linux/Documentation
Ilya Dryomov 9b60e70b3b rbd: add support for single-major device number allocation scheme
Currently each rbd device is allocated its own major number, which
leads to a hard limit of 230-250 images mapped at once.  This commit
adds support for a new single-major device number allocation scheme,
which is hidden behind a new single_major boolean module parameter and
is disabled by default for backwards compatibility reasons.  (Old
userspace cannot correctly unmap images mapped under single-major
scheme and would essentially just unmap a random image, if that.)

$ rbd showmapped
id pool image snap device
0  rbd  b100  -    /dev/rbd0
1  rbd  b101  -    /dev/rbd1
2  rbd  b102  -    /dev/rbd2
3  rbd  b103  -    /dev/rbd3

Old scheme (modprobe rbd):

$ ls -l /dev/rbd*
brw-rw---- 1 root disk 253, 0 Dec 10 12:24 /dev/rbd0
brw-rw---- 1 root disk 252, 0 Dec 10 12:28 /dev/rbd1
brw-rw---- 1 root disk 252, 1 Dec 10 12:28 /dev/rbd1p1
brw-rw---- 1 root disk 252, 2 Dec 10 12:28 /dev/rbd1p2
brw-rw---- 1 root disk 252, 3 Dec 10 12:28 /dev/rbd1p3
brw-rw---- 1 root disk 251, 0 Dec 10 12:28 /dev/rbd2
brw-rw---- 1 root disk 251, 1 Dec 10 12:28 /dev/rbd2p1
brw-rw---- 1 root disk 250, 0 Dec 10 12:24 /dev/rbd3

New scheme (modprobe rbd single_major=Y):

$ ls -l /dev/rbd*
brw-rw---- 1 root disk 253,   0 Dec 10 12:30 /dev/rbd0
brw-rw---- 1 root disk 253, 256 Dec 10 12:30 /dev/rbd1
brw-rw---- 1 root disk 253, 257 Dec 10 12:30 /dev/rbd1p1
brw-rw---- 1 root disk 253, 258 Dec 10 12:30 /dev/rbd1p2
brw-rw---- 1 root disk 253, 259 Dec 10 12:30 /dev/rbd1p3
brw-rw---- 1 root disk 253, 512 Dec 10 12:30 /dev/rbd2
brw-rw---- 1 root disk 253, 513 Dec 10 12:30 /dev/rbd2p1
brw-rw---- 1 root disk 253, 768 Dec 10 12:30 /dev/rbd3

(major 253 was assigned dynamically at module load time)

The new limit is 4096 images mapped at once, and it comes from the fact
that, as before, 256 minor numbers are reserved for each mapping.
(A follow-up commit changes the number of minors reserved and the way
we deal with partitions over that number.)

If single_major is set to true, two new sysfs interfaces show up:
/sys/bus/rbd/{add,remove}_single_major.  These are to be used instead
of /sys/bus/rbd/{add,remove}, which are disabled for backwards
compatibility reasons outlined above.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-12-31 20:31:59 +02:00
..
ABI rbd: add support for single-major device number allocation scheme 2013-12-31 20:31:59 +02:00
accounting Documentation/accounting/getdelays.c: avoid strncpy in accounting tool 2013-07-03 16:08:06 -07:00
acpi gpiolib / ACPI: document the GPIO descriptor based interface 2013-10-19 23:32:50 +02:00
aoe aoe: remove do-nothing NAME="%k" term from example udev rules 2013-09-11 15:59:28 -07:00
arm Allwinner sunXi SoCs machine additions for 3.13 2013-10-28 10:19:38 -07:00
arm64 arm64: Use 42-bit address space with 64K pages 2013-11-05 17:23:52 +00:00
auxdisplay
backlight backlight: lp855x_bl: support new LP8555 device 2013-11-13 12:09:14 +09:00
blackfin
block block: change config option name for cmdline partition parsing 2013-09-30 14:31:02 -07:00
blockdev floppy: Correct documentation of driver options when used as a module. 2013-11-08 09:10:31 -07:00
bus-devices
cdrom
cgroups memcg: support hierarchical memory.numa_stats 2013-11-13 12:09:06 +09:00
connector connector - documentation: simplify netlink message length assignment 2013-10-02 16:03:51 -04:00
console TTY:console: update document console.txt 2013-05-21 10:21:57 -07:00
cpu-freq cpufreq: Implement light weight ->target_index() routine 2013-10-25 22:42:24 +02:00
cpuidle cpuidle: remove cpuidle_unregister_governor() 2013-10-30 01:21:24 +01:00
cris
crypto drivers/dma: remove unused support for MEMSET operations 2013-07-03 16:07:42 -07:00
development-process Documentation: development-process: Update -mm and -next URLs 2013-07-25 12:37:24 +02:00
device-mapper dm cache: resolve small nits and improve Documentation 2013-11-12 13:11:09 -05:00
devicetree - Various DT binding documentation updates. 2013-12-06 08:27:47 -08:00
DocBook doc: fix generation of device-drivers 2013-11-27 20:40:04 -08:00
driver-model spi: Updates for v3.13 2013-11-12 15:01:39 +09:00
dvb [media] get_dvb_firmware: Fix the location of firmware for Terratec HTC 2013-01-01 11:18:26 -02:00
early-userspace Documentation: remove reference to 2.7 kernel in early-userspace 2013-08-20 12:47:28 +02:00
EDID drm: Add 1600x1200 (UXGA) screen resolution to the built-in EDIDs 2013-04-12 14:06:16 +10:00
extcon extcon: Simplify extcon_dev_register() prototype by removing unnecessary parameter 2013-09-27 09:37:01 +09:00
fault-injection doc: fix quite a few typos within Documentation 2012-11-19 14:28:24 +01:00
fb Documentation/fb/viafb.modes fix a typo 2013-08-20 12:41:11 +02:00
filesystems Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2013-11-22 08:38:55 -08:00
firmware_class firmware loader: document firmware cache mechanism 2012-11-14 15:07:18 -08:00
fmc doc: Fix typo "is is" in Documentations 2013-08-27 10:50:52 +02:00
frv
gpio Documentation: gpiolib: add 00-INDEX file 2013-12-03 13:10:48 +01:00
hid HID: uhid: use generic hidinput_input_event() 2013-07-31 10:33:05 +02:00
hwmon Merge branch 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging 2013-11-15 16:35:10 -08:00
i2c i2c: i801: Add Device IDs for Intel Wildcat Point-LP PCH 2013-11-14 18:38:04 +01:00
i2o
ia64 Fix example error_injection_tool 2013-04-02 09:39:55 -07:00
ide
infiniband
input Input: clarify gamepad API ABS values 2013-10-15 23:42:07 -07:00
ioctl ALSA: add DICE driver 2013-10-17 21:18:32 +02:00
isdn
ja_JP HOWTO ja_JP sync 2013-07-24 22:06:34 -07:00
kbuild Documentation/kbuild/kconfig.txt: 'make listnewconfig' replaces: yes "" | make oldconfig 2013-10-08 23:51:50 +02:00
kdump Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-07-04 11:40:58 -07:00
ko_KR Correct unfaithful translation on HOWTO in ko_KR 2013-08-12 17:43:13 -07:00
laptops thinkpad-acpi: Add mute and mic-mute LED functionality 2013-10-17 14:38:44 +02:00
leds Documentation: leds-lp5521,lp5523: update device attribute information 2013-08-26 17:22:13 -07:00
m68k block: remove refs to XD disks from documentation 2013-05-17 15:17:12 +02:00
make
memory-devices
metag doc: fix misspellings with 'codespell' tool 2013-05-28 12:02:12 +02:00
mic misc: mic: Enable OSPM suspend and resume support. 2013-10-05 18:01:42 -07:00
mips
misc-devices doc: fix misspellings with 'codespell' tool 2013-05-28 12:02:12 +02:00
mmc mmc: core: Add in support to expose PRV for v4 MMCs 2013-03-22 12:10:42 -04:00
mn10300
mtd doc: Fix typo "is is" in Documentations 2013-08-27 10:50:52 +02:00
namespaces userns: Recommend use of memory control groups. 2013-01-26 22:20:06 -08:00
netlabel
networking tcp: tsq: restore minimal amount of queueing 2013-11-14 16:25:14 -05:00
nfc NFC: Update pn544 documentation 2013-01-10 01:27:46 +01:00
parisc parisc: document the shadow registers 2013-07-09 22:09:19 +02:00
PCI PCI: Update pci_find_slot() description in pci.txt 2013-09-25 15:43:33 -06:00
pcmcia
power More ACPI and power management updates for 3.13-rc1 2013-11-20 13:25:04 -08:00
powerpc powerpc: Update the 00-Index in Documentation/powerpc 2013-08-27 14:44:27 +10:00
pps USB: serial: invoke dcd_change ldisc's handler. 2013-09-26 09:45:40 -07:00
prctl
pti
ptp ptp: add the PTP_SYS_OFFSET ioctl to the testptp program 2013-09-23 16:46:17 -04:00
rapidio doc: Fix typo in doucmentations 2013-07-25 12:34:15 +02:00
RCU rcu: Fix occurrence of "the the" in checklist.txt 2013-09-25 10:07:02 -07:00
s390 s390/s390dbf: add debug_level_enabled() function 2013-10-24 17:16:53 +02:00
scheduler H8/300 has been dead for several years, the kernel for it has 2013-11-12 14:13:14 +09:00
scsi SCSI misc on 20130915 2013-09-15 17:41:30 -04:00
security ima: new templates management mechanism 2013-10-25 17:17:04 -04:00
serial serial: core: delete .set_wake() callback 2013-10-16 13:16:19 -07:00
sh
sound ALSA: Fix typo in documentation/alsa 2013-10-29 11:38:04 +01:00
spi spi/documentation: Fix usage of __initdata 2013-08-20 12:52:28 +02:00
sysctl vsprintf: check real user/group id for %pK 2013-11-13 12:09:14 +09:00
target target: Remove TF_CIT_TMPL macro 2013-10-16 13:35:02 -07:00
thermal thermal: thermal_core: allow binding with limits on bind_params 2013-09-03 09:10:24 -04:00
timers doc: add missing files to timers/00-INDEX 2013-10-27 21:55:50 +00:00
tpm drivers/tpm: add xen tpmfront interface 2013-08-09 10:57:06 -04:00
trace Documentation/trace/tracepoints.txt: add links to TRACE_EVENT documentation 2013-11-13 12:09:32 +09:00
usb doc: usb: Fix typo in Documentation/usb/gadget_configs.txt 2013-10-31 13:31:39 +01:00
vDSO
video4linux [media] V4L: Add support for integer menu controls with standard menu items 2013-08-18 07:12:59 -03:00
virtual Merge branch 'kvm-ppc-queue' of git://github.com/agraf/linux-2.6 into queue 2013-11-04 10:20:57 +02:00
vm x86, mm: do not leak page->ptl for pmd page tables 2013-11-21 16:42:28 -08:00
w1 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-07-04 11:40:58 -07:00
watchdog watchdog: delete mpcore_wdt driver 2013-07-11 21:47:58 +02:00
wimax
x86 Merge branch 'x86-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-11-12 10:48:30 +09:00
xtensa xtensa: document MMUv3 setup sequence 2013-05-09 01:07:09 -07:00
zh_CN Documentation/zh_CN/SubmittingPatches fix a typo 2013-08-20 12:41:25 +02:00
.gitignore
00-INDEX doc: fix a typo in Documentation/00-INDEX 2013-08-27 10:53:07 +02:00
applying-patches.txt
assoc_array.txt Add a generic associative array implementation. 2013-09-24 10:35:17 +01:00
atomic_ops.txt Documentation: Memory barrier semantics of atomic_xchg() 2013-01-08 14:14:55 -08:00
bad_memory.txt
basic_profiling.txt
bcache.txt Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-07-04 11:40:58 -07:00
binfmt_misc.txt
braille-console.txt
bt8xxgpio.txt
btmrvl.txt
BUG-HUNTING
bus-virt-phys-mapping.txt
cachetlb.txt Documentation: fix typo and update version in cachetlb.txt 2013-08-20 12:46:52 +02:00
Changes remove obsolete references to powertweak 2013-11-27 20:34:32 -08:00
circular-buffers.txt
clk.txt clk: add support for clock reparent on set_rate 2013-08-19 12:27:17 -07:00
coccinelle.txt Coccinelle: Update information about the minimal version required 2013-07-03 22:58:20 +02:00
CodingStyle Documentation/CodingStyle: allow multiple return statements per function 2013-07-03 16:08:01 -07:00
cpu-hotplug.txt MAINTAINERS: update Zwane Mwaikambo's e-mail address 2013-11-13 12:09:14 +09:00
cpu-load.txt
cputopology.txt doc: Documentation/cputopology.txt fix typo 2013-09-04 12:59:47 +02:00
crc32.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt
dell_rbu.txt
devices.txt cuse: add fix minor number to /dev/cuse 2013-10-01 16:44:54 +02:00
digsig.txt
DMA-API-HOWTO.txt DMA-API: provide a helper to set both DMA and coherent DMA masks 2013-09-17 15:32:37 +01:00
DMA-API.txt DMA-API: provide a helper to set both DMA and coherent DMA masks 2013-09-17 15:32:37 +01:00
DMA-attributes.txt doc: Documentation/DMA-attributes.txt fix typo 2013-10-14 15:50:53 +02:00
dma-buf-sharing.txt dma-buf: Expose buffer size to userspace (v2) 2013-09-10 11:36:45 +05:30
DMA-ISA-LPC.txt
dmaengine.txt
dmatest.txt dmatest: add a 'wait' parameter 2013-11-14 11:04:40 -08:00
dontdiff x86: remove offsets.h from .gitignore and dontdiff 2012-11-19 14:10:53 +01:00
dynamic-debug-howto.txt doc: fix misspellings with 'codespell' tool 2013-05-28 12:02:12 +02:00
edac.txt
efi-stub.txt EFI stub documentation updates 2013-09-25 12:34:32 +01:00
eisa.txt
email-clients.txt
flexible-arrays.txt
futex-requeue-pi.txt
gcov.txt gcov: compile specific gcov implementation based on gcc version 2013-11-13 12:09:34 +09:00
highuid.txt
HOWTO Documentation: Updated broken link in HOWTO 2013-06-03 14:22:57 -07:00
hw_random.txt hwrng: Fix a wrong comment in Documentation/hw_random.txt 2013-03-10 18:16:36 +08:00
hwspinlock.txt doc: documentation/hwspinlock.txt fix typo 2013-08-27 10:46:02 +02:00
init.txt
initrd.txt
intel_txt.txt Documentation: remove depends on CONFIG_EXPERIMENTAL 2013-01-11 11:38:03 -08:00
Intel-IOMMU.txt
io_ordering.txt
io-mapping.txt
iostats.txt iostats.txt: add easy-to-find description for field 6 2013-04-29 15:18:50 +02:00
IPMI.txt ipmi: add options to disable openfirmware and PCI scanning 2013-02-27 19:10:21 -08:00
IRQ-affinity.txt doc: fix a typo about irq affinity 2013-08-20 12:59:18 +02:00
IRQ-domain.txt irqdomain: update documentation 2012-12-05 23:52:10 +00:00
IRQ.txt
irqflags-tracing.txt
isapnp.txt
java.txt
kernel-doc-nano-HOWTO.txt kernel-doc: Update references to SGML to refs to XML instead. 2013-05-28 12:02:11 +02:00
kernel-docs.txt
kernel-parameters.txt Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2013-11-21 19:46:00 -08:00
kernel-per-CPU-kthreads.txt kthread: Add pointer to vmstat-avoidance patch 2013-09-25 06:49:46 -07:00
kmemcheck.txt Documentation/kmemcheck: update kmemcheck documentation 2013-08-27 10:47:05 +02:00
kmemleak.txt
kobject.txt
kprobes.txt
kref.txt kref: Add kref_get_unless_zero documentation 2012-11-28 18:36:06 +10:00
ldm.txt
local_ops.txt
lockdep-design.txt
lockstat.txt lockstat: Report avg wait and hold times 2013-10-09 08:19:08 +02:00
lockup-watchdogs.txt
logo.gif
logo.txt
magic-number.txt wanrouter: completely decouple obsolete code from kernel. 2013-01-31 19:20:33 -05:00
Makefile
ManagementStyle
md.txt md: remove doubled description for sync_max, merging it within sync_min/sync_max 2013-07-03 09:43:28 +10:00
media-framework.txt Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media 2013-07-13 12:09:57 -07:00
memory-barriers.txt doc: Fix memory-barrier control-dependency example 2013-08-19 21:39:42 -07:00
memory-hotplug.txt Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-09-06 09:36:28 -07:00
mono.txt
mutex-design.txt locking/doc: Update references to kernel/mutex.c 2013-11-11 12:41:33 +01:00
nommu-mmap.txt
numastat.txt
oops-tracing.txt
padata.txt
parport-lowlevel.txt
parport.txt
percpu-rw-semaphore.txt
phy.txt drivers: phy: add generic PHY framework 2013-09-27 17:35:41 -07:00
pi-futex.txt
pinctrl.txt pinctrl: add documentation for pinctrl_get_group_pins() 2013-10-16 15:35:21 +02:00
pnp.txt
preempt-locking.txt
printk-formats.txt Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-09-06 09:36:28 -07:00
pwm.txt Documentation/pwm: Fix trivial typos 2013-10-24 10:51:33 +02:00
ramoops.txt
rbtree.txt
remoteproc.txt
rfkill.txt
robust-futex-ABI.txt
robust-futexes.txt
rpmsg.txt Documentation: remove __dev* attributes. 2013-01-03 15:57:16 -08:00
rt-mutex-design.txt sched: Rename sched.c as sched/core.c in comments and Documentation 2013-06-19 12:58:42 +02:00
rt-mutex.txt
rtc.txt rtc: add ability to push out an existing wakealarm using sysfs 2013-07-03 16:07:54 -07:00
SAK.txt
SecurityBugs
serial-console.txt
sgi-ioc4.txt
sgi-visws.txt
SM501.txt
smsc_ece1099.txt
sparse.txt Documentation/sparse.txt: document context annotations for lock checking 2012-12-17 17:15:23 -08:00
spinlocks.txt sched: Rename sched.c as sched/core.c in comments and Documentation 2013-06-19 12:58:42 +02:00
stable_api_nonsense.txt
stable_kernel_rules.txt
static-keys.txt
SubmitChecklist Finally eradicate CONFIG_HOTPLUG 2013-06-03 14:20:18 -07:00
SubmittingDrivers
SubmittingPatches Documentation/SubmittingPatches: Request summaries for commit references 2013-08-20 12:58:15 +02:00
svga.txt
sysfs-rules.txt doc: Fix typo in doucmentations 2013-07-25 12:34:15 +02:00
sysrq.txt sysrq: Allow magic SysRq key functions to be disabled through Kconfig 2013-10-16 13:01:44 -07:00
this_cpu_ops.txt percpu: add documentation on this_cpu operations 2013-04-04 10:24:53 -07:00
unaligned-memory-access.txt
unicode.txt
unshare.txt
vfio.txt vfio: fix documentation 2013-09-05 16:36:21 -06:00
VGA-softcursor.txt
vgaarbiter.txt
video-output.txt
vme_api.txt
volatile-considered-harmful.txt
workqueue.txt workqueue: Correct/Drop references to gcwq in Documentation 2013-08-21 10:32:09 -04:00
ww-mutex-design.txt mutex: Add support for wound/wait style locks 2013-06-26 12:10:56 +02:00
xz.txt
zorro.txt