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linux-next/Documentation/ABI/testing/sysfs-bus-rbd

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rbd: replace the rbd sysfs interface The new interface creates directories per mapped image and under each it creates a subdir per available snapshot. This allows keeping a cleaner interface within the sysfs guidelines. The ABI documentation was updated too. Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net> Signed-off-by: Sage Weil <sage@newdream.net>
2010-11-20 06:51:04 +08:00
What: /sys/bus/rbd/
Date: November 2010
rbd: update email address in Documentation Signed-off-by: Sage Weil <sage@newdream.net>
2011-03-22 06:06:50 +08:00
Contact: Yehuda Sadeh <yehuda@newdream.net>,
rbd: replace the rbd sysfs interface The new interface creates directories per mapped image and under each it creates a subdir per available snapshot. This allows keeping a cleaner interface within the sysfs guidelines. The ABI documentation was updated too. Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net> Signed-off-by: Sage Weil <sage@newdream.net>
2010-11-20 06:51:04 +08:00
Sage Weil <sage@newdream.net>
Description:
Being used for adding and removing rbd block devices.
Usage: <mon ip addr> <options> <pool name> <rbd image name> [snap name]
$ echo "192.168.0.1 name=admin rbd foo" > /sys/bus/rbd/add
The snapshot name can be "-" or omitted to map the image read/write. A <dev-id>
will be assigned for any registered block device. If snapshot is used, it will
be mapped read-only.
Removal of a device:
$ echo <dev-id> > /sys/bus/rbd/remove
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>
2013-12-13 21:28:57 +08:00
What: /sys/bus/rbd/add_single_major
Date: December 2013
KernelVersion: 3.14
Contact: Sage Weil <sage@inktank.com>
Description: Available only if rbd module is inserted with single_major
parameter set to true.
Usage is the same as for /sys/bus/rbd/add. If present,
should be used instead of the latter: any attempts to use
/sys/bus/rbd/add if /sys/bus/rbd/add_single_major is
available will fail for backwards compatibility reasons.
What: /sys/bus/rbd/remove_single_major
Date: December 2013
KernelVersion: 3.14
Contact: Sage Weil <sage@inktank.com>
Description: Available only if rbd module is inserted with single_major
parameter set to true.
Usage is the same as for /sys/bus/rbd/remove. If present,
should be used instead of the latter: any attempts to use
/sys/bus/rbd/remove if /sys/bus/rbd/remove_single_major is
available will fail for backwards compatibility reasons.
rbd: replace the rbd sysfs interface The new interface creates directories per mapped image and under each it creates a subdir per available snapshot. This allows keeping a cleaner interface within the sysfs guidelines. The ABI documentation was updated too. Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net> Signed-off-by: Sage Weil <sage@newdream.net>
2010-11-20 06:51:04 +08:00
Entries under /sys/bus/rbd/devices/<dev-id>/
--------------------------------------------
client_id
The ceph unique client id that was assigned for this specific session.
rbd: add an rbd features field Record the features values for each rbd image and each of its snapshots. This is really something that only becomes meaningful for version 2 images, so this is just putting in place code that will form common infrastructure. It may be useful to expand the sysfs entries--and therefore the information we maintain--for the image and for each snapshot. But I'm going to hold off doing that until we start making active use of the feature bits. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-07-14 09:35:12 +08:00
features
A hexadecimal encoding of the feature bits for this image.
rbd: replace the rbd sysfs interface The new interface creates directories per mapped image and under each it creates a subdir per available snapshot. This allows keeping a cleaner interface within the sysfs guidelines. The ABI documentation was updated too. Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net> Signed-off-by: Sage Weil <sage@newdream.net>
2010-11-20 06:51:04 +08:00
major
The block device major number.
rbd: add 'minor' sysfs rbd device attribute Introduce /sys/bus/rbd/devices/<id>/minor sysfs attribute for exporting rbd whole disk minor numbers. This is a step towards single-major device number allocation scheme, but also a good thing on its own. Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com> Reviewed-by: Alex Elder <elder@linaro.org> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2013-12-13 21:28:57 +08:00
minor
The block device minor number. (December 2013, since 3.14.)
rbd: replace the rbd sysfs interface The new interface creates directories per mapped image and under each it creates a subdir per available snapshot. This allows keeping a cleaner interface within the sysfs guidelines. The ABI documentation was updated too. Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net> Signed-off-by: Sage Weil <sage@newdream.net>
2010-11-20 06:51:04 +08:00
name
The name of the rbd image.
rbd: define rbd_dev_image_id() New format 2 rbd images are permanently identified by a unique image id. Each rbd image also has a name, but the name can be changed. A format 2 rbd image will have an object--whose name is based on the image name--which maps an image's name to its image id. Create a new function rbd_dev_image_id() that checks for the existence of the image id object, and if it's found, records the image id in the rbd_device structure. Create a new rbd device attribute (/sys/bus/rbd/<num>/image_id) that makes this information available. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-07-11 09:30:11 +08:00
image_id
The unique id for the rbd image. (For rbd image format 1
this is empty.)
rbd: replace the rbd sysfs interface The new interface creates directories per mapped image and under each it creates a subdir per available snapshot. This allows keeping a cleaner interface within the sysfs guidelines. The ABI documentation was updated too. Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net> Signed-off-by: Sage Weil <sage@newdream.net>
2010-11-20 06:51:04 +08:00
pool
rbd: create pool_id device attribute Add an entry under /sys/bus/rbd/devices/<N>/ named "pool_id" that provides the id for the pool the rbd image is assocatied with. This is in addition to the pool name already provided. Rename the "poolid" field in struct rbd_device to be "pool_id". Update the documentation to reflect the addition of this new entry. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-07-12 23:46:35 +08:00
The name of the storage pool where this rbd image resides.
An rbd image name is unique within its pool.
pool_id
The unique identifier for the rbd image's pool. This is
a permanent attribute of the pool. A pool's id will never
change.
rbd: replace the rbd sysfs interface The new interface creates directories per mapped image and under each it creates a subdir per available snapshot. This allows keeping a cleaner interface within the sysfs guidelines. The ABI documentation was updated too. Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net> Signed-off-by: Sage Weil <sage@newdream.net>
2010-11-20 06:51:04 +08:00
size
The size (in bytes) of the mapped block device.
refresh
Writing to this file will reread the image header data and set
all relevant datastructures accordingly.
current_snap
The current snapshot for which the device is mapped.
rbd: get parent spec for version 2 images Add support for getting the the information identifying the parent image for rbd images that have them. The child image holds a reference to its parent image specification structure. Create a new entry "parent" in /sys/bus/rbd/image/N/ to report the identifying information for the parent image, if any. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
2012-10-26 12:34:42 +08:00
parent
Information identifying the pool, image, and snapshot id for
the parent image in a layered rbd image (format 2 only).
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