Hi,
On Mon, 27 Jan 2014 18:44:42 +0400
Artyom Pervukhin <artyom@xxxxxxxxxx> wrote:
> I've done some additional stracing on the tgtd's side this time, please see below:
>
> Testing 300 targets:
>
> command:
>
> root@sandbox:~ # tgtadm -C 0 --op show --mode target
>
> (command shows full output)
>
> tgtd writes:
>
> write(10, "\0\0\0\0\305\325\4\0", 8) = 8
> write(10, "Target 1: iqn.2014-01:d1\n Sys"..., 316861) = 224000
> write(10, " State: ready\n I_T nexu"..., 92861) = 92861
>
> command:
>
> root@sandbox:~ # tgtadm -C 0 --op show --mode target | wc -c
> 316860
>
> tgtd writes stays the same as above.
>
>
>
> Testing 900 targets:
>
> root@sandbox:~ # tgtadm -C 0 --op show --mode target
>
> (command shows incomplete output)
>
> tgtd writes:
>
> write(10, "\0\0\0\0u\205\16\0", 8) = 8
> write(10, "Target 1: iqn.2014-01:d1\n Sys"..., 951661) = 256000
> write(10, "a: No\n Prevent remova"..., 695661) = 176000
> write(10, " Removable media: No\n "..., 519661) = 176000
> write(10, "T nexus information:\n LUN inf"..., 343661) = 176000
> write(10, " Backing store path: None\n "..., 167661) = 167661
>
> command:
>
> root@sandbox:~ # tgtadm -C 0 --op show --mode target | wc -c
> 929621
>
> tgtd writes:
>
> write(10, "\0\0\0\0u\205\16\0", 8) = 8
> write(10, "Target 1: iqn.2014-01:d1\n Sys"..., 951661) = 944000
> write(10, "t removal: No\n Readon"..., 7661) = -1 EPIPE (Broken pipe)
> --- SIGPIPE (Broken pipe) @ 0 (0) ---
>
>
>
> Seeing this, I assumed the bug is on tgtadm's side.
Thanks a lot for the investigation. The following fixes the problem?
Note that tgtd uses a stream to store what tgtd sends to tgtadm. The
buffer of the stream is managed glibc (internally allocated via
malloc). That's a limit about how many targets you can see via tgtadm.
diff --git a/usr/tgtadm.c b/usr/tgtadm.c
index cc63fbf..8e0d5dd 100644
--- a/usr/tgtadm.c
+++ b/usr/tgtadm.c
@@ -234,7 +234,8 @@ static int ipc_mgmt_connect(int *fd)
static int ipc_mgmt_rsp(int fd, struct tgtadm_req *req)
{
struct tgtadm_rsp rsp;
- int err, rest, len;
+ int err, len, done;
+ char *buf;
retry:
err = recv(fd, &rsp, sizeof(rsp), MSG_WAITALL);
@@ -278,23 +279,28 @@ retry:
}
}
- rest = rsp.len - sizeof(rsp);
- if (!rest)
+ len = rsp.len - sizeof(rsp);
+ if (!len)
return 0;
- while (rest) {
- char buf[BUFSIZE];
- memset(buf, 0, sizeof(buf));
- len = min_t(int, sizeof(buf) - 1, rest);
- err = read(fd, buf, len);
- if (err <= 0) {
- eprintf("\ncan't get the full response, %m\n");
- return errno;
+ buf = malloc(len);
+ done = 0;
+ while (len > done) {
+ int ret;
+ ret = read(fd, buf + done, len - done);
+ if (ret < 0) {
+ if (errno == EAGAIN)
+ continue;
+ fprintf(stderr, "failed to read from tgtd, %d", errno);
+ break;
}
- fputs(buf, stdout);
- rest -= len;
+ done += ret;
}
+ if (done == len)
+ fputs(buf, stdout);
+ free(buf);
+
return 0;
}
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