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https://github.com/checkpoint-restore/criu.git
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295090c1ea
We want to have buffered images to speed up dump and, slightly, restore. Right now we use plan file descriptors to write and read images to/from. Making them buffered cannot be gracefully done on plain fds, so introduce a new class. This will also help if (when?) we will want to do more complex changes with images, e.g. store them all in one file or send them directly to the network. For now the cr_img just contains one int _fd variable. This patch chages the prototype of open_image() to return struct cr_img *, pb_(read|write)* to accept one and fixes the compilation of the rest of the code :) Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
79 lines
2.6 KiB
C
79 lines
2.6 KiB
C
#ifndef __CR_PAGE_READ_H__
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#define __CR_PAGE_READ_H__
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#include "protobuf/pagemap.pb-c.h"
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/*
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* page_read -- engine, that reads pages from image file(s)
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*
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* Several page-read's can be arranged in a chain to read
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* pages from a series of snapshot.
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*
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* A task's address space vs pagemaps+page image pairs can
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* look like this (taken from comment in page-pipe.h):
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*
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* task:
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*
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* 0 0 0 0 1 1 1
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* 0 3 6 B 2 7 C
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* ---+++-----+++++++-----+++++----
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* pm1: ---+++-----++++++-------++++----
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* pm2: ---==+-----====+++-----++===----
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*
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* Here + is present page, - is non prsent, = is present,
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* but is not modified from last snapshot.
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*
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* Thus pagemap.img and pages.img entries are
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*
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* pm1: 03:3,0B:6,18:4
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* pm2: 03:2:P,05:1,0B:4:P,0F:3,17:2,19:3:P
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*
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* where P means "page is in parent pagemap".
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*
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* pg1: 03,04,05,0B,0C,0D,0E,0F,10,18,19,1A,1B
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* pg2: 05,0F,10,11,17,18
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*
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* When trying to restore from these 4 files we'd have
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* to carefull scan pagemap.img's one by one and read or
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* skip pages from pages.img where appropriate.
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*
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* All this is implemented in read_pagemap_page.
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*/
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struct page_read {
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/*
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* gets next vaddr:len pair to work on.
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* Pagemap entries should be returned in sorted order.
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*/
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int (*get_pagemap)(struct page_read *, struct iovec *iov);
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/* reads page from current pagemap */
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int (*read_page)(struct page_read *, unsigned long vaddr, void *);
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/* stop working on current pagemap */
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void (*put_pagemap)(struct page_read *);
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void (*close)(struct page_read *);
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/* Private data of reader */
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struct cr_img *pmi;
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struct cr_img *pi;
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PagemapEntry *pe; /* current pagemap we are on */
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struct page_read *parent; /* parent pagemap (if ->in_parent
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pagemap is met in image, then
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go to this guy for page, see
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read_pagemap_page */
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unsigned long cvaddr; /* vaddr we are on */
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struct iovec bunch; /* record consequent neighbour
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iovecs to punch together */
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unsigned id; /* for logging */
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};
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extern int open_page_read(int pid, struct page_read *, int flags, bool shmem);
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extern int open_page_read_at(int dfd, int pid, struct page_read *pr, int flags, bool shmem);
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extern void pagemap2iovec(PagemapEntry *pe, struct iovec *iov);
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extern void iovec2pagemap(struct iovec *iov, PagemapEntry *pe);
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extern int seek_pagemap_page(struct page_read *pr, unsigned long vaddr, bool warn);
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extern int dedup_one_iovec(struct page_read *pr, struct iovec *iov);
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extern int punch_hole(struct page_read *pr, unsigned long off, unsigned long len, bool cleanup);
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#endif /* __CR_PAGE_READ_H__ */
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