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qemu-nbd: Removed deprecated --partition option

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The option was deprecated in 4.0.0 (commit 0ae2d546); it's now been
long enough with no complaints to follow through with that process.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200123164650.1741798-3-eblake@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
This commit is contained in:
Eric Blake 2020-01-23 10:46:50 -06:00
parent 2e3cb7583a
commit 0bc16997f5
3 changed files with 24 additions and 173 deletions
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15
docs/interop/qemu-nbd.rst
View File

@ -72,13 +72,6 @@ driver options if ``--image-opts`` is specified.
Export the disk as read-only.
.. option:: -P, --partition=NUM
Deprecated: Only expose MBR partition *NUM*. Understands physical
partitions 1-4 and logical partition 5. New code should instead use
:option:`--image-opts` with the raw driver wrapping a subset of the
original image.
.. option:: -B, --bitmap=NAME
If *filename* has a qcow2 persistent bitmap *NAME*, expose
@ -224,14 +217,14 @@ a 1 megabyte subset of a raw file, using the export name 'subset':
-t -x subset -p 10810 \
--image-opts driver=raw,offset=1M,size=1M,file.driver=file,file.filename=file.raw
Serve a read-only copy of just the first MBR partition of a guest
image over a Unix socket with as many as 5 simultaneous readers, with
a persistent process forked as a daemon:
Serve a read-only copy of a guest image over a Unix socket with as
many as 5 simultaneous readers, with a persistent process forked as a
daemon:
::
qemu-nbd --fork --persistent --shared=5 --socket=/path/to/sock \
--partition=1 --read-only --format=qcow2 file.qcow2
--read-only --format=qcow2 file.qcow2
Expose the guest-visible contents of a qcow2 file via a block device
/dev/nbd0 (and possibly creating /dev/nbd0p1 and friends for

49
qemu-deprecated.texi
View File

@ -313,37 +313,6 @@ The above, converted to the current supported format:
@section Related binaries
@subsection qemu-nbd --partition (since 4.0.0)
The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
can only handle MBR partitions, and has never correctly handled
logical partitions beyond partition 5. If you know the offset and
length of the partition (perhaps by using @code{sfdisk} within the
guest), you can achieve the effect of exporting just that subset of
the disk by use of the @option{--image-opts} option with a raw
blockdev using the @code{offset} and @code{size} parameters layered on
top of any other existing blockdev. For example, if partition 1 is
100MiB long starting at 1MiB, the old command:
@code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
can be rewritten as:
@code{qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.file.driver=file,file.file.filename=file.qcow2}
Alternatively, the @code{nbdkit} project provides a more powerful
partition filter on top of its nbd plugin, which can be used to select
an arbitrary MBR or GPT partition on top of any other full-image NBD
export. Using this to rewrite the above example results in:
@code{qemu-nbd -t -k /tmp/sock -f qcow2 file.qcow2 &}
@code{nbdkit -f --filter=partition nbd socket=/tmp/sock partition=1}
Note that if you are exposing the export via /dev/nbd0, it is easier
to just export the entire image and then mount only /dev/nbd0p1 than
it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a
subset of the image.
@subsection qemu-img convert -n -o (since 4.2.0)
All options specified in @option{-o} are image creation options, so
@ -400,3 +369,21 @@ trouble after a recent upgrade.
The "autoload" parameter has been ignored since 2.12.0. All bitmaps
are automatically loaded from qcow2 images.
@section Related binaries
@subsection qemu-nbd --partition (removed in 5.0.0)
The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
could only handle MBR partitions, and never correctly handled logical
partitions beyond partition 5. Exporting a partition can still be
done by utilizing the @option{--image-opts} option with a raw blockdev
using the @code{offset} and @code{size} parameters layered on top of
any other existing blockdev. For example, if partition 1 is 100MiB
long starting at 1MiB, the old command:
@code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
can be rewritten as:
@code{qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.file.driver=file,file.file.filename=file.qcow2}

133
qemu-nbd.c
View File

@ -100,7 +100,6 @@ static void usage(const char *name)
"\n"
"Exposing part of the image:\n"
" -o, --offset=OFFSET offset into the image\n"
" -P, --partition=NUM only expose partition NUM\n"
" -B, --bitmap=NAME expose a persistent dirty bitmap\n"
"\n"
"General purpose options:\n"
@ -156,96 +155,6 @@ QEMU_COPYRIGHT "\n"
, name);
}
struct partition_record
{
uint8_t bootable;
uint8_t start_head;
uint32_t start_cylinder;
uint8_t start_sector;
uint8_t system;
uint8_t end_head;
uint8_t end_cylinder;
uint8_t end_sector;
uint32_t start_sector_abs;
uint32_t nb_sectors_abs;
};
static void read_partition(uint8_t *p, struct partition_record *r)
{
r->bootable = p[0];
r->start_head = p[1];
r->start_cylinder = p[3] | ((p[2] << 2) & 0x0300);
r->start_sector = p[2] & 0x3f;
r->system = p[4];
r->end_head = p[5];
r->end_cylinder = p[7] | ((p[6] << 2) & 0x300);
r->end_sector = p[6] & 0x3f;
r->start_sector_abs = ldl_le_p(p + 8);
r->nb_sectors_abs = ldl_le_p(p + 12);
}
static int find_partition(BlockBackend *blk, int partition,
uint64_t *offset, uint64_t *size)
{
struct partition_record mbr[4];
uint8_t data[MBR_SIZE];
int i;
int ext_partnum = 4;
int ret;
ret = blk_pread(blk, 0, data, sizeof(data));
if (ret < 0) {
error_report("error while reading: %s", strerror(-ret));
exit(EXIT_FAILURE);
}
if (data[510] != 0x55 || data[511] != 0xaa) {
return -EINVAL;
}
for (i = 0; i < 4; i++) {
read_partition(&data[446 + 16 * i], &mbr[i]);
if (!mbr[i].system || !mbr[i].nb_sectors_abs) {
continue;
}
if (mbr[i].system == 0xF || mbr[i].system == 0x5) {
struct partition_record ext[4];
uint8_t data1[MBR_SIZE];
int j;
ret = blk_pread(blk, mbr[i].start_sector_abs * MBR_SIZE,
data1, sizeof(data1));
if (ret < 0) {
error_report("error while reading: %s", strerror(-ret));
exit(EXIT_FAILURE);
}
for (j = 0; j < 4; j++) {
read_partition(&data1[446 + 16 * j], &ext[j]);
if (!ext[j].system || !ext[j].nb_sectors_abs) {
continue;
}
if ((ext_partnum + j + 1) == partition) {
*offset = (uint64_t)ext[j].start_sector_abs << 9;
*size = (uint64_t)ext[j].nb_sectors_abs << 9;
return 0;
}
}
ext_partnum += 4;
} else if ((i + 1) == partition) {
*offset = (uint64_t)mbr[i].start_sector_abs << 9;
*size = (uint64_t)mbr[i].nb_sectors_abs << 9;
return 0;
}
}
return -ENOENT;
}
static void termsig_handler(int signum)
{
atomic_cmpxchg(&state, RUNNING, TERMINATE);
@ -617,7 +526,7 @@ int main(int argc, char **argv)
int64_t fd_size;
QemuOpts *sn_opts = NULL;
const char *sn_id_or_name = NULL;
const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:x:T:D:B:L";
const char *sopt = "hVb:o:p:rsnc:dvk:e:f:tl:x:T:D:B:L";
struct option lopt[] = {
{ "help", no_argument, NULL, 'h' },
{ "version", no_argument, NULL, 'V' },
@ -626,7 +535,6 @@ int main(int argc, char **argv)
{ "socket", required_argument, NULL, 'k' },
{ "offset", required_argument, NULL, 'o' },
{ "read-only", no_argument, NULL, 'r' },
{ "partition", required_argument, NULL, 'P' },
{ "bitmap", required_argument, NULL, 'B' },
{ "connect", required_argument, NULL, 'c' },
{ "disconnect", no_argument, NULL, 'd' },
@ -657,7 +565,6 @@ int main(int argc, char **argv)
int ch;
int opt_ind = 0;
int flags = BDRV_O_RDWR;
int partition = 0;
int ret = 0;
bool seen_cache = false;
bool seen_discard = false;
@ -789,15 +696,6 @@ int main(int argc, char **argv)
readonly = true;
flags &= ~BDRV_O_RDWR;
break;
case 'P':
warn_report("The '-P' option is deprecated; use --image-opts with "
"a raw device wrapper for subset exports instead");
if (qemu_strtoi(optarg, NULL, 0, &partition) < 0 ||
partition < 1 || partition > 8) {
error_report("Invalid partition '%s'", optarg);
exit(EXIT_FAILURE);
}
break;
case 'B':
bitmap = optarg;
break;
@ -894,7 +792,7 @@ int main(int argc, char **argv)
error_report("List mode is incompatible with a file name");
exit(EXIT_FAILURE);
}
if (export_name || export_description || dev_offset || partition ||
if (export_name || export_description || dev_offset ||
device || disconnect || fmt || sn_id_or_name || bitmap ||
seen_aio || seen_discard || seen_cache) {
error_report("List mode is incompatible with per-device settings");
@ -1158,33 +1056,6 @@ int main(int argc, char **argv)
}
fd_size -= dev_offset;
if (partition) {
uint64_t limit;
if (dev_offset) {
error_report("Cannot request partition and offset together");
exit(EXIT_FAILURE);
}
ret = find_partition(blk, partition, &dev_offset, &limit);
if (ret < 0) {
error_report("Could not find partition %d: %s", partition,
strerror(-ret));
exit(EXIT_FAILURE);
}
/*
* MBR partition limits are (32-bit << 9); this assert lets
* the compiler know that we can't overflow 64 bits.
*/
assert(dev_offset + limit >= dev_offset);
if (dev_offset + limit > fd_size) {
error_report("Discovered partition %d at offset %" PRIu64
" size %" PRIu64 ", but size exceeds file length %"
PRId64, partition, dev_offset, limit, fd_size);
exit(EXIT_FAILURE);
}
fd_size = limit;
}
export = nbd_export_new(bs, dev_offset, fd_size, export_name,
export_description, bitmap, readonly, shared > 1,
nbd_export_closed, writethrough, NULL,