[patch]fastboot: remove duplicate unpack_to_rootfs()

[patch]fastboot: remove duplicate unpack_to_rootfs()

[Shaohua Li]

we check if initrd is initramfs first and then do real unpack. The check
isn't required, we can directly do unpack. If initrd isn't initramfs, we
can remove garbage. In my laptop, this saves 0.1s boot time. This
penalizes non-initramfs case, but now initramfs is mostly widely used.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>

diff --git a/init/initramfs.c b/init/initramfs.c
index 644fc01..e51c92b 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -5,6 +5,7 @@
 #include <linux/fcntl.h>
 #include <linux/delay.h>
 #include <linux/string.h>
+#include <linux/dirent.h>
 #include <linux/syscalls.h>
 
 static __initdata char *message;
@@ -520,6 +521,37 @@ skip:
 	initrd_end = 0;
 }
 
+static void __init clean_rootfs(void)
+{
+	int fd = sys_open("/", O_RDONLY, 0);
+	void *buf = malloc(1024);
+	struct linux_dirent64 *dirp = buf;
+	int count;
+
+	memset(buf, 0, PAGE_SIZE);
+	count = sys_getdents64(fd, dirp, PAGE_SIZE);
+	while (count > 0) {
+		while (count > 0) {
+			struct stat st;
+
+			sys_newlstat(dirp->d_name, &st);
+			if (S_ISDIR(st.st_mode))
+				sys_rmdir(dirp->d_name);
+			else
+				sys_unlink(dirp->d_name);
+
+			count -= dirp->d_reclen;
+			dirp = (void *)dirp + dirp->d_reclen;
+		}
+		dirp = buf;
+		memset(buf, 0, 1024);
+		count = sys_getdents64(fd, dirp, PAGE_SIZE);
+	}
+
+	sys_close(fd);
+	free(buf);
+}
+
 static int __init populate_rootfs(void)
 {
 	char *err = unpack_to_rootfs(__initramfs_start,
@@ -531,13 +563,15 @@ static int __init populate_rootfs(void)
 		int fd;
 		printk(KERN_INFO "checking if image is initramfs...");
 		err = unpack_to_rootfs((char *)initrd_start,
-			initrd_end - initrd_start, 1);
+			initrd_end - initrd_start, 0);
 		if (!err) {
 			printk(" it is\n");
-			unpack_to_rootfs((char *)initrd_start,
-				initrd_end - initrd_start, 0);
 			free_initrd();
 			return 0;
+		} else {
+			clean_rootfs();
+			unpack_to_rootfs(__initramfs_start,
+				 __initramfs_end - __initramfs_start, 0);
 		}
 		printk("it isn't (%s); looks like an initrd\n", err);
 		fd = sys_open("/initrd.image", O_WRONLY|O_CREAT, 0700);

Re: [patch]fastboot: remove duplicate unpack_to_rootfs()

[Ingo Molnar]

* Shaohua Li <shaohua.li@intel.com> wrote:

> we check if initrd is initramfs first and then do real unpack. The 
> check isn't required, we can directly do unpack. If initrd isn't 
> initramfs, we can remove garbage. In my laptop, this saves 0.1s boot 
> time. This penalizes non-initramfs case, but now initramfs is mostly 
> widely used.

clever concept!

a few observations about the cleanup function:

> +static void __init clean_rootfs(void)
> +{
> +	int fd = sys_open("/", O_RDONLY, 0);

can this ever fail?

> +	void *buf = malloc(1024);

no error checking for buf==NULL.

> +	struct linux_dirent64 *dirp = buf;
> +	int count;
> +
> +	memset(buf, 0, PAGE_SIZE);

overflow: clearly allocating a 1024 bytes buffer and then clearing 4096 
bytes isnt that good?

you could introduce a default-off CONFIG_DEBUG_ROOTFS_CLEANUP option 
that does two runs of unpack_to_rootfs() and inserts an artificial 
clean_rootfs() inbetween? Even if that debug patch doesnt get integrated 
its a good test for the cleanup function.

> +	count = sys_getdents64(fd, dirp, PAGE_SIZE);

... and then doing an up to 4096 bytes getdents into the buffer. A large 
enough initramfs will overflow this.

> +	while (count > 0) {
> +		while (count > 0) {
> +			struct stat st;
> +
> +			sys_newlstat(dirp->d_name, &st);

can this ever fail? If yes we should at least WARN_ON_ONCE().

> +			if (S_ISDIR(st.st_mode))
> +				sys_rmdir(dirp->d_name);
> +			else
> +				sys_unlink(dirp->d_name);
> +
> +			count -= dirp->d_reclen;

can this ever zero-underflow, with a sufficiently corrupted initramfs? 
We should check for 0 underflow to be sure.

> +			dirp = (void *)dirp + dirp->d_reclen;

likewise, we should size-overflow check this pointer. Failure modes of 
overrunning the buffer are subtle and hard to notice/track down.

> +		}
> +		dirp = buf;
> +		memset(buf, 0, 1024);
> +		count = sys_getdents64(fd, dirp, PAGE_SIZE);

overflow: we do a 4096 bytes getdents into a 1K buffer.

> +	}
> +
> +	sys_close(fd);
> +	free(buf);
> +}
> +
>  static int __init populate_rootfs(void)
>  {
>  	char *err = unpack_to_rootfs(__initramfs_start,
> @@ -531,13 +563,15 @@ static int __init populate_rootfs(void)
>  		int fd;
>  		printk(KERN_INFO "checking if image is initramfs...");
>  		err = unpack_to_rootfs((char *)initrd_start,
> -			initrd_end - initrd_start, 1);
> +			initrd_end - initrd_start, 0);
>  		if (!err) {
>  			printk(" it is\n");
> -			unpack_to_rootfs((char *)initrd_start,
> -				initrd_end - initrd_start, 0);
>  			free_initrd();
>  			return 0;
> +		} else {
> +			clean_rootfs();
> +			unpack_to_rootfs(__initramfs_start,
> +				 __initramfs_end - __initramfs_start, 0);
>  		}

the dry_run variable is now unused in unpack_to_rootfs() and could be 
eliminated.

>  		printk("it isn't (%s); looks like an initrd\n", err);
>  		fd = sys_open("/initrd.image", O_WRONLY|O_CREAT, 0700);

	Ingo

Re: [patch]fastboot: remove duplicate unpack_to_rootfs()

[Ingo Molnar]

* Ingo Molnar <mingo@elte.hu> wrote:

> the dry_run variable is now unused in unpack_to_rootfs() and could be 
> eliminated.

also, while we are materially touching init/initramfs.c, that file has 
collected a few uglies in the past few years, checkpatch --file says:

  total: 7 errors, 7 warnings, 3 checks, 562 lines checked

it has a few other problems as well that can be seen if you look at the 
file. Unused macros:

 /* Diagnostic functions (stubbed out) */
 #define Assert(cond,msg)
 #define Trace(x)
 #define Tracev(x)
 #define Tracevv(x)
 #define Tracec(c,x)
 #define Tracecv(c,x)

 #define STATIC static
 #define INIT __init

lots of no-newline-after-variable-definitions instances:

 {
         int written;
         dry_run = check_only;

no-newline-before-return:

         kfree(header_buf);
         return message;
 }

so it would be nice to start off with a cleanup [strictly no code 
changed] patch.

then it also has an absolutely crazy turn-error-printouts-off hack:

 static __initdata char *message;
 static void __init error(char *x)
 {
         if (!message)
                 message = x;
 }

which is unobvious, 100% unused and should be removed.

those error()s should be pr_debug() perhaps. [this should be a second 
cleanup patch as it changes the code]

Hm?

	Ingo

RE: [patch]fastboot: remove duplicate unpack_to_rootfs()

[Li, Shaohua]

>-----Original Message-----
>From: Ingo Molnar [mailto:mingo@elte.hu]
>Sent: Wednesday, August 13, 2008 3:45 PM
>To: Li, Shaohua
>Cc: lkml; Andrew Morton; Arjan van de Ven
>Subject: Re: [patch]fastboot: remove duplicate unpack_to_rootfs()
>
>
>* Shaohua Li <shaohua.li@intel.com> wrote:
>
>> we check if initrd is initramfs first and then do real unpack. The
>> check isn't required, we can directly do unpack. If initrd isn't
>> initramfs, we can remove garbage. In my laptop, this saves 0.1s boot
>> time. This penalizes non-initramfs case, but now initramfs is mostly
>> widely used.
>
>clever concept!
>
>a few observations about the cleanup function:
>
>> +static void __init clean_rootfs(void)
>> +{
>> +     int fd = sys_open("/", O_RDONLY, 0);
>
>can this ever fail?
I thought there will be a panic if it fails, so I didn't explicitly add a check here. I can add one.

>> +     struct linux_dirent64 *dirp = buf;
>> +     int count;
>> +
>> +     memset(buf, 0, PAGE_SIZE);
>
>overflow: clearly allocating a 1024 bytes buffer and then clearing 4096
>bytes isnt that good?
Oops, I use 4096 first and found it's too big, so changed to 1024, but forgot change all. My bad.

>you could introduce a default-off CONFIG_DEBUG_ROOTFS_CLEANUP option
>that does two runs of unpack_to_rootfs() and inserts an artificial
>clean_rootfs() inbetween? Even if that debug patch doesnt get integrated
>its a good test for the cleanup function.
Actually I did the test already, just forgot change all size.

>> +     while (count > 0) {
>> +             while (count > 0) {
>> +                     struct stat st;
>> +
>> +                     sys_newlstat(dirp->d_name, &st);
>
>can this ever fail? If yes we should at least WARN_ON_ONCE().
I'll add check.

>> +                     if (S_ISDIR(st.st_mode))
>> +                             sys_rmdir(dirp->d_name);
>> +                     else
>> +                             sys_unlink(dirp->d_name);
>> +
>> +                     count -= dirp->d_reclen;
>
>can this ever zero-underflow, with a sufficiently corrupted initramfs?
>We should check for 0 underflow to be sure.
>> +                     dirp = (void *)dirp + dirp->d_reclen;
>
>likewise, we should size-overflow check this pointer. Failure modes of
>overrunning the buffer are subtle and hard to notice/track down.
I'm not quite sure here. Do you think the .d_reclen can be a incorrect value?

>>  static int __init populate_rootfs(void)
>>  {
>>       char *err = unpack_to_rootfs(__initramfs_start,
>> @@ -531,13 +563,15 @@ static int __init populate_rootfs(void)
>>               int fd;
>>               printk(KERN_INFO "checking if image is initramfs...");
>>               err = unpack_to_rootfs((char *)initrd_start,
>> -                     initrd_end - initrd_start, 1);
>> +                     initrd_end - initrd_start, 0);
>>               if (!err) {
>>                       printk(" it is\n");
>> -                     unpack_to_rootfs((char *)initrd_start,
>> -                             initrd_end - initrd_start, 0);
>>                       free_initrd();
>>                       return 0;
>> +             } else {
>> +                     clean_rootfs();
>> +                     unpack_to_rootfs(__initramfs_start,
>> +                              __initramfs_end - __initramfs_start, 0);
>>               }
>
>the dry_run variable is now unused in unpack_to_rootfs() and could be
>eliminated.
Ok, I can cleanup this.

Thanks,
Shaohua

Re: [patch]fastboot: remove duplicate unpack_to_rootfs()

[Andrew Morton]

On Wed, 13 Aug 2008 09:52:36 +0200 Ingo Molnar <mingo@elte.hu> wrote:

> no-newline-before-return:
> 
>          kfree(header_buf);
>          return message;
>  }

I accidentally delete those newlines when nobody is looking.  They don't seem
worth the space they consume.

(what do we do with a function which has multiple `return's?)

Re: [patch]fastboot: remove duplicate unpack_to_rootfs()

[Frans Meulenbroeks]

2008/8/13, Ingo Molnar <mingo@elte.hu>:
>
>  * Ingo Molnar <mingo@elte.hu> wrote:
>
>  > the dry_run variable is now unused in unpack_to_rootfs() and could be
>  > eliminated.
>
>  also, while we are materially touching init/initramfs.c, that file has
>  collected a few uglies in the past few years, checkpatch --file says:
>
>   total: 7 errors, 7 warnings, 3 checks, 562 lines checked
>
>  it has a few other problems as well that can be seen if you look at the
>  file. Unused macros:
>
>   /* Diagnostic functions (stubbed out) */
>   #define Assert(cond,msg)
>   #define Trace(x)
>   #define Tracev(x)
>   #define Tracevv(x)
>   #define Tracec(c,x)
>   #define Tracecv(c,x)
>
>   #define STATIC static
>   #define INIT __init
>
These are not really unused. A few lines later it reads:

#include "../src/inflate.c"

These macros are used within inflate.c

(and perhaps the inclusion of inflate.c is not a good idea, maybe this
should be in lib.a
note that inflate.c is also included in init/do_mounts_rd.c;
fortunately this is all init code (which is probably why include was
used in the first place))

Frans.

Re: [patch]fastboot: remove duplicate unpack_to_rootfs()

[Ingo Molnar]

* Andrew Morton <akpm@linux-foundation.org> wrote:

> On Wed, 13 Aug 2008 09:52:36 +0200 Ingo Molnar <mingo@elte.hu> wrote:
> 
> > no-newline-before-return:
> > 
> >          kfree(header_buf);
> >          return message;
> >  }
> 
> I accidentally delete those newlines when nobody is looking.  They 
> don't seem worth the space they consume.

yeah - for me it's case-dependent. My benchmark for it is absolutely 
objective and easy to describe: i add a newline when it looks nicer and 
more maintainable that way ;-)

> (what do we do with a function which has multiple `return's?)

i really didnt want to make a full scale style discussion out of this. 
Lets ignore my suggestion. The valid case when i use a newline is for 
example when the return obscures what happens:

	if (something) {
		do_one();
		repeat_this();
		return;
	}

as visually it's easy to miss the return - especially if the lines above 
it look similar. So i use:

	if (something) {
		do_one();
		repeat_this();

		return;
	}

because way too often do i miss a stray return somewhere and 
misunderstand the code flow of a function if it does not stand out, even 
with syntax highlighting.

Another case is when there's a long linear block of cleanup statements 
followed by a return:

        q->mode = mode;
        strcpy(q->name, name);
        q->next = NULL;
        *p = q;
        return NULL;
}

i usually add a newline:

        q->mode = mode;
        strcpy(q->name, name);
        q->next = NULL;
        *p = q;

        return NULL;
}

as the 'return NULL' is a separate concept from the preceding 
activities.

So in this case it is not really because the return is specialy, this is 
because i like to separate groups of statements per type of activity. So 
i'd do the same if there were two groups of statements, i'd turn this:

        q->mode = mode;
        strcpy(q->name, name);
        q->next = NULL;
        *p = q;
	other_stuff = 2;
	some_other_stuff(other_stuff)

into this:

        q->mode = mode;
        strcpy(q->name, name);
        q->next = NULL;
        *p = q;

	other_stuff = 2;
	some_other_stuff(other_stuff)

to make sure the two groups of statements stand out. (Sometimes a pure 
newline does a better job at inserting the right kind of visual 
structure than a comment line.)

but again ... these are nuances where reasonable people might disagree, 
and i only made them because this topic lives, is developed and tested 
in tip/fastboot at the moment.

	Ingo

Re: [patch]fastboot: remove duplicate unpack_to_rootfs()

[Ingo Molnar]

* Frans Meulenbroeks <fransmeulenbroeks@gmail.com> wrote:

> 2008/8/13, Ingo Molnar <mingo@elte.hu>:
> >
> >  * Ingo Molnar <mingo@elte.hu> wrote:
> >
> >  > the dry_run variable is now unused in unpack_to_rootfs() and could be
> >  > eliminated.
> >
> >  also, while we are materially touching init/initramfs.c, that file has
> >  collected a few uglies in the past few years, checkpatch --file says:
> >
> >   total: 7 errors, 7 warnings, 3 checks, 562 lines checked
> >
> >  it has a few other problems as well that can be seen if you look at the
> >  file. Unused macros:
> >
> >   /* Diagnostic functions (stubbed out) */
> >   #define Assert(cond,msg)
> >   #define Trace(x)
> >   #define Tracev(x)
> >   #define Tracevv(x)
> >   #define Tracec(c,x)
> >   #define Tracecv(c,x)
> >
> >   #define STATIC static
> >   #define INIT __init
> >
> These are not really unused. A few lines later it reads:
> 
> #include "../src/inflate.c"
> 
> These macros are used within inflate.c

oh, i _knew_ i saw this zlib ugliness sometime in the past.

> (and perhaps the inclusion of inflate.c is not a good idea, maybe this 
> should be in lib.a note that inflate.c is also included in 
> init/do_mounts_rd.c; fortunately this is all init code (which is 
> probably why include was used in the first place))

definitely. It's a different patch though.

	Ingo

RE: [patch]fastboot: remove duplicate unpack_to_rootfs()

[Li, Shaohua]

[-- Attachment #1: Type: text/plain, Size: 695 bytes --]



>-----Original Message-----
>From: Ingo Molnar [mailto:mingo@elte.hu]
>Sent: Wednesday, August 13, 2008 3:45 PM
>To: Li, Shaohua
>Cc: lkml; Andrew Morton; Arjan van de Ven
>Subject: Re: [patch]fastboot: remove duplicate unpack_to_rootfs()
>
>
>* Shaohua Li <shaohua.li@intel.com> wrote:
>
>> we check if initrd is initramfs first and then do real unpack. The
>> check isn't required, we can directly do unpack. If initrd isn't
>> initramfs, we can remove garbage. In my laptop, this saves 0.1s boot
>> time. This penalizes non-initramfs case, but now initramfs is mostly
>> widely used.
Updated patch. Sorry for the attachment, my email client is broken.

Thanks,
Shaohua

[-- Attachment #2: initramfs.patch --]
[-- Type: application/octet-stream, Size: 3902 bytes --]

we check if initrd is initramfs first and then do real unpack. The check
isn't required, we can directly do unpack. If initrd isn't initramfs, we
can remove garbage. In my laptop, this saves 0.1s boot time. This
penalizes non-initramfs case, but now initramfs is mostly widely used.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>

diff --git a/init/initramfs.c b/init/initramfs.c
index 644fc01..da8d030 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -5,6 +5,7 @@
 #include <linux/fcntl.h>
 #include <linux/delay.h>
 #include <linux/string.h>
+#include <linux/dirent.h>
 #include <linux/syscalls.h>
 
 static __initdata char *message;
@@ -121,8 +122,6 @@ static __initdata char *victim;
 static __initdata unsigned count;
 static __initdata loff_t this_header, next_header;
 
-static __initdata int dry_run;
-
 static inline void __init eat(unsigned n)
 {
 	victim += n;
@@ -183,10 +182,6 @@ static int __init do_header(void)
 	parse_header(collected);
 	next_header = this_header + N_ALIGN(name_len) + body_len;
 	next_header = (next_header + 3) & ~3;
-	if (dry_run) {
-		read_into(name_buf, N_ALIGN(name_len), GotName);
-		return 0;
-	}
 	state = SkipIt;
 	if (name_len <= 0 || name_len > PATH_MAX)
 		return 0;
@@ -257,8 +252,6 @@ static int __init do_name(void)
 		free_hash();
 		return 0;
 	}
-	if (dry_run)
-		return 0;
 	clean_path(collected, mode);
 	if (S_ISREG(mode)) {
 		int ml = maybe_link();
@@ -423,10 +416,9 @@ static void __init flush_window(void)
 	outcnt = 0;
 }
 
-static char * __init unpack_to_rootfs(char *buf, unsigned len, int check_only)
+static char * __init unpack_to_rootfs(char *buf, unsigned len)
 {
 	int written;
-	dry_run = check_only;
 	header_buf = kmalloc(110, GFP_KERNEL);
 	symlink_buf = kmalloc(PATH_MAX + N_ALIGN(PATH_MAX) + 1, GFP_KERNEL);
 	name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);
@@ -520,10 +512,57 @@ skip:
 	initrd_end = 0;
 }
 
+#define BUF_SIZE 1024
+static void __init clean_rootfs(void)
+{
+	int fd;
+	void *buf;
+	struct linux_dirent64 *dirp;
+	int count;
+
+	fd = sys_open("/", O_RDONLY, 0);
+	WARN_ON(fd < 0);
+	if (fd < 0)
+		return;
+	buf = kzalloc(BUF_SIZE, GFP_KERNEL);
+	WARN_ON(!buf);
+	if (!buf) {
+		sys_close(fd);
+		return;
+	}
+
+	dirp = buf;
+	count = sys_getdents64(fd, dirp, BUF_SIZE);
+	while (count > 0) {
+		while (count > 0) {
+			struct stat st;
+			int ret;
+
+			ret = sys_newlstat(dirp->d_name, &st);
+			WARN_ON_ONCE(ret);
+			if (!ret) {
+				if (S_ISDIR(st.st_mode))
+					sys_rmdir(dirp->d_name);
+				else
+					sys_unlink(dirp->d_name);
+			}
+
+			count -= dirp->d_reclen;
+			dirp = (void *)dirp + dirp->d_reclen;
+		}
+		dirp = buf;
+		memset(buf, 0, BUF_SIZE);
+		count = sys_getdents64(fd, dirp, BUF_SIZE);
+	}
+
+	sys_close(fd);
+	kfree(buf);
+}
+
 static int __init populate_rootfs(void)
 {
 	char *err = unpack_to_rootfs(__initramfs_start,
-			 __initramfs_end - __initramfs_start, 0);
+			 __initramfs_end - __initramfs_start);
 	if (err)
 		panic(err);
 	if (initrd_start) {
@@ -531,13 +570,15 @@ static int __init populate_rootfs(void)
 		int fd;
 		printk(KERN_INFO "checking if image is initramfs...");
 		err = unpack_to_rootfs((char *)initrd_start,
-			initrd_end - initrd_start, 1);
+			initrd_end - initrd_start);
 		if (!err) {
 			printk(" it is\n");
-			unpack_to_rootfs((char *)initrd_start,
-				initrd_end - initrd_start, 0);
 			free_initrd();
 			return 0;
+		} else {
+			clean_rootfs();
+			unpack_to_rootfs(__initramfs_start,
+				 __initramfs_end - __initramfs_start);
 		}
 		printk("it isn't (%s); looks like an initrd\n", err);
 		fd = sys_open("/initrd.image", O_WRONLY|O_CREAT, 0700);
@@ -550,7 +591,7 @@ static int __init populate_rootfs(void)
 #else
 		printk(KERN_INFO "Unpacking initramfs...");
 		err = unpack_to_rootfs((char *)initrd_start,
-			initrd_end - initrd_start, 0);
+			initrd_end - initrd_start);
 		if (err)
 			panic(err);
 		printk(" done\n");

[PATCH] fastboot: remove duplicate unpack_to_rootfs()

[Arjan van de Ven]

>From 4ea6c5331652555dcc96b86e078b7dceaa38005b Mon Sep 17 00:00:00 2001
From: Li, Shaohua <shaohua.li@intel.com>
Date: Wed, 13 Aug 2008 17:26:01 +0800
Subject: [PATCH] fastboot: remove duplicate unpack_to_rootfs()

we check if initrd is initramfs first and then do the real unpack. The check
isn't required, we can directly do unpack.  If the initrd isn't an
initramfs, we can remove the garbage.  In my laptop, this saves 0.1s boot
time.

This patch penalizes non-initramfs initrd case, but nowadays, initramfs is
the most widely used method for initrds.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Acked-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 init/initramfs.c |   71 ++++++++++++++++++++++++++++++++++++++++++-----------
 1 files changed, 56 insertions(+), 15 deletions(-)

diff --git a/init/initramfs.c b/init/initramfs.c
index d9c941c..d3c56fc 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -5,6 +5,7 @@
 #include <linux/fcntl.h>
 #include <linux/delay.h>
 #include <linux/string.h>
+#include <linux/dirent.h>
 #include <linux/syscalls.h>
 #include <linux/utime.h>
 
@@ -166,8 +167,6 @@ static __initdata char *victim;
 static __initdata unsigned count;
 static __initdata loff_t this_header, next_header;
 
-static __initdata int dry_run;
-
 static inline void __init eat(unsigned n)
 {
 	victim += n;
@@ -229,10 +228,6 @@ static int __init do_header(void)
 	parse_header(collected);
 	next_header = this_header + N_ALIGN(name_len) + body_len;
 	next_header = (next_header + 3) & ~3;
-	if (dry_run) {
-		read_into(name_buf, N_ALIGN(name_len), GotName);
-		return 0;
-	}
 	state = SkipIt;
 	if (name_len <= 0 || name_len > PATH_MAX)
 		return 0;
@@ -303,8 +298,6 @@ static int __init do_name(void)
 		free_hash();
 		return 0;
 	}
-	if (dry_run)
-		return 0;
 	clean_path(collected, mode);
 	if (S_ISREG(mode)) {
 		int ml = maybe_link();
@@ -476,10 +469,9 @@ static void __init flush_window(void)
 	outcnt = 0;
 }
 
-static char * __init unpack_to_rootfs(char *buf, unsigned len, int check_only)
+static char * __init unpack_to_rootfs(char *buf, unsigned len)
 {
 	int written;
-	dry_run = check_only;
 	header_buf = kmalloc(110, GFP_KERNEL);
 	symlink_buf = kmalloc(PATH_MAX + N_ALIGN(PATH_MAX) + 1, GFP_KERNEL);
 	name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);
@@ -574,10 +566,57 @@ skip:
 	initrd_end = 0;
 }
 
+#define BUF_SIZE 1024
+static void __init clean_rootfs(void)
+{
+	int fd;
+	void *buf;
+	struct linux_dirent64 *dirp;
+	int count;
+
+	fd = sys_open("/", O_RDONLY, 0);
+	WARN_ON(fd < 0);
+	if (fd < 0)
+		return;
+	buf = kzalloc(BUF_SIZE, GFP_KERNEL);
+	WARN_ON(!buf);
+	if (!buf) {
+		sys_close(fd);
+		return;
+	}
+
+	dirp = buf;
+	count = sys_getdents64(fd, dirp, BUF_SIZE);
+	while (count > 0) {
+		while (count > 0) {
+			struct stat st;
+			int ret;
+
+			ret = sys_newlstat(dirp->d_name, &st);
+			WARN_ON_ONCE(ret);
+			if (!ret) {
+				if (S_ISDIR(st.st_mode))
+					sys_rmdir(dirp->d_name);
+				else
+					sys_unlink(dirp->d_name);
+			}
+
+			count -= dirp->d_reclen;
+			dirp = (void *)dirp + dirp->d_reclen;
+		}
+		dirp = buf;
+		memset(buf, 0, BUF_SIZE);
+		count = sys_getdents64(fd, dirp, BUF_SIZE);
+	}
+
+	sys_close(fd);
+	kfree(buf);
+}
+
 static int __init populate_rootfs(void)
 {
 	char *err = unpack_to_rootfs(__initramfs_start,
-			 __initramfs_end - __initramfs_start, 0);
+			 __initramfs_end - __initramfs_start);
 	if (err)
 		panic(err);
 	if (initrd_start) {
@@ -585,13 +624,15 @@ static int __init populate_rootfs(void)
 		int fd;
 		printk(KERN_INFO "checking if image is initramfs...");
 		err = unpack_to_rootfs((char *)initrd_start,
-			initrd_end - initrd_start, 1);
+			initrd_end - initrd_start);
 		if (!err) {
 			printk(" it is\n");
-			unpack_to_rootfs((char *)initrd_start,
-				initrd_end - initrd_start, 0);
 			free_initrd();
 			return 0;
+		} else {
+			clean_rootfs();
+			unpack_to_rootfs(__initramfs_start,
+				 __initramfs_end - __initramfs_start);
 		}
 		printk("it isn't (%s); looks like an initrd\n", err);
 		fd = sys_open("/initrd.image", O_WRONLY|O_CREAT, 0700);
@@ -604,7 +645,7 @@ static int __init populate_rootfs(void)
 #else
 		printk(KERN_INFO "Unpacking initramfs...");
 		err = unpack_to_rootfs((char *)initrd_start,
-			initrd_end - initrd_start, 0);
+			initrd_end - initrd_start);
 		if (err)
 			panic(err);
 		printk(" done\n");
-- 
1.6.0.6




-- 
Arjan van de Ven 	Intel Open Source Technology Centre
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