_threshold_us)
+ return 0;
+
+ i = (local_clock_us() - c->congested_last_us) / 1024;
+ if (i < 0)
+ return 0;
+
+ i += atomic_read(&c->congested);
+ if (i >= 0)
+ return 0;
+
+ i += CONGESTED_MAX;
+
+ return i <= 0 ? 1 : fract_exp_two(i, 6);
+}
+
+static void add_sequential(struct task_struct *t)
+{
+ ewma_add(t->sequential_io_avg,
+ t->sequential_io, 8, 0);
+
+ t->sequential_io = 0;
+}
+
+static struct hlist_head *iohash(struct cached_dev *dc, uint64_t k)
+{
+ return &dc->io_hash[hash_64(k, RECENT_IO_BITS)];
+}
+
+static void check_should_skip(struct cached_dev *dc, struct search *s)
+{
+ struct cache_set *c = s->op.c;
+ struct bio *bio = &s->bio.bio;
+
+ long rand;
+ int cutoff = bch_get_congested(c);
+ unsigned mode = cache_mode(dc, bio);
+
+ if (atomic_read(&dc->disk.detaching) ||
+ c->gc_stats.in_use > CUTOFF_CACHE_ADD ||
+ (bio->bi_rw & REQ_DISCARD))
+ goto skip;
+
+ if (mode == CACHE_MODE_NONE ||
+ (mode == CACHE_MODE_WRITEAROUND &&
+ (bio->bi_rw & REQ_WRITE)))
+ goto skip;
+
+ if (bio->bi_sector & (c->sb.block_size - 1) ||
+ bio_sectors(bio) & (c->sb.block_size - 1)) {
+ pr_debug("skipping unaligned io");
+ goto skip;
+ }
+
+ if (!cutoff) {
+ cutoff = dc->sequential_cutoff >> 9;
+
+ if (!cutoff)
+ goto rescale;
+
+ if (mode == CACHE_MODE_WRITEBACK &&
+ (bio->bi_rw & REQ_WRITE) &&
+ (bio->bi_rw & REQ_SYNC))
+ goto rescale;
+ }
+
+ if (dc->sequential_merge) {
+ struct io *i;
+
+ spin_lock(&dc->io_lock);
+
+ hlist_for_each_entry(i, iohash(dc, bio->bi_sector), hash)
+ if (i->last == bio->bi_sector &&
+ time_before(jiffies, i->jiffies))
+ goto found;
+
+ i = list_first_entry(&dc->io_lru, struct io, lru);
+
+ add_sequential(s->task);
+ i->sequential = 0;
+found:
+ if (i->sequential + bio->bi_size > i->sequential)
+ i->sequential += bio->bi_size;
+
+ i->last = bio_end(bio);
+ i->jiffies = jiffies + msecs_to_jiffies(5000);
+ s->task->sequential_io = i->sequential;
+
+ hlist_del(&i->hash);
+ hlist_add_head(&i->hash, iohash(dc, i->last));
+ list_move_tail(&i->lru, &dc->io_lru);
+
+ spin_unlock(&dc->io_lock);
+ } else {
+ s->task->sequential_io = bio->bi_size;
+
+ add_sequential(s->task);
+ }
+
+ rand = get_random_int();
+ cutoff -= bitmap_weight(&rand, BITS_PER_LONG);
+
+ if (cutoff <= (int) (max(s->task->sequential_io,
+ s->task->sequential_io_avg) >> 9))
+ goto skip;
+
+rescale:
+ bch_rescale_priorities(c, bio_sectors(bio));
+ return;
+skip:
+ bch_mark_sectors_bypassed(s, bio_sectors(bio));
+ s->op.skip = true;
+}
+
+static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
+{
+ struct search *s;
+ struct bcache_device *d = bio->bi_bdev->bd_disk->private_data;
+ struct cached_dev *dc = container_of(d, struct cached_dev, disk);
+ int cpu, rw = bio_data_dir(bio);
+
+ cpu = part_stat_lock();
+ part_stat_inc(cpu, &d->disk->part0, ios[rw]);
+ part_stat_add(cpu, &d->disk->part0, sectors[rw], bio_sectors(bio));
+ part_stat_unlock();
+
+ bio->bi_bdev = dc->bdev;
+ bio->bi_sector += dc->sb.data_offset;
+
+ if (cached_dev_get(dc)) {
+ s = search_alloc(bio, d);
+ trace_bcache_request_start(s, bio);
+
+ if (!bio_has_data(bio))
+ request_nodata(dc, s);
+ else if (rw)
+ request_write(dc, s);
+ else
+ request_read(dc, s);
+ } else {
+ if ((bio->bi_rw & REQ_DISCARD) &&
+ !blk_queue_discard(bdev_get_queue(dc->bdev)))
+ bio_endio(bio, 0);
+ else
+ bch_generic_make_request(bio, &d->bio_split_hook);
+ }
+}
+
+static int cached_dev_ioctl(struct bcache_device *d, fmode_t mode,
+ unsigned int cmd, unsigned long arg)
+{
+ struct cached_dev *dc = container_of(d, struct cached_dev, disk);
+ return __blkdev_driver_ioctl(dc->bdev, mode, cmd, arg);
+}
+
+static int cached_dev_congested(void *data, int bits)
+{
+ struct bcache_device *d = data;
+ struct cached_dev *dc = container_of(d, struct cached_dev, disk);
+ struct request_queue *q = bdev_get_queue(dc->bdev);
+ int ret = 0;
+
+ if (bdi_congested(&q->backing_dev_info, bits))
+ return 1;
+
+ if (cached_dev_get(dc)) {
+ unsigned i;
+ struct cache *ca;
+
+ for_each_cache(ca, d->c, i) {
+ q = bdev_get_queue(ca->bdev);
+ ret |= bdi_congested(&q->backing_dev_info, bits);
+ }
+
+ cached_dev_put(dc);
+ }
+
+ return ret;
+}
+
+void bch_cached_dev_request_init(struct cached_dev *dc)
+{
+ struct gendisk *g = dc->disk.disk;
+
+ g->queue->make_request_fn = cached_dev_make_request;
+ g->queue->backing_dev_info.congested_fn = cached_dev_congested;
+ dc->disk.cache_miss = cached_dev_cache_miss;
+ dc->disk.ioctl = cached_dev_ioctl;
+}
+
+/* Flash backed devices */
+
+static int flash_dev_cache_miss(struct btree *b, struct search *s,
+ struct bio *bio, unsigned sectors)
+{
+ /* Zero fill bio */
+
+ while (bio->bi_idx != bio->bi_vcnt) {
+ struct bio_vec *bv = bio_iovec(bio);
+ unsigned j = min(bv->bv_len >> 9, sectors);
+
+ void *p = kmap(bv->bv_page);
+ memset(p + bv->bv_offset, 0, j << 9);
+ kunmap(bv->bv_page);
+
+ bv->bv_len -= j << 9;
+ bv->bv_offset += j << 9;
+
+ if (bv->bv_len)
+ return 0;
+
+ bio->bi_sector += j;
+ bio->bi_size -= j << 9;
+
+ bio->bi_idx++;
+ sectors -= j;
+ }
+
+ s->op.lookup_done = true;
+
+ return 0;
+}
+
+static void flash_dev_make_request(struct request_queue *q, struct bio *bio)
+{
+ struct search *s;
+ struct closure *cl;
+ struct bcache_device *d = bio->bi_bdev->bd_disk->private_data;
+ int cpu, rw = bio_data_dir(bio);
+
+ cpu = part_stat_lock();
+ part_stat_inc(cpu, &d->disk->part0, ios[rw]);
+ part_stat_add(cpu, &d->disk->part0, sectors[rw], bio_sectors(bio));
+ part_stat_unlock();
+
+ s = search_alloc(bio, d);
+ cl = &s->cl;
+ bio = &s->bio.bio;
+
+ trace_bcache_request_start(s, bio);
+
+ if (bio_has_data(bio) && !rw) {
+ closure_call(&s->op.cl, btree_read_async, NULL, cl);
+ } else if (bio_has_data(bio) || s->op.skip) {
+ bch_keybuf_check_overlapping(&s->op.c->moving_gc_keys,
+ &KEY(d->id, bio->bi_sector, 0),
+ &KEY(d->id, bio_end(bio), 0));
+
+ s->writeback = true;
+ s->op.cache_bio = bio;
+
+ closure_call(&s->op.cl, bch_insert_data, NULL, cl);
+ } else {
+ /* No data - probably a cache flush */
+ if (s->op.flush_journal)
+ bch_journal_meta(s->op.c, cl);
+ }
+
+ continue_at(cl, search_free, NULL);
+}
+
+static int flash_dev_ioctl(struct bcache_device *d, fmode_t mode,
+ unsigned int cmd, unsigned long arg)
+{
+ return -ENOTTY;
+}
+
+static int flash_dev_congested(void *data, int bits)
+{
+ struct bcache_device *d = data;
+ struct request_queue *q;
+ struct cache *ca;
+ unsigned i;
+ int ret = 0;
+
+ for_each_cache(ca, d->c, i) {
+ q = bdev_get_queue(ca->bdev);
+ ret |= bdi_congested(&q->backing_dev_info, bits);
+ }
+
+ return ret;
+}
+
+void bch_flash_dev_request_init(struct bcache_device *d)
+{
+ struct gendisk *g = d->disk;
+
+ g->queue->make_request_fn = flash_dev_make_request;
+ g->queue->backing_dev_info.congested_fn = flash_dev_congested;
+ d->cache_miss = flash_dev_cache_miss;
+ d->ioctl = flash_dev_ioctl;
+}
+
+void bch_request_exit(void)
+{
+#ifdef CONFIG_CGROUP_BCACHE
+ cgroup_unload_subsys(&bcache_subsys);
+#endif
+ if (bch_search_cache)
+ kmem_cache_destroy(bch_search_cache);
+}
+
+int __init bch_request_init(void)
+{
+ bch_search_cache = KMEM_CACHE(search, 0);
+ if (!bch_search_cache)
+ return -ENOMEM;
+
+#ifdef CONFIG_CGROUP_BCACHE
+ cgroup_load_subsys(&bcache_subsys);
+ init_bch_cgroup(&bcache_default_cgroup);
+
+ cgroup_add_cftypes(&bcache_subsys, bch_files);
+#endif
+ return 0;
+}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-11-06 12:27:34 +0000