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rbd: move snap_rwsem to the device, rename to header_rwsem 

A new temporary header is allocated each time the header changes, but
only the changed properties are copied over. We don't need a new
semaphore for each header update.

This addresses http://tracker.newdream.net/issues/2174

Signed-off-by: Josh Durgin <josh.durgin@dreamhost.com>
Reviewed-by: Alex Elder <elder@dreamhost.com>
This commit is contained in:
Josh Durgin 2011-11-21 17:11:12 -08:00 committed by Alex Elder
parent 3489b42a72
commit c666601a93
1 changed files with 11 additions and 11 deletions
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22
drivers/block/rbd.c
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@ -82,7 +82,6 @@ struct rbd_image_header {
__u8 obj_order;
__u8 crypt_type;
__u8 comp_type;
struct rw_semaphore snap_rwsem;
struct ceph_snap_context *snapc;
size_t snap_names_len;
u64 snap_seq;
@ -173,6 +172,8 @@ struct rbd_device {
struct ceph_osd_event *watch_event;
struct ceph_osd_request *watch_request;
/* protects updating the header */
struct rw_semaphore header_rwsem;
char snap_name[RBD_MAX_SNAP_NAME_LEN];
u32 cur_snap; /* index+1 of current snapshot within snap context
0 - for the head */
@ -502,7 +503,6 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
if (!header->snapc)
return -ENOMEM;
init_rwsem(&header->snap_rwsem);
header->snap_names_len = le64_to_cpu(ondisk->snap_names_len);
if (snap_count) {
header->snap_names = kmalloc(header->snap_names_len,
@ -597,7 +597,7 @@ static int rbd_header_set_snap(struct rbd_device *dev, u64 *size)
BUILD_BUG_ON(sizeof (dev->snap_name) < sizeof (RBD_SNAP_HEAD_NAME));
down_write(&header->snap_rwsem);
down_write(&dev->header_rwsem);
if (!memcmp(dev->snap_name, RBD_SNAP_HEAD_NAME,
sizeof (RBD_SNAP_HEAD_NAME))) {
@ -620,7 +620,7 @@ static int rbd_header_set_snap(struct rbd_device *dev, u64 *size)
ret = 0;
done:
up_write(&header->snap_rwsem);
up_write(&dev->header_rwsem);
return ret;
}
@ -887,7 +887,6 @@ static int rbd_do_request(struct request *rq,
struct timespec mtime = CURRENT_TIME;
struct rbd_request *req_data;
struct ceph_osd_request_head *reqhead;
struct rbd_image_header *header = &dev->header;
struct ceph_osd_client *osdc;
req_data = kzalloc(sizeof(*req_data), GFP_NOIO);
@ -905,13 +904,13 @@ static int rbd_do_request(struct request *rq,
dout("rbd_do_request obj=%s ofs=%lld len=%lld\n", obj, len, ofs);
down_read(&header->snap_rwsem);
down_read(&dev->header_rwsem);
osdc = &dev->rbd_client->client->osdc;
req = ceph_osdc_alloc_request(osdc, flags, snapc, ops,
false, GFP_NOIO, pages, bio);
if (!req) {
up_read(&header->snap_rwsem);
up_read(&dev->header_rwsem);
ret = -ENOMEM;
goto done_pages;
}
@ -946,7 +945,7 @@ static int rbd_do_request(struct request *rq,
snapc,
&mtime,
req->r_oid, req->r_oid_len);
up_read(&header->snap_rwsem);
up_read(&dev->header_rwsem);
if (linger_req) {
ceph_osdc_set_request_linger(osdc, req);
@ -1718,7 +1717,7 @@ static int __rbd_update_snaps(struct rbd_device *rbd_dev)
/* resized? */
set_capacity(rbd_dev->disk, h.image_size / SECTOR_SIZE);
down_write(&rbd_dev->header.snap_rwsem);
down_write(&rbd_dev->header_rwsem);
snap_seq = rbd_dev->header.snapc->seq;
if (rbd_dev->header.total_snaps &&
@ -1743,7 +1742,7 @@ static int __rbd_update_snaps(struct rbd_device *rbd_dev)
ret = __rbd_init_snaps_header(rbd_dev);
up_write(&rbd_dev->header.snap_rwsem);
up_write(&rbd_dev->header_rwsem);
return ret;
}
@ -2380,8 +2379,9 @@ static ssize_t rbd_add(struct bus_type *bus,
spin_lock_init(&rbd_dev->lock);
INIT_LIST_HEAD(&rbd_dev->node);
INIT_LIST_HEAD(&rbd_dev->snaps);
init_rwsem(&rbd_dev->header_rwsem);
init_rwsem(&rbd_dev->header.snap_rwsem);
init_rwsem(&rbd_dev->header_rwsem);
/* generate unique id: find highest unique id, add one */
rbd_id_get(rbd_dev);