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ceph: use a shared zero page rather than one per messenger 

Each messenger allocates a page to be used when writing zeroes
out in the event of error or other abnormal condition.  Instead,
use the kernel ZERO_PAGE() for that purpose.

Signed-off-by: Alex Elder <elder@dreamhost.com>
Signed-off-by: Sage Weil <sage@newdream.net>
This commit is contained in:
Alex Elder 2012-01-23 15:49:27 -06:00
parent 80834312a4
commit 5766651971
2 changed files with 29 additions and 15 deletions
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1
include/linux/ceph/messenger.h
View File

@ -54,7 +54,6 @@ struct ceph_connection_operations {
struct ceph_messenger {
struct ceph_entity_inst inst; /* my name+address */
struct ceph_entity_addr my_enc_addr;
struct page *zero_page; /* used in certain error cases */
bool nocrc;

43
net/ceph/messenger.c
View File

@ -52,6 +52,9 @@ static char addr_str[MAX_ADDR_STR][MAX_ADDR_STR_LEN];
static DEFINE_SPINLOCK(addr_str_lock);
static int last_addr_str;
static struct page *zero_page; /* used in certain error cases */
static void *zero_page_address; /* kernel virtual addr of zero_page */
const char *ceph_pr_addr(const struct sockaddr_storage *ss)
{
int i;
@ -99,18 +102,41 @@ struct workqueue_struct *ceph_msgr_wq;
int ceph_msgr_init(void)
{
BUG_ON(zero_page != NULL);
zero_page = ZERO_PAGE(0);
page_cache_get(zero_page);
BUG_ON(zero_page_address != NULL);
zero_page_address = kmap(zero_page);
ceph_msgr_wq = alloc_workqueue("ceph-msgr", WQ_NON_REENTRANT, 0);
if (!ceph_msgr_wq) {
pr_err("msgr_init failed to create workqueue\n");
zero_page_address = NULL;
kunmap(zero_page);
page_cache_release(zero_page);
zero_page = NULL;
return -ENOMEM;
}
return 0;
}
EXPORT_SYMBOL(ceph_msgr_init);
void ceph_msgr_exit(void)
{
BUG_ON(ceph_msgr_wq == NULL);
destroy_workqueue(ceph_msgr_wq);
BUG_ON(zero_page_address == NULL);
zero_page_address = NULL;
BUG_ON(zero_page == NULL);
kunmap(zero_page);
page_cache_release(zero_page);
zero_page = NULL;
}
EXPORT_SYMBOL(ceph_msgr_exit);
@ -841,9 +867,9 @@ static int write_partial_msg_pages(struct ceph_connection *con)
max_write = bv->bv_len;
#endif
} else {
page = con->msgr->zero_page;
page = zero_page;
if (crc)
kaddr = page_address(con->msgr->zero_page);
kaddr = zero_page_address;
}
len = min_t(int, max_write - con->out_msg_pos.page_pos,
total_max_write);
@ -914,7 +940,7 @@ static int write_partial_skip(struct ceph_connection *con)
while (con->out_skip > 0) {
struct kvec iov = {
.iov_base = page_address(con->msgr->zero_page),
.iov_base = zero_page_address,
.iov_len = min(con->out_skip, (int)PAGE_CACHE_SIZE)
};
@ -2222,15 +2248,6 @@ struct ceph_messenger *ceph_messenger_create(struct ceph_entity_addr *myaddr,
spin_lock_init(&msgr->global_seq_lock);
/* the zero page is needed if a request is "canceled" while the message
* is being written over the socket */
msgr->zero_page = __page_cache_alloc(GFP_KERNEL | __GFP_ZERO);
if (!msgr->zero_page) {
kfree(msgr);
return ERR_PTR(-ENOMEM);
}
kmap(msgr->zero_page);
if (myaddr)
msgr->inst.addr = *myaddr;
@ -2247,8 +2264,6 @@ EXPORT_SYMBOL(ceph_messenger_create);
void ceph_messenger_destroy(struct ceph_messenger *msgr)
{
dout("destroy %p\n", msgr);
kunmap(msgr->zero_page);
__free_page(msgr->zero_page);
kfree(msgr);
dout("destroyed messenger %p\n", msgr);
}