1 files changed, 578 insertions, 0 deletions

diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c
new file mode 100644
index 000000000..c7dcb7c52
--- /dev/null
+++ b/fs/btrfs/inode-map.c
@@ -0,0 +1,578 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ */
+
+#include <linux/kthread.h>
+#include <linux/pagemap.h>
+
+#include "ctree.h"
+#include "disk-io.h"
+#include "free-space-cache.h"
+#include "inode-map.h"
+#include "transaction.h"
+
+static void fail_caching_thread(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	btrfs_warn(fs_info, "failed to start inode caching task");
+	btrfs_clear_pending_and_info(fs_info, INODE_MAP_CACHE,
+				     "disabling inode map caching");
+	spin_lock(&root->ino_cache_lock);
+	root->ino_cache_state = BTRFS_CACHE_ERROR;
+	spin_unlock(&root->ino_cache_lock);
+	wake_up(&root->ino_cache_wait);
+}
+
+static int caching_kthread(void *data)
+{
+	struct btrfs_root *root = data;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
+	struct btrfs_key key;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	u64 last = (u64)-1;
+	int slot;
+	int ret;
+
+	if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
+		return 0;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		fail_caching_thread(root);
+		return -ENOMEM;
+	}
+
+	/* Since the commit root is read-only, we can safely skip locking. */
+	path->skip_locking = 1;
+	path->search_commit_root = 1;
+	path->reada = READA_FORWARD;
+
+	key.objectid = BTRFS_FIRST_FREE_OBJECTID;
+	key.offset = 0;
+	key.type = BTRFS_INODE_ITEM_KEY;
+again:
+	/* need to make sure the commit_root doesn't disappear */
+	down_read(&fs_info->commit_root_sem);
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0)
+		goto out;
+
+	while (1) {
+		if (btrfs_fs_closing(fs_info))
+			goto out;
+
+		leaf = path->nodes[0];
+		slot = path->slots[0];
+		if (slot >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto out;
+			else if (ret > 0)
+				break;
+
+			if (need_resched() ||
+			    btrfs_transaction_in_commit(fs_info)) {
+				leaf = path->nodes[0];
+
+				if (WARN_ON(btrfs_header_nritems(leaf) == 0))
+					break;
+
+				/*
+				 * Save the key so we can advances forward
+				 * in the next search.
+				 */
+				btrfs_item_key_to_cpu(leaf, &key, 0);
+				btrfs_release_path(path);
+				root->ino_cache_progress = last;
+				up_read(&fs_info->commit_root_sem);
+				schedule_timeout(1);
+				goto again;
+			} else
+				continue;
+		}
+
+		btrfs_item_key_to_cpu(leaf, &key, slot);
+
+		if (key.type != BTRFS_INODE_ITEM_KEY)
+			goto next;
+
+		if (key.objectid >= root->highest_objectid)
+			break;
+
+		if (last != (u64)-1 && last + 1 != key.objectid) {
+			__btrfs_add_free_space(fs_info, ctl, last + 1,
+					       key.objectid - last - 1);
+			wake_up(&root->ino_cache_wait);
+		}
+
+		last = key.objectid;
+next:
+		path->slots[0]++;
+	}
+
+	if (last < root->highest_objectid - 1) {
+		__btrfs_add_free_space(fs_info, ctl, last + 1,
+				       root->highest_objectid - last - 1);
+	}
+
+	spin_lock(&root->ino_cache_lock);
+	root->ino_cache_state = BTRFS_CACHE_FINISHED;
+	spin_unlock(&root->ino_cache_lock);
+
+	root->ino_cache_progress = (u64)-1;
+	btrfs_unpin_free_ino(root);
+out:
+	wake_up(&root->ino_cache_wait);
+	up_read(&fs_info->commit_root_sem);
+
+	btrfs_free_path(path);
+
+	return ret;
+}
+
+static void start_caching(struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
+	struct task_struct *tsk;
+	int ret;
+	u64 objectid;
+
+	if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
+		return;
+
+	spin_lock(&root->ino_cache_lock);
+	if (root->ino_cache_state != BTRFS_CACHE_NO) {
+		spin_unlock(&root->ino_cache_lock);
+		return;
+	}
+
+	root->ino_cache_state = BTRFS_CACHE_STARTED;
+	spin_unlock(&root->ino_cache_lock);
+
+	ret = load_free_ino_cache(fs_info, root);
+	if (ret == 1) {
+		spin_lock(&root->ino_cache_lock);
+		root->ino_cache_state = BTRFS_CACHE_FINISHED;
+		spin_unlock(&root->ino_cache_lock);
+		wake_up(&root->ino_cache_wait);
+		return;
+	}
+
+	/*
+	 * It can be quite time-consuming to fill the cache by searching
+	 * through the extent tree, and this can keep ino allocation path
+	 * waiting. Therefore at start we quickly find out the highest
+	 * inode number and we know we can use inode numbers which fall in
+	 * [highest_ino + 1, BTRFS_LAST_FREE_OBJECTID].
+	 */
+	ret = btrfs_find_free_objectid(root, &objectid);
+	if (!ret && objectid <= BTRFS_LAST_FREE_OBJECTID) {
+		__btrfs_add_free_space(fs_info, ctl, objectid,
+				       BTRFS_LAST_FREE_OBJECTID - objectid + 1);
+	}
+
+	tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu",
+			  root->root_key.objectid);
+	if (IS_ERR(tsk))
+		fail_caching_thread(root);
+}
+
+int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
+{
+	if (!btrfs_test_opt(root->fs_info, INODE_MAP_CACHE))
+		return btrfs_find_free_objectid(root, objectid);
+
+again:
+	*objectid = btrfs_find_ino_for_alloc(root);
+
+	if (*objectid != 0)
+		return 0;
+
+	start_caching(root);
+
+	wait_event(root->ino_cache_wait,
+		   root->ino_cache_state == BTRFS_CACHE_FINISHED ||
+		   root->ino_cache_state == BTRFS_CACHE_ERROR ||
+		   root->free_ino_ctl->free_space > 0);
+
+	if (root->ino_cache_state == BTRFS_CACHE_FINISHED &&
+	    root->free_ino_ctl->free_space == 0)
+		return -ENOSPC;
+	else if (root->ino_cache_state == BTRFS_CACHE_ERROR)
+		return btrfs_find_free_objectid(root, objectid);
+	else
+		goto again;
+}
+
+void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
+
+	if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
+		return;
+again:
+	if (root->ino_cache_state == BTRFS_CACHE_FINISHED) {
+		__btrfs_add_free_space(fs_info, pinned, objectid, 1);
+	} else {
+		down_write(&fs_info->commit_root_sem);
+		spin_lock(&root->ino_cache_lock);
+		if (root->ino_cache_state == BTRFS_CACHE_FINISHED) {
+			spin_unlock(&root->ino_cache_lock);
+			up_write(&fs_info->commit_root_sem);
+			goto again;
+		}
+		spin_unlock(&root->ino_cache_lock);
+
+		start_caching(root);
+
+		__btrfs_add_free_space(fs_info, pinned, objectid, 1);
+
+		up_write(&fs_info->commit_root_sem);
+	}
+}
+
+/*
+ * When a transaction is committed, we'll move those inode numbers which are
+ * smaller than root->ino_cache_progress from pinned tree to free_ino tree, and
+ * others will just be dropped, because the commit root we were searching has
+ * changed.
+ *
+ * Must be called with root->fs_info->commit_root_sem held
+ */
+void btrfs_unpin_free_ino(struct btrfs_root *root)
+{
+	struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
+	struct rb_root *rbroot = &root->free_ino_pinned->free_space_offset;
+	spinlock_t *rbroot_lock = &root->free_ino_pinned->tree_lock;
+	struct btrfs_free_space *info;
+	struct rb_node *n;
+	u64 count;
+
+	if (!btrfs_test_opt(root->fs_info, INODE_MAP_CACHE))
+		return;
+
+	while (1) {
+		spin_lock(rbroot_lock);
+		n = rb_first(rbroot);
+		if (!n) {
+			spin_unlock(rbroot_lock);
+			break;
+		}
+
+		info = rb_entry(n, struct btrfs_free_space, offset_index);
+		BUG_ON(info->bitmap); /* Logic error */
+
+		if (info->offset > root->ino_cache_progress)
+			count = 0;
+		else
+			count = min(root->ino_cache_progress - info->offset + 1,
+				    info->bytes);
+
+		rb_erase(&info->offset_index, rbroot);
+		spin_unlock(rbroot_lock);
+		if (count)
+			__btrfs_add_free_space(root->fs_info, ctl,
+					       info->offset, count);
+		kmem_cache_free(btrfs_free_space_cachep, info);
+	}
+}
+
+#define INIT_THRESHOLD	((SZ_32K / 2) / sizeof(struct btrfs_free_space))
+#define INODES_PER_BITMAP (PAGE_SIZE * 8)
+
+/*
+ * The goal is to keep the memory used by the free_ino tree won't
+ * exceed the memory if we use bitmaps only.
+ */
+static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
+{
+	struct btrfs_free_space *info;
+	struct rb_node *n;
+	int max_ino;
+	int max_bitmaps;
+
+	n = rb_last(&ctl->free_space_offset);
+	if (!n) {
+		ctl->extents_thresh = INIT_THRESHOLD;
+		return;
+	}
+	info = rb_entry(n, struct btrfs_free_space, offset_index);
+
+	/*
+	 * Find the maximum inode number in the filesystem. Note we
+	 * ignore the fact that this can be a bitmap, because we are
+	 * not doing precise calculation.
+	 */
+	max_ino = info->bytes - 1;
+
+	max_bitmaps = ALIGN(max_ino, INODES_PER_BITMAP) / INODES_PER_BITMAP;
+	if (max_bitmaps <= ctl->total_bitmaps) {
+		ctl->extents_thresh = 0;
+		return;
+	}
+
+	ctl->extents_thresh = (max_bitmaps - ctl->total_bitmaps) *
+				PAGE_SIZE / sizeof(*info);
+}
+
+/*
+ * We don't fall back to bitmap, if we are below the extents threshold
+ * or this chunk of inode numbers is a big one.
+ */
+static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
+		       struct btrfs_free_space *info)
+{
+	if (ctl->free_extents < ctl->extents_thresh ||
+	    info->bytes > INODES_PER_BITMAP / 10)
+		return false;
+
+	return true;
+}
+
+static const struct btrfs_free_space_op free_ino_op = {
+	.recalc_thresholds	= recalculate_thresholds,
+	.use_bitmap		= use_bitmap,
+};
+
+static void pinned_recalc_thresholds(struct btrfs_free_space_ctl *ctl)
+{
+}
+
+static bool pinned_use_bitmap(struct btrfs_free_space_ctl *ctl,
+			      struct btrfs_free_space *info)
+{
+	/*
+	 * We always use extents for two reasons:
+	 *
+	 * - The pinned tree is only used during the process of caching
+	 *   work.
+	 * - Make code simpler. See btrfs_unpin_free_ino().
+	 */
+	return false;
+}
+
+static const struct btrfs_free_space_op pinned_free_ino_op = {
+	.recalc_thresholds	= pinned_recalc_thresholds,
+	.use_bitmap		= pinned_use_bitmap,
+};
+
+void btrfs_init_free_ino_ctl(struct btrfs_root *root)
+{
+	struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
+	struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
+
+	spin_lock_init(&ctl->tree_lock);
+	ctl->unit = 1;
+	ctl->start = 0;
+	ctl->private = NULL;
+	ctl->op = &free_ino_op;
+	INIT_LIST_HEAD(&ctl->trimming_ranges);
+	mutex_init(&ctl->cache_writeout_mutex);
+
+	/*
+	 * Initially we allow to use 16K of ram to cache chunks of
+	 * inode numbers before we resort to bitmaps. This is somewhat
+	 * arbitrary, but it will be adjusted in runtime.
+	 */
+	ctl->extents_thresh = INIT_THRESHOLD;
+
+	spin_lock_init(&pinned->tree_lock);
+	pinned->unit = 1;
+	pinned->start = 0;
+	pinned->private = NULL;
+	pinned->extents_thresh = 0;
+	pinned->op = &pinned_free_ino_op;
+}
+
+int btrfs_save_ino_cache(struct btrfs_root *root,
+			 struct btrfs_trans_handle *trans)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
+	struct btrfs_path *path;
+	struct inode *inode;
+	struct btrfs_block_rsv *rsv;
+	struct extent_changeset *data_reserved = NULL;
+	u64 num_bytes;
+	u64 alloc_hint = 0;
+	int ret;
+	int prealloc;
+	bool retry = false;
+
+	/* only fs tree and subvol/snap needs ino cache */
+	if (root->root_key.objectid != BTRFS_FS_TREE_OBJECTID &&
+	    (root->root_key.objectid < BTRFS_FIRST_FREE_OBJECTID ||
+	     root->root_key.objectid > BTRFS_LAST_FREE_OBJECTID))
+		return 0;
+
+	/* Don't save inode cache if we are deleting this root */
+	if (btrfs_root_refs(&root->root_item) == 0)
+		return 0;
+
+	if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
+		return 0;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	rsv = trans->block_rsv;
+	trans->block_rsv = &fs_info->trans_block_rsv;
+
+	num_bytes = trans->bytes_reserved;
+	/*
+	 * 1 item for inode item insertion if need
+	 * 4 items for inode item update (in the worst case)
+	 * 1 items for slack space if we need do truncation
+	 * 1 item for free space object
+	 * 3 items for pre-allocation
+	 */
+	trans->bytes_reserved = btrfs_calc_trans_metadata_size(fs_info, 10);
+	ret = btrfs_block_rsv_add(root, trans->block_rsv,
+				  trans->bytes_reserved,
+				  BTRFS_RESERVE_NO_FLUSH);
+	if (ret)
+		goto out;
+	trace_btrfs_space_reservation(fs_info, "ino_cache", trans->transid,
+				      trans->bytes_reserved, 1);
+again:
+	inode = lookup_free_ino_inode(root, path);
+	if (IS_ERR(inode) && (PTR_ERR(inode) != -ENOENT || retry)) {
+		ret = PTR_ERR(inode);
+		goto out_release;
+	}
+
+	if (IS_ERR(inode)) {
+		BUG_ON(retry); /* Logic error */
+		retry = true;
+
+		ret = create_free_ino_inode(root, trans, path);
+		if (ret)
+			goto out_release;
+		goto again;
+	}
+
+	BTRFS_I(inode)->generation = 0;
+	ret = btrfs_update_inode(trans, root, inode);
+	if (ret) {
+		btrfs_abort_transaction(trans, ret);
+		goto out_put;
+	}
+
+	if (i_size_read(inode) > 0) {
+		ret = btrfs_truncate_free_space_cache(trans, NULL, inode);
+		if (ret) {
+			if (ret != -ENOSPC)
+				btrfs_abort_transaction(trans, ret);
+			goto out_put;
+		}
+	}
+
+	spin_lock(&root->ino_cache_lock);
+	if (root->ino_cache_state != BTRFS_CACHE_FINISHED) {
+		ret = -1;
+		spin_unlock(&root->ino_cache_lock);
+		goto out_put;
+	}
+	spin_unlock(&root->ino_cache_lock);
+
+	spin_lock(&ctl->tree_lock);
+	prealloc = sizeof(struct btrfs_free_space) * ctl->free_extents;
+	prealloc = ALIGN(prealloc, PAGE_SIZE);
+	prealloc += ctl->total_bitmaps * PAGE_SIZE;
+	spin_unlock(&ctl->tree_lock);
+
+	/* Just to make sure we have enough space */
+	prealloc += 8 * PAGE_SIZE;
+
+	ret = btrfs_delalloc_reserve_space(inode, &data_reserved, 0, prealloc);
+	if (ret)
+		goto out_put;
+
+	ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, prealloc,
+					      prealloc, prealloc, &alloc_hint);
+	if (ret) {
+		btrfs_delalloc_release_extents(BTRFS_I(inode), prealloc);
+		btrfs_delalloc_release_metadata(BTRFS_I(inode), prealloc, true);
+		goto out_put;
+	}
+
+	ret = btrfs_write_out_ino_cache(root, trans, path, inode);
+	btrfs_delalloc_release_extents(BTRFS_I(inode), prealloc);
+out_put:
+	iput(inode);
+out_release:
+	trace_btrfs_space_reservation(fs_info, "ino_cache", trans->transid,
+				      trans->bytes_reserved, 0);
+	btrfs_block_rsv_release(fs_info, trans->block_rsv,
+				trans->bytes_reserved);
+out:
+	trans->block_rsv = rsv;
+	trans->bytes_reserved = num_bytes;
+
+	btrfs_free_path(path);
+	extent_changeset_free(data_reserved);
+	return ret;
+}
+
+int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
+{
+	struct btrfs_path *path;
+	int ret;
+	struct extent_buffer *l;
+	struct btrfs_key search_key;
+	struct btrfs_key found_key;
+	int slot;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	search_key.objectid = BTRFS_LAST_FREE_OBJECTID;
+	search_key.type = -1;
+	search_key.offset = (u64)-1;
+	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
+	if (ret < 0)
+		goto error;
+	BUG_ON(ret == 0); /* Corruption */
+	if (path->slots[0] > 0) {
+		slot = path->slots[0] - 1;
+		l = path->nodes[0];
+		btrfs_item_key_to_cpu(l, &found_key, slot);
+		*objectid = max_t(u64, found_key.objectid,
+				  BTRFS_FIRST_FREE_OBJECTID - 1);
+	} else {
+		*objectid = BTRFS_FIRST_FREE_OBJECTID - 1;
+	}
+	ret = 0;
+error:
+	btrfs_free_path(path);
+	return ret;
+}
+
+int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid)
+{
+	int ret;
+	mutex_lock(&root->objectid_mutex);
+
+	if (unlikely(root->highest_objectid >= BTRFS_LAST_FREE_OBJECTID)) {
+		btrfs_warn(root->fs_info,
+			   "the objectid of root %llu reaches its highest value",
+			   root->root_key.objectid);
+		ret = -ENOSPC;
+		goto out;
+	}
+
+	*objectid = ++root->highest_objectid;
+	ret = 0;
+out:
+	mutex_unlock(&root->objectid_mutex);
+	return ret;
+}