Date: Tue, 18 Sep 2001 15:09:33 +0300 From: Maxim Sobolev <sobomax@FreeBSD.org> To: chris@calldei.com Cc: phk@critter.freebsd.dk, brent@rcfile.org, current@FreeBSD.org, hackers@FreeBSD.org, marcel@FreeBSD.org Subject: Re: Junior Kernel Hacker task: improve vnode->v_tag Message-ID: <3BA7397D.A82C213@FreeBSD.org> References: <20010908030110.E548@holly.calldei.com> <200109081154.OAA95138@www.abc.com.ua> <20010908150620.F548@holly.calldei.com>
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Chris Costello wrote:
> On Saturday, September 08, 2001, Maxim Sobolev wrote:
> > I don't like idea to hardcode the same string ("procfs"), with the
> > same meaning in several places across kernel. As for your proposition
> > to use f_fstypename to set v_tag, it is even more bogus because
> > value of the f_fstypename is supplied from the user level, so
> > potentially it could be anything and we can't make any reasonable
> > assumptions about mapping between its value and type of the filesystem
> > in question.
>
> How do you figure? The contents if `f_fstypename' must match
> a configured file system exactly, so it could _not_ be anything.
> To quote sys/kern/vfs_syscalls.c:mount():
Oh, yes, you are correct obviously (don't know what I was thinking about). In this
case, it looks like v_tag is redundant, because f_fstypename could be used instead
in a few places where v_tag is abused (the same applies to the statfs.f_type
because essentually it is the same thing as v_tag). Poul, what do you think about
it? In the meantime, I found another place in the kernel where VT_* macros are
[ab]used - it is Linuxlator, attached please find patches to fix it - please
review.
-Maxim
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Index: linux_stats.c
===================================================================
RCS file: /home/ncvs/src/sys/compat/linux/linux_stats.c,v
retrieving revision 1.37
diff -d -u -r1.37 linux_stats.c
--- linux_stats.c 2001/09/12 08:36:57 1.37
+++ linux_stats.c 2001/09/18 11:52:02
@@ -187,10 +187,6 @@
l_int f_spare[6];
};
-#ifndef VT_NWFS
-#define VT_NWFS VT_TFS /* XXX - bug compat. with sys/fs/nwfs/nwfs_node.h */
-#endif
-
#define LINUX_CODA_SUPER_MAGIC 0x73757245L
#define LINUX_EXT2_SUPER_MAGIC 0xEF53L
#define LINUX_HPFS_SUPER_MAGIC 0xf995e849L
@@ -202,34 +198,30 @@
#define LINUX_PROC_SUPER_MAGIC 0x9fa0L
#define LINUX_UFS_SUPER_MAGIC 0x00011954L /* XXX - UFS_MAGIC in Linux */
-/*
- * ext2fs uses the VT_UFS tag. A mounted ext2 filesystem will therefore
- * be seen as an ufs filesystem.
- */
static long
-bsd_to_linux_ftype(int tag)
+bsd_to_linux_ftype(const char *fstypename)
{
- switch (tag) {
- case VT_CODA:
+ if (strcmp(fstypename, "coda") == 0)
return (LINUX_CODA_SUPER_MAGIC);
- case VT_HPFS:
+ else if (strcmp(fstypename, "hpfs") == 0)
return (LINUX_HPFS_SUPER_MAGIC);
- case VT_ISOFS:
+ else if (strcmp(fstypename, "cd9660") == 0)
return (LINUX_ISOFS_SUPER_MAGIC);
- case VT_MSDOSFS:
+ else if (strcmp(fstypename, "msdosfs") == 0)
return (LINUX_MSDOS_SUPER_MAGIC);
- case VT_NFS:
+ else if (strcmp(fstypename, "nfs") == 0)
return (LINUX_NFS_SUPER_MAGIC);
- case VT_NTFS:
+ else if (strcmp(fstypename, "ntfs") == 0)
return (LINUX_NTFS_SUPER_MAGIC);
- case VT_NWFS:
+ else if (strcmp(fstypename, "nwfs") == 0)
return (LINUX_NCP_SUPER_MAGIC);
- case VT_PROCFS:
+ else if (strcmp(fstypename, "procfs") == 0)
return (LINUX_PROC_SUPER_MAGIC);
- case VT_UFS:
+ else if (strcmp(fstypename, "ufs") == 0)
return (LINUX_UFS_SUPER_MAGIC);
- }
+ else if (strcmp(fstypename, "ext2fs") == 0)
+ return (LINUX_EXT2_SUPER_MAGIC);
return (0L);
}
@@ -265,7 +257,7 @@
if (error)
return error;
bsd_statfs->f_flags = mp->mnt_flag & MNT_VISFLAGMASK;
- linux_statfs.f_type = bsd_to_linux_ftype(bsd_statfs->f_type);
+ linux_statfs.f_type = bsd_to_linux_ftype(bsd_statfs->f_fstypename);
linux_statfs.f_bsize = bsd_statfs->f_bsize;
linux_statfs.f_blocks = bsd_statfs->f_blocks;
linux_statfs.f_bfree = bsd_statfs->f_bfree;
@@ -301,7 +293,7 @@
if (error)
return error;
bsd_statfs->f_flags = mp->mnt_flag & MNT_VISFLAGMASK;
- linux_statfs.f_type = bsd_to_linux_ftype(bsd_statfs->f_type);
+ linux_statfs.f_type = bsd_to_linux_ftype(bsd_statfs->f_fstypename);
linux_statfs.f_bsize = bsd_statfs->f_bsize;
linux_statfs.f_blocks = bsd_statfs->f_blocks;
linux_statfs.f_bfree = bsd_statfs->f_bfree;
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