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https://github.com/checkpoint-restore/criu.git
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32a48b67b7
when decide that data is no longer needed, there are two cases: -if data neighbours previous block of "no needed" data, extend bunch block(it holds begining and size of concequent "no needed" data) by length of curent block and go next. -if data not neighbours bunch block(or bunch block size will be bigger than MAX_BUNCH_SIZE), than we punch bunch block and set bunch block to curent block. in the end make cleanup to punch last bunch block. changes in v1: punch_hole takes whole page_read make restriction more precise Signed-off-by: Tikhomirov Pavel <snorcht@gmail.com> Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
78 lines
2.4 KiB
C
78 lines
2.4 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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int fd;
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int fd_pg;
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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);
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extern int open_page_read_at(int dfd, int pid, struct page_read *pr, int flags);
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extern void pagemap2iovec(PagemapEntry *pe, struct iovec *iov);
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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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