Re: [uml-devel] UML hostfs bugs

["wang lianwei" <lianwei.wang@gmail.com>]

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yes, you are right. see this patches.


diff -urNp linux-2.6.10/fs/hostfs/hostfs.h linux-2.6.10-src
/fs/hostfs/hostfs.h
--- linux-2.6.10/fs/hostfs/hostfs.h      2006-04-12 15:12:51.000000000 +0800
+++ linux-2.6.10-src/fs/hostfs/hostfs.h   2006-08-16 15:58:59.149590168+0800
@@ -40,6 +40,7 @@ extern int access_file(char *path, int r
 extern int open_file(char *path, int r, int w, int append);
 extern int file_type(const char *path, int *maj, int *min);
 extern void *open_dir(char *path, int *err_out);
+extern void seek_dir(void *stream, unsigned long long pos);
 extern char *read_dir(void *stream, unsigned long long *pos,
                      unsigned long long *ino_out, int *len_out);
 extern void close_file(void *stream);



diff -urNp linux-2.6.10/fs/hostfs/hostfs_kern.c linux-2.6.10-src
/fs/hostfs/hostfs_kern.c
--- linux-2.6.10/fs/hostfs/hostfs_kern.c 2006-04-12 15:12:51.000000000 +0800
+++ linux-2.6.10-src/fs/hostfs/hostfs_kern.c      2006-08-16 15:51:
08.105199800 +0800
@@ -338,6 +338,7 @@ int hostfs_readdir(struct file *file, vo
        kfree(name);
        if(dir == NULL) return(-error);
        next = file->f_pos;
+      seek_dir(dir, next);
        while((name = read_dir(dir, &next, &ino, &len)) != NULL){
                error = (*filldir)(ent, name, len, file->f_pos,
                                   ino, DT_UNKNOWN);



diff -urNp linux-2.6.10/fs/hostfs/hostfs_user.c linux-2.6.10-src
/fs/hostfs/hostfs_user.c
--- linux-2.6.x/fs/hostfs/hostfs_user.c 2006-04-12 15:12:52.000000000 +0800
+++ linux-2.6.10-src/fs/hostfs/hostfs_user.c      2006-08-16 15:53:
31.618382480 +0800
@@ -116,13 +116,19 @@ void *open_dir(char *path, int *err_out)
        return(dir);
 }

+void seek_dir(void *stream, unsigned long long pos)
+{
+        DIR *dir = stream;
+
+        seekdir(dir, pos);
+}
+
 char *read_dir(void *stream, unsigned long long *pos,
               unsigned long long *ino_out, int *len_out)
 {
        DIR *dir = stream;
        struct dirent *ent;

-       seekdir(dir, *pos);
        ent = readdir(dir);
        if(ent == NULL) return(NULL);
        *len_out = strlen(ent->d_name);





2006/8/16, Blaisorblade <blaisorblade@yahoo.it>:
>
> On Monday 14 August 2006 13:07, wang lianwei wrote:
> > Answers:
> >
> > 1. I test it on ext3 filesystem.
> >
> > 2. You are right. Sometimes the pos telldir returned is not the next
> entry
> > offset. just as your point out:
> >       position 0 -> readdir "." -> you call telldir -> it _again_ says
> > you're at 0.
> >
> > 3. I also try to resolve it by remove the seekdir(only use the
> > sequence readdir call), It is also worked.
>
> I can guess what the patch does but please generate with the additional -p
> option so it's easier to read (otherwise the recipient _has_ to read the
> source). Compliments for the solution, it's really simpler and better than
> my
> proposal.
>
> Also, you have to regenerate it anyway for another (tiny) reason: it is
> not
> always safe to use "seekdir" in kernelspace code, you need (sadly) a new
> wrapper in hostfs_user.c and to call it instead of seekdir in
> hostfs_kern.c;
> almost surely you'll get an "undeclared function" warning but
> miscompilations
> in some rare cases are also possible, say for stat(): it is defined almost
> only as a static inline function, or for some structures having different
> definitions in userspace and kernelspace.
>
> > --- linux-2.6.x/fs/hostfs/hostfs_kern.c 2006-04-12 15:12:51.000000000+0800
> > +++ linux-2.6.10-src/fs/hostfs/hostfs_kern.c      2006-08-14 18:25:
> > 13.772237744 +0800
> > @@ -338,6 +338,7 @@
> >         kfree(name);
> >         if(dir == NULL) return(-error);
> >         next = file->f_pos;
> > +       seekdir(dir,next);
> >         while((name = read_dir(dir, &next, &ino, &len)) != NULL){
> >                 error = (*filldir)(ent, name, len, file->f_pos,
> >                                    ino, DT_UNKNOWN);
> >
> >
> > --- linux-2.6.x/fs/hostfs/hostfs_user.c 2006-04-12 15:12:52.000000000+0800
> > +++ linux-2.6.10-src/fs/hostfs/hostfs_user.c      2006-08-14 18:36:
> > 24.276305632 +0800
> > @@ -122,7 +122,6 @@
> >         DIR *dir = stream;
> >         struct dirent *ent;
> >
> > -       seekdir(dir, *pos);
> >         ent = readdir(dir);
> >         if(ent == NULL) return(NULL);
> >         *len_out = strlen(ent->d_name);
>
> --
> Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
> Paolo Giarrusso, aka Blaisorblade
> http://www.user-mode-linux.org/~blaisorblade
> Chiacchiera con i tuoi amici in tempo reale!
> http://it.yahoo.com/mail_it/foot/*http://it.messenger.yahoo.com
>
>

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