dnbd3.git/src/kernel/dnbd3_main.h, branch isfant

[KERNEL] Add Rocky 9 support

2023-06-07T16:11:43+00:00

Co-authored-by: Jonathan Bauer Co-authored-by: Manuel Messner

Fix linter issues to satisfy Linux kernel code style

2022-10-05T05:46:29+00:00

[KERNEL] Refactor to use workqueues and blk-mq only

2022-02-18T20:34:55+00:00

Using workqueues frees us from having to manage the lifecycle of three dedicated threads. Discovery (alt server checks) and sending keepalive packets is now done using work on the power efficient system queue. Sending and receiving happens via dedicated work queues with higher priority. blk-mq has also been around for quite a while in the kernel, so switching to it doesn't hurt backwards compatibility. As the code is now refactored to work more as blk-mq is designed, backwards compatibility even improved while at the same time freeing us from an arsenal of macros that were required to make the blk-mq port look and feel like the old implementation. For example, the code now compiles on CentOS 7 with kernel 3.10 without requiring special macros to detect the heavily modified RedHat kernel with all its backported features. A few other design limitations have been rectified along the way, e.g. switching to another server now doesn't internally disconnect from the current one first, which theoretically could lead to a non-working setup, if the new server isn't reachable and then - because of some transient network error - switching back also fails. As the discover-thread was torn down from the disconnect call, the connection would also not repair itself eventually. we now establish the new connection in parallel to the old one, and only if that succeeds do we replace the old one with it, similar to how the automatic alt-server switch already does it.

[KERNEL] Add support for Linux kernels without blk-mq (e.g. CentOS 7)

2021-06-16T09:41:00+00:00

[KERNEL] Removes duplicate word 'of' in license headers

2021-04-16T06:20:06+00:00

[KERNEL] Implement best_count logic for load balancing

2021-03-26T12:44:47+00:00

Similar logic already exists in the fuse client: Count how many times in a row a server was fastest when measuring RTTs, and lower the switching threshold more the higher the count gets.

[KERNEL] Use sockaddr instead of dnbd3_host_t where possible

2021-03-24T15:07:15+00:00

Convert dnbd3_host_t to struct sockaddr immediately when adding alt servers, so we don't have to convert it every time we establish a connection. Additionally we can now use %pISpc in printf-like functions instead of having if/else constructs whenever we want to print an address.

[KERNEL] Synchronous add/remove of alt-servers via IOCTL

2021-03-23T15:00:55+00:00

[KERNEL] Refactor code to satisfy Linux kernel code style

2021-03-12T13:52:47+00:00

[KERNEL] Fix several connect/disconnect race conditions

2020-11-19T12:48:14+00:00

Previously disconnect was protected against concurrent calls, but connect wasn't. It was easy to crash the kernel when calling connect and disconnect IOCTLs in a tight loop concurrently. A global lock was introduced to make sure only one caller can change the connection state at a time. dev->connection_lock needs to be aquired when calling dnbd3_net_connect or _disconnect. This atomic_t based locking mechanism should be turned into a mutex in a next step, relying on mutex_trylock for cases where we don't have the cmpxchg-schedule() loop. Along the way it was noticed that the send/receive timeouts don't apply to kernel_connect, which might have been the case in older 3.x kernel versions. A crude workaround using nonblocking connect has been introduced to emulate this, but a clean solution for this is welcomed. Also, devices are now properly closed on module unload.