(Re-posting Josh's prescient patch--it fixes a newly identified issue.)
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@xxxxxxxxxxxxx>
Reviewed-by: Alex Elder <elder@xxxxxxxxxxxxx>
---
drivers/block/rbd.c | 20 ++++++++++----------
1 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index bc75d82..50117dd 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -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;
}
@@ -2380,6 +2379,7 @@ 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);
/* generate unique id: find highest unique id, add one */
rbd_id_get(rbd_dev);
--
1.7.5.4
--
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