Re: [PATCH 1/2] dma-buf: heaps: DMA_HEAP_IOCTL_ALLOC_READ_FILE framework
From: Christian König
Date: Mon Jul 15 2024 - 08:33:20 EST
Am 15.07.24 um 11:11 schrieb Daniel Vetter:
On Thu, Jul 11, 2024 at 11:00:02AM +0200, Christian König wrote:
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.
I'm not sure any of those help, because internally they're all still based
on struct page (or maybe in the future on folios). And that's the thing
dma-buf can't give you, at least without peaking behind the curtain.
I think an entirely different option would be malloc+udmabuf. That
essentially handles the impendence-mismatch between direct I/O and dma-buf
on the dma-buf side. The downside is that it'll make the permanently
pinned memory accounting and tracking issues even more apparent, but I
guess eventually we do need to sort that one out.
Oh, very good idea!
Just one minor correction: it's not malloc+udmabuf, but rather
create_memfd()+udmabuf.
And you need to complete your direct I/O before creating the udmabuf
since that reference will prevent direct I/O from working.
Regards,
Christian.
And since all the patches here are only for the pages system heap I'm
guess udmabuf should work out for the use-case here? Worth a shot at
least.
-Sima
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@xxxxxxxx>
---
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 */