file.c File Reference

#include "vm/vm.h"
#include "userprog/process.h"
#include "threads/mmu.h"

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Functions
static bool	file_backed_swap_in (struct page *page, void *kva)
static bool	file_backed_swap_out (struct page *page)
static void	file_backed_destroy (struct page *page)
void	vm_file_init (void)
bool	file_backed_initializer (struct page *page, enum vm_type type, void *kva)
void *	do_mmap (void *addr, size_t length, int writable, struct file *file, off_t offset)
void	do_munmap (void *addr)

Variables
static const struct page_operations	file_ops

Function Documentation

do_mmap()

void * do_mmap	(	void *	addr,
		size_t	length,
		int	writable,
		struct file *	file,
		off_t	offset
	)

                                         {
    struct file *re_file = file_reopen(file);
 
    void * mmap_addr = addr; // 페이지 확장 시, 리턴 주소 값 변경 방지
    size_t read_bytes = length > file_length(file) ? file_length(file) : length; // 실제 읽어올 바이트 수
    size_t zero_bytes = PGSIZE - (read_bytes % PGSIZE); // 페이지에서 read_bytes를 제외한 공간은 0으로 채운다.
 
    // 읽으려는 바이트 수만큼 페이지를 할당한다.
    while (read_bytes > 0 || zero_bytes > 0) {
        size_t page_read_bytes = read_bytes < PGSIZE ? read_bytes : PGSIZE;
        size_t page_zero_bytes = page_read_bytes == PGSIZE ? 0 : PGSIZE - page_read_bytes;
 
        struct segment_aux *segment_aux = (struct segment_aux*)malloc(sizeof(struct segment_aux));
        segment_aux->file = re_file;
        segment_aux->offset = offset;
        segment_aux->page_read_bytes = page_read_bytes;
 
        // vm_alloc_page가 안되는 이유? -> aux(segment_aux) 값으로 파일에 대한 정보를 넘겨줘야한다.
        if (!vm_alloc_page_with_initializer (VM_FILE, mmap_addr, writable, lazy_load_segment, segment_aux)) {
            free(mmap_addr); // 안전장치
            return NULL;
        }
        read_bytes -= page_read_bytes;
        zero_bytes -= page_zero_bytes;
 
        // 페이지 하나 할당에 따른 주소값, 오프셋 변경
        mmap_addr += PGSIZE;
        offset += page_read_bytes;
    }
    return addr;
}

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do_munmap()

void do_munmap

(

void *

addr

)

                       {
    while (true) {
        struct page* page = spt_find_page(&thread_current()->spt, addr);
 
        if (page == NULL)
            break;
 
        struct segment_aux * segment_aux = (struct segment_aux *) page->uninit.aux;
 
        // dirty bit(사용된 적이 있으면) -> 파일에 다시 쓰고 dirty bit를 0으로 만들어줌
        if(pml4_is_dirty(thread_current()->pml4, page->va)) {
            file_write_at(segment_aux->file, addr, segment_aux->page_read_bytes, segment_aux->offset); // ? i-node에 내가 쓰던 파일이 해제됨을 알린다고 보면 될 듯?
            pml4_set_dirty (thread_current()->pml4, page->va, 0);
        }
 
        pml4_clear_page(thread_current()->pml4, page->va);
        addr += PGSIZE;
    }
}

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file_backed_destroy()

static void file_backed_destroy ( struct page *  page )

static

                                        {
    struct file_page *file_page UNUSED = &page->file;
}

file_backed_initializer()

bool file_backed_initializer	(	struct page *	page,
		enum vm_type	type,
		void *	kva
	)

                                                                          {
    /* Set up the handler */
    page->operations = &file_ops;
 
    struct file_page *file_page = &page->file;
    
    return true;
}

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file_backed_swap_in()

static bool file_backed_swap_in ( struct page *  page, void *  kva  )

static

                                                   {
    struct file_page *file_page UNUSED = &page->file;
    if (page == NULL)
        return false;
 
    struct segment_aux *segment_aux = (struct segment_aux *)page->uninit.aux;
 
    struct file *file = segment_aux->file;
    off_t offset = segment_aux->offset;
    size_t page_read_bytes = segment_aux->page_read_bytes;
    size_t page_zero_bytes = PGSIZE - page_read_bytes;
 
    file_seek (file, offset);
 
    if (file_read (file, kva, page_read_bytes) != (int) page_read_bytes) {
        // palloc_free_page (kva);
        return false;
    }
 
    memset (kva + page_read_bytes, 0, page_zero_bytes);
 
    return true;
}

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file_backed_swap_out()

static bool file_backed_swap_out ( struct page *  page )

static

                                         {
    struct file_page *file_page UNUSED = &page->file;
    if (page == NULL)
        return false;
 
    struct segment_aux * segment_aux = (struct segment_aux *) page->uninit.aux;
 
    // CHECK dirty page
    if(pml4_is_dirty(thread_current()->pml4, page->va)){
        file_write_at(segment_aux->file, page->va, segment_aux->page_read_bytes, segment_aux->offset);
        pml4_set_dirty (thread_current()->pml4, page->va, 0);
    }
 
    pml4_clear_page(thread_current()->pml4, page->va);
 
    return true;
}

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vm_file_init()

void vm_file_init

(

void

)

                    {
}

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Variable Documentation

file_ops

const struct page_operations file_ops

static

Initial value:

= {
    .swap_in = file_backed_swap_in,
    .swap_out = file_backed_swap_out,
    .destroy = file_backed_destroy,
    .type = VM_FILE,
}