Messages in this thread Patch in this message | | | From | Sergey Senozhatsky <> | Subject | [PATCHv2 5/7] zram: add dynamic device add/remove functionality | Date | Sun, 1 Mar 2015 17:42:41 +0900 |
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Introduce zram-control sysfs class, which has two sysfs attrs: - zram_add -- add a new specific (device_id) zram device - zram_remove -- remove a specific (device_id) zram device
Usage example: # add a new specific zram device echo 4 > /sys/class/zram-control/zram_add
# remove a specific zram device echo 4 > /sys/class/zram-control/zram_remove
There is no automatic device_id generation, so user is expected to provide one.
NOTE, there might be users who already depend on the fact that at least zram0 device gets always created by zram_init(). Thus, due to compatibility reasons, along with requested device_id (f.e. 5) zram0 will also be created.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> --- Documentation/ABI/testing/sysfs-class-zram | 23 ++++++ drivers/block/zram/zram_drv.c | 117 +++++++++++++++++++++++++++++ 2 files changed, 140 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-class-zram
diff --git a/Documentation/ABI/testing/sysfs-class-zram b/Documentation/ABI/testing/sysfs-class-zram new file mode 100644 index 0000000..4cbde8d --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-zram @@ -0,0 +1,23 @@ +What: /sys/class/zram-control/ +Date: March 2015 +KernelVersion: 4.0 +Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> +Description: + The zram-control/ class sub-directory belongs to zram + device class + +What: /sys/class/zram-control/zram_add +Date: March 2015 +KernelVersion: 4.0 +Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> +Description: + Add a specific /dev/zramX device, where X is a device_id + provided by user + + What: /sys/class/zram-control/zram_add +Date: March 2015 +KernelVersion: 4.0 +Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> +Description: + Remove a specific /dev/zramX device, where X is a device_id + provided by user diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index bab8b20..8609c92 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -33,16 +33,23 @@ #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"; /* Module params (documentation at end) */ static unsigned int num_devices = 1; +#define ZRAM_CTL_ADD 1 +#define ZRAM_CTL_REMOVE 2 + #define ZRAM_ATTR_RO(name) \ static ssize_t name##_show(struct device *d, \ struct device_attribute *attr, char *b) \ @@ -1173,6 +1180,107 @@ static void zram_remove(struct zram *zram) kfree(zram); } +/* lookup if there is any device pointer that match the given device_id. + * return device pointer if so, or ERR_PTR() otherwise. */ +static struct zram *zram_lookup(int dev_id) +{ + struct zram *zram; + + zram = idr_find(&zram_index_idr, dev_id); + if (zram) + return zram; + return ERR_PTR(-ENODEV); +} + +/* common zram-control add/remove handler */ +static int zram_control(int cmd, const char *buf) +{ + struct zram *zram; + int ret = -ENOSYS, err, dev_id; + + /* dev_id is gendisk->first_minor, which is `int' */ + ret = kstrtoint(buf, 10, &dev_id); + if (ret || dev_id < 0) + return ret; + + mutex_lock(&zram_index_mutex); + zram = zram_lookup(dev_id); + + switch (cmd) { + case ZRAM_CTL_ADD: + if (!IS_ERR(zram)) { + ret = -EEXIST; + break; + } + ret = zram_add(dev_id); + break; + case ZRAM_CTL_REMOVE: + if (IS_ERR(zram)) { + ret = PTR_ERR(zram); + break; + } + + /* First, make ->disksize device attr RO, closing + * ZRAM_CTL_REMOVE vs disksize_store() race window */ + ret = sysfs_chmod_file(&disk_to_dev(zram->disk)->kobj, + &dev_attr_disksize.attr, S_IRUGO); + if (ret) + break; + + ret = zram_reset_device(zram); + if (ret == 0) { + /* ->disksize is RO and there are no ->bd_openers */ + zram_remove(zram); + break; + } + + /* If there are still device bd_openers, try to make ->disksize + * RW again and return. even if we fail to make ->disksize RW, + * user still has RW ->reset attr. so it's possible to destroy + * that device */ + err = sysfs_chmod_file(&disk_to_dev(zram->disk)->kobj, + &dev_attr_disksize.attr, + S_IWUSR | S_IRUGO); + if (err) + ret = err; + break; + } + mutex_unlock(&zram_index_mutex); + + return ret; +} + +/* zram module control sysfs attributes */ +static ssize_t zram_add_store(struct class *class, + struct class_attribute *attr, + const char *buf, + size_t count) +{ + int ret = zram_control(ZRAM_CTL_ADD, buf); + return ret ? ret : count; +} + +static ssize_t zram_remove_store(struct class *class, + struct class_attribute *attr, + const char *buf, + size_t count) +{ + int ret = zram_control(ZRAM_CTL_REMOVE, buf); + return ret ? ret : count; +} + +static struct class_attribute zram_control_class_attrs[] = { + __ATTR_WO(zram_add), + __ATTR_WO(zram_remove), + __ATTR_NULL, +}; + +static struct class zram_control_class = { + .name = "zram-control", + .owner = THIS_MODULE, + .class_attrs = zram_control_class_attrs, +}; + static int zram_exit_cb(int id, void *ptr, void *data) { zram_remove(ptr); @@ -1181,6 +1289,7 @@ static int zram_exit_cb(int id, void *ptr, void *data) static void destroy_devices(void) { + class_destroy(&zram_control_class); idr_for_each(&zram_index_idr, &zram_exit_cb, NULL); idr_destroy(&zram_index_idr); unregister_blkdev(zram_major, "zram"); @@ -1197,6 +1306,12 @@ static int __init zram_init(void) return -EINVAL; } + 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"); @@ -1204,7 +1319,9 @@ static int __init zram_init(void) } for (dev_id = 0; dev_id < num_devices; dev_id++) { + mutex_lock(&zram_index_mutex); ret = zram_add(dev_id); + mutex_unlock(&zram_index_mutex); if (ret != 0) goto out_error; } -- 2.3.1.167.g7f4ba4b
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