mirror of
https://github.com/checkpoint-restore/criu.git
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2acc741a3a
We switch generic-object-id concept with sys_kcmp approach, which implies changes of image format a bit (and since it's early time for project overall, we're allowed to). In short -- previously every file descriptor had an ID generated by a kernel and exported via procfs. If the appropriate file descriptors were the same objects in kernel memory -- the IDs did match up to bit. It allows us to figure out which files were actually the identical ones and should be restored in a special way. Once sys_kcmp system call was merged into the kernel, we've got a new opprotunity -- to use this syscall instead. The syscall basically compares kernel objects and returns ordered results suitable for objects sorting in a userspace. For us it means -- we treat every file descriptor as a combination of 'genid' and 'subid'. While 'genid' serves for fast comparison between fds, the 'subid' is kind of a second key, which guarantees uniqueness of genid+subid tuple over all file descritors found in a process (or group of processes). To be able to find and dump file descriptors in a single pass we collect every fd into a global rbtree, where (!) each node might become a root for a subtree as well. The main tree carries only non-equal genid. If we find genid which is already in tree, we need to make sure that it's either indeed a duplicate or not. For this we use sys_kcmp syscall and if we find that file descriptors are different -- we simply put new fd into a subtree. Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Acked-by: Pavel Emelyanov <xemul@parallels.com>
45 lines
810 B
C
45 lines
810 B
C
#ifndef FILES_H_
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#define FILES_H_
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#include "compiler.h"
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#include "types.h"
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#include "list.h"
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#include "image.h"
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enum fdinfo_states {
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FD_STATE_PREP, /* Create unix sockets */
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FD_STATE_CREATE, /* Create and send fd */
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FD_STATE_RECV, /* Receive fd */
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FD_STATE_MAX
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};
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struct fmap_fd {
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struct fmap_fd *next;
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unsigned long start;
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int pid;
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int fd;
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};
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struct fdinfo_desc {
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u64 id;
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u64 addr;
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int pid;
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u32 real_pid; /* futex */
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u32 users; /* futex */
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struct list_head list;
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};
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struct fdinfo_list_entry {
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struct list_head list;
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int fd;
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int pid;
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u32 real_pid;
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};
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extern int prepare_fds(int pid);
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extern int prepare_fd_pid(int pid);
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extern int prepare_shared_fdinfo(void);
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extern int try_fixup_file_map(int pid, struct vma_entry *vma_entry, int fd);
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#endif /* FILES_H_ */
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