diff options
author | phk <phk@FreeBSD.org> | 2002-09-27 21:54:37 +0000 |
---|---|---|
committer | phk <phk@FreeBSD.org> | 2002-09-27 21:54:37 +0000 |
commit | f1d8f5aa089c376680a2bb65debde728e4b5dd20 (patch) | |
tree | bdc9178af8493d916410bc241437832dc57fd2e1 /sys/geom | |
parent | bd4b8491399a8df6b7aea34dc30845289f3bc0f8 (diff) | |
download | FreeBSD-src-f1d8f5aa089c376680a2bb65debde728e4b5dd20.zip FreeBSD-src-f1d8f5aa089c376680a2bb65debde728e4b5dd20.tar.gz |
Extensively rework the geom_bsd method, put a lot of comments in, betting
that this will make people use this for their future copy&paste operations.
Rework the detection of raw-disk offsets in disklabels. This actually
unearthed a number of bugs in the (now) previous version.
Also accept labels which don't have a magic RAW_PART, provided they don't
confuse us too much.
Change the order of our sanity-checks on labels found on disks to be more
robust.
Check against MAXPARTITIONS in our sanity-check and reject disklabels
we cannot cope with.
Create new g_bsd_modify() function to implment disklabel modifying
ioctls.
Implement DIOCSDINFO and DIOCWDINFO with the provision that the latter
still not writes your change back to disk. I didn't have the nerves
for that yet.
In the start routine, use g_call_me() for complex ioctls to prevent
sleeping.
Sponsored by: DARPA & NAI Labs.
Diffstat (limited to 'sys/geom')
-rw-r--r-- | sys/geom/geom_bsd.c | 528 |
1 files changed, 424 insertions, 104 deletions
diff --git a/sys/geom/geom_bsd.c b/sys/geom/geom_bsd.c index 8c501e8..d7cd742 100644 --- a/sys/geom/geom_bsd.c +++ b/sys/geom/geom_bsd.c @@ -33,9 +33,12 @@ * SUCH DAMAGE. * * $FreeBSD$ + * + * This is the method for dealing with BSD disklabels. It has been + * extensively (by my standards at least) commented, in the vain hope that + * it will server as the source in future copy&paste operations. */ - #include <sys/param.h> #ifndef _KERNEL #include <stdio.h> @@ -60,12 +63,26 @@ #define BSD_CLASS_NAME "BSD" +/* + * Our private data about one instance. All the rest is handled by the + * slice code and stored in the its softc, so this is just the stuff + * specific to BSD disklabels. + */ struct g_bsd_softc { off_t labeloffset; + off_t rawoffset; struct disklabel ondisk; struct disklabel inram; }; +/* + * The next 4 functions isolate us from how the compiler lays out and pads + * "struct disklabel". We treat what we read from disk as a bytestream and + * explicitly convert it into a struct disklabel. This makes us compiler- + * endianes- and wordsize- agnostic. + * For now we only have little-endian formats to deal with. + */ + static void g_bsd_ledec_partition(u_char *ptr, struct partition *d) { @@ -181,28 +198,203 @@ g_bsd_leenc_disklabel(u_char *ptr, struct disklabel *d) #endif +/* + * For reasons which were valid and just in their days, FreeBSD/i386 uses + * absolute disk-addresses in disklabels. The way it works is that the + * p_offset field of all partitions have the first sector number of the + * disk slice added to them. This was hidden kernel-magic, userland did + * not see these offsets. These two functions subtract and add them + * while converting from the "ondisk" to the "inram" labels and vice + * versa. + */ static void ondisk2inram(struct g_bsd_softc *sc) { struct partition *ppp; - unsigned offset; + struct disklabel *dl; int i; sc->inram = sc->ondisk; - offset = sc->inram.d_partitions[RAW_PART].p_offset; - for (i = 0; i < 8; i++) { - ppp = &sc->inram.d_partitions[i]; - if (ppp->p_offset >= offset) - ppp->p_offset -= offset; + dl= &sc->inram; + + /* Basic sanity-check needed to avoid mistakes */ + if (dl->d_magic != DISKMAGIC || dl->d_magic2 != DISKMAGIC) + return; + if (dl->d_npartitions > MAXPARTITIONS) + return; + + sc->rawoffset = dl->d_partitions[RAW_PART].p_offset; + for (i = 0; i < dl->d_npartitions; i++) { + ppp = &dl->d_partitions[i]; + if (ppp->p_size != 0 && ppp->p_offset < sc->rawoffset) + sc->rawoffset = 0; + } + if (sc->rawoffset > 0) { + + if (dl->d_partitions[RAW_PART].p_size + + sc->rawoffset == dl->d_secperunit) { + } + for (i = 0; i < dl->d_npartitions; i++) { + ppp = &dl->d_partitions[i]; + ppp->p_offset -= sc->rawoffset; + } + } + dl->d_checksum = 0; + dl->d_checksum = dkcksum(&sc->inram); +} + +static void +inram2ondisk(struct g_bsd_softc *sc) +{ + struct partition *ppp; + int i; + + sc->ondisk = sc->inram; + if (sc->rawoffset != 0) { + for (i = 0; i < sc->inram.d_npartitions; i++) { + ppp = &sc->ondisk.d_partitions[i]; + ppp->p_offset += sc->rawoffset; + } + } + sc->ondisk.d_checksum = 0; + sc->ondisk.d_checksum = dkcksum(&sc->ondisk); +} + +/* + * Check that this looks like a valid disklabel, but be prepared + * to get any kind of junk. The checksum must be checked only + * after this function returns success to prevent a bogus d_npartitions + * value from tripping us up. + */ +static int +g_bsd_checklabel(struct disklabel *dl) +{ + struct partition *ppp; + int i; + + if (dl->d_magic != DISKMAGIC || dl->d_magic2 != DISKMAGIC) + return(EINVAL); + /* + * If the label specifies more partitions than we can handle + * we have to reject it: If people updated the label they would + * trash it, and that would break the checksum. + */ + if (dl->d_npartitions > MAXPARTITIONS) + return(EINVAL); + + for (i = 0; i < dl->d_npartitions; i++) { + ppp = &dl->d_partitions[i]; + /* Cannot extend past unit */ + if (ppp->p_size != 0 && + ppp->p_offset + ppp->p_size > dl->d_secperunit) { + return(EINVAL); + } } - sc->inram.d_checksum = 0; - sc->inram.d_checksum = dkcksum(&sc->inram); + return(0); } /* - * It is rather fortunate that this checksum only covers up to the - * actual end of actual data, otherwise the pointer-screwup in - * alpha architectures would have been much harder to handle. + * Modify our slicer to match proposed disklabel, if possible. + * First carry out all the simple checks, then lock topology + * and check that no open providers are affected negatively + * then carry out all the changes. + * + * NB: Returns with topology held only if successful return. + */ +static int +g_bsd_modify(struct g_geom *gp, struct disklabel *dl) +{ + int i, error; + struct partition *ppp; + struct g_slicer *gsp; + struct g_consumer *cp; + u_int secsize; + off_t mediasize; + + /* Basic check that this is indeed a disklabel */ + error = g_bsd_checklabel(dl); + if (error) + return(error); + + /* Make sure the checksum is OK */ + if (dkcksum(dl) != 0) + return(EINVAL); + + /* Get dimensions of our device */ + cp = LIST_FIRST(&gp->consumer); + error = g_getattr("GEOM::sectorsize", cp, &secsize); + if (error) + return(error); + error = g_getattr("GEOM::mediasize", cp, &mediasize); + if (error) + return(error); + +#ifdef nolonger + /* + * The raw-partition must start at zero. We do not check that the + * size == mediasize because this is overly restrictive. We have + * already tested in g_bsd_checklabel() that it is not longer. + * XXX: RAW_PART is archaic anyway, and we should drop it. + */ + if (dl->d_partitions[RAW_PART].p_offset != 0) + return (EINVAL); +#endif + +#ifdef notyet + /* + * Indications are that the d_secperunit is not correctly + * initialized in many cases, and since we don't need it + * for anything, we dont strictly need this test. + * Preemptive action to avoid confusing people in disklabel(8) + * may be in order. + */ + /* The label cannot claim a larger size than the media */ + if ((off_t)dl->d_secperunit * dl->d_secsize > mediasize) + return (EINVAL); +#endif + + + /* ... or a smaller sector size */ + if (dl->d_secsize < secsize) + return (EINVAL); + + /* ... or a non-multiple sector size */ + if (dl->d_secsize % secsize != 0) + return (EINVAL); + + g_topology_lock(); + + /* Don't munge open parititions */ + gsp = gp->softc; + for (i = 0; i < dl->d_npartitions; i++) { + ppp = &dl->d_partitions[i]; + + error = g_slice_config(gp, i, G_SLICE_CONFIG_CHECK, + (off_t)ppp->p_offset * dl->d_secsize, + (off_t)ppp->p_size * dl->d_secsize, + "%s%c", gp->name, 'a' + i); + if (error) { + g_topology_unlock(); + return (error); + } + } + + + /* Look good, go for it... */ + for (i = 0; i < gsp->nslice; i++) { + ppp = &dl->d_partitions[i]; + g_slice_config(gp, i, G_SLICE_CONFIG_SET, + (off_t)ppp->p_offset * dl->d_secsize, + (off_t)ppp->p_size * dl->d_secsize, + "%s%c", gp->name, 'a' + i); + } + return (0); +} + +/* + * Calculate a disklabel checksum for a little-endian byte-stream. + * We need access to the decoded disklabel because the checksum only + * covers the partition data for the first d_npartitions. */ static int g_bsd_lesum(struct disklabel *dl, u_char *p) @@ -219,6 +411,13 @@ g_bsd_lesum(struct disklabel *dl, u_char *p) return (sum); } +/* + * This is an internal helper function, called multiple times from the taste + * function to try to locate a disklabel on the disk. More civilized formats + * will not need this, as there is only one possible place on disk to look + * for the magic spot. + */ + static int g_bsd_try(struct g_slicer *gsp, struct g_consumer *cp, int secsize, struct g_bsd_softc *ms, off_t offset) { @@ -227,26 +426,100 @@ g_bsd_try(struct g_slicer *gsp, struct g_consumer *cp, int secsize, struct g_bsd struct disklabel *dl; off_t secoff; - dl = &ms->ondisk; + /* + * We need to read entire aligned sectors, and we assume that the + * disklabel does not span sectors, so one sector is enough. + */ + error = 0; secoff = offset % secsize; buf = g_read_data(cp, offset - secoff, secsize, &error); if (buf == NULL || error != 0) return(ENOENT); + + /* Decode into our native format */ + dl = &ms->ondisk; g_bsd_ledec_disklabel(buf + secoff, dl); - if (dl->d_magic == DISKMAGIC && - dl->d_magic2 == DISKMAGIC && - g_bsd_lesum(dl, buf + secoff) == 0) - error = 0; - else + + ondisk2inram(ms); + + dl = &ms->inram; + /* Does it look like a label at all ? */ + if (g_bsd_checklabel(dl)) + error = ENOENT; + /* ... and does the raw data have a good checksum ? */ + if (error == 0 && g_bsd_lesum(dl, buf + secoff) != 0) error = ENOENT; + + /* Remember to free the buffer g_read_data() gave us */ g_free(buf); + + /* If we had a label, record it properly */ if (error == 0) { - gsp->frontstuff = 16 * secsize; + gsp->frontstuff = 16 * secsize; /* XXX */ ms->labeloffset = offset; } return(error); } +/* + * Implement certain ioctls to modify disklabels with. This function + * is called by the event handler thread with topology locked as result + * of the g_call_me() in g_bsd_start(). It is not necessary to keep + * topology locked all the time but make sure to return with topology + * locked as well. + */ + +static void +g_bsd_ioctl(void *arg) +{ + struct bio *bp; + struct g_geom *gp; + struct g_slicer *gsp; + struct g_bsd_softc *ms; + struct disklabel *dl; + struct g_ioctl *gio; + + /* We don't need topology for now */ + g_topology_unlock(); + + /* Get hold of the interesting bits from the bio */ + bp = arg; + gp = bp->bio_to->geom; + gsp = gp->softc; + ms = gsp->softc; + gio = (struct g_ioctl *)bp->bio_data; + + /* The disklabel to set is the ioctl argument */ + dl = gio->data; + + /* Validate and modify our slice instance to match */ + bp->bio_error = g_bsd_modify(gp, dl); /* picks up topology lock */ + if (bp->bio_error != 0) { + g_topology_lock(); + g_io_deliver(bp); + return; + } + /* Update our copy of the disklabel */ + ms->inram = *dl; + inram2ondisk(ms); + + /* XXX: DIOCWDINFO write to disk */ + + /* return the request */ + g_io_deliver(bp); +} + +/*- + * This start routine is only called for non-trivial requests, all the + * trivial ones are handled autonomously by the slice code. + * For requests we handle here, we must call the g_io_deliver() on the + * bio, and return non-zero to indicate to the slice code that we did so. + * This code executes in the "DOWN" I/O path, this means: + * * No sleeping. + * * Don't grab the topology lock. + * * Don't call biowait, g_getattr(), g_setattr() or g_read_data() + */ + static int g_bsd_start(struct bio *bp) { @@ -254,26 +527,55 @@ g_bsd_start(struct bio *bp) struct g_bsd_softc *ms; struct g_slicer *gsp; struct g_ioctl *gio; + int error; gp = bp->bio_to->geom; gsp = gp->softc; ms = gsp->softc; + + /* We only handle ioctl(2) requests of the right format. */ if (strcmp(bp->bio_attribute, "GEOM::ioctl")) return(0); else if (bp->bio_length != sizeof *gio) return(0); + + /* Get hold of the ioctl parameters */ gio = (struct g_ioctl *)bp->bio_data; - if (gio->cmd == DIOCGDINFO) { + + switch(gio->cmd) { + case DIOCGDINFO: + /* Return a copy of the disklabel to userland */ bcopy(&ms->inram, gio->data, sizeof ms->inram); bp->bio_error = 0; g_io_deliver(bp); return (1); + case DIOCSDINFO: + case DIOCWDINFO: + /* + * These we cannot do without the topology lock and some + * some I/O requests. Ask the event-handler to schedule + * us in a less restricted environment. + */ + error = g_call_me(g_bsd_ioctl, bp); + if (error) + g_io_fail(bp, error); + /* + * We must return non-zero to indicate that we will deal + * with this bio, even though we have not done so yet. + */ + return (1); + default: + return (0); } - return (0); } +/* + * Dump configuration information in XML format. + * Notice that the function is called once for the geom and once for each + * consumer and provider. We let g_slice_dumpconf() do most of the work. + */ static void -g_bsd_dumpconf(struct sbuf *sb, char *indent, struct g_geom *gp, struct g_consumer *cp __unused, struct g_provider *pp) +g_bsd_dumpconf(struct sbuf *sb, char *indent, struct g_geom *gp, struct g_consumer *cp, struct g_provider *pp) { struct g_bsd_softc *ms; struct g_slicer *gsp; @@ -287,125 +589,143 @@ g_bsd_dumpconf(struct sbuf *sb, char *indent, struct g_geom *gp, struct g_consum g_slice_dumpconf(sb, indent, gp, cp, pp); } +/* + * The taste function is called from the event-handler, with the topology + * lock already held and a provider to examine. The flags are unused. + * + * If flags == G_TF_NORMAL, the idea is to take a bite of the provider and + * if we find valid, consistent magic on it, build a geom on it. + * any magic bits which indicate that we should automatically put a BSD + * geom on it. + * + * There may be cases where the operator would like to put a BSD-geom on + * providers which do not meet all of the requirements. This can be done + * by instead passing the G_TF_INSIST flag, which will override these + * checks. + * + * The final flags value is G_TF_TRANSPARENT, which instructs the method + * to put a geom on top of the provider and configure it to be as transparent + * as possible. This is not really relevant to the BSD method and therefore + * not implemented here. + */ + static struct g_geom * g_bsd_taste(struct g_class *mp, struct g_provider *pp, int flags) { struct g_geom *gp; struct g_consumer *cp; - struct g_provider *pp2; - int error, i, j, npart; + int error, i; struct g_bsd_softc *ms; struct disklabel *dl; u_int secsize; - u_int fwsectors, fwheads; - off_t mediasize; - struct partition *ppp, *ppr; struct g_slicer *gsp; g_trace(G_T_TOPOLOGY, "bsd_taste(%s,%s)", mp->name, pp->name); g_topology_assert(); + + /* We don't implement transparent inserts */ + if (flags == G_TF_TRANSPARENT) + return (NULL); + + /* + * The BSD-method will not automatically configure itself recursively + * Note that it is legal to examine the class-name of our provider, + * nothing else should ever be examined inside the provider. + */ if (flags == G_TF_NORMAL && !strcmp(pp->geom->class->name, BSD_CLASS_NAME)) return (NULL); - gp = g_slice_new(mp, 8, pp, &cp, &ms, sizeof *ms, g_bsd_start); + + /* + * BSD labels are a subclass of the general "slicing" topology so + * a lot of the work can be done by the common "slice" code. + * Create a geom with space for MAXPARTITIONS providers, one consumer + * and a softc structure for us. Specify the provider to attach + * the consumer to and our "start" routine for special requests. + * The provider is opened with mode (1,0,0) so we can do reads + * from it. + */ + gp = g_slice_new(mp, MAXPARTITIONS, pp, &cp, &ms, + sizeof *ms, g_bsd_start); if (gp == NULL) return (NULL); - gsp = gp->softc; + + /* + * Now that we have attached to and opened our provider, we do + * not need the topology lock until we change the topology again + * next time. + */ g_topology_unlock(); + + /* + * Fill in the optional details, in our case we have a dumpconf + * routine which the "slice" code should call at the right time + */ gp->dumpconf = g_bsd_dumpconf; - npart = 0; - while (1) { /* a trick to allow us to use break */ + + /* Get the geom_slicer softc from the geom */ + gsp = gp->softc; + + /* + * The do...while loop here allows us to have multiple escapes + * using a simple "break". This improves code clarity without + * ending up in deep nesting and without using goto or come from. + */ + do { + /* + * If the provider is an MBR we will only auto attach + * to type 165 slices in the G_TF_NORMAL case. We will + * attach to any other type (BSD was handles above) + */ error = g_getattr("MBR::type", cp, &i); if (!error && i != 165 && flags == G_TF_NORMAL) break; + + /* Get sector size, we need it to read data. */ error = g_getattr("GEOM::sectorsize", cp, &secsize); - if (error) { - secsize = 512; - printf("g_bsd_taste: error %d Sectors are %d bytes\n", - error, secsize); - } - error = g_getattr("GEOM::mediasize", cp, &mediasize); - if (error) { - mediasize = 0; - printf("g_error %d Mediasize is %lld bytes\n", - error, (long long)mediasize); - } + if (error || secsize < 512) + break; + + /* First look for a label at the start of the second sector */ error = g_bsd_try(gsp, cp, secsize, ms, secsize); + + /* Next, loot for it 64 bytes into the first sector */ if (error) error = g_bsd_try(gsp, cp, secsize, ms, 64); + + /* If we didn't find a label, punt */ if (error) break; - dl = &ms->ondisk; - if (bootverbose) - g_hexdump(dl, sizeof(*dl)); - if (dl->d_secsize < secsize) - break; - if (dl->d_secsize > secsize) - secsize = dl->d_secsize; - ppr = &dl->d_partitions[2]; - for (i = 0; i < 8; i++) { - ppp = &dl->d_partitions[i]; - if (ppp->p_size == 0) - continue; - npart++; - g_topology_lock(); - pp2 = g_slice_addslice(gp, i, - ((off_t)(ppp->p_offset - ppr->p_offset)) << 9ULL, - ((off_t)ppp->p_size) << 9ULL, - "%s%c", pp->name, 'a' + i); + + /* + * Proccess the found disklabel, and modify our "slice" + * instance to match it, if possible. + */ + dl = &ms->inram; + error = g_bsd_modify(gp, dl); /* picks up topology lock */ + if (!error) g_topology_unlock(); - g_error_provider(pp2, 0); - } - ondisk2inram(ms); break; - } - if (npart == 0 && ( - (flags == G_TF_INSIST && mediasize != 0) || - (flags == G_TF_TRANSPARENT))) { - dl = &ms->ondisk; - bzero(dl, sizeof *dl); - dl->d_magic = DISKMAGIC; - dl->d_magic2 = DISKMAGIC; - ppp = &dl->d_partitions[RAW_PART]; - ppp->p_offset = 0; - ppp->p_size = mediasize / secsize; - dl->d_npartitions = MAXPARTITIONS; - dl->d_interleave = 1; - dl->d_secsize = secsize; - dl->d_rpm = 3600; - j = sizeof fwsectors; - error = g_io_getattr("GEOM::fwsectors", cp, &j, &fwsectors); - if (error) - dl->d_nsectors = 32; - else - dl->d_nsectors = fwsectors; - error = g_io_getattr("GEOM::fwheads", cp, &j, &fwheads); - if (error) - dl->d_ntracks = 64; - else - dl->d_ntracks = fwheads; - dl->d_secpercyl = dl->d_nsectors * dl->d_ntracks; - dl->d_ncylinders = ppp->p_size / dl->d_secpercyl; - dl->d_secperunit = ppp->p_size; - dl->d_checksum = 0; - dl->d_checksum = dkcksum(dl); - ms->inram = ms->ondisk; - g_topology_lock(); - pp2 = g_slice_addslice(gp, RAW_PART, - 0, mediasize, "%s%c", pp->name, 'a' + RAW_PART); - g_topology_unlock(); - g_error_provider(pp2, 0); - npart = 1; - } + } while (0); + + /* Success of failure, we can close our provider now */ g_topology_lock(); error = g_access_rel(cp, -1, 0, 0); - if (npart > 0) + + /* If we have configured any providers, return the new geom. */ + if (gsp->nprovider > 0) return (gp); + /* + * ...else push the "self-destruct" button, by spoiling our own + * consumer. This triggers a call to g_std_spoiled which will + * dismantle what was setup. + */ g_std_spoiled(cp); return (NULL); } -static struct g_class g_bsd_class = { +/* Finally, register with GEOM infrastructure. */ +static struct g_class g_bsd_class = { BSD_CLASS_NAME, g_bsd_taste, NULL, |