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rbd: separate mapping info in rbd_dev 

Several fields in a struct rbd_dev are related to what is mapped, as
opposed to the actual base rbd image.  If the base image is mapped
these are almost unneeded, but if a snapshot is mapped they describe
information about that snapshot.

In some contexts this can be a little bit confusing.  So group these
mapping-related field into a structure to make it clear what they
are describing.

This also includes a minor change that rearranges the fields in the
in-core image header structure so that invariant fields are at the
top, followed by those that change.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This commit is contained in:
Alex Elder 2012-08-31 17:29:51 -05:00
parent c9aadfe786
commit f84344f334
1 changed files with 45 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

83
drivers/block/rbd.c
View File

@ -81,13 +81,15 @@
* block device image metadata (in-memory version)
*/
struct rbd_image_header {
u64 image_size;
/* These four fields never change for a given rbd image */
char *object_prefix;
__u8 obj_order;
__u8 crypt_type;
__u8 comp_type;
struct ceph_snap_context *snapc;
/* The remaining fields need to be updated occasionally */
u64 image_size;
struct ceph_snap_context *snapc;
char *snap_names;
u64 *snap_sizes;
@ -146,6 +148,13 @@ struct rbd_snap {
u64 id;
};
struct rbd_mapping {
char *snap_name;
u64 snap_id;
bool snap_exists;
bool read_only;
};
/*
* a single device
*/
@ -174,13 +183,8 @@ struct rbd_device {
/* protects updating the header */
struct rw_semaphore header_rwsem;
/* name of the snapshot this device reads from */
char *snap_name;
/* id of the snapshot this device reads from */
u64 snap_id; /* current snapshot id */
/* whether the snap_id this device reads from still exists */
bool snap_exists;
bool read_only;
struct rbd_mapping mapping;
struct list_head node;
@ -261,11 +265,11 @@ static int rbd_open(struct block_device *bdev, fmode_t mode)
{
struct rbd_device *rbd_dev = bdev->bd_disk->private_data;
if ((mode & FMODE_WRITE) && rbd_dev->read_only)
if ((mode & FMODE_WRITE) && rbd_dev->mapping.read_only)
return -EROFS;
rbd_get_dev(rbd_dev);
set_device_ro(bdev, rbd_dev->read_only);
set_device_ro(bdev, rbd_dev->mapping.read_only);
return 0;
}
@ -375,7 +379,7 @@ enum {
static match_table_t rbd_opts_tokens = {
/* int args above */
/* string args above */
{Opt_read_only, "read_only"},
{Opt_read_only, "mapping.read_only"},
{Opt_read_only, "ro"}, /* Alternate spelling */
{Opt_read_write, "read_write"},
{Opt_read_write, "rw"}, /* Alternate spelling */
@ -583,13 +587,13 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
header->snap_sizes = NULL;
}
header->image_size = le64_to_cpu(ondisk->image_size);
header->obj_order = ondisk->options.order;
header->crypt_type = ondisk->options.crypt_type;
header->comp_type = ondisk->options.comp_type;
/* Allocate and fill in the snapshot context */
header->image_size = le64_to_cpu(ondisk->image_size);
size = sizeof (struct ceph_snap_context);
size += snap_count * sizeof (header->snapc->snaps[0]);
header->snapc = kzalloc(size, GFP_KERNEL);
@ -645,23 +649,24 @@ static int rbd_header_set_snap(struct rbd_device *rbd_dev, u64 *size)
down_write(&rbd_dev->header_rwsem);
if (!memcmp(rbd_dev->snap_name, RBD_SNAP_HEAD_NAME,
if (!memcmp(rbd_dev->mapping.snap_name, RBD_SNAP_HEAD_NAME,
sizeof (RBD_SNAP_HEAD_NAME))) {
rbd_dev->snap_id = CEPH_NOSNAP;
rbd_dev->snap_exists = false;
rbd_dev->read_only = rbd_dev->rbd_opts.read_only;
rbd_dev->mapping.snap_id = CEPH_NOSNAP;
rbd_dev->mapping.snap_exists = false;
rbd_dev->mapping.read_only = rbd_dev->rbd_opts.read_only;
if (size)
*size = rbd_dev->header.image_size;
} else {
u64 snap_id = 0;
ret = snap_by_name(&rbd_dev->header, rbd_dev->snap_name,
ret = snap_by_name(&rbd_dev->header,
rbd_dev->mapping.snap_name,
&snap_id, size);
if (ret < 0)
goto done;
rbd_dev->snap_id = snap_id;
rbd_dev->snap_exists = true;
rbd_dev->read_only = true; /* No choice for snapshots */
rbd_dev->mapping.snap_id = snap_id;
rbd_dev->mapping.snap_exists = true;
rbd_dev->mapping.read_only = true;
}
ret = 0;
@ -1532,7 +1537,7 @@ static void rbd_rq_fn(struct request_queue *q)
size = blk_rq_bytes(rq);
ofs = blk_rq_pos(rq) * SECTOR_SIZE;
rq_bio = rq->bio;
if (do_write && rbd_dev->read_only) {
if (do_write && rbd_dev->mapping.read_only) {
__blk_end_request_all(rq, -EROFS);
continue;
}
@ -1541,7 +1546,8 @@ static void rbd_rq_fn(struct request_queue *q)
down_read(&rbd_dev->header_rwsem);
if (rbd_dev->snap_id != CEPH_NOSNAP && !rbd_dev->snap_exists) {
if (rbd_dev->mapping.snap_id != CEPH_NOSNAP &&
!rbd_dev->mapping.snap_exists) {
up_read(&rbd_dev->header_rwsem);
dout("request for non-existent snapshot");
spin_lock_irq(q->queue_lock);
@ -1595,7 +1601,7 @@ static void rbd_rq_fn(struct request_queue *q)
coll, cur_seg);
else
rbd_req_read(rq, rbd_dev,
rbd_dev->snap_id,
rbd_dev->mapping.snap_id,
ofs,
op_size, bio,
coll, cur_seg);
@ -1767,7 +1773,7 @@ static int rbd_header_add_snap(struct rbd_device *rbd_dev,
struct ceph_mon_client *monc;
/* we should create a snapshot only if we're pointing at the head */
if (rbd_dev->snap_id != CEPH_NOSNAP)
if (rbd_dev->mapping.snap_id != CEPH_NOSNAP)
return -EINVAL;
monc = &rbd_dev->rbd_client->client->monc;
@ -1821,7 +1827,7 @@ static int __rbd_refresh_header(struct rbd_device *rbd_dev, u64 *hver)
down_write(&rbd_dev->header_rwsem);
/* resized? */
if (rbd_dev->snap_id == CEPH_NOSNAP) {
if (rbd_dev->mapping.snap_id == CEPH_NOSNAP) {
sector_t size = (sector_t) h.image_size / SECTOR_SIZE;
dout("setting size to %llu sectors", (unsigned long long) size);
@ -2004,7 +2010,7 @@ static ssize_t rbd_snap_show(struct device *dev,
{
struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
return sprintf(buf, "%s\n", rbd_dev->snap_name);
return sprintf(buf, "%s\n", rbd_dev->mapping.snap_name);
}
static ssize_t rbd_image_refresh(struct device *dev,
@ -2205,11 +2211,12 @@ static int rbd_dev_snap_devs_update(struct rbd_device *rbd_dev)
/* Existing snapshot not in the new snap context */
if (rbd_dev->snap_id == snap->id)
rbd_dev->snap_exists = false;
if (rbd_dev->mapping.snap_id == snap->id)
rbd_dev->mapping.snap_exists = false;
__rbd_remove_snap_dev(snap);
dout("%ssnap id %llu has been removed\n",
rbd_dev->snap_id == snap->id ? "mapped " : "",
rbd_dev->mapping.snap_id == snap->id ?
"mapped " : "",
(unsigned long long) snap->id);
/* Done with this list entry; advance */
@ -2522,18 +2529,18 @@ static int rbd_add_parse_args(struct rbd_device *rbd_dev,
* The snapshot name is optional. If none is is supplied,
* we use the default value.
*/
rbd_dev->snap_name = dup_token(&buf, &len);
if (!rbd_dev->snap_name)
rbd_dev->mapping.snap_name = dup_token(&buf, &len);
if (!rbd_dev->mapping.snap_name)
goto out_err;
if (!len) {
/* Replace the empty name with the default */
kfree(rbd_dev->snap_name);
rbd_dev->snap_name
kfree(rbd_dev->mapping.snap_name);
rbd_dev->mapping.snap_name
= kmalloc(sizeof (RBD_SNAP_HEAD_NAME), GFP_KERNEL);
if (!rbd_dev->snap_name)
if (!rbd_dev->mapping.snap_name)
goto out_err;
memcpy(rbd_dev->snap_name, RBD_SNAP_HEAD_NAME,
memcpy(rbd_dev->mapping.snap_name, RBD_SNAP_HEAD_NAME,
sizeof (RBD_SNAP_HEAD_NAME));
}
@ -2642,7 +2649,7 @@ err_out_client:
rbd_put_client(rbd_dev);
err_put_id:
if (rbd_dev->pool_name) {
kfree(rbd_dev->snap_name);
kfree(rbd_dev->mapping.snap_name);
kfree(rbd_dev->header_name);
kfree(rbd_dev->image_name);
kfree(rbd_dev->pool_name);
@ -2695,7 +2702,7 @@ static void rbd_dev_release(struct device *dev)
unregister_blkdev(rbd_dev->major, rbd_dev->name);
/* done with the id, and with the rbd_dev */
kfree(rbd_dev->snap_name);
kfree(rbd_dev->mapping.snap_name);
kfree(rbd_dev->header_name);
kfree(rbd_dev->pool_name);
kfree(rbd_dev->image_name);