orangefs: fix orangefs_superblock locking
* switch orangefs_remount() to taking ORANGEFS_SB(sb) instead of sb
* remove from the list _before_ orangefs_unmount() - request_mutex
in the latter will make sure that nothing observed in the loop in
ORANGEFS_DEV_REMOUNT_ALL handling will get freed until the end
of loop
* on removal, keep the forward pointer and zero the back one. That
way we can drop and regain the spinlock in the loop body (again,
ORANGEFS_DEV_REMOUNT_ALL one) and still be able to get to the
rest of the list.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>
diff --git a/fs/orangefs/super.c b/fs/orangefs/super.c
index 5a89b80..b9da9a0 100644
--- a/fs/orangefs/super.c
+++ b/fs/orangefs/super.c
@@ -210,7 +210,7 @@
* the client regains all of the mount information from us.
* NOTE: this function assumes that the request_mutex is already acquired!
*/
-int orangefs_remount(struct super_block *sb)
+int orangefs_remount(struct orangefs_sb_info_s *orangefs_sb)
{
struct orangefs_kernel_op_s *new_op;
int ret = -EINVAL;
@@ -221,7 +221,7 @@
if (!new_op)
return -ENOMEM;
strncpy(new_op->upcall.req.fs_mount.orangefs_config_server,
- ORANGEFS_SB(sb)->devname,
+ orangefs_sb->devname,
ORANGEFS_MAX_SERVER_ADDR_LEN);
gossip_debug(GOSSIP_SUPER_DEBUG,
@@ -244,8 +244,8 @@
* short-lived mapping that the system interface uses
* to map this superblock to a particular mount entry
*/
- ORANGEFS_SB(sb)->id = new_op->downcall.resp.fs_mount.id;
- ORANGEFS_SB(sb)->mount_pending = 0;
+ orangefs_sb->id = new_op->downcall.resp.fs_mount.id;
+ orangefs_sb->mount_pending = 0;
}
op_release(new_op);
@@ -485,7 +485,12 @@
* finally, add this sb to our list of known orangefs
* sb's
*/
- add_orangefs_sb(sb);
+ gossip_debug(GOSSIP_SUPER_DEBUG,
+ "Adding SB %p to orangefs superblocks\n",
+ ORANGEFS_SB(sb));
+ spin_lock(&orangefs_superblocks_lock);
+ list_add_tail(&ORANGEFS_SB(sb)->list, &orangefs_superblocks);
+ spin_unlock(&orangefs_superblocks_lock);
op_release(new_op);
return dget(sb->s_root);
@@ -512,10 +517,21 @@
* issue the unmount to userspace to tell it to remove the
* dynamic mount info it has for this superblock
*/
- orangefs_unmount_sb(sb);
+ orangefs_unmount_sb(sb);
/* remove the sb from our list of orangefs specific sb's */
- remove_orangefs_sb(sb);
+
+ spin_lock(&orangefs_superblocks_lock);
+ __list_del_entry(&ORANGEFS_SB(sb)->list); /* not list_del_init */
+ ORANGEFS_SB(sb)->list.prev = NULL;
+ spin_unlock(&orangefs_superblocks_lock);
+
+ /*
+ * make sure that ORANGEFS_DEV_REMOUNT_ALL loop that might've seen us
+ * gets completed before we free the dang thing.
+ */
+ mutex_lock(&request_mutex);
+ mutex_unlock(&request_mutex);
/* free the orangefs superblock private data */
kfree(ORANGEFS_SB(sb));