Messages in this thread | | | Date | Wed, 3 Sep 2008 15:41:31 -0700 | From | Nye Liu <> | Subject | Re: [PATCH] INITRAMFS: Add option to preserve mtime from INITRAMFS cpio images |
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On Wed, Sep 03, 2008 at 03:22:31PM -0700, Andrew Morton wrote: > On Wed, 3 Sep 2008 13:29:38 -0700 > > Signed-off-by: Nye Liu <nyet@nyet.org> > > > > diff --git a/init/initramfs.c b/init/initramfs.c > > index 644fc01..ebfc049 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 +73,38 @@ static void __init free_hash(void) > > } > > } > > > > +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); > > + 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); > > + sys_utime(de->name, &de->mtime); > > gargh. Why does this work? It's normally a big fail to pass a kernel > address into a system call. I guess we're running under KERNEL_DS here > and getname() and strncpy_from_user() did the right thing.
Possibly, i was not aware of that limitation :( I'll look into it
> On what CPU architecture was this tested?
ppc and powerpc
> Wouldn't it be simpler to put a timespec into struct dir_entry then go > direct to do_utimes() here?
No, if i understand your question correctly. I have to do the mtime modifications in two passes (see last comment below)
> > > + kfree(de->name); > > + kfree(de); > > + } > > +} > > + > > +static __initdata struct utimbuf mtime; > > + > > /* cpio header parsing */ > > > > static __initdata unsigned long ino, major, minor, nlink; > > @@ -97,6 +130,7 @@ static void __init parse_header(char *s) > > uid = parsed[2]; > > gid = parsed[3]; > > nlink = parsed[4]; > > + mtime.actime = mtime.modtime = parsed[5]; > > body_len = parsed[6]; > > major = parsed[7]; > > minor = parsed[8]; > > @@ -130,6 +164,7 @@ 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 +306,7 @@ 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 +314,14 @@ 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); > > + sys_utime(collected, &mtime); > > } > > } > > return 0; > > @@ -294,6 +332,8 @@ static int __init do_copy(void) > > if (count >= body_len) { > > sys_write(wfd, victim, body_len); > > sys_close(wfd); > > + sys_utime(vcollected, &mtime); > > and here?
see below regarding two passes.
> > + kfree(vcollected); > > eat(body_len); > > state = SkipIt; > > return 0; > > @@ -305,12 +345,26 @@ static int __init do_copy(void) > > } > > } > > > > +static long __init do_lutime(char __user *filename, > > + struct utimbuf __user *times) > > +{ > > + struct timespec t[2]; > > + > > + t[0].tv_sec = times->actime; > > + t[0].tv_nsec = 0; > > + t[1].tv_sec = times->modtime; > > + t[1].tv_nsec = 0; > > + > > + return do_utimes(AT_FDCWD, filename, t, AT_SYMLINK_NOFOLLOW); > > +} > > + > > 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); > > + 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 :)
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