#include <crypto/hash.h>
 #include <linux/kernel.h>
 #include <linux/bio.h>
-#include <linux/buffer_head.h>
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/pagemap.h>
 #include <linux/swap.h>
 #include <linux/migrate.h>
 #include <linux/sched/mm.h>
+#include <linux/iomap.h>
 #include <asm/unaligned.h>
 #include "misc.h"
 #include "ctree.h"
 
 struct btrfs_dio_data {
        u64 reserve;
-       u64 unsubmitted_oe_range_start;
-       u64 unsubmitted_oe_range_end;
-       int overwrite;
+       loff_t length;
+       ssize_t submitted;
+       struct extent_changeset *data_reserved;
 };
 
 static const struct inode_operations btrfs_dir_inode_operations;
 }
 
 static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend,
-                             struct extent_state **cached_state, int writing)
+                             struct extent_state **cached_state, bool writing)
 {
        struct btrfs_ordered_extent *ordered;
        int ret = 0;
 }
 
 
-static int btrfs_get_blocks_direct_read(struct extent_map *em,
-                                       struct buffer_head *bh_result,
-                                       struct inode *inode,
-                                       u64 start, u64 len)
-{
-       struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
-
-       if (em->block_start == EXTENT_MAP_HOLE ||
-                       test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
-               return -ENOENT;
-
-       len = min(len, em->len - (start - em->start));
-
-       bh_result->b_blocknr = (em->block_start + (start - em->start)) >>
-               inode->i_blkbits;
-       bh_result->b_size = len;
-       bh_result->b_bdev = fs_info->fs_devices->latest_bdev;
-       set_buffer_mapped(bh_result);
-
-       return 0;
-}
-
 static int btrfs_get_blocks_direct_write(struct extent_map **map,
-                                        struct buffer_head *bh_result,
                                         struct inode *inode,
                                         struct btrfs_dio_data *dio_data,
                                         u64 start, u64 len)
        }
 
        /* this will cow the extent */
-       len = bh_result->b_size;
        free_extent_map(em);
        *map = em = btrfs_new_extent_direct(BTRFS_I(inode), start, len);
        if (IS_ERR(em)) {
        len = min(len, em->len - (start - em->start));
 
 skip_cow:
-       bh_result->b_blocknr = (em->block_start + (start - em->start)) >>
-               inode->i_blkbits;
-       bh_result->b_size = len;
-       bh_result->b_bdev = fs_info->fs_devices->latest_bdev;
-       set_buffer_mapped(bh_result);
-
-       if (!test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
-               set_buffer_new(bh_result);
-
        /*
         * Need to update the i_size under the extent lock so buffered
         * readers will get the updated i_size when we unlock.
         */
-       if (!dio_data->overwrite && start + len > i_size_read(inode))
+       if (start + len > i_size_read(inode))
                i_size_write(inode, start + len);
 
-       WARN_ON(dio_data->reserve < len);
        dio_data->reserve -= len;
-       dio_data->unsubmitted_oe_range_end = start + len;
-       current->journal_info = dio_data;
 out:
        return ret;
 }
 
-static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
-                                  struct buffer_head *bh_result, int create)
+static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start,
+               loff_t length, unsigned int flags, struct iomap *iomap,
+               struct iomap *srcmap)
 {
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct extent_map *em;
        struct extent_state *cached_state = NULL;
        struct btrfs_dio_data *dio_data = NULL;
-       u64 start = iblock << inode->i_blkbits;
        u64 lockstart, lockend;
-       u64 len = bh_result->b_size;
+       const bool write = !!(flags & IOMAP_WRITE);
        int ret = 0;
+       u64 len = length;
+       bool unlock_extents = false;
 
-       if (!create)
+       if (!write)
                len = min_t(u64, len, fs_info->sectorsize);
 
        lockstart = start;
        lockend = start + len - 1;
 
-       if (current->journal_info) {
-               /*
-                * Need to pull our outstanding extents and set journal_info to NULL so
-                * that anything that needs to check if there's a transaction doesn't get
-                * confused.
-                */
-               dio_data = current->journal_info;
-               current->journal_info = NULL;
+       /*
+        * The generic stuff only does filemap_write_and_wait_range, which
+        * isn't enough if we've written compressed pages to this area, so we
+        * need to flush the dirty pages again to make absolutely sure that any
+        * outstanding dirty pages are on disk.
+        */
+       if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
+                    &BTRFS_I(inode)->runtime_flags)) {
+               ret = filemap_fdatawrite_range(inode->i_mapping, start,
+                                              start + length - 1);
+               if (ret)
+                       return ret;
+       }
+
+       dio_data = kzalloc(sizeof(*dio_data), GFP_NOFS);
+       if (!dio_data)
+               return -ENOMEM;
+
+       dio_data->length = length;
+       if (write) {
+               dio_data->reserve = round_up(length, fs_info->sectorsize);
+               ret = btrfs_delalloc_reserve_space(BTRFS_I(inode),
+                               &dio_data->data_reserved,
+                               start, dio_data->reserve);
+               if (ret) {
+                       extent_changeset_free(dio_data->data_reserved);
+                       kfree(dio_data);
+                       return ret;
+               }
        }
+       iomap->private = dio_data;
+
 
        /*
         * If this errors out it's because we couldn't invalidate pagecache for
         * this range and we need to fallback to buffered.
         */
-       if (lock_extent_direct(inode, lockstart, lockend, &cached_state,
-                              create)) {
+       if (lock_extent_direct(inode, lockstart, lockend, &cached_state, write)) {
                ret = -ENOTBLK;
                goto err;
        }
                goto unlock_err;
        }
 
-       if (create) {
-               ret = btrfs_get_blocks_direct_write(&em, bh_result, inode,
-                                                   dio_data, start, len);
+       len = min(len, em->len - (start - em->start));
+       if (write) {
+               ret = btrfs_get_blocks_direct_write(&em, inode, dio_data,
+                                                   start, len);
                if (ret < 0)
                        goto unlock_err;
-
-               unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
-                                    lockend, &cached_state);
+               unlock_extents = true;
+               /* Recalc len in case the new em is smaller than requested */
+               len = min(len, em->len - (start - em->start));
        } else {
-               ret = btrfs_get_blocks_direct_read(em, bh_result, inode,
-                                                  start, len);
-               /* Can be negative only if we read from a hole */
-               if (ret < 0) {
-                       ret = 0;
-                       free_extent_map(em);
-                       goto unlock_err;
-               }
                /*
                 * We need to unlock only the end area that we aren't using.
                 * The rest is going to be unlocked by the endio routine.
                 */
-               lockstart = start + bh_result->b_size;
-               if (lockstart < lockend) {
-                       unlock_extent_cached(&BTRFS_I(inode)->io_tree,
-                                            lockstart, lockend, &cached_state);
-               } else {
-                       free_extent_state(cached_state);
-               }
+               lockstart = start + len;
+               if (lockstart < lockend)
+                       unlock_extents = true;
+       }
+
+       if (unlock_extents)
+               unlock_extent_cached(&BTRFS_I(inode)->io_tree,
+                                    lockstart, lockend, &cached_state);
+       else
+               free_extent_state(cached_state);
+
+       /*
+        * Translate extent map information to iomap.
+        * We trim the extents (and move the addr) even though iomap code does
+        * that, since we have locked only the parts we are performing I/O in.
+        */
+       if ((em->block_start == EXTENT_MAP_HOLE) ||
+           (test_bit(EXTENT_FLAG_PREALLOC, &em->flags) && !write)) {
+               iomap->addr = IOMAP_NULL_ADDR;
+               iomap->type = IOMAP_HOLE;
+       } else {
+               iomap->addr = em->block_start + (start - em->start);
+               iomap->type = IOMAP_MAPPED;
        }
+       iomap->offset = start;
+       iomap->bdev = fs_info->fs_devices->latest_bdev;
+       iomap->length = len;
 
        free_extent_map(em);
 
        unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
                             &cached_state);
 err:
-       if (dio_data)
-               current->journal_info = dio_data;
+       if (dio_data) {
+               btrfs_delalloc_release_space(BTRFS_I(inode),
+                               dio_data->data_reserved, start,
+                               dio_data->reserve, true);
+               btrfs_delalloc_release_extents(BTRFS_I(inode), dio_data->reserve);
+               extent_changeset_free(dio_data->data_reserved);
+               kfree(dio_data);
+       }
+       return ret;
+}
+
+static int btrfs_dio_iomap_end(struct inode *inode, loff_t pos, loff_t length,
+               ssize_t written, unsigned int flags, struct iomap *iomap)
+{
+       int ret = 0;
+       struct btrfs_dio_data *dio_data = iomap->private;
+       size_t submitted = dio_data->submitted;
+       const bool write = !!(flags & IOMAP_WRITE);
+
+       if (!write && (iomap->type == IOMAP_HOLE)) {
+               /* If reading from a hole, unlock and return */
+               unlock_extent(&BTRFS_I(inode)->io_tree, pos, pos + length - 1);
+               goto out;
+       }
+
+       if (submitted < length) {
+               pos += submitted;
+               length -= submitted;
+               if (write)
+                       __endio_write_update_ordered(BTRFS_I(inode), pos,
+                                       length, false);
+               else
+                       unlock_extent(&BTRFS_I(inode)->io_tree, pos,
+                                     pos + length - 1);
+               ret = -ENOTBLK;
+       }
+
+       if (write) {
+               if (dio_data->reserve)
+                       btrfs_delalloc_release_space(BTRFS_I(inode),
+                                       dio_data->data_reserved, pos,
+                                       dio_data->reserve, true);
+               btrfs_delalloc_release_extents(BTRFS_I(inode), dio_data->length);
+               extent_changeset_free(dio_data->data_reserved);
+       }
+out:
+       kfree(dio_data);
+       iomap->private = NULL;
+
        return ret;
 }
 
                              dip->logical_offset + dip->bytes - 1);
        }
 
-       dio_end_io(dip->dio_bio);
+       bio_endio(dip->dio_bio);
        kfree(dip);
 }
 
        dip->disk_bytenr = (u64)dio_bio->bi_iter.bi_sector << 9;
        dip->dio_bio = dio_bio;
        refcount_set(&dip->refs, 1);
-
-       if (write) {
-               struct btrfs_dio_data *dio_data = current->journal_info;
-
-               /*
-                * Setting range start and end to the same value means that
-                * no cleanup will happen in btrfs_direct_IO
-                */
-               dio_data->unsubmitted_oe_range_end = dip->logical_offset +
-                       dip->bytes;
-               dio_data->unsubmitted_oe_range_start =
-                       dio_data->unsubmitted_oe_range_end;
-       }
        return dip;
 }
 
-static void btrfs_submit_direct(struct bio *dio_bio, struct inode *inode,
-                               loff_t file_offset)
+static blk_qc_t btrfs_submit_direct(struct inode *inode, struct iomap *iomap,
+               struct bio *dio_bio, loff_t file_offset)
 {
        const bool write = (bio_op(dio_bio) == REQ_OP_WRITE);
        const bool csum = !(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM);
        int ret;
        blk_status_t status;
        struct btrfs_io_geometry geom;
+       struct btrfs_dio_data *dio_data = iomap->private;
 
        dip = btrfs_create_dio_private(dio_bio, inode, file_offset);
        if (!dip) {
                                file_offset + dio_bio->bi_iter.bi_size - 1);
                }
                dio_bio->bi_status = BLK_STS_RESOURCE;
-               dio_end_io(dio_bio);
-               return;
+               bio_endio(dio_bio);
+               return BLK_QC_T_NONE;
        }
 
        if (!write && csum) {
                        goto out_err;
                }
 
+               dio_data->submitted += clone_len;
                clone_offset += clone_len;
                start_sector += clone_len >> 9;
                file_offset += clone_len;
        } while (submit_len > 0);
-       return;
+       return BLK_QC_T_NONE;
 
 out_err:
        dip->dio_bio->bi_status = status;
        btrfs_dio_private_put(dip);
+       return BLK_QC_T_NONE;
 }
 
 static ssize_t check_direct_IO(struct btrfs_fs_info *fs_info,
        return retval;
 }
 
-static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
+static const struct iomap_ops btrfs_dio_iomap_ops = {
+       .iomap_begin            = btrfs_dio_iomap_begin,
+       .iomap_end              = btrfs_dio_iomap_end,
+};
+
+static const struct iomap_dio_ops btrfs_dio_ops = {
+       .submit_io              = btrfs_submit_direct,
+};
+
+ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 {
        struct file *file = iocb->ki_filp;
        struct inode *inode = file->f_mapping->host;
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
-       struct btrfs_dio_data dio_data = { 0 };
        struct extent_changeset *data_reserved = NULL;
        loff_t offset = iocb->ki_pos;
        size_t count = 0;
-       int flags = 0;
-       bool wakeup = true;
        bool relock = false;
        ssize_t ret;
 
        if (check_direct_IO(fs_info, iter, offset))
                return 0;
 
-       inode_dio_begin(inode);
-
-       /*
-        * The generic stuff only does filemap_write_and_wait_range, which
-        * isn't enough if we've written compressed pages to this area, so
-        * we need to flush the dirty pages again to make absolutely sure
-        * that any outstanding dirty pages are on disk.
-        */
        count = iov_iter_count(iter);
-       if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
-                    &BTRFS_I(inode)->runtime_flags))
-               filemap_fdatawrite_range(inode->i_mapping, offset,
-                                        offset + count - 1);
-
        if (iov_iter_rw(iter) == WRITE) {
                /*
                 * If the write DIO is beyond the EOF, we need update
                 * not unlock the i_mutex at this case.
                 */
                if (offset + count <= inode->i_size) {
-                       dio_data.overwrite = 1;
                        inode_unlock(inode);
                        relock = true;
                }
-               ret = btrfs_delalloc_reserve_space(BTRFS_I(inode), &data_reserved,
-                                                  offset, count);
-               if (ret)
-                       goto out;
-
-               /*
-                * We need to know how many extents we reserved so that we can
-                * do the accounting properly if we go over the number we
-                * originally calculated.  Abuse current->journal_info for this.
-                */
-               dio_data.reserve = round_up(count,
-                                           fs_info->sectorsize);
-               dio_data.unsubmitted_oe_range_start = (u64)offset;
-               dio_data.unsubmitted_oe_range_end = (u64)offset;
-               current->journal_info = &dio_data;
                down_read(&BTRFS_I(inode)->dio_sem);
-       } else if (test_bit(BTRFS_INODE_READDIO_NEED_LOCK,
-                                    &BTRFS_I(inode)->runtime_flags)) {
-               inode_dio_end(inode);
-               flags = DIO_LOCKING | DIO_SKIP_HOLES;
-               wakeup = false;
        }
 
-       ret = __blockdev_direct_IO(iocb, inode,
-                                  fs_info->fs_devices->latest_bdev,
-                                  iter, btrfs_get_blocks_direct, NULL,
-                                  btrfs_submit_direct, flags);
-       if (iov_iter_rw(iter) == WRITE) {
+       ret = iomap_dio_rw(iocb, iter, &btrfs_dio_iomap_ops, &btrfs_dio_ops,
+                       is_sync_kiocb(iocb));
+
+       if (ret == -ENOTBLK)
+               ret = 0;
+
+       if (iov_iter_rw(iter) == WRITE)
                up_read(&BTRFS_I(inode)->dio_sem);
-               current->journal_info = NULL;
-               if (ret < 0 && ret != -EIOCBQUEUED) {
-                       if (dio_data.reserve)
-                               btrfs_delalloc_release_space(BTRFS_I(inode),
-                                       data_reserved, offset, dio_data.reserve,
-                                       true);
-                       /*
-                        * On error we might have left some ordered extents
-                        * without submitting corresponding bios for them, so
-                        * cleanup them up to avoid other tasks getting them
-                        * and waiting for them to complete forever.
-                        */
-                       if (dio_data.unsubmitted_oe_range_start <
-                           dio_data.unsubmitted_oe_range_end)
-                               __endio_write_update_ordered(BTRFS_I(inode),
-                                       dio_data.unsubmitted_oe_range_start,
-                                       dio_data.unsubmitted_oe_range_end -
-                                       dio_data.unsubmitted_oe_range_start,
-                                       false);
-               } else if (ret >= 0 && (size_t)ret < count)
-                       btrfs_delalloc_release_space(BTRFS_I(inode), data_reserved,
-                                       offset, count - (size_t)ret, true);
-               btrfs_delalloc_release_extents(BTRFS_I(inode), count);
-       }
-out:
-       if (wakeup)
-               inode_dio_end(inode);
+
        if (relock)
                inode_lock(inode);
 
        .writepage      = btrfs_writepage,
        .writepages     = btrfs_writepages,
        .readahead      = btrfs_readahead,
-       .direct_IO      = btrfs_direct_IO,
+       .direct_IO      = noop_direct_IO,
        .invalidatepage = btrfs_invalidatepage,
        .releasepage    = btrfs_releasepage,
 #ifdef CONFIG_MIGRATION