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fs: dlm: define max send buffer 

This patch will set the maximum transmit buffer size for rcom messages
with "names" to 4096 bytes. It's a leftover change of
commit 4798cbbfbd ("fs: dlm: rework receive handling"). Fact is that we
cannot allocate a contiguous transmit buffer length above of 4096 bytes.
It seems at some places the upper layer protocol will calculate according
to dlm_config.ci_buffer_size the possible payload of a dlm recovery
message. As compiler setting we will use now the maximum possible
message which dlm can send out. Commit 4e192ee68e ("fs: dlm: disallow
buffer size below default") disallow a buffer setting smaller than the
4096 bytes and above 4096 bytes is definitely wrong because we will then
write out of buffer space as we cannot allocate a contiguous buffer above
4096 bytes. The ci_buffer_size is still there to define the possible
maximum receive buffer size of a recvmsg() which should be at least the
maximum possible dlm message size.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This commit is contained in:
Alexander Aring 2020-11-02 20:04:17 -05:00 committed by David Teigland
parent 5cbec208dc
commit 9f8f9c774a
4 changed files with 7 additions and 5 deletions
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2
fs/dlm/lockspace.c
View File

@ -572,7 +572,7 @@ static int new_lockspace(const char *name, const char *cluster,
mutex_init(&ls->ls_requestqueue_mutex);
mutex_init(&ls->ls_clear_proc_locks);
ls->ls_recover_buf = kmalloc(dlm_config.ci_buffer_size, GFP_NOFS);
ls->ls_recover_buf = kmalloc(LOWCOMMS_MAX_TX_BUFFER_LEN, GFP_NOFS);
if (!ls->ls_recover_buf)
goto out_lkbidr;

2
fs/dlm/lowcomms.h
View File

@ -12,6 +12,8 @@
#ifndef __LOWCOMMS_DOT_H__
#define __LOWCOMMS_DOT_H__
#define LOWCOMMS_MAX_TX_BUFFER_LEN 4096
int dlm_lowcomms_start(void);
void dlm_lowcomms_stop(void);
void dlm_lowcomms_exit(void);

2
fs/dlm/member.c
View File

@ -270,7 +270,7 @@ int dlm_slots_assign(struct dlm_ls *ls, int *num_slots, int *slots_size,
log_slots(ls, gen, num, NULL, array, array_size);
max_slots = (dlm_config.ci_buffer_size - sizeof(struct dlm_rcom) -
max_slots = (LOWCOMMS_MAX_TX_BUFFER_LEN - sizeof(struct dlm_rcom) -
sizeof(struct rcom_config)) / sizeof(struct rcom_slot);
if (num > max_slots) {

6
fs/dlm/rcom.c
View File

@ -162,7 +162,7 @@ int dlm_rcom_status(struct dlm_ls *ls, int nodeid, uint32_t status_flags)
set_rcom_status(ls, (struct rcom_status *)rc->rc_buf, status_flags);
allow_sync_reply(ls, &rc->rc_id);
memset(ls->ls_recover_buf, 0, dlm_config.ci_buffer_size);
memset(ls->ls_recover_buf, 0, LOWCOMMS_MAX_TX_BUFFER_LEN);
send_rcom(ls, mh, rc);
@ -284,7 +284,7 @@ int dlm_rcom_names(struct dlm_ls *ls, int nodeid, char *last_name, int last_len)
memcpy(rc->rc_buf, last_name, last_len);
allow_sync_reply(ls, &rc->rc_id);
memset(ls->ls_recover_buf, 0, dlm_config.ci_buffer_size);
memset(ls->ls_recover_buf, 0, LOWCOMMS_MAX_TX_BUFFER_LEN);
send_rcom(ls, mh, rc);
@ -304,7 +304,7 @@ static void receive_rcom_names(struct dlm_ls *ls, struct dlm_rcom *rc_in)
nodeid = rc_in->rc_header.h_nodeid;
inlen = rc_in->rc_header.h_length - sizeof(struct dlm_rcom);
outlen = dlm_config.ci_buffer_size - sizeof(struct dlm_rcom);
outlen = LOWCOMMS_MAX_TX_BUFFER_LEN - sizeof(struct dlm_rcom);
error = create_rcom(ls, nodeid, DLM_RCOM_NAMES_REPLY, outlen, &rc, &mh);
if (error)