[PATCH 1/2] dma-buf: heaps: DMA_HEAP_IOCTL_ALLOC_READ_FILE framework
Christian König
christian.koenig at amd.com
Thu Jul 11 09:00:02 UTC 2024
Am 11.07.24 um 09:42 schrieb Huan Yang:
> Some user may need load file into dma-buf, current
> way is:
> 1. allocate a dma-buf, get dma-buf fd
> 2. mmap dma-buf fd into vaddr
> 3. read(file_fd, vaddr, fsz)
> This is too heavy if fsz reached to GB.
You need to describe a bit more why that is to heavy. I can only assume
you need to save memory bandwidth and avoid the extra copy with the CPU.
> This patch implement a feature called DMA_HEAP_IOCTL_ALLOC_READ_FILE.
> User need to offer a file_fd which you want to load into dma-buf, then,
> it promise if you got a dma-buf fd, it will contains the file content.
Interesting idea, that has at least more potential than trying to enable
direct I/O on mmap()ed DMA-bufs.
The approach with the new IOCTL might not work because it is a very
specialized use case.
But IIRC there was a copy_file_range callback in the file_operations
structure you could use for that. I'm just not sure when and how that's
used with the copy_file_range() system call.
Regards,
Christian.
>
> Notice, file_fd depends on user how to open this file. So, both buffer
> I/O and Direct I/O is supported.
>
> Signed-off-by: Huan Yang <link at vivo.com>
> ---
> drivers/dma-buf/dma-heap.c | 525 +++++++++++++++++++++++++++++++++-
> include/linux/dma-heap.h | 57 +++-
> include/uapi/linux/dma-heap.h | 32 +++
> 3 files changed, 611 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c
> index 2298ca5e112e..abe17281adb8 100644
> --- a/drivers/dma-buf/dma-heap.c
> +++ b/drivers/dma-buf/dma-heap.c
> @@ -15,9 +15,11 @@
> #include <linux/list.h>
> #include <linux/slab.h>
> #include <linux/nospec.h>
> +#include <linux/highmem.h>
> #include <linux/uaccess.h>
> #include <linux/syscalls.h>
> #include <linux/dma-heap.h>
> +#include <linux/vmalloc.h>
> #include <uapi/linux/dma-heap.h>
>
> #define DEVNAME "dma_heap"
> @@ -43,12 +45,462 @@ struct dma_heap {
> struct cdev heap_cdev;
> };
>
> +/**
> + * struct dma_heap_file - wrap the file, read task for dma_heap allocate use.
> + * @file: file to read from.
> + *
> + * @cred: kthread use, user cred copy to use for the read.
> + *
> + * @max_batch: maximum batch size to read, if collect match batch,
> + * trigger read, default 128MB, must below file size.
> + *
> + * @fsz: file size.
> + *
> + * @direct: use direct IO?
> + */
> +struct dma_heap_file {
> + struct file *file;
> + struct cred *cred;
> + size_t max_batch;
> + size_t fsz;
> + bool direct;
> +};
> +
> +/**
> + * struct dma_heap_file_work - represents a dma_heap file read real work.
> + * @vaddr: contigous virtual address alloc by vmap, file read need.
> + *
> + * @start_size: file read start offset, same to @dma_heap_file_task->roffset.
> + *
> + * @need_size: file read need size, same to @dma_heap_file_task->rsize.
> + *
> + * @heap_file: file wrapper.
> + *
> + * @list: child node of @dma_heap_file_control->works.
> + *
> + * @refp: same @dma_heap_file_task->ref, if end of read, put ref.
> + *
> + * @failp: if any work io failed, set it true, pointp @dma_heap_file_task->fail.
> + */
> +struct dma_heap_file_work {
> + void *vaddr;
> + ssize_t start_size;
> + ssize_t need_size;
> + struct dma_heap_file *heap_file;
> + struct list_head list;
> + atomic_t *refp;
> + bool *failp;
> +};
> +
> +/**
> + * struct dma_heap_file_task - represents a dma_heap file read process
> + * @ref: current file work counter, if zero, allocate and read
> + * done.
> + *
> + * @roffset: last read offset, current prepared work' begin file
> + * start offset.
> + *
> + * @rsize: current allocated page size use to read, if reach rbatch,
> + * trigger commit.
> + *
> + * @rbatch: current prepared work's batch, below @dma_heap_file's
> + * batch.
> + *
> + * @heap_file: current dma_heap_file
> + *
> + * @parray: used for vmap, size is @dma_heap_file's batch's number
> + * pages.(this is maximum). Due to single thread file read,
> + * one page array reuse each work prepare is OK.
> + * Each index in parray is PAGE_SIZE.(vmap need)
> + *
> + * @pindex: current allocated page filled in @parray's index.
> + *
> + * @fail: any work failed when file read?
> + *
> + * dma_heap_file_task is the production of file read, will prepare each work
> + * during allocate dma_buf pages, if match current batch, then trigger commit
> + * and prepare next work. After all batch queued, user going on prepare dma_buf
> + * and so on, but before return dma_buf fd, need to wait file read end and
> + * check read result.
> + */
> +struct dma_heap_file_task {
> + atomic_t ref;
> + size_t roffset;
> + size_t rsize;
> + size_t rbatch;
> + struct dma_heap_file *heap_file;
> + struct page **parray;
> + unsigned int pindex;
> + bool fail;
> +};
> +
> +/**
> + * struct dma_heap_file_control - global control of dma_heap file read.
> + * @works: @dma_heap_file_work's list head.
> + *
> + * @lock: only lock for @works.
> + *
> + * @threadwq: wait queue for @work_thread, if commit work, @work_thread
> + * wakeup and read this work's file contains.
> + *
> + * @workwq: used for main thread wait for file read end, if allocation
> + * end before file read. @dma_heap_file_task ref effect this.
> + *
> + * @work_thread: file read kthread. the dma_heap_file_task work's consumer.
> + *
> + * @heap_fwork_cachep: @dma_heap_file_work's cachep, it's alloc/free frequently.
> + *
> + * @nr_work: global number of how many work committed.
> + */
> +struct dma_heap_file_control {
> + struct list_head works;
> + spinlock_t lock;
> + wait_queue_head_t threadwq;
> + wait_queue_head_t workwq;
> + struct task_struct *work_thread;
> + struct kmem_cache *heap_fwork_cachep;
> + atomic_t nr_work;
> +};
> +
> +static struct dma_heap_file_control *heap_fctl;
> static LIST_HEAD(heap_list);
> static DEFINE_MUTEX(heap_list_lock);
> static dev_t dma_heap_devt;
> static struct class *dma_heap_class;
> static DEFINE_XARRAY_ALLOC(dma_heap_minors);
>
> +/**
> + * map_pages_to_vaddr - map each scatter page into contiguous virtual address.
> + * @heap_ftask: prepared and need to commit's work.
> + *
> + * Cached pages need to trigger file read, this function map each scatter page
> + * into contiguous virtual address, so that file read can easy use.
> + * Now that we get vaddr page, cached pages can return to original user, so we
> + * will not effect dma-buf export even if file read not end.
> + */
> +static void *map_pages_to_vaddr(struct dma_heap_file_task *heap_ftask)
> +{
> + return vmap(heap_ftask->parray, heap_ftask->pindex, VM_MAP,
> + PAGE_KERNEL);
> +}
> +
> +bool dma_heap_prepare_file_read(struct dma_heap_file_task *heap_ftask,
> + struct page *page)
> +{
> + struct page **array = heap_ftask->parray;
> + int index = heap_ftask->pindex;
> + int num = compound_nr(page), i;
> + unsigned long sz = page_size(page);
> +
> + heap_ftask->rsize += sz;
> + for (i = 0; i < num; ++i)
> + array[index++] = &page[i];
> + heap_ftask->pindex = index;
> +
> + return heap_ftask->rsize >= heap_ftask->rbatch;
> +}
> +
> +static struct dma_heap_file_work *
> +init_file_work(struct dma_heap_file_task *heap_ftask)
> +{
> + struct dma_heap_file_work *heap_fwork;
> + struct dma_heap_file *heap_file = heap_ftask->heap_file;
> +
> + if (READ_ONCE(heap_ftask->fail))
> + return NULL;
> +
> + heap_fwork = kmem_cache_alloc(heap_fctl->heap_fwork_cachep, GFP_KERNEL);
> + if (unlikely(!heap_fwork))
> + return NULL;
> +
> + heap_fwork->vaddr = map_pages_to_vaddr(heap_ftask);
> + if (unlikely(!heap_fwork->vaddr)) {
> + kmem_cache_free(heap_fctl->heap_fwork_cachep, heap_fwork);
> + return NULL;
> + }
> +
> + heap_fwork->heap_file = heap_file;
> + heap_fwork->start_size = heap_ftask->roffset;
> + heap_fwork->need_size = heap_ftask->rsize;
> + heap_fwork->refp = &heap_ftask->ref;
> + heap_fwork->failp = &heap_ftask->fail;
> + atomic_inc(&heap_ftask->ref);
> + return heap_fwork;
> +}
> +
> +static void destroy_file_work(struct dma_heap_file_work *heap_fwork)
> +{
> + vunmap(heap_fwork->vaddr);
> + atomic_dec(heap_fwork->refp);
> + wake_up(&heap_fctl->workwq);
> +
> + kmem_cache_free(heap_fctl->heap_fwork_cachep, heap_fwork);
> +}
> +
> +int dma_heap_submit_file_read(struct dma_heap_file_task *heap_ftask)
> +{
> + struct dma_heap_file_work *heap_fwork = init_file_work(heap_ftask);
> + struct page *last = NULL;
> + struct dma_heap_file *heap_file = heap_ftask->heap_file;
> + size_t start = heap_ftask->roffset;
> + struct file *file = heap_file->file;
> + size_t fsz = heap_file->fsz;
> +
> + if (unlikely(!heap_fwork))
> + return -ENOMEM;
> +
> + /**
> + * If file size is not page aligned, direct io can't process the tail.
> + * So, if reach to tail, remain the last page use buffer read.
> + */
> + if (heap_file->direct && start + heap_ftask->rsize > fsz) {
> + heap_fwork->need_size -= PAGE_SIZE;
> + last = heap_ftask->parray[heap_ftask->pindex - 1];
> + }
> +
> + spin_lock(&heap_fctl->lock);
> + list_add_tail(&heap_fwork->list, &heap_fctl->works);
> + spin_unlock(&heap_fctl->lock);
> + atomic_inc(&heap_fctl->nr_work);
> +
> + wake_up(&heap_fctl->threadwq);
> +
> + if (last) {
> + char *buf, *pathp;
> + ssize_t err;
> + void *buffer;
> +
> + buf = kmalloc(PATH_MAX, GFP_KERNEL);
> + if (unlikely(!buf))
> + return -ENOMEM;
> +
> + start = PAGE_ALIGN_DOWN(fsz);
> +
> + pathp = file_path(file, buf, PATH_MAX);
> + if (IS_ERR(pathp)) {
> + kfree(buf);
> + return PTR_ERR(pathp);
> + }
> +
> + buffer = kmap_local_page(last); // use page's kaddr.
> + err = kernel_read_file_from_path(pathp, start, &buffer,
> + fsz - start, &fsz,
> + READING_POLICY);
> + kunmap_local(buffer);
> + kfree(buf);
> + if (err < 0) {
> + pr_err("failed to use buffer kernel_read_file %s, err=%ld, [%ld, %ld], f_sz=%ld\n",
> + pathp, err, start, fsz, fsz);
> +
> + return err;
> + }
> + }
> +
> + heap_ftask->roffset += heap_ftask->rsize;
> + heap_ftask->rsize = 0;
> + heap_ftask->pindex = 0;
> + heap_ftask->rbatch = min_t(size_t,
> + PAGE_ALIGN(fsz) - heap_ftask->roffset,
> + heap_ftask->rbatch);
> + return 0;
> +}
> +
> +bool dma_heap_wait_for_file_read(struct dma_heap_file_task *heap_ftask)
> +{
> + wait_event_freezable(heap_fctl->workwq,
> + atomic_read(&heap_ftask->ref) == 0);
> + return heap_ftask->fail;
> +}
> +
> +bool dma_heap_destroy_file_read(struct dma_heap_file_task *heap_ftask)
> +{
> + bool fail;
> +
> + dma_heap_wait_for_file_read(heap_ftask);
> + fail = heap_ftask->fail;
> + kvfree(heap_ftask->parray);
> + kfree(heap_ftask);
> + return fail;
> +}
> +
> +struct dma_heap_file_task *
> +dma_heap_declare_file_read(struct dma_heap_file *heap_file)
> +{
> + struct dma_heap_file_task *heap_ftask =
> + kzalloc(sizeof(*heap_ftask), GFP_KERNEL);
> + if (unlikely(!heap_ftask))
> + return NULL;
> +
> + /**
> + * Batch is the maximum size which we prepare work will meet.
> + * So, direct alloc this number's page array is OK.
> + */
> + heap_ftask->parray = kvmalloc_array(heap_file->max_batch >> PAGE_SHIFT,
> + sizeof(struct page *), GFP_KERNEL);
> + if (unlikely(!heap_ftask->parray))
> + goto put;
> +
> + heap_ftask->heap_file = heap_file;
> + heap_ftask->rbatch = heap_file->max_batch;
> + return heap_ftask;
> +put:
> + kfree(heap_ftask);
> + return NULL;
> +}
> +
> +static void __work_this_io(struct dma_heap_file_work *heap_fwork)
> +{
> + struct dma_heap_file *heap_file = heap_fwork->heap_file;
> + struct file *file = heap_file->file;
> + ssize_t start = heap_fwork->start_size;
> + ssize_t size = heap_fwork->need_size;
> + void *buffer = heap_fwork->vaddr;
> + const struct cred *old_cred;
> + ssize_t err;
> +
> + // use real task's cred to read this file.
> + old_cred = override_creds(heap_file->cred);
> + err = kernel_read_file(file, start, &buffer, size, &heap_file->fsz,
> + READING_POLICY);
> + if (err < 0) {
> + pr_err("use kernel_read_file, err=%ld, [%ld, %ld], f_sz=%ld\n",
> + err, start, (start + size), heap_file->fsz);
> + WRITE_ONCE(*heap_fwork->failp, true);
> + }
> + // recovery to my cred.
> + revert_creds(old_cred);
> +}
> +
> +static int dma_heap_file_control_thread(void *data)
> +{
> + struct dma_heap_file_control *heap_fctl =
> + (struct dma_heap_file_control *)data;
> + struct dma_heap_file_work *worker, *tmp;
> + int nr_work;
> +
> + LIST_HEAD(pages);
> + LIST_HEAD(workers);
> +
> + while (true) {
> + wait_event_freezable(heap_fctl->threadwq,
> + atomic_read(&heap_fctl->nr_work) > 0);
> +recheck:
> + spin_lock(&heap_fctl->lock);
> + list_splice_init(&heap_fctl->works, &workers);
> + spin_unlock(&heap_fctl->lock);
> +
> + if (unlikely(kthread_should_stop())) {
> + list_for_each_entry_safe(worker, tmp, &workers, list) {
> + list_del(&worker->list);
> + destroy_file_work(worker);
> + }
> + break;
> + }
> +
> + nr_work = 0;
> + list_for_each_entry_safe(worker, tmp, &workers, list) {
> + ++nr_work;
> + list_del(&worker->list);
> + __work_this_io(worker);
> +
> + destroy_file_work(worker);
> + }
> + atomic_sub(nr_work, &heap_fctl->nr_work);
> +
> + if (atomic_read(&heap_fctl->nr_work) > 0)
> + goto recheck;
> + }
> + return 0;
> +}
> +
> +size_t dma_heap_file_size(struct dma_heap_file *heap_file)
> +{
> + return heap_file->fsz;
> +}
> +
> +static int prepare_dma_heap_file(struct dma_heap_file *heap_file, int file_fd,
> + size_t batch)
> +{
> + struct file *file;
> + size_t fsz;
> + int ret;
> +
> + file = fget(file_fd);
> + if (!file)
> + return -EINVAL;
> +
> + fsz = i_size_read(file_inode(file));
> + if (fsz < batch) {
> + ret = -EINVAL;
> + goto err;
> + }
> +
> + /**
> + * Selinux block our read, but actually we are reading the stand-in
> + * for this file.
> + * So save current's cred and when going to read, override mine, and
> + * end of read, revert.
> + */
> + heap_file->cred = prepare_kernel_cred(current);
> + if (unlikely(!heap_file->cred)) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> + heap_file->file = file;
> + heap_file->max_batch = batch;
> + heap_file->fsz = fsz;
> +
> + heap_file->direct = file->f_flags & O_DIRECT;
> +
> +#define DMA_HEAP_SUGGEST_DIRECT_IO_SIZE (1UL << 30)
> + if (!heap_file->direct && fsz >= DMA_HEAP_SUGGEST_DIRECT_IO_SIZE)
> + pr_warn("alloc read file better to use O_DIRECT to read larget file\n");
> +
> + return 0;
> +
> +err:
> + fput(file);
> + return ret;
> +}
> +
> +static void destroy_dma_heap_file(struct dma_heap_file *heap_file)
> +{
> + fput(heap_file->file);
> + put_cred(heap_file->cred);
> +}
> +
> +static int dma_heap_buffer_alloc_read_file(struct dma_heap *heap, int file_fd,
> + size_t batch, unsigned int fd_flags,
> + unsigned int heap_flags)
> +{
> + struct dma_buf *dmabuf;
> + int fd;
> + struct dma_heap_file heap_file;
> +
> + fd = prepare_dma_heap_file(&heap_file, file_fd, batch);
> + if (fd)
> + goto error_file;
> +
> + dmabuf = heap->ops->allocate_read_file(heap, &heap_file, fd_flags,
> + heap_flags);
> + if (IS_ERR(dmabuf)) {
> + fd = PTR_ERR(dmabuf);
> + goto error;
> + }
> +
> + fd = dma_buf_fd(dmabuf, fd_flags);
> + if (fd < 0) {
> + dma_buf_put(dmabuf);
> + /* just return, as put will call release and that will free */
> + }
> +
> +error:
> + destroy_dma_heap_file(&heap_file);
> +error_file:
> + return fd;
> +}
> +
> static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len,
> u32 fd_flags,
> u64 heap_flags)
> @@ -93,6 +545,38 @@ static int dma_heap_open(struct inode *inode, struct file *file)
> return 0;
> }
>
> +static long dma_heap_ioctl_allocate_read_file(struct file *file, void *data)
> +{
> + struct dma_heap_allocation_file_data *heap_allocation_file = data;
> + struct dma_heap *heap = file->private_data;
> + int fd;
> +
> + if (heap_allocation_file->fd || !heap_allocation_file->file_fd)
> + return -EINVAL;
> +
> + if (heap_allocation_file->fd_flags & ~DMA_HEAP_VALID_FD_FLAGS)
> + return -EINVAL;
> +
> + if (heap_allocation_file->heap_flags & ~DMA_HEAP_VALID_HEAP_FLAGS)
> + return -EINVAL;
> +
> + if (!heap->ops->allocate_read_file)
> + return -EINVAL;
> +
> + fd = dma_heap_buffer_alloc_read_file(
> + heap, heap_allocation_file->file_fd,
> + heap_allocation_file->batch ?
> + PAGE_ALIGN(heap_allocation_file->batch) :
> + DEFAULT_ADI_BATCH,
> + heap_allocation_file->fd_flags,
> + heap_allocation_file->heap_flags);
> + if (fd < 0)
> + return fd;
> +
> + heap_allocation_file->fd = fd;
> + return 0;
> +}
> +
> static long dma_heap_ioctl_allocate(struct file *file, void *data)
> {
> struct dma_heap_allocation_data *heap_allocation = data;
> @@ -121,6 +605,7 @@ static long dma_heap_ioctl_allocate(struct file *file, void *data)
>
> static unsigned int dma_heap_ioctl_cmds[] = {
> DMA_HEAP_IOCTL_ALLOC,
> + DMA_HEAP_IOCTL_ALLOC_AND_READ,
> };
>
> static long dma_heap_ioctl(struct file *file, unsigned int ucmd,
> @@ -170,6 +655,9 @@ static long dma_heap_ioctl(struct file *file, unsigned int ucmd,
> case DMA_HEAP_IOCTL_ALLOC:
> ret = dma_heap_ioctl_allocate(file, kdata);
> break;
> + case DMA_HEAP_IOCTL_ALLOC_AND_READ:
> + ret = dma_heap_ioctl_allocate_read_file(file, kdata);
> + break;
> default:
> ret = -ENOTTY;
> goto err;
> @@ -316,11 +804,44 @@ static int dma_heap_init(void)
>
> dma_heap_class = class_create(DEVNAME);
> if (IS_ERR(dma_heap_class)) {
> - unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS);
> - return PTR_ERR(dma_heap_class);
> + ret = PTR_ERR(dma_heap_class);
> + goto fail_class;
> }
> dma_heap_class->devnode = dma_heap_devnode;
>
> + heap_fctl = kzalloc(sizeof(*heap_fctl), GFP_KERNEL);
> + if (unlikely(!heap_fctl)) {
> + ret = -ENOMEM;
> + goto fail_alloc;
> + }
> +
> + INIT_LIST_HEAD(&heap_fctl->works);
> + init_waitqueue_head(&heap_fctl->threadwq);
> + init_waitqueue_head(&heap_fctl->workwq);
> +
> + heap_fctl->work_thread = kthread_run(dma_heap_file_control_thread,
> + heap_fctl, "heap_fwork_t");
> + if (IS_ERR(heap_fctl->work_thread)) {
> + ret = -ENOMEM;
> + goto fail_thread;
> + }
> +
> + heap_fctl->heap_fwork_cachep = KMEM_CACHE(dma_heap_file_work, 0);
> + if (unlikely(!heap_fctl->heap_fwork_cachep)) {
> + ret = -ENOMEM;
> + goto fail_cache;
> + }
> +
> return 0;
> +
> +fail_cache:
> + kthread_stop(heap_fctl->work_thread);
> +fail_thread:
> + kfree(heap_fctl);
> +fail_alloc:
> + class_destroy(dma_heap_class);
> +fail_class:
> + unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS);
> + return ret;
> }
> subsys_initcall(dma_heap_init);
> diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h
> index 064bad725061..9c25383f816c 100644
> --- a/include/linux/dma-heap.h
> +++ b/include/linux/dma-heap.h
> @@ -12,12 +12,17 @@
> #include <linux/cdev.h>
> #include <linux/types.h>
>
> +#define DEFAULT_ADI_BATCH (128 << 20)
> +
> struct dma_heap;
> +struct dma_heap_file_task;
> +struct dma_heap_file;
>
> /**
> * struct dma_heap_ops - ops to operate on a given heap
> * @allocate: allocate dmabuf and return struct dma_buf ptr
> - *
> + * @allocate_read_file: allocate dmabuf and read file, then return struct
> + * dma_buf ptr.
> * allocate returns dmabuf on success, ERR_PTR(-errno) on error.
> */
> struct dma_heap_ops {
> @@ -25,6 +30,11 @@ struct dma_heap_ops {
> unsigned long len,
> u32 fd_flags,
> u64 heap_flags);
> +
> + struct dma_buf *(*allocate_read_file)(struct dma_heap *heap,
> + struct dma_heap_file *heap_file,
> + u32 fd_flags,
> + u64 heap_flags);
> };
>
> /**
> @@ -65,4 +75,49 @@ const char *dma_heap_get_name(struct dma_heap *heap);
> */
> struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info);
>
> +/**
> + * dma_heap_destroy_file_read - waits for a file read to complete then destroy it
> + * Returns: true if the file read failed, false otherwise
> + */
> +bool dma_heap_destroy_file_read(struct dma_heap_file_task *heap_ftask);
> +
> +/**
> + * dma_heap_wait_for_file_read - waits for a file read to complete
> + * Returns: true if the file read failed, false otherwise
> + */
> +bool dma_heap_wait_for_file_read(struct dma_heap_file_task *heap_ftask);
> +
> +/**
> + * dma_heap_alloc_file_read - Declare a task to read file when allocate pages.
> + * @heap_file: target file to read
> + *
> + * Return NULL if failed, otherwise return a struct pointer.
> + */
> +struct dma_heap_file_task *
> +dma_heap_declare_file_read(struct dma_heap_file *heap_file);
> +
> +/**
> + * dma_heap_prepare_file_read - cache each allocated page until we meet this batch.
> + * @heap_ftask: prepared and need to commit's work.
> + * @page: current allocated page. don't care which order.
> + *
> + * Returns true if reach to batch, false so go on prepare.
> + */
> +bool dma_heap_prepare_file_read(struct dma_heap_file_task *heap_ftask,
> + struct page *page);
> +
> +/**
> + * dma_heap_commit_file_read - prepare collect enough memory, going to trigger IO
> + * @heap_ftask: info that current IO needs
> + *
> + * This commit will also check if reach to tail read.
> + * For direct I/O submissions, it is necessary to pay attention to file reads
> + * that are not page-aligned. For the unaligned portion of the read, buffer IO
> + * needs to be triggered.
> + * Returns:
> + * 0 if all right, -errno if something wrong
> + */
> +int dma_heap_submit_file_read(struct dma_heap_file_task *heap_ftask);
> +size_t dma_heap_file_size(struct dma_heap_file *heap_file);
> +
> #endif /* _DMA_HEAPS_H */
> diff --git a/include/uapi/linux/dma-heap.h b/include/uapi/linux/dma-heap.h
> index a4cf716a49fa..8c20e8b74eed 100644
> --- a/include/uapi/linux/dma-heap.h
> +++ b/include/uapi/linux/dma-heap.h
> @@ -39,6 +39,27 @@ struct dma_heap_allocation_data {
> __u64 heap_flags;
> };
>
> +/**
> + * struct dma_heap_allocation_file_data - metadata passed from userspace for
> + * allocations and read file
> + * @fd: will be populated with a fd which provides the
> + * handle to the allocated dma-buf
> + * @file_fd: file descriptor to read from(suggested to use O_DIRECT open file)
> + * @batch: how many memory alloced then file read(bytes), default 128MB
> + * will auto aligned to PAGE_SIZE
> + * @fd_flags: file descriptor flags used when allocating
> + * @heap_flags: flags passed to heap
> + *
> + * Provided by userspace as an argument to the ioctl
> + */
> +struct dma_heap_allocation_file_data {
> + __u32 fd;
> + __u32 file_fd;
> + __u32 batch;
> + __u32 fd_flags;
> + __u64 heap_flags;
> +};
> +
> #define DMA_HEAP_IOC_MAGIC 'H'
>
> /**
> @@ -50,4 +71,15 @@ struct dma_heap_allocation_data {
> #define DMA_HEAP_IOCTL_ALLOC _IOWR(DMA_HEAP_IOC_MAGIC, 0x0,\
> struct dma_heap_allocation_data)
>
> +/**
> + * DOC: DMA_HEAP_IOCTL_ALLOC_AND_READ - allocate memory from pool and both
> + * read file when allocate memory.
> + *
> + * Takes a dma_heap_allocation_file_data struct and returns it with the fd field
> + * populated with the dmabuf handle of the allocation. When return, the dma-buf
> + * content is read from file.
> + */
> +#define DMA_HEAP_IOCTL_ALLOC_AND_READ \
> + _IOWR(DMA_HEAP_IOC_MAGIC, 0x1, struct dma_heap_allocation_file_data)
> +
> #endif /* _UAPI_LINUX_DMABUF_POOL_H */
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