The patch titled
Subject: zram: introduce automatic device_id generation
has been removed from the -mm tree. Its filename was
zram-introduce-automatic-device_id-generation.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
From: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Subject: zram: introduce automatic device_id generation
The existing device creation interface requires user to provide new and
unique device_id for every device being created. This might be difficult
to handle (f.e. in automated scripts).
Extend zram-control/zram_add interface to support read and write
operations. Write operation remains the same:
echo X > /sys/class/zram-control/zram_add
will add /dev/zramX (or return error).
Read operation is treated as 'pick up available device_id, add new device
and return device_id'.
Example:
cat /sys/class/zram-control/zram_add
2
cat /sys/class/zram-control/zram_add
3
so user-space can proceed with /dev/zram2, /dev/zram3 init and usage.
An attempt to use already used device_id (-EEXIST)
echo 3 > /sys/class/zram-control/zram_add
-bash: echo: write error: File exists
Returning zram_add error code back to user (-ENOMEM in this case)
cat /sys/class/zram-control/zram_add
cat: /sys/class/zram-control/zram_add: Cannot allocate memory
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-class-zram | 7 +++-
Documentation/blockdev/zram.txt | 10 ++++++
drivers/block/zram/zram_drv.c | 31 +++++++++++++++++--
3 files changed, 43 insertions(+), 5 deletions(-)
diff -puN Documentation/ABI/testing/sysfs-class-zram~zram-introduce-automatic-device_id-generation Documentation/ABI/testing/sysfs-class-zram
--- a/Documentation/ABI/testing/sysfs-class-zram~zram-introduce-automatic-device_id-generation
+++ a/Documentation/ABI/testing/sysfs-class-zram
@@ -11,8 +11,11 @@ Date: March 2015
KernelVersion: 4.1
Contact: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Description:
- Add a specific /dev/zramX device, where X is a device_id
- provided by user
+ RW attribuite. Write operation adds a specific /dev/zramX
+ device, where X is a device_id provided by user.
+ Read operation will automatically pick up avilable device_id
+ X, add /dev/zramX device and return that device_id X back to
+ user.
What: /sys/class/zram-control/zram_add
Date: March 2015
diff -puN Documentation/blockdev/zram.txt~zram-introduce-automatic-device_id-generation Documentation/blockdev/zram.txt
--- a/Documentation/blockdev/zram.txt~zram-introduce-automatic-device_id-generation
+++ a/Documentation/blockdev/zram.txt
@@ -110,6 +110,16 @@ In order to add a new /dev/zramX device
To remove the existing /dev/zramX device (where X is a device id) execute
echo X > /sys/class/zram-control/zram_remove
+Additionally, zram also handles automatic device_id generation and assignment.
+
+ cat /sys/class/zram-control/zram_add
+ 1
+ cat /sys/class/zram-control/zram_add
+ 2
+
+this will pick up available device_id X, add corresponding /dev/zramX
+device and return its device_id X back to user (or error code).
+
8) Stats:
Per-device statistics are exported as various nodes under /sys/block/zram<id>/
diff -puN drivers/block/zram/zram_drv.c~zram-introduce-automatic-device_id-generation drivers/block/zram/zram_drv.c
--- a/drivers/block/zram/zram_drv.c~zram-introduce-automatic-device_id-generation
+++ a/drivers/block/zram/zram_drv.c
@@ -1140,8 +1140,15 @@ static int zram_add(int device_id)
if (!zram)
return ret;
- ret = idr_alloc(&zram_index_idr, zram, device_id,
- device_id + 1, GFP_KERNEL);
+ if (device_id < 0) {
+ /* generate new device_id */
+ ret = idr_alloc(&zram_index_idr, zram, 0, 0, GFP_KERNEL);
+ device_id = ret;
+ } else {
+ /* use provided device_id */
+ ret = idr_alloc(&zram_index_idr, zram, device_id,
+ device_id + 1, GFP_KERNEL);
+ }
if (ret < 0)
goto out_free_dev;
@@ -1334,6 +1341,24 @@ static ssize_t zram_add_store(struct cla
return ret ? ret : count;
}
+static ssize_t zram_add_show(struct class *class,
+ struct class_attribute *attr,
+ char *buf)
+{
+ int ret;
+
+ mutex_lock(&zram_index_mutex);
+ /* read operation on zram_add is - pick up device_id
+ * automatically, add corresponding device and return
+ * that device_id back to user */
+ ret = zram_add(-1);
+ mutex_unlock(&zram_index_mutex);
+
+ if (ret < 0)
+ return ret;
+ return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
+}
+
static ssize_t zram_remove_store(struct class *class,
struct class_attribute *attr,
const char *buf,
@@ -1345,7 +1370,7 @@ static ssize_t zram_remove_store(struct
}
static struct class_attribute zram_control_class_attrs[] = {
- __ATTR_WO(zram_add),
+ __ATTR_RW(zram_add),
__ATTR_WO(zram_remove),
__ATTR_NULL,
};
_
Patches currently in -mm which might be from sergey.senozhatsky@xxxxxxxxx are
origin.patch
revert-zram-move-compact_store-to-sysfs-functions-area.patch
zram-introduce-automatic-device_id-generation-fix.patch
zram-do-not-let-user-enforce-new-device-dev_id.patch
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