diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-class-zram | 24 | ||||
| -rw-r--r-- | Documentation/blockdev/zram.txt | 23 | ||||
| -rw-r--r-- | drivers/block/zram/zram_drv.c | 100 |
3 files changed, 141 insertions, 6 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. diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt index 65e94301e57b..c4de576093af 100644 --- a/Documentation/blockdev/zram.txt +++ b/Documentation/blockdev/zram.txt @@ -99,7 +99,24 @@ size of the disk when not in use so a huge zram is wasteful. mkfs.ext4 /dev/zram1 mount /dev/zram1 /tmp -7) Stats: +7) Add/remove zram devices + +zram provides a control interface, which enables dynamic (on-demand) device +addition and removal. + +In order to add a new /dev/zramX device, perform read operation on hot_add +attribute. This will return either new device's device id (meaning that you +can use /dev/zram<id>) or error code. + +Example: + cat /sys/class/zram-control/hot_add + 1 + +To remove the existing /dev/zramX device (where X is a device id) +execute + echo X > /sys/class/zram-control/hot_remove + +8) Stats: Per-device statistics are exported as various nodes under /sys/block/zram<id>/ A brief description of exported device attritbutes. For more details please @@ -174,11 +191,11 @@ line of text and contains the following stats separated by whitespace: zero_pages num_migrated -8) Deactivate: +9) Deactivate: swapoff /dev/zram0 umount /dev/zram1 -9) Reset: +10) Reset: Write any positive value to 'reset' sysfs node echo 1 > /sys/block/zram0/reset echo 1 > /sys/block/zram1/reset diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 6a3b36d5bad6..830f0eb501fa 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -29,10 +29,14 @@ #include <linux/vmalloc.h> #include <linux/err.h> #include <linux/idr.h> +#include <linux/sysfs.h> #include "zram_drv.h" static DEFINE_IDR(zram_index_idr); +/* idr index must be protected */ +static DEFINE_MUTEX(zram_index_mutex); + static int zram_major; static const char *default_compressor = "lzo"; @@ -1273,24 +1277,104 @@ out_free_dev: return ret; } -static void zram_remove(struct zram *zram) +static int zram_remove(struct zram *zram) { - pr_info("Removed device: %s\n", zram->disk->disk_name); + struct block_device *bdev; + + bdev = bdget_disk(zram->disk, 0); + if (!bdev) + return -ENOMEM; + + mutex_lock(&bdev->bd_mutex); + if (bdev->bd_openers || zram->claim) { + mutex_unlock(&bdev->bd_mutex); + bdput(bdev); + return -EBUSY; + } + + zram->claim = true; + mutex_unlock(&bdev->bd_mutex); + /* * Remove sysfs first, so no one will perform a disksize - * store while we destroy the devices + * store while we destroy the devices. This also helps during + * hot_remove -- zram_reset_device() is the last holder of + * ->init_lock, no later/concurrent disksize_store() or any + * other sysfs handlers are possible. */ sysfs_remove_group(&disk_to_dev(zram->disk)->kobj, &zram_disk_attr_group); + /* Make sure all the pending I/O are finished */ + fsync_bdev(bdev); zram_reset_device(zram); + bdput(bdev); + + pr_info("Removed device: %s\n", zram->disk->disk_name); + idr_remove(&zram_index_idr, zram->disk->first_minor); blk_cleanup_queue(zram->disk->queue); del_gendisk(zram->disk); put_disk(zram->disk); kfree(zram); + return 0; +} + +/* zram-control sysfs attributes */ +static ssize_t hot_add_show(struct class *class, + struct class_attribute *attr, + char *buf) +{ + int ret; + + mutex_lock(&zram_index_mutex); + ret = zram_add(); + mutex_unlock(&zram_index_mutex); + + if (ret < 0) + return ret; + return scnprintf(buf, PAGE_SIZE, "%d\n", ret); +} + +static ssize_t hot_remove_store(struct class *class, + struct class_attribute *attr, + const char *buf, + size_t count) +{ + struct zram *zram; + int ret, dev_id; + + /* dev_id is gendisk->first_minor, which is `int' */ + ret = kstrtoint(buf, 10, &dev_id); + if (ret) + return ret; + if (dev_id < 0) + return -EINVAL; + + mutex_lock(&zram_index_mutex); + + zram = idr_find(&zram_index_idr, dev_id); + if (zram) + ret = zram_remove(zram); + else + ret = -ENODEV; + + mutex_unlock(&zram_index_mutex); + return ret ? ret : count; } +static struct class_attribute zram_control_class_attrs[] = { + __ATTR_RO(hot_add), + __ATTR_WO(hot_remove), + __ATTR_NULL, +}; + +static struct class zram_control_class = { + .name = "zram-control", + .owner = THIS_MODULE, + .class_attrs = zram_control_class_attrs, +}; + static int zram_remove_cb(int id, void *ptr, void *data) { zram_remove(ptr); @@ -1299,6 +1383,7 @@ static int zram_remove_cb(int id, void *ptr, void *data) static void destroy_devices(void) { + class_unregister(&zram_control_class); idr_for_each(&zram_index_idr, &zram_remove_cb, NULL); idr_destroy(&zram_index_idr); unregister_blkdev(zram_major, "zram"); @@ -1308,14 +1393,23 @@ static int __init zram_init(void) { int ret; + ret = class_register(&zram_control_class); + if (ret) { + pr_warn("Unable to register zram-control class\n"); + return ret; + } + zram_major = register_blkdev(0, "zram"); if (zram_major <= 0) { pr_warn("Unable to get major number\n"); + class_unregister(&zram_control_class); return -EBUSY; } while (num_devices != 0) { + mutex_lock(&zram_index_mutex); ret = zram_add(); + mutex_unlock(&zram_index_mutex); if (ret < 0) goto out_error; num_devices--; |