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Pavel Emelyanov 640708a2cf procfs: introduce the /proc/<pid>/map_files/ directory 
This one behaves similarly to the /proc/<pid>/fd/ one - it contains
symlinks one for each mapping with file, the name of a symlink is
"vma->vm_start-vma->vm_end", the target is the file.  Opening a symlink
results in a file that point exactly to the same inode as them vma's one.

For example the ls -l of some arbitrary /proc/<pid>/map_files/

 | lr-x------ 1 root root 64 Aug 26 06:40 7f8f80403000-7f8f80404000 -> /lib64/libc-2.5.so
 | lr-x------ 1 root root 64 Aug 26 06:40 7f8f8061e000-7f8f80620000 -> /lib64/libselinux.so.1
 | lr-x------ 1 root root 64 Aug 26 06:40 7f8f80826000-7f8f80827000 -> /lib64/libacl.so.1.1.0
 | lr-x------ 1 root root 64 Aug 26 06:40 7f8f80a2f000-7f8f80a30000 -> /lib64/librt-2.5.so
 | lr-x------ 1 root root 64 Aug 26 06:40 7f8f80a30000-7f8f80a4c000 -> /lib64/ld-2.5.so

This *helps* checkpointing process in three ways:

1. When dumping a task mappings we do know exact file that is mapped
   by particular region.  We do this by opening
   /proc/$pid/map_files/$address symlink the way we do with file
   descriptors.

2. This also helps in determining which anonymous shared mappings are
   shared with each other by comparing the inodes of them.

3. When restoring a set of processes in case two of them has a mapping
   shared, we map the memory by the 1st one and then open its
   /proc/$pid/map_files/$address file and map it by the 2nd task.

Using /proc/$pid/maps for this is quite inconvenient since it brings
repeatable re-reading and reparsing for this text file which slows down
restore procedure significantly.  Also as being pointed in (3) it is a way
easier to use top level shared mapping in children as
/proc/$pid/map_files/$address when needed.

[akpm@linux-foundation.org: coding-style fixes]
[gorcunov@openvz.org: make map_files depend on CHECKPOINT_RESTORE]
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Reviewed-by: Vasiliy Kulikov <segoon@openwall.com>
Reviewed-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Tejun Heo <tj@kernel.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2012-01-10 16:30:54 -08:00
..
9p 9p: propagate umode_t 2012-01-03 22:55:01 -05:00
adfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
affs affs: propagate umode_t 2012-01-03 22:55:04 -05:00
afs switch ->create() to umode_t 2012-01-03 22:54:53 -05:00
autofs4 vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
befs vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
bfs switch ->create() to umode_t 2012-01-03 22:54:53 -05:00
btrfs btrfs: pass __GFP_WRITE for buffered write page allocations 2012-01-10 16:30:44 -08:00
cachefiles fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
ceph ceph: d_alloc_root() may fail 2012-01-09 16:36:12 -05:00
cifs Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-01-08 12:19:57 -08:00
coda switch ->create() to umode_t 2012-01-03 22:54:53 -05:00
configfs configfs: convert to umode_t 2012-01-03 22:54:57 -05:00
cramfs Merge branches 'vfsmount-guts', 'umode_t' and 'partitions' into Z 2012-01-06 23:15:54 -05:00
debugfs Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-01-08 12:19:57 -08:00
devpts devpts: fix double-free on mount failure 2012-01-08 20:19:03 -05:00
dlm net: remove ipv6_addr_copy() 2011-11-22 16:43:32 -05:00
ecryptfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
efs vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
exofs Merge branch 'for-linus' of git://git.open-osd.org/linux-open-osd 2012-01-09 12:51:01 -08:00
exportfs
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ext2 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2012-01-09 12:51:21 -08:00
ext3 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2012-01-09 12:51:21 -08:00
ext4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-01-09 17:37:37 -08:00
fat Merge branch 'usb-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb 2012-01-09 12:09:47 -08:00
freevxfs fs: propagate umode_t, misc bits 2012-01-03 22:55:10 -05:00
fscache
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fuse vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
gfs2 Merge branch 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm 2012-01-08 13:10:57 -08:00
hfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
hfsplus vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
hostfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
hpfs switch ->mknod() to umode_t 2012-01-03 22:54:54 -05:00
hppfs vfs: for usbfs, etc. internal vfsmounts ->mnt_sb->s_root == ->mnt_root 2012-01-03 22:52:41 -05:00
hugetlbfs hugetlbfs: propagate umode_t 2012-01-03 22:55:05 -05:00
isofs isofs: inode leak on mount failure 2012-01-09 10:48:11 -05:00
jbd Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2012-01-09 12:51:21 -08:00
jbd2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-01-08 13:21:22 -08:00
jffs2 vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
jfs Merge branch 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm 2012-01-08 13:10:57 -08:00
lockd vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
logfs logfs: propagate umode_t 2012-01-03 22:55:06 -05:00
minix Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-01-08 12:19:57 -08:00
ncpfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
nfs Merge branch 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm 2012-01-08 13:10:57 -08:00
nfs_common
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nfsd Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-01-08 13:21:22 -08:00
nilfs2 Merge branch 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm 2012-01-08 13:10:57 -08:00
nls NLS: raname "maxlen" to "maxout" in UTF conversion routines 2011-11-26 19:58:47 -08:00
notify vfs: move fsnotify junk to struct mount 2012-01-03 22:57:12 -05:00
ntfs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
ocfs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-01-08 13:21:22 -08:00
omfs omfs: propagate umode_t 2012-01-03 22:55:01 -05:00
openpromfs vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
proc procfs: introduce the /proc/<pid>/map_files/ directory 2012-01-10 16:30:54 -08:00
pstore pstore: gracefully handle NULL pstore_info functions 2011-11-18 13:49:00 -08:00
qnx4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-01-08 13:21:22 -08:00
quota vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
ramfs pohmelfs: propagate umode_t 2012-01-03 22:55:07 -05:00
reiserfs reiserfs: don't lock root inode searching 2012-01-10 16:30:54 -08:00
romfs vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
squashfs vfs: fix the stupidity with i_dentry in inode destructors 2012-01-03 22:52:40 -05:00
sysfs sysfs: propagate umode_t 2012-01-03 22:55:03 -05:00
sysv vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
ubifs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
udf Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2012-01-09 12:51:21 -08:00
ufs vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
xfs Merge branch 'for-linus' of git://oss.sgi.com/xfs/xfs 2012-01-09 12:50:15 -08:00
Kconfig Merge branch 'for-linus' of git://git.open-osd.org/linux-open-osd 2012-01-09 12:51:01 -08:00
Kconfig.binfmt fs: binfmt_elf: create Kconfig variable for PIE randomization 2012-01-10 16:30:51 -08:00
Makefile Merge branches 'vfsmount-guts', 'umode_t' and 'partitions' into Z 2012-01-06 23:15:54 -05:00
aio.c aio: allocate kiocbs in batches 2011-11-02 16:07:03 -07:00
anon_inodes.c
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attr.c switch is_sxid() to umode_t 2012-01-03 22:55:11 -05:00
bad_inode.c switch ->mknod() to umode_t 2012-01-03 22:54:54 -05:00
binfmt_aout.c
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binfmt_elf.c fs: binfmt_elf: create Kconfig variable for PIE randomization 2012-01-10 16:30:51 -08:00
binfmt_elf_fdpic.c
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binfmt_em86.c
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binfmt_flat.c
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binfmt_misc.c vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
binfmt_script.c
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binfmt_som.c
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bio-integrity.c fs: add export.h to files using EXPORT_SYMBOL/THIS_MODULE macros 2011-10-31 19:30:31 -04:00
bio.c bio: change some signed vars to unsigned 2011-11-16 09:21:50 +01:00
block_dev.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
buffer.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
char_dev.c char_dev.c: fix up some whitespace errors 2011-12-13 11:18:17 -08:00
compat.c switch open and mkdir syscalls to umode_t 2012-01-03 22:55:19 -05:00
compat_binfmt_elf.c
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compat_ioctl.c vfs: fix up ENOIOCTLCMD error handling 2012-01-05 15:40:12 -08:00
dcache.c vfs: new helper - d_make_root() 2012-01-09 19:23:45 -05:00
dcookies.c
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direct-io.c direct-io: merge direct_io_walker into __blockdev_direct_IO 2011-10-28 14:58:58 +02:00
drop_caches.c
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eventfd.c
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eventpoll.c epoll: fix spurious lockdep warnings 2011-10-31 17:30:57 -07:00
exec.c tracepoint: add tracepoints for debugging oom_score_adj 2012-01-10 16:30:44 -08:00
fcntl.c
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fhandle.c vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb 2012-01-06 23:16:53 -05:00
fifo.c
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file.c
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file_table.c vfs: prevent remount read-only if pending removes 2012-01-06 23:20:13 -05:00
filesystems.c vfs: convert fs_supers to hlist 2012-01-03 22:52:39 -05:00
fs-writeback.c Merge branch 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm 2012-01-08 13:10:57 -08:00
fs_struct.c
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generic_acl.c switch posix_acl_equiv_mode() to umode_t * 2011-08-01 02:10:06 -04:00
inode.c mm: account reaped page cache on inode cache pruning 2012-01-10 16:30:42 -08:00
internal.h vfs: protect remounting superblock read-only 2012-01-06 23:20:12 -05:00
ioctl.c vfs: fix up ENOIOCTLCMD error handling 2012-01-05 15:40:12 -08:00
ioprio.c fs: add export.h to files using EXPORT_SYMBOL/THIS_MODULE macros 2011-10-31 19:30:31 -04:00
libfs.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
locks.c vfs: fix handling of lock allocation failure in lease-break case 2011-12-26 10:25:26 -08:00
mbcache.c
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mount.h vfs: keep list of mounts for each superblock 2012-01-06 23:20:12 -05:00
mpage.c
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namei.c Merge branches 'vfsmount-guts', 'umode_t' and 'partitions' into Z 2012-01-06 23:15:54 -05:00
namespace.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-01-08 13:21:22 -08:00
no-block.c
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open.c switch security_path_chmod() to struct path * 2012-01-06 23:16:53 -05:00
pipe.c vfs: pipe.c is really non-modular 2012-01-03 22:52:41 -05:00
pnode.c vfs: switch pnode.h macros to struct mount * 2012-01-03 22:57:11 -05:00
pnode.h vfs: switch pnode.h macros to struct mount * 2012-01-03 22:57:11 -05:00
posix_acl.c vfs: pass all mask flags check_acl and posix_acl_permission 2011-10-28 14:58:54 +02:00
proc_namespace.c vfs: switch ->show_options() to struct dentry * 2012-01-06 23:19:54 -05:00
read_write.c Cross Memory Attach 2011-10-31 17:30:44 -07:00
read_write.h
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readdir.c
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select.c
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seq_file.c constify seq_file stuff 2012-01-03 22:52:40 -05:00
signalfd.c
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splice.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
stack.c filesystems: add set_nlink() 2011-11-02 12:53:43 +01:00
stat.c readlinkat: ensure we return ENOENT for the empty pathname for normal lookups 2011-11-02 12:53:42 +01:00
statfs.c vfs: new helper - vfs_ustat() 2012-01-03 22:53:07 -05:00
super.c vfs: prevent remount read-only if pending removes 2012-01-06 23:20:13 -05:00
sync.c fs: move code out of buffer.c 2012-01-03 22:54:07 -05:00
timerfd.c
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utimes.c
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xattr.c vfs: mnt_drop_write_file() 2012-01-03 22:52:40 -05:00
xattr_acl.c
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