summaryrefslogtreecommitdiff
path: root/Documentation/ABI
diff options
context:
space:
mode:
authorSergey Senozhatsky <sergey.senozhatsky@gmail.com>2015-06-25 15:00:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-06-25 17:00:36 -0700
commit6566d1a32bf725a4fa9119f16270505451ad01ac (patch)
treec2faa0b705f3da2d0cb10f520127f41df17e7148 /Documentation/ABI
parentf405c445a4866caa43101c231721123805a23bbf (diff)
zram: add dynamic device add/remove functionality
We currently don't support on-demand device creation. The one and only way to have N zram devices is to specify num_devices module parameter (default value: 1). IOW if, for some reason, at some point, user wants to have N + 1 devies he/she must umount all the existing devices, unload the module, load the module passing num_devices equals to N + 1. And do this again, if needed. This patch introduces zram control sysfs class, which has two sysfs attrs: - hot_add -- add a new zram device - hot_remove -- remove a specific (device_id) zram device hot_add sysfs attr is read-only and has only automatic device id assignment mode (as requested by Minchan Kim). read operation performed on this attr creates a new zram device and returns back its device_id or error status. Usage example: # add a new specific zram device cat /sys/class/zram-control/hot_add 2 # remove a specific zram device echo 4 > /sys/class/zram-control/hot_remove Returning zram_add() error code back to user (-ENOMEM in this case) cat /sys/class/zram-control/hot_add cat: /sys/class/zram-control/hot_add: Cannot allocate memory NOTE, there might be users who already depend on the fact that at least zram0 device gets always created by zram_init(). Preserve this behavior. [minchan@kernel.org: use zram->claim to avoid lockdep splat] Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/ABI')
-rw-r--r--Documentation/ABI/testing/sysfs-class-zram24
1 files changed, 24 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-zram b/Documentation/ABI/testing/sysfs-class-zram
new file mode 100644
index 000000000000..48ddacbe0e69
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-zram
@@ -0,0 +1,24 @@
+What: /sys/class/zram-control/
+Date: August 2015
+KernelVersion: 4.2
+Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+ The zram-control/ class sub-directory belongs to zram
+ device class
+
+What: /sys/class/zram-control/hot_add
+Date: August 2015
+KernelVersion: 4.2
+Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+ RO attribute. Read operation will cause zram to add a new
+ device and return its device id back to user (so one can
+ use /dev/zram<id>), or error code.
+
+What: /sys/class/zram-control/hot_remove
+Date: August 2015
+KernelVersion: 4.2
+Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+ WO attribute. Remove a specific /dev/zramX device, where X
+ is a device_id provided by user.