The commit is pushed to "branch-rh7-3.10.0-229.7.2.vz7.8.x-ovz" and will appear
at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-229.7.2.vz7.8.6
------>
commit 9e421edd0c467fb8d3a230520421a58f55e2a46e
Author: Andrew Vagin <ava...@openvz.org>
Date: Thu Oct 15 15:04:18 2015 +0400
ms/shm: add memfd_create() syscall
The patch is required for CRIU.
https://jira.sw.ru/browse/PSBM-39834
ML: 9183df25fe7b194563db3fec6dc3202a5855839c
memfd_create() is similar to mmap(MAP_ANON), but returns a file-descriptor
that you can pass to mmap(). It can support sealing and avoids any
connection to user-visible mount-points. Thus, it's not subject to quotas
on mounted file-systems, but can be used like malloc()'ed memory, but with
a file-descriptor to it.
memfd_create() returns the raw shmem file, so calls like ftruncate() can
be used to modify the underlying inode. Also calls like fstat() will
return proper information and mark the file as regular file. If you want
sealing, you can specify MFD_ALLOW_SEALING. Otherwise, sealing is not
supported (like on all other regular files).
Compared to O_TMPFILE, it does not require a tmpfs mount-point and is not
subject to a filesystem size limit. It is still properly accounted to
memcg limits, though, and to the same overcommit or no-overcommit
accounting as all user memory.
Signed-off-by: David Herrmann <dh.herrm...@gmail.com>
Acked-by: Hugh Dickins <hu...@google.com>
Cc: Michael Kerrisk <mtk.manpa...@gmail.com>
Cc: Ryan Lortie <de...@desrt.ca>
Cc: Lennart Poettering <lenn...@poettering.net>
Cc: Daniel Mack <zon...@gmail.com>
Cc: Andy Lutomirski <l...@amacapital.net>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Conflicts:
arch/x86/syscalls/syscall_32.tbl
arch/x86/syscalls/syscall_64.tbl
Signed-off-by: Andrew Vagin <ava...@openvz.org>
---
arch/x86/syscalls/syscall_32.tbl | 1 +
arch/x86/syscalls/syscall_64.tbl | 1 +
include/linux/syscalls.h | 1 +
kernel/sys_ni.c | 1 +
mm/shmem.c | 73 ++++++++++++++++++++++++++++++++++++++++
5 files changed, 77 insertions(+)
diff --git a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl
index 5d1de5d..4d0e1b4 100644
--- a/arch/x86/syscalls/syscall_32.tbl
+++ b/arch/x86/syscalls/syscall_32.tbl
@@ -357,6 +357,7 @@
348 i386 process_vm_writev sys_process_vm_writev
compat_sys_process_vm_writev
349 i386 kcmp sys_kcmp
350 i386 finit_module sys_finit_module
+356 i386 memfd_create sys_memfd_create
500 i386 fairsched_mknod sys_fairsched_mknod
501 i386 fairsched_rmnod sys_fairsched_rmnod
diff --git a/arch/x86/syscalls/syscall_64.tbl b/arch/x86/syscalls/syscall_64.tbl
index 3ed05b4..2415f42 100644
--- a/arch/x86/syscalls/syscall_64.tbl
+++ b/arch/x86/syscalls/syscall_64.tbl
@@ -321,6 +321,7 @@
312 common kcmp sys_kcmp
313 common finit_module sys_finit_module
316 common renameat2 sys_renameat2
+319 common memfd_create sys_memfd_create
320 common kexec_file_load sys_kexec_file_load
497 64 fairsched_nodemask sys_fairsched_nodemask
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index c89c938..2c2e396 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -786,6 +786,7 @@ asmlinkage long sys_timerfd_settime(int ufd, int flags,
asmlinkage long sys_timerfd_gettime(int ufd, struct itimerspec __user *otmr);
asmlinkage long sys_eventfd(unsigned int count);
asmlinkage long sys_eventfd2(unsigned int count, int flags);
+asmlinkage long sys_memfd_create(const char __user *uname_ptr, unsigned int
flags);
asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len);
asmlinkage long sys_old_readdir(unsigned int, struct old_linux_dirent __user
*, unsigned int);
asmlinkage long sys_pselect6(int, fd_set __user *, fd_set __user *,
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 7c98d8f..75a69b0 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -194,6 +194,7 @@ cond_syscall(compat_sys_timerfd_settime);
cond_syscall(compat_sys_timerfd_gettime);
cond_syscall(sys_eventfd);
cond_syscall(sys_eventfd2);
+cond_syscall(sys_memfd_create);
/* performance counters: */
cond_syscall(sys_perf_event_open);
diff --git a/mm/shmem.c b/mm/shmem.c
index 3964468..bc8e08b 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -66,7 +66,9 @@ static struct vfsmount *shm_mnt;
#include <linux/highmem.h>
#include <linux/seq_file.h>
#include <linux/magic.h>
+#include <linux/syscalls.h>
#include <linux/fcntl.h>
+#include <uapi/linux/memfd.h>
#include <bc/beancounter.h>
#include <bc/vmpages.h>
@@ -2854,6 +2856,77 @@ static int shmem_show_options(struct seq_file *seq,
struct dentry *root)
shmem_show_mpol(seq, sbinfo->mpol);
return 0;
}
+
+#define MFD_NAME_PREFIX "memfd:"
+#define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
+#define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
+
+#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING)
+
+SYSCALL_DEFINE2(memfd_create,
+ const char __user *, uname,
+ unsigned int, flags)
+{
+ struct shmem_inode_info *info;
+ struct file *file;
+ int fd, error;
+ char *name;
+ long len;
+
+ if (flags & ~(unsigned int)MFD_ALL_FLAGS)
+ return -EINVAL;
+
+ /* length includes terminating zero */
+ len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
+ if (len <= 0)
+ return -EFAULT;
+ if (len > MFD_NAME_MAX_LEN + 1)
+ return -EINVAL;
+
+ name = kmalloc(len + MFD_NAME_PREFIX_LEN, GFP_TEMPORARY);
+ if (!name)
+ return -ENOMEM;
+
+ strcpy(name, MFD_NAME_PREFIX);
+ if (copy_from_user(&name[MFD_NAME_PREFIX_LEN], uname, len)) {
+ error = -EFAULT;
+ goto err_name;
+ }
+
+ /* terminating-zero may have changed after strnlen_user() returned */
+ if (name[len + MFD_NAME_PREFIX_LEN - 1]) {
+ error = -EFAULT;
+ goto err_name;
+ }
+
+ fd = get_unused_fd_flags((flags & MFD_CLOEXEC) ? O_CLOEXEC : 0);
+ if (fd < 0) {
+ error = fd;
+ goto err_name;
+ }
+
+ file = shmem_file_setup(name, 0, VM_NORESERVE);
+ if (IS_ERR(file)) {
+ error = PTR_ERR(file);
+ goto err_fd;
+ }
+ info = SHMEM_I(file_inode(file));
+ file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
+ file->f_flags |= O_RDWR | O_LARGEFILE;
+ if (flags & MFD_ALLOW_SEALING)
+ info->seals &= ~F_SEAL_SEAL;
+
+ fd_install(fd, file);
+ kfree(name);
+ return fd;
+
+err_fd:
+ put_unused_fd(fd);
+err_name:
+ kfree(name);
+ return error;
+}
+
#endif /* CONFIG_TMPFS */
static void shmem_put_super(struct super_block *sb)
_______________________________________________
Devel mailing list
Devel@openvz.org
https://lists.openvz.org/mailman/listinfo/devel
