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ceph: explicitly specify page alignment in network messages

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The alignment used for reading data into or out of pages used to be taken
from the data_off field in the message header.  This only worked as long
as the page alignment matched the object offset, breaking direct io to
non-page aligned offsets.

Instead, explicitly specify the page alignment next to the page vector
in the ceph_msg struct, and use that instead of the message header (which
probably shouldn't be trusted).  The alloc_msg callback is responsible for
filling in this field properly when it sets up the page vector.

Signed-off-by: Sage Weil <sage@newdream.net>
This commit is contained in:
Sage Weil 2010-11-09 12:40:00 -08:00
parent b7495fc2ff
commit c5c6b19d4b
3 changed files with 9 additions and 5 deletions
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1
include/linux/ceph/messenger.h
View file

@ -82,6 +82,7 @@ struct ceph_msg {
struct ceph_buffer *middle;
struct page **pages; /* data payload. NOT OWNER. */
unsigned nr_pages; /* size of page array */
unsigned page_alignment; /* io offset in first page */
struct ceph_pagelist *pagelist; /* instead of pages */
struct list_head list_head;
struct kref kref;

10
net/ceph/messenger.c
View file

@ -540,8 +540,7 @@ static void prepare_write_message(struct ceph_connection *con)
/* initialize page iterator */
con->out_msg_pos.page = 0;
if (m->pages)
con->out_msg_pos.page_pos =
le16_to_cpu(m->hdr.data_off) & ~PAGE_MASK;
con->out_msg_pos.page_pos = m->page_alignment;
else
con->out_msg_pos.page_pos = 0;
con->out_msg_pos.data_pos = 0;
@ -1491,7 +1490,7 @@ static int read_partial_message(struct ceph_connection *con)
struct ceph_msg *m = con->in_msg;
int ret;
int to, left;
unsigned front_len, middle_len, data_len, data_off;
unsigned front_len, middle_len, data_len;
int datacrc = con->msgr->nocrc;
int skip;
u64 seq;
@ -1527,7 +1526,6 @@ static int read_partial_message(struct ceph_connection *con)
data_len = le32_to_cpu(con->in_hdr.data_len);
if (data_len > CEPH_MSG_MAX_DATA_LEN)
return -EIO;
data_off = le16_to_cpu(con->in_hdr.data_off);
/* verify seq# */
seq = le64_to_cpu(con->in_hdr.seq);
@ -1575,7 +1573,7 @@ static int read_partial_message(struct ceph_connection *con)
con->in_msg_pos.page = 0;
if (m->pages)
con->in_msg_pos.page_pos = data_off & ~PAGE_MASK;
con->in_msg_pos.page_pos = m->page_alignment;
else
con->in_msg_pos.page_pos = 0;
con->in_msg_pos.data_pos = 0;
@ -2300,6 +2298,7 @@ struct ceph_msg *ceph_msg_new(int type, int front_len, gfp_t flags)
/* data */
m->nr_pages = 0;
m->page_alignment = 0;
m->pages = NULL;
m->pagelist = NULL;
m->bio = NULL;
@ -2369,6 +2368,7 @@ static struct ceph_msg *ceph_alloc_msg(struct ceph_connection *con,
type, front_len);
return NULL;
}
msg->page_alignment = le16_to_cpu(hdr->data_off);
}
memcpy(&msg->hdr, &con->in_hdr, sizeof(con->in_hdr));

3
net/ceph/osd_client.c
View file

@ -391,6 +391,8 @@ void ceph_osdc_build_request(struct ceph_osd_request *req,
req->r_request->hdr.data_len = cpu_to_le32(data_len);
}
req->r_request->page_alignment = req->r_page_alignment;
BUG_ON(p > msg->front.iov_base + msg->front.iov_len);
msg_size = p - msg->front.iov_base;
msg->front.iov_len = msg_size;
@ -1657,6 +1659,7 @@ static struct ceph_msg *get_reply(struct ceph_connection *con,
}
m->pages = req->r_pages;
m->nr_pages = req->r_num_pages;
m->page_alignment = req->r_page_alignment;
#ifdef CONFIG_BLOCK
m->bio = req->r_bio;
#endif