On 03/02/2012 11:21 AM, Sage Weil wrote:
On Wed, 29 Feb 2012, Alex Elder wrote:
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<[email protected]>
---
v2: Updated to use kernel ZERO_PAGE()
include/linux/ceph/messenger.h | 1
net/ceph/messenger.c | 43
+++++++++++++++++++++++++++--------------
2 files changed, 29 insertions(+), 15 deletions(-)
Index: b/include/linux/ceph/messenger.h
===================================================================
--- a/include/linux/ceph/messenger.h
+++ b/include/linux/ceph/messenger.h
@@ -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;
Index: b/net/ceph/messenger.c
===================================================================
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -52,6 +52,9 @@ static char addr_str[MAX_ADDR_STR][MAX_A
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);
I've always assumed that kmap() used up an expensive slot, and that pages
should be kmapped only when needed. Myabe this should still be done
inside write_partial_msg_pages()?
I think that's only for high memory pages, and especially for
the kernel zero page I doubt that's where it sits. But you
make a good point.
I'll look into it a bit and if we're not guaranteed it's
"free" to do this I'll re-post with the kmap done inside where
it's needed. I'll follow up either way.
-Alex
+
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(struc
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 cep
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_cr
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);
}
--
To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
