mirror of
https://github.com/checkpoint-restore/criu
synced 2025-08-22 18:07:57 +00:00
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>
35 lines
660 B
C
35 lines
660 B
C
#ifndef FILE_IDS_H__
|
|
#define FILE_IDS_H__
|
|
|
|
#include "compiler.h"
|
|
#include "types.h"
|
|
#include "rbtree.h"
|
|
|
|
#define FD_ID_INVALID (-1UL)
|
|
#define FD_PID_INVALID ((int)-2UL)
|
|
|
|
struct fd_id_entry {
|
|
struct rb_node node;
|
|
|
|
struct rb_root subtree_root;
|
|
struct rb_node subtree_node;
|
|
|
|
union {
|
|
struct {
|
|
u32 genid; /* generic id, may have duplicates */
|
|
u32 subid; /* subid is always unique */
|
|
} key;
|
|
u64 id;
|
|
} u;
|
|
|
|
pid_t pid;
|
|
int fd;
|
|
} __aligned(sizeof(long));
|
|
|
|
#define MAKE_FD_GENID(dev, ino, pos) \
|
|
(((u32)(dev) ^ (u32)(ino) ^ (u32)(pos)))
|
|
|
|
extern struct fd_id_entry *fd_id_entry_collect(u32 genid, pid_t pid, int fd);
|
|
|
|
#endif /* FILE_IDS_H__ */
|