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Message-Id: <20080816015815.11e2a1b4.akpm@linux-foundation.org>
Date: Sat, 16 Aug 2008 01:58:15 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Nye Liu <nyet@...t.org>
Cc: linux-kernel@...r.kernel.org, nyet@....com
Subject: Re: [PATCH] INITRAMFS: Add option to preserve mtime from INITRAMFS
cpio images
On Tue, 5 Aug 2008 12:52:32 -0700 Nye Liu <nyet@...t.org> wrote:
> From: Nye Liu <nyet@...t.org>
>
> When unpacking the cpio into the initramfs, mtimes are not preserved by
> default. This patch adds an INITRAMFS_PRESERVE_MTIME option that allows
> mtimes stored in the cpio image to be used when constructing the
> initramfs. For embedded applications that run exclusively out of the
> initramfs, this is invaluable.
>
> Signed-off-by: Nye Liu <nyet@...t.org>
>
> ---
>
> diff --git a/init/initramfs.c b/init/initramfs.c
> index 644fc01..0dd0a73 100644
> --- a/init/initramfs.c
> +++ b/init/initramfs.c
> @@ -7,6 +7,12 @@
> #include <linux/string.h>
> #include <linux/syscalls.h>
>
> +#ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
> +#include <linux/utime.h>
> +#include <linux/namei.h>
> +#include <linux/list.h>
> +#endif
It would be better to do it unconditionally if possible - remove the
config option and all the ifdefs.
> static __initdata char *message;
> static void __init error(char *x)
> {
> @@ -72,6 +78,38 @@ static void __init free_hash(void)
> }
> }
>
> +#ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
> +static __initdata LIST_HEAD(dir_list);
> +struct dir_entry {
> + struct list_head list;
> + char *name;
> + struct utimbuf mtime;
> +};
> +
> +static void __init dir_add(const char *name, struct utimbuf mtime)
> +{
> + struct dir_entry *de = kmalloc(sizeof(struct dir_entry), GFP_KERNEL);
kmalloc() can fail..
> + INIT_LIST_HEAD(&de->list);
> + de->name = kstrdup(name, GFP_KERNEL);
> + de->mtime = mtime;
> + list_add(&de->list, &dir_list);
> +}
> +
> +static void __init dir_utime(void)
> +{
> + struct list_head *e, *tmp;
> + list_for_each_safe(e, tmp, &dir_list) {
> + struct dir_entry *de = list_entry(e, struct dir_entry, list);
> + list_del(e);
> + sys_utime(de->name, &de->mtime);
> + kfree(de->name);
> + kfree(de);
> + }
> +}
> +
> +static __initdata struct utimbuf mtime;
> +#endif
> +
> /* cpio header parsing */
>
> static __initdata unsigned long ino, major, minor, nlink;
> @@ -97,6 +135,9 @@ static void __init parse_header(char *s)
> uid = parsed[2];
> gid = parsed[3];
> nlink = parsed[4];
> +#ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
> + mtime.actime = mtime.modtime = parsed[5];
> +#endif
> body_len = parsed[6];
> major = parsed[7];
> minor = parsed[8];
> @@ -130,6 +171,10 @@ static inline void __init eat(unsigned n)
> count -= n;
> }
>
> +#ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
> +static __initdata char *vcollected;
> +#endif
> +
> static __initdata char *collected;
> static __initdata int remains;
> static __initdata char *collect;
> @@ -271,6 +316,9 @@ static int __init do_name(void)
> if (wfd >= 0) {
> sys_fchown(wfd, uid, gid);
> sys_fchmod(wfd, mode);
> +#ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
> + vcollected = kstrdup(collected, GFP_KERNEL);
> +#endif
> state = CopyFile;
> }
> }
> @@ -278,12 +326,18 @@ static int __init do_name(void)
> sys_mkdir(collected, mode);
> sys_chown(collected, uid, gid);
> sys_chmod(collected, mode);
> +#ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
> + dir_add(collected, mtime);
> +#endif
> } else if (S_ISBLK(mode) || S_ISCHR(mode) ||
> S_ISFIFO(mode) || S_ISSOCK(mode)) {
> if (maybe_link() == 0) {
> sys_mknod(collected, mode, rdev);
> sys_chown(collected, uid, gid);
> sys_chmod(collected, mode);
> +#ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
> + sys_utime(collected, &mtime);
> +#endif
> }
> }
> return 0;
> @@ -294,6 +348,10 @@ static int __init do_copy(void)
> if (count >= body_len) {
> sys_write(wfd, victim, body_len);
> sys_close(wfd);
> +#ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
> + sys_utime(vcollected, &mtime);
> + kfree(vcollected);
> +#endif
> eat(body_len);
> state = SkipIt;
> return 0;
> @@ -305,12 +363,48 @@ static int __init do_copy(void)
> }
> }
>
> +#ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
> +static long __init sys_lutime(char __user * filename,
> + struct utimbuf __user * times)
Please avoid using the sys_ namespace. That is for system calls.
Please pass the patch through scripts/checkpatch.pl and review the report.
> +{
> + int error;
> + struct path path;
> + struct inode * inode;
> + struct iattr newattrs;
> +
> + error = user_lpath(filename, &path);
> + if (error) return error;
> +
> + inode = path.dentry->d_inode;
> +
> + newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
> + error = 0;
> + if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
> + goto pput_and_out;
> +
> + newattrs.ia_atime.tv_sec = times->actime;
> + newattrs.ia_atime.tv_nsec = 0;
> + newattrs.ia_mtime.tv_sec = times->modtime;
> + newattrs.ia_mtime.tv_nsec = 0;
> + newattrs.ia_valid |= ATTR_ATIME_SET | ATTR_MTIME_SET;
> + mutex_lock(&inode->i_mutex);
> + error = notify_change(path.dentry, &newattrs);
> + mutex_unlock(&inode->i_mutex);
> +pput_and_out:
> + path_put(&path);
> + return error;
> +}
How does this differ from sys_utime()?
Can this use do_utimes()?
> +#endif
> +
> static int __init do_symlink(void)
> {
> collected[N_ALIGN(name_len) + body_len] = '\0';
> clean_path(collected, 0);
> sys_symlink(collected + N_ALIGN(name_len), collected);
> sys_lchown(collected, uid, gid);
> +#ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
> + sys_lutime(collected, &mtime);
> +#endif
> state = SkipIt;
> next_state = Reset;
> return 0;
> @@ -466,6 +560,9 @@ static char * __init unpack_to_rootfs(char *buf, unsigned len, int check_only)
> buf += inptr;
> len -= inptr;
> }
> +#ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
> + dir_utime();
> +#endif
> kfree(window);
> kfree(name_buf);
> kfree(symlink_buf);
> diff --git a/usr/Kconfig b/usr/Kconfig
> index 86cecb5..f7d9f60 100644
> --- a/usr/Kconfig
> +++ b/usr/Kconfig
> @@ -44,3 +44,13 @@ config INITRAMFS_ROOT_GID
> owned by group root in the initial ramdisk image.
>
> If you are not sure, leave it set to "0".
> +
> +config INITRAMFS_PRESERVE_MTIME
> + bool "Preserve mtimes from INITRAMFS image"
> + depends on BLK_DEV_INITRD
> + default n
> + help
> + Preserve mtimes (last modified times) for all items stored in the
> + initramfs image.
> +
> + If you are not sure, leave it set to "N"
--
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