From 4cd989fdc75241cd9c183ff3f9a2a384f0246ae1 Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Fri, 31 May 2013 17:40:45 -0500 Subject: [PATCH] rbd: use rwsem to protect header updates Updating an image header needs to be protected to ensure it's done consistently. However distinct headers can be updated concurrently without a problem. Instead of using the global control lock to serialize headder updates, just rely on the header semaphore. (It's already used, this just moves it out to cover a broader section of the code.) That leaves the control mutex protecting only the creation of rbd clients, so rename it. This resolves: http://tracker.ceph.com/issues/5222 Signed-off-by: Alex Elder Reviewed-by: Josh Durgin --- drivers/block/rbd.c | 26 ++++++++++---------------- 1 file changed, 10 insertions(+), 16 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 8258c90cfa38..14afe36e8ab0 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -372,7 +372,7 @@ enum rbd_dev_flags { RBD_DEV_FLAG_REMOVING, /* this mapping is being removed */ }; -static DEFINE_MUTEX(ctl_mutex); /* Serialize open/close/setup/teardown */ +static DEFINE_MUTEX(client_mutex); /* Serialize client creation */ static LIST_HEAD(rbd_dev_list); /* devices */ static DEFINE_SPINLOCK(rbd_dev_list_lock); @@ -518,7 +518,7 @@ static const struct block_device_operations rbd_bd_ops = { /* * Initialize an rbd client instance. Success or not, this function - * consumes ceph_opts. Caller holds ctl_mutex. + * consumes ceph_opts. Caller holds client_mutex. */ static struct rbd_client *rbd_client_create(struct ceph_options *ceph_opts) { @@ -675,13 +675,13 @@ static struct rbd_client *rbd_get_client(struct ceph_options *ceph_opts) { struct rbd_client *rbdc; - mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING); + mutex_lock_nested(&client_mutex, SINGLE_DEPTH_NESTING); rbdc = rbd_client_find(ceph_opts); if (rbdc) /* using an existing client */ ceph_destroy_options(ceph_opts); else rbdc = rbd_client_create(ceph_opts); - mutex_unlock(&ctl_mutex); + mutex_unlock(&client_mutex); return rbdc; } @@ -835,7 +835,6 @@ static int rbd_header_from_disk(struct rbd_device *rbd_dev, /* We won't fail any more, fill in the header */ - down_write(&rbd_dev->header_rwsem); if (first_time) { header->object_prefix = object_prefix; header->obj_order = ondisk->options.order; @@ -864,8 +863,6 @@ static int rbd_header_from_disk(struct rbd_device *rbd_dev, if (rbd_dev->mapping.size != header->image_size) rbd_dev->mapping.size = header->image_size; - up_write(&rbd_dev->header_rwsem); - return 0; out_2big: ret = -EIO; @@ -3353,7 +3350,7 @@ static int rbd_dev_refresh(struct rbd_device *rbd_dev) int ret; rbd_assert(rbd_image_format_valid(rbd_dev->image_format)); - mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING); + down_write(&rbd_dev->header_rwsem); mapping_size = rbd_dev->mapping.size; if (rbd_dev->image_format == 1) ret = rbd_dev_v1_header_info(rbd_dev); @@ -3363,7 +3360,8 @@ static int rbd_dev_refresh(struct rbd_device *rbd_dev) /* If it's a mapped snapshot, validate its EXISTS flag */ rbd_exists_validate(rbd_dev); - mutex_unlock(&ctl_mutex); + up_write(&rbd_dev->header_rwsem); + if (mapping_size != rbd_dev->mapping.size) { sector_t size; @@ -4292,12 +4290,10 @@ static int rbd_dev_v2_header_info(struct rbd_device *rbd_dev) bool first_time = rbd_dev->header.object_prefix == NULL; int ret; - down_write(&rbd_dev->header_rwsem); - if (first_time) { ret = rbd_dev_v2_header_onetime(rbd_dev); if (ret) - goto out; + return ret; } /* @@ -4312,7 +4308,7 @@ static int rbd_dev_v2_header_info(struct rbd_device *rbd_dev) ret = rbd_dev_v2_parent_info(rbd_dev); if (ret) - goto out; + return ret; /* * Print a warning if this is the initial probe and @@ -4329,7 +4325,7 @@ static int rbd_dev_v2_header_info(struct rbd_device *rbd_dev) ret = rbd_dev_v2_image_size(rbd_dev); if (ret) - goto out; + return ret; if (rbd_dev->spec->snap_id == CEPH_NOSNAP) if (rbd_dev->mapping.size != rbd_dev->header.image_size) @@ -4337,8 +4333,6 @@ static int rbd_dev_v2_header_info(struct rbd_device *rbd_dev) ret = rbd_dev_v2_snap_context(rbd_dev); dout("rbd_dev_v2_snap_context returned %d\n", ret); -out: - up_write(&rbd_dev->header_rwsem); return ret; } -- 2.39.5