kernel/linux.git/fs/dlm/lowcomms.h, branch linux-6.0.y

fs: dlm: memory cache for lowcomms hotpath

2021-12-07T18:42:26+00:00

This patch introduces a kmem cache for dlm_msg handles which are used always if dlm sends a message out. Even if their are covered by midcomms layer or not. Signed-off-by: Alexander Aring Signed-off-by: David Teigland

fs: dlm: memory cache for writequeue_entry

2021-12-07T18:42:26+00:00

This patch introduces a kmem cache for writequeue entry. A writequeue entry get quite a lot allocated if dlm transmit messages. Signed-off-by: Alexander Aring Signed-off-by: David Teigland

fs: dlm: let handle callback data as void

2021-11-02T19:39:20+00:00

This patch changes the dlm_lowcomms_new_msg() function pointer private data from "struct mhandle *" to "void *" to provide different structures than just "struct mhandle". Signed-off-by: Alexander Aring Signed-off-by: David Teigland

fs: dlm: implement delayed ack handling

2021-08-19T16:33:03+00:00

This patch changes that we don't ack each message. Lowcomms will take care about to send an ack back after a bulk of messages was processed. Currently it's only when the whole receive buffer was processed, there might better positions to send an ack back but only the lowcomms implementation know when there are more data to receive. This patch has also disadvantages that we might retransmit more on errors, however this is a very rare case. Tested with make_panic on gfs2 with three nodes by running: trace-cmd record -p function -l 'dlm_send_ack' sleep 100 and trace-cmd report | wc -l Before patch: - 20548 - 21376 - 21398 After patch: - 18338 - 20679 - 19949 Signed-off-by: Alexander Aring Signed-off-by: David Teigland

fs: dlm: rename socket and app buffer defines

2021-06-02T16:53:04+00:00

This patch renames DEFAULT_BUFFER_SIZE to DLM_MAX_SOCKET_BUFSIZE and LOWCOMMS_MAX_TX_BUFFER_LEN to DLM_MAX_APP_BUFSIZE as they are proper names to define what's behind those values. The DLM_MAX_SOCKET_BUFSIZE defines the maximum size of buffer which can be handled on socket layer, the DLM_MAX_APP_BUFSIZE defines the maximum size of buffer which can be handled by the DLM application layer. Signed-off-by: Alexander Aring Signed-off-by: David Teigland

fs: dlm: add reliable connection if reconnect

2021-05-25T14:22:20+00:00

This patch introduce to make a tcp lowcomms connection reliable even if reconnects occurs. This is done by an application layer re-transmission handling and sequence numbers in dlm protocols. There are three new dlm commands: DLM_OPTS: This will encapsulate an existing dlm message (and rcom message if they don't have an own application side re-transmission handling). As optional handling additional tlv's (type length fields) can be appended. This can be for example a sequence number field. However because in DLM_OPTS the lockspace field is unused and a sequence number is a mandatory field it isn't made as a tlv and we put the sequence number inside the lockspace id. The possibility to add optional options are still there for future purposes. DLM_ACK: Just a dlm header to acknowledge the receive of a DLM_OPTS message to it's sender. DLM_FIN: This provides a 4 way handshake for connection termination inclusive support for half-closed connections. It's provided on application layer because SCTP doesn't support half-closed sockets, the shutdown() call can interrupted by e.g. TCP resets itself and a hard logic to implement it because the othercon paradigm in lowcomms. The 4-way termination handshake also solve problems to synchronize peer EOF arrival and that the cluster manager removes the peer in the node membership handling of DLM. In some cases messages can be still transmitted in this time and we need to wait for the node membership event. To provide a reliable connection the node will retransmit all unacknowledges message to it's peer on reconnect. The receiver will then filtering out the next received message and drop all messages which are duplicates. As RCOM_STATUS and RCOM_NAMES messages are the first messages which are exchanged and they have they own re-transmission handling, there exists logic that these messages must be first. If these messages arrives we store the dlm version field. This handling is on DLM 3.1 and after this patch 3.2 the same. A backwards compatibility handling has been added which seems to work on tests without tcpkill, however it's not recommended to use DLM 3.1 and 3.2 at the same time, because DLM 3.2 tries to fix long term bugs in the DLM protocol. Signed-off-by: Alexander Aring Signed-off-by: David Teigland

fs: dlm: move out some hash functionality

2021-05-25T14:22:20+00:00

This patch moves out some lowcomms hash functionality into lowcomms header to provide them to other layers like midcomms as well. Signed-off-by: Alexander Aring Signed-off-by: David Teigland

fs: dlm: add functionality to re-transmit a message

2021-05-25T14:22:20+00:00

This patch introduces a retransmit functionality for a lowcomms message handle. It's just allocates a new buffer and transmit it again, no special handling about prioritize it because keeping bytestream in order. To avoid another connection look some refactor was done to make a new buffer allocation with a preexisting connection pointer. Signed-off-by: Alexander Aring Signed-off-by: David Teigland

fs: dlm: make buffer handling per msg

2021-05-25T14:22:20+00:00

This patch makes the void pointer handle for lowcomms functionality per message and not per page allocation entry. A refcount handling for the handle was added to keep the message alive until the user doesn't need it anymore. There exists now a per message callback which will be called when allocating a new buffer. This callback will be guaranteed to be called according the order of the sending buffer, which can be used that the caller increments a sequence number for the dlm message handle. For transition process we cast the dlm_mhandle to dlm_msg and vice versa until the midcomms layer will implement a specific dlm_mhandle structure. Signed-off-by: Alexander Aring Signed-off-by: David Teigland

fs: dlm: add shutdown hook

2021-03-09T14:56:42+00:00

This patch fixes issues which occurs when dlm lowcomms synchronize their workqueues but dlm application layer already released the lockspace. In such cases messages like: dlm: gfs2: release_lockspace final free dlm: invalid lockspace 3841231384 from 1 cmd 1 type 11 are printed on the kernel log. This patch is solving this issue by introducing a new "shutdown" hook before calling "stop" hook when the lockspace is going to be released finally. This should pretend any dlm messages sitting in the workqueues during or after lockspace removal. It's necessary to call dlm_scand_stop() as I instrumented dlm_lowcomms_get_buffer() code to report a warning after it's called after dlm_midcomms_shutdown() functionality, see below: WARNING: CPU: 1 PID: 3794 at fs/dlm/midcomms.c:1003 dlm_midcomms_get_buffer+0x167/0x180 Modules linked in: joydev iTCO_wdt intel_pmc_bxt iTCO_vendor_support drm_ttm_helper ttm pcspkr serio_raw i2c_i801 i2c_smbus drm_kms_helper virtio_scsi lpc_ich virtio_balloon virtio_console xhci_pci xhci_pci_renesas cec qemu_fw_cfg drm [last unloaded: qxl] CPU: 1 PID: 3794 Comm: dlm_scand Tainted: G W 5.11.0+ #26 Hardware name: Red Hat KVM/RHEL-AV, BIOS 1.13.0-2.module+el8.3.0+7353+9de0a3cc 04/01/2014 RIP: 0010:dlm_midcomms_get_buffer+0x167/0x180 Code: 5d 41 5c 41 5d 41 5e 41 5f c3 0f 0b 45 31 e4 5b 5d 4c 89 e0 41 5c 41 5d 41 5e 41 5f c3 4c 89 e7 45 31 e4 e8 3b f1 ec ff eb 86 <0f> 0b 4c 89 e7 45 31 e4 e8 2c f1 ec ff e9 74 ff ff ff 0f 1f 80 00 RSP: 0018:ffffa81503f8fe60 EFLAGS: 00010202 RAX: 0000000000000008 RBX: ffff8f969827f200 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffffffffad1e89a0 RDI: ffff8f96a5294160 RBP: 0000000000000001 R08: 0000000000000000 R09: ffff8f96a250bc60 R10: 00000000000045d3 R11: 0000000000000000 R12: ffff8f96a250bc60 R13: ffffa81503f8fec8 R14: 0000000000000070 R15: 0000000000000c40 FS: 0000000000000000(0000) GS:ffff8f96fbc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055aa3351c000 CR3: 000000010bf22000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: dlm_scan_rsbs+0x420/0x670 ? dlm_uevent+0x20/0x20 dlm_scand+0xbf/0xe0 kthread+0x13a/0x150 ? __kthread_bind_mask+0x60/0x60 ret_from_fork+0x22/0x30 To synchronize all dlm scand messages we stop it right before shutdown hook. Signed-off-by: Alexander Aring Signed-off-by: David Teigland