From 589d30e0b3e649e2660f9a67be88e235b28bc319 Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Tue, 10 Jul 2012 20:30:11 -0500 Subject: [PATCH] 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//image_id) that makes this information available. Signed-off-by: Alex Elder Reviewed-by: Josh Durgin --- Documentation/ABI/testing/sysfs-bus-rbd | 5 ++ drivers/block/rbd.c | 100 ++++++++++++++++++++++++ 2 files changed, 105 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-rbd b/Documentation/ABI/testing/sysfs-bus-rbd index 3c17b62899f..7cbbe343af5 100644 --- a/Documentation/ABI/testing/sysfs-bus-rbd +++ b/Documentation/ABI/testing/sysfs-bus-rbd @@ -33,6 +33,11 @@ name The name of the rbd image. +image_id + + The unique id for the rbd image. (For rbd image format 1 + this is empty.) + pool The name of the storage pool where this rbd image resides. diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index b8956131950..34f46c3b188 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -66,6 +66,8 @@ #define RBD_SNAP_HEAD_NAME "-" +#define RBD_IMAGE_ID_LEN_MAX 64 + /* * An RBD device name will be "rbd#", where the "rbd" comes from * RBD_DRV_NAME above, and # is a unique integer identifier. @@ -173,6 +175,8 @@ struct rbd_device { spinlock_t lock; /* queue lock */ struct rbd_image_header header; + char *image_id; + size_t image_id_len; char *image_name; size_t image_name_len; char *header_name; @@ -1987,6 +1991,14 @@ static ssize_t rbd_name_show(struct device *dev, return sprintf(buf, "%s\n", rbd_dev->image_name); } +static ssize_t rbd_image_id_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct rbd_device *rbd_dev = dev_to_rbd_dev(dev); + + return sprintf(buf, "%s\n", rbd_dev->image_id); +} + static ssize_t rbd_snap_show(struct device *dev, struct device_attribute *attr, char *buf) @@ -2015,6 +2027,7 @@ static DEVICE_ATTR(client_id, S_IRUGO, rbd_client_id_show, NULL); static DEVICE_ATTR(pool, S_IRUGO, rbd_pool_show, NULL); static DEVICE_ATTR(pool_id, S_IRUGO, rbd_pool_id_show, NULL); static DEVICE_ATTR(name, S_IRUGO, rbd_name_show, NULL); +static DEVICE_ATTR(image_id, S_IRUGO, rbd_image_id_show, NULL); static DEVICE_ATTR(refresh, S_IWUSR, NULL, rbd_image_refresh); static DEVICE_ATTR(current_snap, S_IRUGO, rbd_snap_show, NULL); static DEVICE_ATTR(create_snap, S_IWUSR, NULL, rbd_snap_add); @@ -2026,6 +2039,7 @@ static struct attribute *rbd_attrs[] = { &dev_attr_pool.attr, &dev_attr_pool_id.attr, &dev_attr_name.attr, + &dev_attr_image_id.attr, &dev_attr_current_snap.attr, &dev_attr_refresh.attr, &dev_attr_create_snap.attr, @@ -2553,6 +2567,75 @@ out_err: return err_ptr; } +/* + * An rbd format 2 image has a unique identifier, distinct from the + * name given to it by the user. Internally, that identifier is + * what's used to specify the names of objects related to the image. + * + * A special "rbd id" object is used to map an rbd image name to its + * id. If that object doesn't exist, then there is no v2 rbd image + * with the supplied name. + * + * This function will record the given rbd_dev's image_id field if + * it can be determined, and in that case will return 0. If any + * errors occur a negative errno will be returned and the rbd_dev's + * image_id field will be unchanged (and should be NULL). + */ +static int rbd_dev_image_id(struct rbd_device *rbd_dev) +{ + int ret; + size_t size; + char *object_name; + void *response; + void *p; + + /* + * First, see if the format 2 image id file exists, and if + * so, get the image's persistent id from it. + */ + size = sizeof (RBD_ID_PREFIX) + rbd_dev->image_name_len; + object_name = kmalloc(size, GFP_NOIO); + if (!object_name) + return -ENOMEM; + sprintf(object_name, "%s%s", RBD_ID_PREFIX, rbd_dev->image_name); + dout("rbd id object name is %s\n", object_name); + + /* Response will be an encoded string, which includes a length */ + + size = sizeof (__le32) + RBD_IMAGE_ID_LEN_MAX; + response = kzalloc(size, GFP_NOIO); + if (!response) { + ret = -ENOMEM; + goto out; + } + + ret = rbd_req_sync_exec(rbd_dev, object_name, + "rbd", "get_id", + NULL, 0, + response, RBD_IMAGE_ID_LEN_MAX, + CEPH_OSD_FLAG_READ, NULL); + dout("%s: rbd_req_sync_exec returned %d\n", __func__, ret); + if (ret < 0) + goto out; + + p = response; + rbd_dev->image_id = ceph_extract_encoded_string(&p, + p + RBD_IMAGE_ID_LEN_MAX, + &rbd_dev->image_id_len, + GFP_NOIO); + if (IS_ERR(rbd_dev->image_id)) { + ret = PTR_ERR(rbd_dev->image_id); + rbd_dev->image_id = NULL; + } else { + dout("image_id is %s\n", rbd_dev->image_id); + } +out: + kfree(response); + kfree(object_name); + + return ret; +} + static ssize_t rbd_add(struct bus_type *bus, const char *buf, size_t count) @@ -2600,6 +2683,21 @@ static ssize_t rbd_add(struct bus_type *bus, goto err_out_client; rbd_dev->pool_id = rc; + rc = rbd_dev_image_id(rbd_dev); + if (!rc) { + rc = -ENOTSUPP; /* Not actually supporting format 2 yet */ + goto err_out_client; + } + + /* Version 1 images have no id; empty string is used */ + + rbd_dev->image_id = kstrdup("", GFP_KERNEL); + if (!rbd_dev->image_id) { + rc = -ENOMEM; + goto err_out_client; + } + rbd_dev->image_id_len = 0; + /* Create the name of the header object */ rbd_dev->header_name = kmalloc(rbd_dev->image_name_len @@ -2691,6 +2789,7 @@ err_out_header: err_out_client: kfree(rbd_dev->header_name); rbd_put_client(rbd_dev); + kfree(rbd_dev->image_id); err_out_args: kfree(rbd_dev->mapping.snap_name); kfree(rbd_dev->image_name); @@ -2746,6 +2845,7 @@ static void rbd_dev_release(struct device *dev) /* done with the id, and with the rbd_dev */ kfree(rbd_dev->mapping.snap_name); + kfree(rbd_dev->image_id); kfree(rbd_dev->header_name); kfree(rbd_dev->pool_name); kfree(rbd_dev->image_name); -- 2.46.0