// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 */

#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/writeback.h>
#include <linux/sched/mm.h>
#include "misc.h"
#include "ctree.h"
#include "transaction.h"
#include "btrfs_inode.h"
#include "extent_io.h"
#include "disk-io.h"
#include "compression.h"
#include "delalloc-space.h"
#include "qgroup.h"

static struct kmem_cache *btrfs_ordered_extent_cache;

static u64 entry_end(struct btrfs_ordered_extent *entry)
{
        if (entry->file_offset + entry->num_bytes < entry->file_offset)
                return (u64)-1;
        return entry->file_offset + entry->num_bytes;
}

/* returns NULL if the insertion worked, or it returns the node it did find
 * in the tree
 */
static struct rb_node *tree_insert(struct rb_root *root, u64 file_offset,
                                   struct rb_node *node)
{
        struct rb_node **p = &root->rb_node;
        struct rb_node *parent = NULL;
        struct btrfs_ordered_extent *entry;

        while (*p) {
                parent = *p;
                entry = rb_entry(parent, struct btrfs_ordered_extent, rb_node);

                if (file_offset < entry->file_offset)
                        p = &(*p)->rb_left;
                else if (file_offset >= entry_end(entry))
                        p = &(*p)->rb_right;
                else
                        return parent;
        }

        rb_link_node(node, parent, p);
        rb_insert_color(node, root);
        return NULL;
}

/*
 * look for a given offset in the tree, and if it can't be found return the
 * first lesser offset
 */
static struct rb_node *__tree_search(struct rb_root *root, u64 file_offset,
                                     struct rb_node **prev_ret)
{
        struct rb_node *n = root->rb_node;
        struct rb_node *prev = NULL;
        struct rb_node *test;
        struct btrfs_ordered_extent *entry;
        struct btrfs_ordered_extent *prev_entry = NULL;

        while (n) {
                entry = rb_entry(n, struct btrfs_ordered_extent, rb_node);
                prev = n;
                prev_entry = entry;

                if (file_offset < entry->file_offset)
                        n = n->rb_left;
                else if (file_offset >= entry_end(entry))
                        n = n->rb_right;
                else
                        return n;
        }
        if (!prev_ret)
                return NULL;

        while (prev && file_offset >= entry_end(prev_entry)) {
                test = rb_next(prev);
                if (!test)
                        break;
                prev_entry = rb_entry(test, struct btrfs_ordered_extent,
                                      rb_node);
                if (file_offset < entry_end(prev_entry))
                        break;

                prev = test;
        }
        if (prev)
                prev_entry = rb_entry(prev, struct btrfs_ordered_extent,
                                      rb_node);
        while (prev && file_offset < entry_end(prev_entry)) {
                test = rb_prev(prev);
                if (!test)
                        break;
                prev_entry = rb_entry(test, struct btrfs_ordered_extent,
                                      rb_node);
                prev = test;
        }
        *prev_ret = prev;
        return NULL;
}

static int range_overlaps(struct btrfs_ordered_extent *entry, u64 file_offset,
                          u64 len)
{
        if (file_offset + len <= entry->file_offset ||
            entry->file_offset + entry->num_bytes <= file_offset)
                return 0;
        return 1;
}

/*
 * look find the first ordered struct that has this offset, otherwise
 * the first one less than this offset
 */
static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
                                          u64 file_offset)
{
        struct rb_root *root = &tree->tree;
        struct rb_node *prev = NULL;
        struct rb_node *ret;
        struct btrfs_ordered_extent *entry;

        if (tree->last) {
                entry = rb_entry(tree->last, struct btrfs_ordered_extent,
                                 rb_node);
                if (in_range(file_offset, entry->file_offset, entry->num_bytes))
                        return tree->last;
        }
        ret = __tree_search(root, file_offset, &prev);
        if (!ret)
                ret = prev;
        if (ret)
                tree->last = ret;
        return ret;
}

/*
 * Allocate and add a new ordered_extent into the per-inode tree.
 *
 * The tree is given a single reference on the ordered extent that was
 * inserted.
 */
static int __btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
                                      u64 disk_bytenr, u64 num_bytes,
                                      u64 disk_num_bytes, int type, int dio,
                                      int compress_type)
{
        struct btrfs_root *root = inode->root;
        struct btrfs_fs_info *fs_info = root->fs_info;
        struct btrfs_ordered_inode_tree *tree = &inode->ordered_tree;
        struct rb_node *node;
        struct btrfs_ordered_extent *entry;
        int ret;

        if (type == BTRFS_ORDERED_NOCOW || type == BTRFS_ORDERED_PREALLOC) {
                /* For nocow write, we can release the qgroup rsv right now */
                ret = btrfs_qgroup_free_data(inode, NULL, file_offset, num_bytes);
                if (ret < 0)
                        return ret;
                ret = 0;
        } else {
                /*
                 * The ordered extent has reserved qgroup space, release now
                 * and pass the reserved number for qgroup_record to free.
                 */
                ret = btrfs_qgroup_release_data(inode, file_offset, num_bytes);
                if (ret < 0)
                        return ret;
        }
        entry = kmem_cache_zalloc(btrfs_ordered_extent_cache, GFP_NOFS);
        if (!entry)
                return -ENOMEM;

        entry->file_offset = file_offset;
        entry->disk_bytenr = disk_bytenr;
        entry->num_bytes = num_bytes;
        entry->disk_num_bytes = disk_num_bytes;
        entry->bytes_left = num_bytes;
        entry->inode = igrab(&inode->vfs_inode);
        entry->compress_type = compress_type;
        entry->truncated_len = (u64)-1;
        entry->qgroup_rsv = ret;
        entry->physical = (u64)-1;
        entry->disk = NULL;
        entry->partno = (u8)-1;

        ASSERT(type == BTRFS_ORDERED_REGULAR ||
               type == BTRFS_ORDERED_NOCOW ||
               type == BTRFS_ORDERED_PREALLOC ||
               type == BTRFS_ORDERED_COMPRESSED);
        set_bit(type, &entry->flags);

        percpu_counter_add_batch(&fs_info->ordered_bytes, num_bytes,
                                 fs_info->delalloc_batch);

        if (dio)
                set_bit(BTRFS_ORDERED_DIRECT, &entry->flags);

        /* one ref for the tree */
        refcount_set(&entry->refs, 1);
        init_waitqueue_head(&entry->wait);
        INIT_LIST_HEAD(&entry->list);
        INIT_LIST_HEAD(&entry->log_list);
        INIT_LIST_HEAD(&entry->root_extent_list);
        INIT_LIST_HEAD(&entry->work_list);
        init_completion(&entry->completion);

        trace_btrfs_ordered_extent_add(inode, entry);

        spin_lock_irq(&tree->lock);
        node = tree_insert(&tree->tree, file_offset,
                           &entry->rb_node);
        if (node)
                btrfs_panic(fs_info, -EEXIST,
                                "inconsistency in ordered tree at offset %llu",
                                file_offset);
        spin_unlock_irq(&tree->lock);

        spin_lock(&root->ordered_extent_lock);
        list_add_tail(&entry->root_extent_list,
                      &root->ordered_extents);
        root->nr_ordered_extents++;
        if (root->nr_ordered_extents == 1) {
                spin_lock(&fs_info->ordered_root_lock);
                BUG_ON(!list_empty(&root->ordered_root));
                list_add_tail(&root->ordered_root, &fs_info->ordered_roots);
                spin_unlock(&fs_info->ordered_root_lock);
        }
        spin_unlock(&root->ordered_extent_lock);

        /*
         * We don't need the count_max_extents here, we can assume that all of
         * that work has been done at higher layers, so this is truly the
         * smallest the extent is going to get.
         */
        spin_lock(&inode->lock);
        btrfs_mod_outstanding_extents(inode, 1);
        spin_unlock(&inode->lock);

        return 0;
}

int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
                             u64 disk_bytenr, u64 num_bytes, u64 disk_num_bytes,
                             int type)
{
        ASSERT(type == BTRFS_ORDERED_REGULAR ||
               type == BTRFS_ORDERED_NOCOW ||
               type == BTRFS_ORDERED_PREALLOC);
        return __btrfs_add_ordered_extent(inode, file_offset, disk_bytenr,
                                          num_bytes, disk_num_bytes, type, 0,
                                          BTRFS_COMPRESS_NONE);
}

int btrfs_add_ordered_extent_dio(struct btrfs_inode *inode, u64 file_offset,
                                 u64 disk_bytenr, u64 num_bytes,
                                 u64 disk_num_bytes, int type)
{
        ASSERT(type == BTRFS_ORDERED_REGULAR ||
               type == BTRFS_ORDERED_NOCOW ||
               type == BTRFS_ORDERED_PREALLOC);
        return __btrfs_add_ordered_extent(inode, file_offset, disk_bytenr,
                                          num_bytes, disk_num_bytes, type, 1,
                                          BTRFS_COMPRESS_NONE);
}

int btrfs_add_ordered_extent_compress(struct btrfs_inode *inode, u64 file_offset,
                                      u64 disk_bytenr, u64 num_bytes,
                                      u64 disk_num_bytes, int compress_type)
{
        ASSERT(compress_type != BTRFS_COMPRESS_NONE);
        return __btrfs_add_ordered_extent(inode, file_offset, disk_bytenr,
                                          num_bytes, disk_num_bytes,
                                          BTRFS_ORDERED_COMPRESSED, 0,
                                          compress_type);
}

/*
 * Add a struct btrfs_ordered_sum into the list of checksums to be inserted
 * when an ordered extent is finished.  If the list covers more than one
 * ordered extent, it is split across multiples.
 */
void btrfs_add_ordered_sum(struct btrfs_ordered_extent *entry,
                           struct btrfs_ordered_sum *sum)
{
        struct btrfs_ordered_inode_tree *tree;

        tree = &BTRFS_I(entry->inode)->ordered_tree;
        spin_lock_irq(&tree->lock);
        list_add_tail(&sum->list, &entry->list);
        spin_unlock_irq(&tree->lock);
}

/*
 * Finish IO for one ordered extent across a given range.  The range can
 * contain several ordered extents.
 *
 * @found_ret:   Return the finished ordered extent
 * @file_offset: File offset for the finished IO
 *               Will also be updated to one byte past the range that is
 *               recordered as finished. This allows caller to walk forward.
 * @io_size:     Length of the finish IO range
 * @uptodate:    If the IO finished without problem
 *
 * Return true if any ordered extent is finished in the range, and update
 * @found_ret and @file_offset.
 * Return false otherwise.
 *
 * NOTE: Although The range can cross multiple ordered extents, only one
 * ordered extent will be updated during one call. The caller is responsible to
 * iterate all ordered extents in the range.
 */
bool btrfs_dec_test_first_ordered_pending(struct btrfs_inode *inode,
                                   struct btrfs_ordered_extent **finished_ret,
                                   u64 *file_offset, u64 io_size, int uptodate)
{
        struct btrfs_fs_info *fs_info = inode->root->fs_info;
        struct btrfs_ordered_inode_tree *tree = &inode->ordered_tree;
        struct rb_node *node;
        struct btrfs_ordered_extent *entry = NULL;
        bool finished = false;
        unsigned long flags;
        u64 dec_end;
        u64 dec_start;
        u64 to_dec;

        spin_lock_irqsave(&tree->lock, flags);
        node = tree_search(tree, *file_offset);
        if (!node)
                goto out;

        entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
        if (!in_range(*file_offset, entry->file_offset, entry->num_bytes))
                goto out;

        dec_start = max(*file_offset, entry->file_offset);
        dec_end = min(*file_offset + io_size,
                      entry->file_offset + entry->num_bytes);
        *file_offset = dec_end;
        if (dec_start > dec_end) {
                btrfs_crit(fs_info, "bad ordering dec_start %llu end %llu",
                           dec_start, dec_end);
        }
        to_dec = dec_end - dec_start;
        if (to_dec > entry->bytes_left) {
                btrfs_crit(fs_info,
                           "bad ordered accounting left %llu size %llu",
                           entry->bytes_left, to_dec);
        }
        entry->bytes_left -= to_dec;
        if (!uptodate)
                set_bit(BTRFS_ORDERED_IOERR, &entry->flags);

        if (entry->bytes_left == 0) {
                /*
                 * Ensure only one caller can set the flag and finished_ret
                 * accordingly
                 */
                finished = !test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
                /* test_and_set_bit implies a barrier */
                cond_wake_up_nomb(&entry->wait);
        }
out:
        if (finished && finished_ret && entry) {
                *finished_ret = entry;
                refcount_inc(&entry->refs);
        }
        spin_unlock_irqrestore(&tree->lock, flags);
        return finished;
}

/*
 * Finish IO for one ordered extent across a given range.  The range can only
 * contain one ordered extent.
 *
 * @cached:      The cached ordered extent. If not NULL, we can skip the tree
 *               search and use the ordered extent directly.
 *               Will be also used to store the finished ordered extent.
 * @file_offset: File offset for the finished IO
 * @io_size:     Length of the finish IO range
 * @uptodate:    If the IO finishes without problem
 *
 * Return true if the ordered extent is finished in the range, and update
 * @cached.
 * Return false otherwise.
 *
 * NOTE: The range can NOT cross multiple ordered extents.
 * Thus caller should ensure the range doesn't cross ordered extents.
 */
bool btrfs_dec_test_ordered_pending(struct btrfs_inode *inode,
                                    struct btrfs_ordered_extent **cached,
                                    u64 file_offset, u64 io_size, int uptodate)
{
        struct btrfs_ordered_inode_tree *tree = &inode->ordered_tree;
        struct rb_node *node;
        struct btrfs_ordered_extent *entry = NULL;
        unsigned long flags;
        bool finished = false;

        spin_lock_irqsave(&tree->lock, flags);
        if (cached && *cached) {
                entry = *cached;
                goto have_entry;
        }

        node = tree_search(tree, file_offset);
        if (!node)
                goto out;

        entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
have_entry:
        if (!in_range(file_offset, entry->file_offset, entry->num_bytes))
                goto out;

        if (io_size > entry->bytes_left)
                btrfs_crit(inode->root->fs_info,
                           "bad ordered accounting left %llu size %llu",
                       entry->bytes_left, io_size);

        entry->bytes_left -= io_size;
        if (!uptodate)
                set_bit(BTRFS_ORDERED_IOERR, &entry->flags);

        if (entry->bytes_left == 0) {
                /*
                 * Ensure only one caller can set the flag and finished_ret
                 * accordingly
                 */
                finished = !test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
                /* test_and_set_bit implies a barrier */
                cond_wake_up_nomb(&entry->wait);
        }
out:
        if (finished && cached && entry) {
                *cached = entry;
                refcount_inc(&entry->refs);
        }
        spin_unlock_irqrestore(&tree->lock, flags);
        return finished;
}

/*
 * used to drop a reference on an ordered extent.  This will free
 * the extent if the last reference is dropped
 */
void btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry)
{
        struct list_head *cur;
        struct btrfs_ordered_sum *sum;

        trace_btrfs_ordered_extent_put(BTRFS_I(entry->inode), entry);

        if (refcount_dec_and_test(&entry->refs)) {
                ASSERT(list_empty(&entry->root_extent_list));
                ASSERT(list_empty(&entry->log_list));
                ASSERT(RB_EMPTY_NODE(&entry->rb_node));
                if (entry->inode)
                        btrfs_add_delayed_iput(entry->inode);
                while (!list_empty(&entry->list)) {
                        cur = entry->list.next;
                        sum = list_entry(cur, struct btrfs_ordered_sum, list);
                        list_del(&sum->list);
                        kvfree(sum);
                }
                kmem_cache_free(btrfs_ordered_extent_cache, entry);
        }
}

/*
 * remove an ordered extent from the tree.  No references are dropped
 * and waiters are woken up.
 */
void btrfs_remove_ordered_extent(struct btrfs_inode *btrfs_inode,
                                 struct btrfs_ordered_extent *entry)
{
        struct btrfs_ordered_inode_tree *tree;
        struct btrfs_root *root = btrfs_inode->root;
        struct btrfs_fs_info *fs_info = root->fs_info;
        struct rb_node *node;
        bool pending;

        /* This is paired with btrfs_add_ordered_extent. */
        spin_lock(&btrfs_inode->lock);
        btrfs_mod_outstanding_extents(btrfs_inode, -1);
        spin_unlock(&btrfs_inode->lock);
        if (root != fs_info->tree_root)
                btrfs_delalloc_release_metadata(btrfs_inode, entry->num_bytes,
                                                false);

        percpu_counter_add_batch(&fs_info->ordered_bytes, -entry->num_bytes,
                                 fs_info->delalloc_batch);

        tree = &btrfs_inode->ordered_tree;
        spin_lock_irq(&tree->lock);
        node = &entry->rb_node;
        rb_erase(node, &tree->tree);
        RB_CLEAR_NODE(node);
        if (tree->last == node)
                tree->last = NULL;
        set_bit(BTRFS_ORDERED_COMPLETE, &entry->flags);
        pending = test_and_clear_bit(BTRFS_ORDERED_PENDING, &entry->flags);
        spin_unlock_irq(&tree->lock);

        /*
         * The current running transaction is waiting on us, we need to let it
         * know that we're complete and wake it up.
         */
        if (pending) {
                struct btrfs_transaction *trans;

                /*
                 * The checks for trans are just a formality, it should be set,
                 * but if it isn't we don't want to deref/assert under the spin
                 * lock, so be nice and check if trans is set, but ASSERT() so
                 * if it isn't set a developer will notice.
                 */
                spin_lock(&fs_info->trans_lock);
                trans = fs_info->running_transaction;
                if (trans)
                        refcount_inc(&trans->use_count);
                spin_unlock(&fs_info->trans_lock);

                ASSERT(trans);
                if (trans) {
                        if (atomic_dec_and_test(&trans->pending_ordered))
                                wake_up(&trans->pending_wait);
                        btrfs_put_transaction(trans);
                }
        }

        spin_lock(&root->ordered_extent_lock);
        list_del_init(&entry->root_extent_list);
        root->nr_ordered_extents--;

        trace_btrfs_ordered_extent_remove(btrfs_inode, entry);

        if (!root->nr_ordered_extents) {
                spin_lock(&fs_info->ordered_root_lock);
                BUG_ON(list_empty(&root->ordered_root));
                list_del_init(&root->ordered_root);
                spin_unlock(&fs_info->ordered_root_lock);
        }
        spin_unlock(&root->ordered_extent_lock);
        wake_up(&entry->wait);
}

static void btrfs_run_ordered_extent_work(struct btrfs_work *work)
{
        struct btrfs_ordered_extent *ordered;

        ordered = container_of(work, struct btrfs_ordered_extent, flush_work);
        btrfs_start_ordered_extent(ordered, 1);
        complete(&ordered->completion);
}

/*
 * wait for all the ordered extents in a root.  This is done when balancing
 * space between drives.
 */
u64 btrfs_wait_ordered_extents(struct btrfs_root *root, u64 nr,
                               const u64 range_start, const u64 range_len)
{
        struct btrfs_fs_info *fs_info = root->fs_info;
        LIST_HEAD(splice);
        LIST_HEAD(skipped);
        LIST_HEAD(works);
        struct btrfs_ordered_extent *ordered, *next;
        u64 count = 0;
        const u64 range_end = range_start + range_len;

        mutex_lock(&root->ordered_extent_mutex);
        spin_lock(&root->ordered_extent_lock);
        list_splice_init(&root->ordered_extents, &splice);
        while (!list_empty(&splice) && nr) {
                ordered = list_first_entry(&splice, struct btrfs_ordered_extent,
                                           root_extent_list);

                if (range_end <= ordered->disk_bytenr ||
                    ordered->disk_bytenr + ordered->disk_num_bytes <= range_start) {
                        list_move_tail(&ordered->root_extent_list, &skipped);
                        cond_resched_lock(&root->ordered_extent_lock);
                        continue;
                }

                list_move_tail(&ordered->root_extent_list,
                               &root->ordered_extents);
                refcount_inc(&ordered->refs);
                spin_unlock(&root->ordered_extent_lock);

                btrfs_init_work(&ordered->flush_work,
                                btrfs_run_ordered_extent_work, NULL, NULL);
                list_add_tail(&ordered->work_list, &works);
                btrfs_queue_work(fs_info->flush_workers, &ordered->flush_work);

                cond_resched();
                spin_lock(&root->ordered_extent_lock);
                if (nr != U64_MAX)
                        nr--;
                count++;
        }
        list_splice_tail(&skipped, &root->ordered_extents);
        list_splice_tail(&splice, &root->ordered_extents);
        spin_unlock(&root->ordered_extent_lock);

        list_for_each_entry_safe(ordered, next, &works, work_list) {
                list_del_init(&ordered->work_list);
                wait_for_completion(&ordered->completion);
                btrfs_put_ordered_extent(ordered);
                cond_resched();
        }
        mutex_unlock(&root->ordered_extent_mutex);

        return count;
}

void btrfs_wait_ordered_roots(struct btrfs_fs_info *fs_info, u64 nr,
                             const u64 range_start, const u64 range_len)
{
        struct btrfs_root *root;
        struct list_head splice;
        u64 done;

        INIT_LIST_HEAD(&splice);

        mutex_lock(&fs_info->ordered_operations_mutex);
        spin_lock(&fs_info->ordered_root_lock);
        list_splice_init(&fs_info->ordered_roots, &splice);
        while (!list_empty(&splice) && nr) {
                root = list_first_entry(&splice, struct btrfs_root,
                                        ordered_root);
                root = btrfs_grab_root(root);
                BUG_ON(!root);
                list_move_tail(&root->ordered_root,
                               &fs_info->ordered_roots);
                spin_unlock(&fs_info->ordered_root_lock);

                done = btrfs_wait_ordered_extents(root, nr,
                                                  range_start, range_len);
                btrfs_put_root(root);

                spin_lock(&fs_info->ordered_root_lock);
                if (nr != U64_MAX) {
                        nr -= done;
                }
        }
        list_splice_tail(&splice, &fs_info->ordered_roots);
        spin_unlock(&fs_info->ordered_root_lock);
        mutex_unlock(&fs_info->ordered_operations_mutex);
}

/*
 * Used to start IO or wait for a given ordered extent to finish.
 *
 * If wait is one, this effectively waits on page writeback for all the pages
 * in the extent, and it waits on the io completion code to insert
 * metadata into the btree corresponding to the extent
 */
void btrfs_start_ordered_extent(struct btrfs_ordered_extent *entry, int wait)
{
        u64 start = entry->file_offset;
        u64 end = start + entry->num_bytes - 1;
        struct btrfs_inode *inode = BTRFS_I(entry->inode);

        trace_btrfs_ordered_extent_start(inode, entry);

        /*
         * pages in the range can be dirty, clean or writeback.  We
         * start IO on any dirty ones so the wait doesn't stall waiting
         * for the flusher thread to find them
         */
        if (!test_bit(BTRFS_ORDERED_DIRECT, &entry->flags))
                filemap_fdatawrite_range(inode->vfs_inode.i_mapping, start, end);
        if (wait) {
                wait_event(entry->wait, test_bit(BTRFS_ORDERED_COMPLETE,
                                                 &entry->flags));
        }
}

/*
 * Used to wait on ordered extents across a large range of bytes.
 */
int btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)
{
        int ret = 0;
        int ret_wb = 0;
        u64 end;
        u64 orig_end;
        struct btrfs_ordered_extent *ordered;

        if (start + len < start) {
                orig_end = INT_LIMIT(loff_t);
        } else {
                orig_end = start + len - 1;
                if (orig_end > INT_LIMIT(loff_t))
                        orig_end = INT_LIMIT(loff_t);
        }

        /* start IO across the range first to instantiate any delalloc
         * extents
         */
        ret = btrfs_fdatawrite_range(inode, start, orig_end);
        if (ret)
                return ret;

        /*
         * If we have a writeback error don't return immediately. Wait first
         * for any ordered extents that haven't completed yet. This is to make
         * sure no one can dirty the same page ranges and call writepages()
         * before the ordered extents complete - to avoid failures (-EEXIST)
         * when adding the new ordered extents to the ordered tree.
         */
        ret_wb = filemap_fdatawait_range(inode->i_mapping, start, orig_end);

        end = orig_end;
        while (1) {
                ordered = btrfs_lookup_first_ordered_extent(BTRFS_I(inode), end);
                if (!ordered)
                        break;
                if (ordered->file_offset > orig_end) {
                        btrfs_put_ordered_extent(ordered);
                        break;
                }
                if (ordered->file_offset + ordered->num_bytes <= start) {
                        btrfs_put_ordered_extent(ordered);
                        break;
                }
                btrfs_start_ordered_extent(ordered, 1);
                end = ordered->file_offset;
                /*
                 * If the ordered extent had an error save the error but don't
                 * exit without waiting first for all other ordered extents in
                 * the range to complete.
                 */
                if (test_bit(BTRFS_ORDERED_IOERR, &ordered->flags))
                        ret = -EIO;
                btrfs_put_ordered_extent(ordered);
                if (end == 0 || end == start)
                        break;
                end--;
        }
        return ret_wb ? ret_wb : ret;
}

/*
 * find an ordered extent corresponding to file_offset.  return NULL if
 * nothing is found, otherwise take a reference on the extent and return it
 */
struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct btrfs_inode *inode,
                                                         u64 file_offset)
{
        struct btrfs_ordered_inode_tree *tree;
        struct rb_node *node;
        struct btrfs_ordered_extent *entry = NULL;
        unsigned long flags;

        tree = &inode->ordered_tree;
        spin_lock_irqsave(&tree->lock, flags);
        node = tree_search(tree, file_offset);
        if (!node)
                goto out;

        entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
        if (!in_range(file_offset, entry->file_offset, entry->num_bytes))
                entry = NULL;
        if (entry)
                refcount_inc(&entry->refs);
out:
        spin_unlock_irqrestore(&tree->lock, flags);
        return entry;
}

/* Since the DIO code tries to lock a wide area we need to look for any ordered
 * extents that exist in the range, rather than just the start of the range.
 */
struct btrfs_ordered_extent *btrfs_lookup_ordered_range(
                struct btrfs_inode *inode, u64 file_offset, u64 len)
{
        struct btrfs_ordered_inode_tree *tree;
        struct rb_node *node;
        struct btrfs_ordered_extent *entry = NULL;

        tree = &inode->ordered_tree;
        spin_lock_irq(&tree->lock);
        node = tree_search(tree, file_offset);
        if (!node) {
                node = tree_search(tree, file_offset + len);
                if (!node)
                        goto out;
        }

        while (1) {
                entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
                if (range_overlaps(entry, file_offset, len))
                        break;

                if (entry->file_offset >= file_offset + len) {
                        entry = NULL;
                        break;
                }
                entry = NULL;
                node = rb_next(node);
                if (!node)
                        break;
        }
out:
        if (entry)
                refcount_inc(&entry->refs);
        spin_unlock_irq(&tree->lock);
        return entry;
}

/*
 * Adds all ordered extents to the given list. The list ends up sorted by the
 * file_offset of the ordered extents.
 */
void btrfs_get_ordered_extents_for_logging(struct btrfs_inode *inode,
                                           struct list_head *list)
{
        struct btrfs_ordered_inode_tree *tree = &inode->ordered_tree;
        struct rb_node *n;

        ASSERT(inode_is_locked(&inode->vfs_inode));

        spin_lock_irq(&tree->lock);
        for (n = rb_first(&tree->tree); n; n = rb_next(n)) {
                struct btrfs_ordered_extent *ordered;

                ordered = rb_entry(n, struct btrfs_ordered_extent, rb_node);

                if (test_bit(BTRFS_ORDERED_LOGGED, &ordered->flags))
                        continue;

                ASSERT(list_empty(&ordered->log_list));
                list_add_tail(&ordered->log_list, list);
                refcount_inc(&ordered->refs);
        }
        spin_unlock_irq(&tree->lock);
}

/*
 * lookup and return any extent before 'file_offset'.  NULL is returned
 * if none is found
 */
struct btrfs_ordered_extent *
btrfs_lookup_first_ordered_extent(struct btrfs_inode *inode, u64 file_offset)
{
        struct btrfs_ordered_inode_tree *tree;
        struct rb_node *node;
        struct btrfs_ordered_extent *entry = NULL;

        tree = &inode->ordered_tree;
        spin_lock_irq(&tree->lock);
        node = tree_search(tree, file_offset);
        if (!node)
                goto out;

        entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
        refcount_inc(&entry->refs);
out:
        spin_unlock_irq(&tree->lock);
        return entry;
}

/*
 * btrfs_flush_ordered_range - Lock the passed range and ensures all pending
 * ordered extents in it are run to completion.
 *
 * @inode:        Inode whose ordered tree is to be searched
 * @start:        Beginning of range to flush
 * @end:          Last byte of range to lock
 * @cached_state: If passed, will return the extent state responsible for the
 * locked range. It's the caller's responsibility to free the cached state.
 *
 * This function always returns with the given range locked, ensuring after it's
 * called no order extent can be pending.
 */
void btrfs_lock_and_flush_ordered_range(struct btrfs_inode *inode, u64 start,
                                        u64 end,
                                        struct extent_state **cached_state)
{
        struct btrfs_ordered_extent *ordered;
        struct extent_state *cache = NULL;
        struct extent_state **cachedp = &cache;

        if (cached_state)
                cachedp = cached_state;

        while (1) {
                lock_extent_bits(&inode->io_tree, start, end, cachedp);
                ordered = btrfs_lookup_ordered_range(inode, start,
                                                     end - start + 1);
                if (!ordered) {
                        /*
                         * If no external cached_state has been passed then
                         * decrement the extra ref taken for cachedp since we
                         * aren't exposing it outside of this function
                         */
                        if (!cached_state)
                                refcount_dec(&cache->refs);
                        break;
                }
                unlock_extent_cached(&inode->io_tree, start, end, cachedp);
                btrfs_start_ordered_extent(ordered, 1);
                btrfs_put_ordered_extent(ordered);
        }
}

static int clone_ordered_extent(struct btrfs_ordered_extent *ordered, u64 pos,
                                u64 len)
{
        struct inode *inode = ordered->inode;
        u64 file_offset = ordered->file_offset + pos;
        u64 disk_bytenr = ordered->disk_bytenr + pos;
        u64 num_bytes = len;
        u64 disk_num_bytes = len;
        int type;
        unsigned long flags_masked = ordered->flags & ~(1 << BTRFS_ORDERED_DIRECT);
        int compress_type = ordered->compress_type;
        unsigned long weight;
        int ret;

        weight = hweight_long(flags_masked);
        WARN_ON_ONCE(weight > 1);
        if (!weight)
                type = 0;
        else
                type = __ffs(flags_masked);

        if (test_bit(BTRFS_ORDERED_COMPRESSED, &ordered->flags)) {
                WARN_ON_ONCE(1);
                ret = btrfs_add_ordered_extent_compress(BTRFS_I(inode),
                                file_offset, disk_bytenr, num_bytes,
                                disk_num_bytes, compress_type);
        } else if (test_bit(BTRFS_ORDERED_DIRECT, &ordered->flags)) {
                ret = btrfs_add_ordered_extent_dio(BTRFS_I(inode), file_offset,
                                disk_bytenr, num_bytes, disk_num_bytes, type);
        } else {
                ret = btrfs_add_ordered_extent(BTRFS_I(inode), file_offset,
                                disk_bytenr, num_bytes, disk_num_bytes, type);
        }

        return ret;
}

int btrfs_split_ordered_extent(struct btrfs_ordered_extent *ordered, u64 pre,
                                u64 post)
{
        struct inode *inode = ordered->inode;
        struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
        struct rb_node *node;
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        int ret = 0;

        spin_lock_irq(&tree->lock);
        /* Remove from tree once */
        node = &ordered->rb_node;
        rb_erase(node, &tree->tree);
        RB_CLEAR_NODE(node);
        if (tree->last == node)
                tree->last = NULL;

        ordered->file_offset += pre;
        ordered->disk_bytenr += pre;
        ordered->num_bytes -= (pre + post);
        ordered->disk_num_bytes -= (pre + post);
        ordered->bytes_left -= (pre + post);

        /* Re-insert the node */
        node = tree_insert(&tree->tree, ordered->file_offset, &ordered->rb_node);
        if (node)
                btrfs_panic(fs_info, -EEXIST,
                        "zoned: inconsistency in ordered tree at offset %llu",
                            ordered->file_offset);

        spin_unlock_irq(&tree->lock);

        if (pre)
                ret = clone_ordered_extent(ordered, 0, pre);
        if (ret == 0 && post)
                ret = clone_ordered_extent(ordered, pre + ordered->disk_num_bytes,
                                           post);

        return ret;
}

int __init ordered_data_init(void)
{
        btrfs_ordered_extent_cache = kmem_cache_create("btrfs_ordered_extent",
                                     sizeof(struct btrfs_ordered_extent), 0,
                                     SLAB_MEM_SPREAD,
                                     NULL);
        if (!btrfs_ordered_extent_cache)

                return -ENOMEM;

        return 0;
}

void __cold ordered_data_exit(void)
{
        kmem_cache_destroy(btrfs_ordered_extent_cache);
}