[PATCH 1/2] dma-buf: heaps: DMA_HEAP_IOCTL_ALLOC_READ_FILE framework
Huan Yang
link at vivo.com
Fri Jul 12 02:14:39 UTC 2024
在 2024/7/12 9:59, Huan Yang 写道:
> Hi Christian,
>
> 在 2024/7/11 19:39, Christian König 写道:
>> Am 11.07.24 um 11:18 schrieb Huan Yang:
>>> Hi Christian,
>>>
>>> Thanks for your reply.
>>>
>>> 在 2024/7/11 17:00, Christian König 写道:
>>>> 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.
>>>
>>> Sorry for the oversimplified explanation. But, yes, you're right, we
>>> want to avoid this.
>>>
>>> As we are dealing with embedded devices, the available memory and
>>> computing power for users are usually limited.(The maximum available
>>> memory is currently
>>>
>>> 24GB, typically ranging from 8-12GB. )
>>>
>>> Also, the CPU computing power is also usually in short supply, due
>>> to limited battery capacity and limited heat dissipation capabilities.
>>>
>>> So, we hope to avoid ineffective paths as much as possible.
>>>
>>>>
>>>>> 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.
>>>
>>> Thank you for your advice. maybe the "read file" behavior can be
>>> attached to an existing allocation?
>>
>> The point is there are already system calls to do something like that.
>>
>> See copy_file_range()
>> (https://man7.org/linux/man-pages/man2/copy_file_range.2.html)
>> and send_file()
>> (https://man7.org/linux/man-pages/man2/sendfile.2.html).
>
> That's helpfull to learn it, thanks.
>
> In terms of only DMA-BUF supporting direct I/O,
> copy_file_range/send_file may help to achieve this functionality.
>
> However, my patchset also aims to achieve parallel copying of file
> contents while allocating the DMA-BUF, which is something that the
> current set of calls may not be able to accomplish.
You can see cover-letter, here are the normal test and this IOCTL's
compare in memory pressure, even if buffered I/O in this ioctl can have
50% improve by parallel.
dd a 3GB file for test, 12G RAM phone, UFS4.0, stressapptest 4G memory pressure.
1. original
```shel
# create a model file
dd if=/dev/zero of=./model.txt bs=1M count=3072
# drop page cache
echo 3 > /proc/sys/vm/drop_caches
./dmabuf-heap-file-read mtk_mm-uncached normal
> result is total cost 13087213847ns
```
2.DMA_HEAP_IOCTL_ALLOC_AND_READ O_DIRECT
```shel
# create a model file
dd if=/dev/zero of=./model.txt bs=1M count=3072
# drop page cache
echo 3 > /proc/sys/vm/drop_caches
./dmabuf-heap-file-read mtk_mm-uncached direct_io
> result is total cost 2902386846ns
# use direct_io_check can check the content if is same to file.
```
3. DMA_HEAP_IOCTL_ALLOC_AND_READ BUFFER I/O
```shel
# create a model file
dd if=/dev/zero of=./model.txt bs=1M count=3072
# drop page cache
echo 3 > /proc/sys/vm/drop_caches
./dmabuf-heap-file-read mtk_mm-uncached normal_io
> result is total cost 5735579385ns
```
>
> Perhaps simply returning the DMA-BUF file descriptor and then
> implementing copy_file_range, while populating the memory and content
> during the copy process, could achieve this? At present, it seems that
> it will be quite complex - We need to ensure that only the returned
> DMA-BUF file descriptor will fail in case of memory not fill, like
> mmap, vmap, attach, and so on.
>
>>
>> What we probably could do is to internally optimize those.
>>
>>> I am currently creating a new ioctl to remind the user that memory
>>> is being allocated and read, and I am also unsure
>>>
>>> whether it is appropriate to add additional parameters to the
>>> existing allocate behavior.
>>>
>>> Please, give me more suggestion. Thanks.
>>>
>>>>
>>>> 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.
>>>
>>> Sorry, I'm not familiar with this, but I will look into it. However,
>>> this type of callback function is not currently implemented when
>>> exporting
>>>
>>> the dma_buf file, which means that I need to implement the callback
>>> for it?
>>
>> If I'm not completely mistaken the copy_file_range, splice_read and
>> splice_write callbacks on the struct file_operations
>> (https://elixir.bootlin.com/linux/v6.10-rc7/source/include/linux/fs.h#L1999).
>>
>> Can be used to implement what you want to do.
> Yes.
>>
>> Regards,
>> Christian.
>>
>>>
>>>>
>>>> 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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