/* * Copyright (c) 2013-2019 Huawei Technologies Co., Ltd. All rights reserved. * Copyright (c) 2020-2021 Huawei Device Co., Ltd. All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, * are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, this list of * conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright notice, this list * of conditions and the following disclaimer in the documentation and/or other materials * provided with the distribution. * * 3. Neither the name of the copyright holder nor the names of its contributors may be used * to endorse or promote products derived from this software without specific prior written * permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /** * @defgroup los_vm_filemap vm filemap definition * @ingroup kernel */ #ifndef __LOS_VM_FILEMAP_H__ #define __LOS_VM_FILEMAP_H__ #include "fs/file.h" #include "los_vm_map.h" #include "los_vm_page.h" #include "los_vm_common.h" #include "los_vm_phys.h" #ifdef __cplusplus #if __cplusplus extern "C" { #endif /* __cplusplus */ #endif /* __cplusplus */ /************************************************************************************************** 磁盘高速缓存是一种软件机制，它允许系统把通常存放在磁盘上的一些数据保留在 RAM 中，以便对那些数据的 进一步访问不用再访问磁盘而能尽快得到满足。 页高速缓存中的信息单位是一个完整的页。 一个页包含的磁盘块在物理上不一定相邻，所以不能用设备号和块号标识，而是通过页的所有者和所有者数据中的索引来识别。 页高速缓存可以缓存以下内容 A.普通文件数据 B.含有目录的页 C.直接从快设备读取的页 D.用户进程数据的页 E.特殊文件系统的文件页 **************************************************************************************************/ #if 0 //@note_#if0 //page_mapping描述的是一个文件在内存中被映射了多少页,<文件,文件页的关系> /* file mapped in VMM pages */ struct page_mapping {//记录文件页和文件关系的结构体,叫文件页映射 LOS_DL_LIST page_list; /* all pages */ //链表上挂的是属于该文件的所有FilePage，这些页的内容都来源同一个文件 SPIN_LOCK_S list_lock; /* lock protecting it */ //操作page_list的自旋锁 LosMux mux_lock; /* mutex lock */ // //操作page_mapping的互斥量 unsigned long nrpages; /* number of total pages */ //page_list的节点数量 unsigned long flags; //@note_why 全量代码中也没查到源码中对其操作 Atomic ref; /* reference counting */ //引用次数(自增/自减),对应add_mapping/dec_mapping struct file *host; /* owner of this mapping *///属于哪个文件的映射 }; /* map: full_path(owner) <-> mapping */ //叫文件映射 struct file_map { //为在内核层面文件在内存的身份证,每个需映射到内存的文件必须创建一个file_map，都挂到全局g_file_mapping链表上 LOS_DL_LIST head; //链表节点,用于挂到g_file_mapping上 LosMux lock; /* lock to protect this mapping */ struct page_mapping mapping; //每个文件都有唯一的page_mapping标识其在内存的身份 char *owner; /* owner: full path of file *///文件全路径来标识唯一性 }; #endif //文件页结构体 typedef struct FilePage { LOS_DL_LIST node; //节点,节点挂到page_mapping.page_list上,链表以 pgoff 从小到大方式排序. LOS_DL_LIST lru; //lru节点, 结合 LosVmPhysSeg: LOS_DL_LIST lruList[VM_NR_LRU_LISTS] 理解 LOS_DL_LIST i_mmap; /* list of mappings */ //链表记录文件页被哪些进程映射 MapInfo.node挂上来 UINT32 n_maps; /* num of mapping */ //记录被进程映射的次数 struct VmPhysSeg *physSeg; /* physical memory that file page belongs to */ //物理段:物理页框 = 1:N struct VmPage *vmPage; //物理页框 struct page_mapping *mapping; //此结构由文件系统提供，用于描述装入点 见于 ..\third_party\NuttX\include\nuttx\fs\fs.h VM_OFFSET_T pgoff; //页标，文件被切成一页一页读到内存 UINT32 flags; //标签 UINT16 dirtyOff; //脏页的页内偏移地址 UINT16 dirtyEnd; //脏页的结束位置 } LosFilePage; //虚拟地址和文件页的映射信息 typedef struct MapInfo {//在一个进程使用文件页之前,需要提前做好文件页在此内存空间的映射关系,如此通过虚拟内存就可以对文件页读写操作. LOS_DL_LIST node; //节点,挂到page->i_mmap链表上.链表上记录要操作文件页的进程对这个page的映射信息 VADDR_T vaddr; //虚拟地址.每个进程访问同一个文件页的虚拟地址都是不一样的 LosFilePage *page; //文件页中只记录物理地址,是不会变的.但它是需要被多个进程访问,和映射的. LosArchMmu *archMmu;//mmu完成vaddr和page->vmPage->physAddr物理地址的映射 } LosMapInfo; //Flags由 bitmap 管理 enum OsPageFlags { FILE_PAGE_FREE, //空闲页 FILE_PAGE_LOCKED, //被锁页 FILE_PAGE_REFERENCED, //被引用页 FILE_PAGE_DIRTY, //脏页 FILE_PAGE_LRU, //LRU置换页 FILE_PAGE_ACTIVE, //活动页 FILE_PAGE_SHARED, //共享页 }; #define PGOFF_MAX 2000 #define MAX_SHRINK_PAGECACHE_TRY 2 #define VM_FILEMAP_MAX_SCAN (SYS_MEM_SIZE_DEFAULT >> PAGE_SHIFT) //扫描文件映射页最大数量 #define VM_FILEMAP_MIN_SCAN 32 //扫描文件映射页最小数量 //给页面贴上被锁的标签 STATIC INLINE VOID OsSetPageLocked(LosVmPage *page) { LOS_BitmapSet(&page->flags, FILE_PAGE_LOCKED); } //给页面撕掉被锁的标签 STATIC INLINE VOID OsCleanPageLocked(LosVmPage *page) { LOS_BitmapClr(&page->flags, FILE_PAGE_LOCKED); } //给页面贴上数据被修改的标签 STATIC INLINE VOID OsSetPageDirty(LosVmPage *page) { LOS_BitmapSet(&page->flags, FILE_PAGE_DIRTY); } //给页面撕掉数据被修改的标签 STATIC INLINE VOID OsCleanPageDirty(LosVmPage *page) { LOS_BitmapClr(&page->flags, FILE_PAGE_DIRTY); } //给页面贴上活动的标签 STATIC INLINE VOID OsSetPageActive(LosVmPage *page) { LOS_BitmapSet(&page->flags, FILE_PAGE_ACTIVE); } //给页面撕掉活动的标签 STATIC INLINE VOID OsCleanPageActive(LosVmPage *page) { LOS_BitmapClr(&page->flags, FILE_PAGE_ACTIVE); } //给页面贴上置换页的标签 STATIC INLINE VOID OsSetPageLRU(LosVmPage *page) { LOS_BitmapSet(&page->flags, FILE_PAGE_LRU); } //给页面贴上被释放的标签 STATIC INLINE VOID OsSetPageFree(LosVmPage *page) { LOS_BitmapSet(&page->flags, FILE_PAGE_FREE); } //给页面撕掉被释放的标签 STATIC INLINE VOID OsCleanPageFree(LosVmPage *page) { LOS_BitmapClr(&page->flags, FILE_PAGE_FREE); } //给页面贴上被引用的标签 STATIC INLINE VOID OsSetPageReferenced(LosVmPage *page) { LOS_BitmapSet(&page->flags, FILE_PAGE_REFERENCED); } //给页面撕掉被引用的标签 STATIC INLINE VOID OsCleanPageReferenced(LosVmPage *page) { LOS_BitmapClr(&page->flags, FILE_PAGE_REFERENCED); } //页面是否活动 STATIC INLINE BOOL OsIsPageActive(LosVmPage *page) { return BIT_GET(page->flags, FILE_PAGE_ACTIVE); } //页面是否被锁 STATIC INLINE BOOL OsIsPageLocked(LosVmPage *page) { return BIT_GET(page->flags, FILE_PAGE_LOCKED); } //页面是否被引用，只被一个进程引用的页叫私有页，多个进程引用就是共享页，此为共享内存的本质所在 STATIC INLINE BOOL OsIsPageReferenced(LosVmPage *page) { return BIT_GET(page->flags, FILE_PAGE_REFERENCED); } //页面是否为脏页，所谓脏页就是页内数据是否被更新过，只有脏页才会有写时拷贝 STATIC INLINE BOOL OsIsPageDirty(LosVmPage *page) { return BIT_GET(page->flags, FILE_PAGE_DIRTY); } //文件页是否映射过了 STATIC INLINE BOOL OsIsPageMapped(LosFilePage *page) { return (page->n_maps != 0);//由映射的次数来判断 } /* The follow three functions is used to SHM module */ STATIC INLINE VOID OsSetPageShared(LosVmPage *page)//给页面贴上共享页标签 { LOS_BitmapSet(&page->flags, FILE_PAGE_SHARED);//设为共享页面,共享页位 置0 } //给页面撕掉共享页标签 STATIC INLINE VOID OsCleanPageShared(LosVmPage *page) { LOS_BitmapClr(&page->flags, FILE_PAGE_SHARED);//共享页位 置0 } //是否为共享页 STATIC INLINE BOOL OsIsPageShared(LosVmPage *page) { return BIT_GET(page->flags, FILE_PAGE_SHARED); } INT32 OsVfsFileMmap(struct file *filep, LosVmMapRegion *region); LosFilePage *OsPageCacheAlloc(struct page_mapping *mapping, VM_OFFSET_T pgoff); LosFilePage *OsFindGetEntry(struct page_mapping *mapping, VM_OFFSET_T pgoff); LosMapInfo *OsGetMapInfo(LosFilePage *page, LosArchMmu *archMmu, VADDR_T vaddr); VOID OsAddMapInfo(LosFilePage *page, LosArchMmu *archMmu, VADDR_T vaddr); VOID OsDelMapInfo(LosVmMapRegion *region, LosVmPgFault *pgFault, BOOL cleanDirty); VOID OsFileCacheFlush(struct page_mapping *mapping); VOID OsFileCacheRemove(struct page_mapping *mapping); VOID OsUnmapPageLocked(LosFilePage *page, LosMapInfo *info); VOID OsUnmapAllLocked(LosFilePage *page); VOID OsLruCacheAdd(LosFilePage *fpage, enum OsLruList lruType); VOID OsLruCacheDel(LosFilePage *fpage); LosFilePage *OsDumpDirtyPage(LosFilePage *oldPage); VOID OsDoFlushDirtyPage(LosFilePage *fpage); VOID OsDeletePageCacheLru(LosFilePage *page); STATUS_T OsNamedMMap(struct file *filep, LosVmMapRegion *region); VOID OsPageRefDecNoLock(LosFilePage *page); VOID OsPageRefIncLocked(LosFilePage *page); int OsTryShrinkMemory(size_t nPage); VOID OsMarkPageDirty(LosFilePage *fpage, LosVmMapRegion *region, int off, int len); typedef struct ProcessCB LosProcessCB; VOID OsVmmFileRegionFree(struct file *filep, LosProcessCB *processCB); #ifdef __cplusplus #if __cplusplus } #endif /* __cplusplus */ #endif /* __cplusplus */ #endif /* __LOS_VM_FILEMAP_H__ */