nbd: Treat flags vs. command type as separate fields

Current upstream NBD documents that requests have a 16-bit flags,
followed by a 16-bit type integer; although older versions mentioned
only a 32-bit field with masking to find flags.  Since the protocol
is in network order (big-endian over the wire), the ABI is unchanged;
but dealing with the flags as a separate field rather than masking
will make it easier to add support for upcoming NBD extensions that
increase the number of both flags and commands.

Improve some comments in nbd.h based on the current upstream
NBD protocol (https://github.com/yoe/nbd/blob/master/doc/proto.md),
and touch some nearby code to keep checkpatch.pl happy.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-3-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
5 files changed
tree: ad00a53ab79e04ddcc2d09fd21ade2640f3da955
  1. audio/
  2. backends/
  3. block/
  4. bsd-user/
  5. contrib/
  6. crypto/
  7. default-configs/
  8. disas/
  9. docs/
  10. fpu/
  11. fsdev/
  12. gdb-xml/
  13. hw/
  14. include/
  15. io/
  16. libdecnumber/
  17. linux-headers/
  18. linux-user/
  19. migration/
  20. nbd/
  21. net/
  22. pc-bios/
  23. po/
  24. qapi/
  25. qga/
  26. qobject/
  27. qom/
  28. replay/
  29. roms/
  30. scripts/
  31. slirp/
  32. stubs/
  33. target-alpha/
  34. target-arm/
  35. target-cris/
  36. target-i386/
  37. target-lm32/
  38. target-m68k/
  39. target-microblaze/
  40. target-mips/
  41. target-moxie/
  42. target-openrisc/
  43. target-ppc/
  44. target-s390x/
  45. target-sh4/
  46. target-sparc/
  47. target-tilegx/
  48. target-tricore/
  49. target-unicore32/
  50. target-xtensa/
  51. tcg/
  52. tests/
  53. trace/
  54. ui/
  55. util/
  56. .dir-locals.el
  57. .exrc
  58. .gitignore
  59. .gitmodules
  60. .mailmap
  61. .travis.yml
  62. accel.c
  63. aio-posix.c
  64. aio-win32.c
  65. arch_init.c
  66. async.c
  67. atomic_template.h
  68. balloon.c
  69. block.c
  70. blockdev-nbd.c
  71. blockdev.c
  72. blockjob.c
  73. bootdevice.c
  74. bt-host.c
  75. bt-vhci.c
  76. Changelog
  77. CODING_STYLE
  78. configure
  79. COPYING
  80. COPYING.LIB
  81. cpu-exec-common.c
  82. cpu-exec.c
  83. cpus-common.c
  84. cpus.c
  85. cputlb.c
  86. device-hotplug.c
  87. device_tree.c
  88. disas.c
  89. dma-helpers.c
  90. dump.c
  91. exec.c
  92. gdbstub.c
  93. HACKING
  94. hmp-commands-info.hx
  95. hmp-commands.hx
  96. hmp.c
  97. hmp.h
  98. iohandler.c
  99. ioport.c
  100. iothread.c
  101. kvm-all.c
  102. kvm-stub.c
  103. LICENSE
  104. main-loop.c
  105. MAINTAINERS
  106. Makefile
  107. Makefile.objs
  108. Makefile.target
  109. memory.c
  110. memory_mapping.c
  111. module-common.c
  112. monitor.c
  113. numa.c
  114. os-posix.c
  115. os-win32.c
  116. page_cache.c
  117. qapi-schema.json
  118. qdev-monitor.c
  119. qdict-test-data.txt
  120. qemu-bridge-helper.c
  121. qemu-char.c
  122. qemu-doc.texi
  123. qemu-ga.texi
  124. qemu-img-cmds.hx
  125. qemu-img.c
  126. qemu-img.texi
  127. qemu-io-cmds.c
  128. qemu-io.c
  129. qemu-nbd.c
  130. qemu-nbd.texi
  131. qemu-option-trace.texi
  132. qemu-options-wrapper.h
  133. qemu-options.h
  134. qemu-options.hx
  135. qemu-seccomp.c
  136. qemu-tech.texi
  137. qemu-timer.c
  138. qemu.nsi
  139. qemu.sasl
  140. qmp.c
  141. qtest.c
  142. README
  143. replication.c
  144. replication.h
  145. rules.mak
  146. softmmu_template.h
  147. spice-qemu-char.c
  148. tcg-runtime.c
  149. tci.c
  150. thread-pool.c
  151. thunk.c
  152. tpm.c
  153. trace-events
  154. translate-all.c
  155. translate-all.h
  156. translate-common.c
  157. user-exec.c
  158. VERSION
  159. version.rc
  160. vl.c
  161. xen-common-stub.c
  162. xen-common.c
  163. xen-hvm-stub.c
  164. xen-hvm.c
  165. xen-mapcache.c