Date: Thu, 06 Jun 2013 10:54:32 -0600 From: Ian Lepore <ian@FreeBSD.org> To: Rick Macklem <rmacklem@uoguelph.ca> Cc: Craig Rodrigues <rodrigc@crodrigues.org>, freebsd-current <freebsd-current@FreeBSD.org>, Lars Eggert <lars@netapp.com> Subject: Re: mounting root from NFS via ROOTDEVNAME Message-ID: <1370537672.1086.30.camel@revolution.hippie.lan> In-Reply-To: <433498856.127008.1370217441419.JavaMail.root@erie.cs.uoguelph.ca> References: <433498856.127008.1370217441419.JavaMail.root@erie.cs.uoguelph.ca>
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[-- Attachment #1 --]
On Sun, 2013-06-02 at 19:57 -0400, Rick Macklem wrote:
> Ian Lepore wrote:
> > On Sat, 2013-06-01 at 20:28 -0400, Rick Macklem wrote:
> > > Lars Eggert wrote:
> > > > Hi,
> > > >
> > > > to conclude this thread, the patch below allows one to specify an
> > > > nfs
> > > > rootfs via the ROOTDEVNAME kernel option, which will be mounted
> > > > when
> > > > BOOTP does not return a root-path option.
> > > >
> > > > Lars
> > > >
> > > My only concern with this (mainly because I don't understand the
> > > rules
> > > applied to boot alternatives well enough) is that a few arm configs
> > > have
> > > both BOOTP, BOOTP_NFSROOT and ROOTDEVNAME specified, where
> > > ROOTDEVNAME
> > > is set to "ufs:...". I don't think this patch will break them, since
> > > I
> > > think they'll use NFS and ignore the ROOTDEVNAME, but I'm not
> > > completely
> > > sure. Does someone else know how HL201 boots, for example?
> > >
> > > Lars, if you have a src commit, you can consider this reviewed by
> > > me. If
> > > not, maybe Craig can review it and then I'll commit it.
> > >
> > > Thanks for doing this, rick
> > >
> > > >
> > > > diff --git a/sys/nfs/bootp_subr.c b/sys/nfs/bootp_subr.c
> > > > index 2c57a91..972fb12 100644
> > > > --- a/sys/nfs/bootp_subr.c
> > > > +++ b/sys/nfs/bootp_subr.c
> > > > @@ -45,6 +45,7 @@ __FBSDID("$FreeBSD$");
> > > >
> > > > #include "opt_bootp.h"
> > > > #include "opt_nfs.h"
> > > > +#include "opt_rootdevname.h"
> > > >
> > > > #include <sys/param.h>
> > > > #include <sys/systm.h>
> > > > @@ -870,8 +871,20 @@ bootpc_call(struct bootpc_globalcontext
> > > > *gctx,
> > > > struct thread *td)
> > > > rtimo = time_second +
> > > > BOOTP_SETTLE_DELAY;
> > > > printf(" (got root path)");
> > > > - } else
> > > > + } else {
> > > > printf(" (no root path)");
> > > > +#ifdef ROOTDEVNAME
> > > > + /*
> > > > + * If we'll mount rootfs from
> > > > + * ROOTDEVNAME, we can accept
> > > > + * offers without root paths.
> > > > + */
> > > > + gotrootpath = 1;
> > > > + rtimo = time_second +
> > > > + BOOTP_SETTLE_DELAY;
> > > > + printf(" (ROOTDEVNAME)");
> > > > +#endif
> > > > + }
> > > > printf("\n");
> > > > }
> > > > } /* while secs */
> > > > @@ -1440,6 +1453,16 @@ bootpc_decode_reply(struct nfsv3_diskless
> > > > *nd,
> > > > struct bootpc_ifcontext *ifctx,
> > > >
> > > > p = bootpc_tag(&gctx->tag, &ifctx->reply, ifctx->replylen,
> > > > TAG_ROOT);
> > > > +#ifdef ROOTDEVNAME
> > > > + /*
> > > > + * If there was no root path in BOOTP, use the one in
> > > > ROOTDEVNAME.
> > > > + */
> > > > + if (p == NULL) {
> > > > + p = strdup(ROOTDEVNAME, M_TEMP);
> > > > + if (strcmp(strsep(&p, ":"), "nfs") != 0)
> > > > + panic("ROOTDEVNAME is not an NFS mount point");
> > > > + }
> > > > +#endif
> > > > if (p != NULL) {
> > > > if (gctx->setrootfs != NULL) {
> > > > printf("rootfs %s (ignored) ", p);
> > > >
> >
> > I've seen several requests over the past year for an nfs ROOTDEVNAME
> > along with BOOTP to work properly from ARM developers (myself
> > included),
> > so I don't think we should worry about breaking existing config that
> > happens to be checked in but a) hasn't been tested by anyone for ages,
> > and b) doesn't work anyway (ROOTDEVNAME just gets ignored).
> >
> > -- Ian
> >
> Cool. Thanks. Would you like to review and/or test the above?
>
> I'll be happy to commit it if Lars doesn't have a src commit bit. (I've
> seen his posts, but can't remember if he is a committer?)
>
> rick
Well, I started out just testing Lars' patch (it works) but that
inspired me to pick up the work I toyed with months ago in this area, to
try to get BOOTP_NFSROOT to respect other root-path options such as
setting vfs.root.mountfrom in the environment and using the RB_DFLTROOT
boot option. The attached patch does those things, as follows:
This maintains the historical BOOTP_NFSROOT behavior of panicking on a
failure to mount the root path provided by the server, unless you've
provided an alternative via ROOTDEVNAME or vfs.root.mountfrom. I was
afraid to change this behavior because it amounts to a bit of a retry
loop that could eventually recover from a transient network or server
problem.
The user can now override the root path from loader(8) even if the
kernel is compiled with BOOTP_NFSROOT. If vfs.root.mountfrom is set in
the environment it is used unconditionally -- it always overrides the
BOOTP info. If it begins with [old]nfs: then the BOOTP code uses it
instead of the server-provided info. If it specifies some other
filesystem then the bootp code will not panic and the code in
vfs_mountroot.c will invoke the right filesystem to do the mount.
If the kernel is compiled with the ROOTDEVNAME option, then that name is
used by the BOOTP code if either
* The server doesn't provide a pathname.
* The boothowto flags include RB_DFLTROOT.
The latter allows the user to specify an alternate path in ROOTDEVNAME
such as ufs:/dev/da0s1a and boot from that path by setting
boot_dftlroot=1 in loader(8) or using the '-r' option in boot(8).
The one thing not provided here is automatic failover from a
server-provided path to a compiled-in one without the user manually
requesting that. The code just isn't currently structured in a way that
makes that possible with a lot of rewrite. I think the ability to set
vfs.root.mountfrom and to use ROOTDEVNAME automatically when the server
doesn't provide a name covers the most common needs.
I'll commit this in a few days unless there are objections or glitches
in testing.
-- Ian
[-- Attachment #2 --]
Index: sys/nfs/bootp_subr.c
===================================================================
--- sys/nfs/bootp_subr.c (revision 251469)
+++ sys/nfs/bootp_subr.c (working copy)
@@ -45,6 +45,7 @@ __FBSDID("$FreeBSD$");
#include "opt_bootp.h"
#include "opt_nfs.h"
+#include "opt_rootdevname.h"
#include <sys/param.h>
#include <sys/systm.h>
@@ -55,6 +56,7 @@ __FBSDID("$FreeBSD$");
#include <sys/mount.h>
#include <sys/mbuf.h>
#include <sys/proc.h>
+#include <sys/reboot.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
@@ -167,6 +169,7 @@ struct bootpc_tagcontext {
struct bootpc_globalcontext {
STAILQ_HEAD(, bootpc_ifcontext) interfaces;
u_int32_t xid;
+ int any_root_overrides;
int gotrootpath;
int gotgw;
int ifnum;
@@ -865,13 +868,14 @@ bootpc_call(struct bootpc_globalcontext *gctx, str
BOOTP_SETTLE_DELAY;
} else
printf(" (ignored)");
- if (ifctx->gotrootpath) {
+ if (ifctx->gotrootpath ||
+ gctx->any_root_overrides) {
gotrootpath = 1;
rtimo = time_second +
BOOTP_SETTLE_DELAY;
- printf(" (got root path)");
- } else
- printf(" (no root path)");
+ if (ifctx->gotrootpath)
+ printf(" (got root path)");
+ }
printf("\n");
}
} /* while secs */
@@ -1371,7 +1375,7 @@ static void
bootpc_decode_reply(struct nfsv3_diskless *nd, struct bootpc_ifcontext *ifctx,
struct bootpc_globalcontext *gctx)
{
- char *p;
+ char *p, *s;
unsigned int ip;
ifctx->gotgw = 0;
@@ -1438,8 +1442,28 @@ bootpc_decode_reply(struct nfsv3_diskless *nd, str
}
}
- p = bootpc_tag(&gctx->tag, &ifctx->reply, ifctx->replylen,
+ /*
+ * Choose a root filesystem. If a value is forced in the environment
+ * and it contains "nfs:", use it unconditionally. Otherwise, use
+ * ROOTDEVNAME if it contains "nfs:" and either the server didn't
+ * provide a name or the boot options say to force ROOTDEVNAME.
+ */
+ p = NULL;
+ if ((s = getenv("vfs.root.mountfrom")) != NULL) {
+ if ((p = strstr(s, "nfs:")) != NULL)
+ p = strdup(p + 4, M_TEMP);
+ freeenv(s);
+ }
+ if (p == NULL) {
+ p = bootpc_tag(&gctx->tag, &ifctx->reply, ifctx->replylen,
TAG_ROOT);
+ }
+#ifdef ROOTDEVNAME
+ if ((p == NULL || (boothowto & RB_DFLTROOT) != 0) &&
+ (p = strstr(ROOTDEVNAME, "nfs:")) != NULL) {
+ p += 4;
+ }
+#endif
if (p != NULL) {
if (gctx->setrootfs != NULL) {
printf("rootfs %s (ignored) ", p);
@@ -1544,6 +1568,17 @@ bootpc_init(void)
gctx->starttime = time_second;
/*
+ * If ROOTDEVNAME is defined or vfs.root.mountfrom is set then we have
+ * root-path overrides that can potentially let us boot even if we don't
+ * get a root path from the server, so we can treat that as a non-error.
+ */
+#ifdef ROOTDEVNAME
+ gctx->any_root_overrides = 1;
+#else
+ gctx->any_root_overrides = testenv("vfs.root.mountfrom");
+#endif
+
+ /*
* Find a network interface.
*/
CURVNET_SET(TD_TO_VNET(td));
@@ -1652,19 +1687,10 @@ retry:
bootpc_compose_query(ifctx, td);
error = bootpc_call(gctx, td);
-
if (error != 0) {
-#ifdef BOOTP_NFSROOT
- panic("BOOTP call failed");
-#else
printf("BOOTP call failed\n");
-#endif
}
- rootdevnames[0] = "nfs:";
-#ifdef NFSCLIENT
- rootdevnames[1] = "oldnfs:";
-#endif
mountopts(&nd->root_args, NULL);
STAILQ_FOREACH(ifctx, &gctx->interfaces, next)
@@ -1672,7 +1698,7 @@ retry:
bootpc_decode_reply(nd, ifctx, gctx);
#ifdef BOOTP_NFSROOT
- if (gctx->gotrootpath == 0)
+ if (gctx->gotrootpath == 0 && gctx->any_root_overrides == 0)
panic("bootpc: No root path offered");
#endif
@@ -1699,9 +1725,16 @@ retry:
error = md_mount(&nd->root_saddr, nd->root_hostnam,
nd->root_fh, &nd->root_fhsize,
&nd->root_args, td);
- if (error != 0)
- panic("nfs_boot: mountd root, error=%d", error);
-
+ if (error != 0) {
+ if (gctx->any_root_overrides == 0)
+ panic("nfs_boot: mount root, error=%d", error);
+ else
+ goto out;
+ }
+ rootdevnames[0] = "nfs:";
+#ifdef NFSCLIENT
+ rootdevnames[1] = "oldnfs:";
+#endif
nfs_diskless_valid = 3;
}
Index: sys/kern/vfs_mountroot.c
===================================================================
--- sys/kern/vfs_mountroot.c (revision 251469)
+++ sys/kern/vfs_mountroot.c (working copy)
@@ -714,8 +714,8 @@ parse_mount(char **conf)
goto out;
}
- if (strcmp(fs, "zfs") != 0 && dev[0] != '\0' &&
- !parse_mount_dev_present(dev)) {
+ if (strcmp(fs, "zfs") != 0 && strstr(fs, "nfs") == NULL &&
+ dev[0] != '\0' && !parse_mount_dev_present(dev)) {
printf("mountroot: waiting for device %s ...\n", dev);
delay = hz / 10;
timeout = root_mount_timeout * hz;
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