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    SubjectRe: [PATCH] INITRAMFS: Add option to preserve mtime from INITRAMFS cpio images
    On Wed, Sep 03, 2008 at 03:48:40PM -0700, Andrew Morton wrote:
    > On Wed, 3 Sep 2008 15:41:31 -0700
    > Nye Liu <nyet@nyet.org> wrote:
    >
    > > > > 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);
    > > > > + do_lutime(collected, &mtime);
    > > > > state = SkipIt;
    > > > > next_state = Reset;
    > > > > return 0;
    > > > > @@ -466,6 +520,7 @@ static char * __init unpack_to_rootfs(char *buf, unsigned len, int check_only)
    > > > > buf += inptr;
    > > > > len -= inptr;
    > > > > }
    > > > > + dir_utime();
    > > >
    > > > Perhaps this is the simplest implementation - I didn't check the fine
    > > > details. What's your thinking here?
    > > >
    > >
    > > The main problem is that i need to save off the entire list for later
    > > processing of the directory mtimes... if i process the directory mtimes
    > > in the same pass as the file/link mtimes, touching the directory inode
    > > when creating/modifying the file/links updates the directory mtime, and
    > > overwrites whatever mtime i set the directory to when i created it.
    > >
    > > The only solution is to do a two pass, which is why the list is
    > > necessary. If there is a better way, i did not find it :(
    > >
    > > It could be that i misunderstood your question though :)
    >
    > I'm wondering whether this code need to use `struct utimbuf' at all.
    > Or at least, as much as it does. utimbuf is more a userspace-facing
    > thing whereas in-kernel timespecs and timevals are more common.
    >
    > The code as you have it does a fair few conversions into utimbuf format
    > (both directly and via the existing functions which it calls). Would
    > it be simpler if it dealt in terms of timespecs?
    >

    or maybe this, this one ONLY using do_utimes() and a single wrapper
    to convert the time_t

    diff --git a/init/initramfs.c b/init/initramfs.c
    index 644fc01..1360a67 100644
    --- a/init/initramfs.c
    +++ b/init/initramfs.c
    @@ -6,6 +6,7 @@
    #include <linux/delay.h>
    #include <linux/string.h>
    #include <linux/syscalls.h>
    +#include <linux/utime.h>

    static __initdata char *message;
    static void __init error(char *x)
    @@ -72,6 +73,51 @@ static void __init free_hash(void)
    }
    }

    +static long __init do_utime(char __user *filename,
    + time_t mtime)
    +{
    + struct timespec t[2];
    +
    + t[0].tv_sec = mtime;
    + t[0].tv_nsec = 0;
    + t[1].tv_sec = mtime;
    + t[1].tv_nsec = 0;
    +
    + return do_utimes(AT_FDCWD, filename, t, AT_SYMLINK_NOFOLLOW);
    +}
    +
    +static __initdata LIST_HEAD(dir_list);
    +struct dir_entry {
    + struct list_head list;
    + char *name;
    + time_t mtime;
    +};
    +
    +static void __init dir_add(const char *name, time_t mtime)
    +{
    + struct dir_entry *de = kmalloc(sizeof(struct dir_entry), GFP_KERNEL);
    + if (!de)
    + panic("can't allocate dir_entry buffer");
    + 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);
    + do_utime(de->name, de->mtime);
    + kfree(de->name);
    + kfree(de);
    + }
    +}
    +
    +static __initdata time_t mtime;
    +
    /* cpio header parsing */

    static __initdata unsigned long ino, major, minor, nlink;
    @@ -97,6 +143,7 @@ static void __init parse_header(char *s)
    uid = parsed[2];
    gid = parsed[3];
    nlink = parsed[4];
    + mtime = parsed[5];
    body_len = parsed[6];
    major = parsed[7];
    minor = parsed[8];
    @@ -130,6 +177,7 @@ static inline void __init eat(unsigned n)
    count -= n;
    }

    +static __initdata char *vcollected;
    static __initdata char *collected;
    static __initdata int remains;
    static __initdata char *collect;
    @@ -271,6 +319,7 @@ static int __init do_name(void)
    if (wfd >= 0) {
    sys_fchown(wfd, uid, gid);
    sys_fchmod(wfd, mode);
    + vcollected = kstrdup(collected, GFP_KERNEL);
    state = CopyFile;
    }
    }
    @@ -278,12 +327,14 @@ static int __init do_name(void)
    sys_mkdir(collected, mode);
    sys_chown(collected, uid, gid);
    sys_chmod(collected, mode);
    + dir_add(collected, mtime);
    } 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);
    + do_utime(collected, mtime);
    }
    }
    return 0;
    @@ -294,6 +345,8 @@ static int __init do_copy(void)
    if (count >= body_len) {
    sys_write(wfd, victim, body_len);
    sys_close(wfd);
    + do_utime(vcollected, mtime);
    + kfree(vcollected);
    eat(body_len);
    state = SkipIt;
    return 0;
    @@ -311,6 +364,7 @@ static int __init do_symlink(void)
    clean_path(collected, 0);
    sys_symlink(collected + N_ALIGN(name_len), collected);
    sys_lchown(collected, uid, gid);
    + do_utime(collected, mtime);
    state = SkipIt;
    next_state = Reset;
    return 0;
    @@ -466,6 +520,7 @@ static char * __init unpack_to_rootfs(char *buf, unsigned len, int check_only)
    buf += inptr;
    len -= inptr;
    }
    + dir_utime();
    kfree(window);
    kfree(name_buf);
    kfree(symlink_buf);
    --
    Nye Liu
    nliu@mrv.com
    (818) 772-6235x248
    (818) 772-0576 fax
    "Who would be stupid enough to quote a fictitious character?"
    -- Don Quixote


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