criu/include/file-ids.h

#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)

#define MAKE_FD_GENID(dev, ino, pos) \
	(((u32)(dev) ^ (u32)(ino) ^ (u32)(pos)))

extern long fd_id_entry_collect(u64 genid, pid_t pid, int fd);

#endif /* FILE_IDS_H__ */
files: Use sys_kcmp to find file descriptor duplicates v4 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> 2012-02-28 18:27:28 +04:00			`#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)`

			`#define MAKE_FD_GENID(dev, ino, pos) \`
			`(((u32)(dev) ^ (u32)(ino) ^ (u32)(pos)))`

dump: files tree - return id upon collect instead on inner structure Hide the structure - it's not required. [ xemul: Ranem long id into u32 id and adopt to current tree ] Signed-off-by: Stanislav Kinsbursky <skinsbursky@openvz.org> Signed-off-by: Pavel Emelyanov <xemul@parallels.com> 2012-03-23 20:23:00 +04:00			`extern long fd_id_entry_collect(u64 genid, pid_t pid, int fd);`
files: Use sys_kcmp to find file descriptor duplicates v4 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> 2012-02-28 18:27:28 +04:00
			`#endif /* FILE_IDS_H__ */`