qemu-nbd: Removed deprecated --partition option
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
parent
2e3cb7583a
commit
0bc16997f5
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@ -72,13 +72,6 @@ driver options if ``--image-opts`` is specified.
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Export the disk as read-only.
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.. option:: -P, --partition=NUM
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Deprecated: Only expose MBR partition *NUM*. Understands physical
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partitions 1-4 and logical partition 5. New code should instead use
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:option:`--image-opts` with the raw driver wrapping a subset of the
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original image.
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.. option:: -B, --bitmap=NAME
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If *filename* has a qcow2 persistent bitmap *NAME*, expose
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@ -224,14 +217,14 @@ a 1 megabyte subset of a raw file, using the export name 'subset':
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-t -x subset -p 10810 \
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--image-opts driver=raw,offset=1M,size=1M,file.driver=file,file.filename=file.raw
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Serve a read-only copy of just the first MBR partition of a guest
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image over a Unix socket with as many as 5 simultaneous readers, with
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a persistent process forked as a daemon:
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Serve a read-only copy of a guest image over a Unix socket with as
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many as 5 simultaneous readers, with a persistent process forked as a
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daemon:
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::
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qemu-nbd --fork --persistent --shared=5 --socket=/path/to/sock \
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--partition=1 --read-only --format=qcow2 file.qcow2
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--read-only --format=qcow2 file.qcow2
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Expose the guest-visible contents of a qcow2 file via a block device
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/dev/nbd0 (and possibly creating /dev/nbd0p1 and friends for
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@ -313,37 +313,6 @@ The above, converted to the current supported format:
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@section Related binaries
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@subsection qemu-nbd --partition (since 4.0.0)
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The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
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can only handle MBR partitions, and has never correctly handled
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logical partitions beyond partition 5. If you know the offset and
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length of the partition (perhaps by using @code{sfdisk} within the
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guest), you can achieve the effect of exporting just that subset of
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the disk by use of the @option{--image-opts} option with a raw
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blockdev using the @code{offset} and @code{size} parameters layered on
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top of any other existing blockdev. For example, if partition 1 is
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100MiB long starting at 1MiB, the old command:
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@code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
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can be rewritten as:
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@code{qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.file.driver=file,file.file.filename=file.qcow2}
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Alternatively, the @code{nbdkit} project provides a more powerful
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partition filter on top of its nbd plugin, which can be used to select
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an arbitrary MBR or GPT partition on top of any other full-image NBD
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export. Using this to rewrite the above example results in:
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@code{qemu-nbd -t -k /tmp/sock -f qcow2 file.qcow2 &}
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@code{nbdkit -f --filter=partition nbd socket=/tmp/sock partition=1}
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Note that if you are exposing the export via /dev/nbd0, it is easier
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to just export the entire image and then mount only /dev/nbd0p1 than
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it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a
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subset of the image.
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@subsection qemu-img convert -n -o (since 4.2.0)
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All options specified in @option{-o} are image creation options, so
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@ -400,3 +369,21 @@ trouble after a recent upgrade.
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The "autoload" parameter has been ignored since 2.12.0. All bitmaps
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are automatically loaded from qcow2 images.
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@section Related binaries
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@subsection qemu-nbd --partition (removed in 5.0.0)
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The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
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could only handle MBR partitions, and never correctly handled logical
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partitions beyond partition 5. Exporting a partition can still be
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done by utilizing the @option{--image-opts} option with a raw blockdev
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using the @code{offset} and @code{size} parameters layered on top of
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any other existing blockdev. For example, if partition 1 is 100MiB
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long starting at 1MiB, the old command:
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@code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
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can be rewritten as:
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@code{qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.file.driver=file,file.file.filename=file.qcow2}
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133
qemu-nbd.c
133
qemu-nbd.c
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@ -100,7 +100,6 @@ static void usage(const char *name)
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"\n"
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"Exposing part of the image:\n"
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" -o, --offset=OFFSET offset into the image\n"
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" -P, --partition=NUM only expose partition NUM\n"
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" -B, --bitmap=NAME expose a persistent dirty bitmap\n"
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"\n"
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"General purpose options:\n"
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@ -156,96 +155,6 @@ QEMU_COPYRIGHT "\n"
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, name);
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}
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struct partition_record
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{
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uint8_t bootable;
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uint8_t start_head;
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uint32_t start_cylinder;
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uint8_t start_sector;
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uint8_t system;
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uint8_t end_head;
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uint8_t end_cylinder;
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uint8_t end_sector;
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uint32_t start_sector_abs;
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uint32_t nb_sectors_abs;
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};
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static void read_partition(uint8_t *p, struct partition_record *r)
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{
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r->bootable = p[0];
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r->start_head = p[1];
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r->start_cylinder = p[3] | ((p[2] << 2) & 0x0300);
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r->start_sector = p[2] & 0x3f;
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r->system = p[4];
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r->end_head = p[5];
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r->end_cylinder = p[7] | ((p[6] << 2) & 0x300);
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r->end_sector = p[6] & 0x3f;
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r->start_sector_abs = ldl_le_p(p + 8);
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r->nb_sectors_abs = ldl_le_p(p + 12);
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}
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static int find_partition(BlockBackend *blk, int partition,
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uint64_t *offset, uint64_t *size)
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{
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struct partition_record mbr[4];
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uint8_t data[MBR_SIZE];
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int i;
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int ext_partnum = 4;
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int ret;
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ret = blk_pread(blk, 0, data, sizeof(data));
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if (ret < 0) {
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error_report("error while reading: %s", strerror(-ret));
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exit(EXIT_FAILURE);
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}
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if (data[510] != 0x55 || data[511] != 0xaa) {
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return -EINVAL;
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}
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for (i = 0; i < 4; i++) {
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read_partition(&data[446 + 16 * i], &mbr[i]);
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if (!mbr[i].system || !mbr[i].nb_sectors_abs) {
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continue;
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}
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if (mbr[i].system == 0xF || mbr[i].system == 0x5) {
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struct partition_record ext[4];
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uint8_t data1[MBR_SIZE];
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int j;
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ret = blk_pread(blk, mbr[i].start_sector_abs * MBR_SIZE,
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data1, sizeof(data1));
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if (ret < 0) {
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error_report("error while reading: %s", strerror(-ret));
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exit(EXIT_FAILURE);
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}
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for (j = 0; j < 4; j++) {
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read_partition(&data1[446 + 16 * j], &ext[j]);
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if (!ext[j].system || !ext[j].nb_sectors_abs) {
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continue;
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}
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if ((ext_partnum + j + 1) == partition) {
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*offset = (uint64_t)ext[j].start_sector_abs << 9;
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*size = (uint64_t)ext[j].nb_sectors_abs << 9;
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return 0;
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}
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}
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ext_partnum += 4;
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} else if ((i + 1) == partition) {
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*offset = (uint64_t)mbr[i].start_sector_abs << 9;
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*size = (uint64_t)mbr[i].nb_sectors_abs << 9;
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return 0;
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}
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}
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return -ENOENT;
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}
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static void termsig_handler(int signum)
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{
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atomic_cmpxchg(&state, RUNNING, TERMINATE);
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@ -617,7 +526,7 @@ int main(int argc, char **argv)
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int64_t fd_size;
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QemuOpts *sn_opts = NULL;
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const char *sn_id_or_name = NULL;
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const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:x:T:D:B:L";
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const char *sopt = "hVb:o:p:rsnc:dvk:e:f:tl:x:T:D:B:L";
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struct option lopt[] = {
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{ "help", no_argument, NULL, 'h' },
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{ "version", no_argument, NULL, 'V' },
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@ -626,7 +535,6 @@ int main(int argc, char **argv)
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{ "socket", required_argument, NULL, 'k' },
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{ "offset", required_argument, NULL, 'o' },
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{ "read-only", no_argument, NULL, 'r' },
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{ "partition", required_argument, NULL, 'P' },
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{ "bitmap", required_argument, NULL, 'B' },
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{ "connect", required_argument, NULL, 'c' },
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{ "disconnect", no_argument, NULL, 'd' },
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@ -657,7 +565,6 @@ int main(int argc, char **argv)
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int ch;
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int opt_ind = 0;
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int flags = BDRV_O_RDWR;
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int partition = 0;
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int ret = 0;
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bool seen_cache = false;
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bool seen_discard = false;
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@ -789,15 +696,6 @@ int main(int argc, char **argv)
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readonly = true;
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flags &= ~BDRV_O_RDWR;
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break;
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case 'P':
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warn_report("The '-P' option is deprecated; use --image-opts with "
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"a raw device wrapper for subset exports instead");
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if (qemu_strtoi(optarg, NULL, 0, &partition) < 0 ||
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partition < 1 || partition > 8) {
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error_report("Invalid partition '%s'", optarg);
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exit(EXIT_FAILURE);
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}
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break;
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case 'B':
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bitmap = optarg;
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break;
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@ -894,7 +792,7 @@ int main(int argc, char **argv)
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error_report("List mode is incompatible with a file name");
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exit(EXIT_FAILURE);
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}
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if (export_name || export_description || dev_offset || partition ||
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if (export_name || export_description || dev_offset ||
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device || disconnect || fmt || sn_id_or_name || bitmap ||
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seen_aio || seen_discard || seen_cache) {
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error_report("List mode is incompatible with per-device settings");
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@ -1158,33 +1056,6 @@ int main(int argc, char **argv)
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}
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fd_size -= dev_offset;
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if (partition) {
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uint64_t limit;
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if (dev_offset) {
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error_report("Cannot request partition and offset together");
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exit(EXIT_FAILURE);
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}
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ret = find_partition(blk, partition, &dev_offset, &limit);
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if (ret < 0) {
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error_report("Could not find partition %d: %s", partition,
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strerror(-ret));
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exit(EXIT_FAILURE);
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}
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/*
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* MBR partition limits are (32-bit << 9); this assert lets
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* the compiler know that we can't overflow 64 bits.
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*/
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assert(dev_offset + limit >= dev_offset);
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if (dev_offset + limit > fd_size) {
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error_report("Discovered partition %d at offset %" PRIu64
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" size %" PRIu64 ", but size exceeds file length %"
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PRId64, partition, dev_offset, limit, fd_size);
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exit(EXIT_FAILURE);
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}
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fd_size = limit;
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}
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export = nbd_export_new(bs, dev_offset, fd_size, export_name,
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export_description, bitmap, readonly, shared > 1,
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nbd_export_closed, writethrough, NULL,
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