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page-xfer: receive information about presence of a parent from a page server (v2)

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We need to know this to insert holes. Currently xfer->parent isn't
initialized for remote sessions. In most cases it has a non-zero value,
so generate_iovs() is called with has_parent = true.

bash test/zdtm.sh -p -P -i 3 ns/transition/fork
(00.000106) Error (sysctl.c:194): Can't open sysctl net/ipv4/tcp_wmem: No such file or directory
(00.017048)    420: Error (image.c:231): Unable to open pagemap-420.img: No such file or directory
(00.017065)    420: Error (image.c:231): Unable to open pages-420.img: No such file or directory
(00.017090)    420: Error (page-read.c:73): No parent for snapshot pagemap
(00.017290)     86: Error (cr-restore.c:1185): 420 exited, status=1
(00.017317) Error (cr-restore.c:1831): Restoring FAILED.

v2: add a new command to open a page server. It's required to save
backward compatibility. If someone tries to use an old version of
page server, he will get an error.

Reported-by: Mr Jenkins
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Andrey Vagin 2014-11-07 21:40:57 +03:00 • committed by Pavel Emelyanov
parent 5f13a31e9d
commit 7c896efff5
1 changed files with 30 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

34
page-xfer.c
View file

@ -40,6 +40,7 @@ static int open_page_local_xfer(struct page_xfer *xfer, int fd_type, long id);
#define PS_IOV_ADD 1
#define PS_IOV_HOLE 2
#define PS_IOV_OPEN 3
#define PS_IOV_OPEN2 4
#define PS_IOV_FLUSH 0x1023
#define PS_IOV_FLUSH_N_CLOSE 0x1024
@ -79,7 +80,8 @@ static void page_server_close(void)
cxfer.loc_xfer.close(&cxfer.loc_xfer);
}
static int page_server_open(struct page_server_iov *pi)
static void close_page_xfer(struct page_xfer *xfer);
static int page_server_open(int sk, struct page_server_iov *pi)
{
int type;
long id;
@ -94,6 +96,17 @@ static int page_server_open(struct page_server_iov *pi)
return -1;
cxfer.dst_id = pi->dst_id;
if (sk >= 0) {
char has_parent = !!cxfer.loc_xfer.parent;
if (write(sk, &has_parent, 1) != 1) {
pr_perror("Unable to send reponse");
close_page_xfer(&cxfer.loc_xfer);
return -1;
}
}
return 0;
}
@ -101,7 +114,7 @@ static int prep_loc_xfer(struct page_server_iov *pi)
{
if (cxfer.dst_id != pi->dst_id) {
pr_warn("Deprecated IO w/o open\n");
return page_server_open(pi);
return page_server_open(-1, pi);
} else
return 0;
}
@ -192,7 +205,10 @@ static int page_server_serve(int sk)
switch (pi.cmd) {
case PS_IOV_OPEN:
ret = page_server_open(&pi);
ret = page_server_open(-1, &pi);
break;
case PS_IOV_OPEN2:
ret = page_server_open(sk, &pi);
break;
case PS_IOV_ADD:
ret = page_server_add(sk, &pi);
@ -482,6 +498,7 @@ static void close_server_xfer(struct page_xfer *xfer)
static int open_page_server_xfer(struct page_xfer *xfer, int fd_type, long id)
{
struct page_server_iov pi;
char has_parent;
xfer->sk = page_server_sk;
xfer->write_pagemap = write_pagemap_to_server;
@ -489,8 +506,9 @@ static int open_page_server_xfer(struct page_xfer *xfer, int fd_type, long id)
xfer->write_hole = write_hole_to_server;
xfer->close = close_server_xfer;
xfer->dst_id = encode_pm_id(fd_type, id);
xfer->parent = NULL;
pi.cmd = PS_IOV_OPEN;
pi.cmd = PS_IOV_OPEN2;
pi.dst_id = xfer->dst_id;
pi.vaddr = 0;
pi.nr_pages = 0;
@ -500,6 +518,14 @@ static int open_page_server_xfer(struct page_xfer *xfer, int fd_type, long id)
return -1;
}
if (read(xfer->sk, &has_parent, 1) != 1) {
pr_perror("The page server doesn't answer");
return -1;
}
if (has_parent)
xfer->parent = (void *) 1; /* This is required for generate_iovs() */
return 0;
}