[dm-devel] patch for handling clariion I/O to

[Edward Goggin]

Christophe,

This patch attempts to prevent an I/O hang which can occur with host I/O
to an "in-active" CLARiiON snapshot LU.  While the snapshot LU is
presented to the host, inquiry, TUR, and read capacity commands succeed,
but read and write commands are failed.

The patch is not entirely CLARiiON specific since I've added a field to
the multipath structure (failallpaths) and I've modified the interface
of the sg_read function in libcheckers/readsector0.c.  If you prefer
that I do this with a solution which is entirely isolated to the
CLARiiON, I can do that instead.

Thanks,

Ed Goggin

diff --git a/libcheckers/emc_clariion.c b/libcheckers/emc_clariion.c
index a883e3d..e4004a7 100644
--- a/libcheckers/emc_clariion.c
+++ b/libcheckers/emc_clariion.c
@@ -3,6 +3,7 @@
  */
 #include <stdio.h>
 #include <stdlib.h>
+#include <stddef.h>
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -14,6 +15,14 @@
 #include "checkers.h"
 
 #include "../libmultipath/sg_include.h"
+#include "../libmultipath/vector.h"
+#include "../libmultipath/structs.h"
+
+#define container_of(ptr, type, member) ({			\
+        const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
+        (type *)( (char *)__mptr - offsetof(type,member) );})
+
+int sg_read (int sg_fd, unsigned char * buff, unsigned char *
senseBuff);
 
 #define INQUIRY_CMD     0x12
 #define INQUIRY_CMDLEN  6
@@ -40,13 +49,18 @@ void emc_clariion_free (struct checker *
 
 int emc_clariion(struct checker * c)
 {
-	unsigned char sense_buffer[256] = { 0, };
+	unsigned char sense_buffer[256] = { 0, }, *sbb;
 	unsigned char sb[128] = { 0, };
 	unsigned char inqCmdBlk[INQUIRY_CMDLEN] = {INQUIRY_CMD, 1, 0xC0,
0,
 						sizeof(sb), 0};
 	struct sg_io_hdr io_hdr;
 	struct emc_clariion_checker_context * ct =
 		(struct emc_clariion_checker_context *)c->context;
+	struct path *p;
+	int ret;
+
+	p = container_of(c, struct path, checker);
+
 
 	memset(&io_hdr, 0, sizeof (struct sg_io_hdr));
 	io_hdr.interface_id = 'S';
@@ -110,7 +124,27 @@ int emc_clariion(struct checker * c)
 		ct->wwn_set = 1;
 	}
 	
-	
-	MSG(c, "emc_clariion_checker: Path healthy");
-        return PATH_UP;
+	if (p->mpp && p->mpp->failallpaths) {
+		ret = PATH_DOWN;
+		MSG(c, "emc_clariion_checker: Path to inactive
snapshot.");
+	}
+	else {
+		unsigned char buf[512];
+
+		ret = sg_read(c->fd, &buf[0], sbb = &sense_buffer[0]);
+
+		if (((sbb[2]&0xf) == 5) && (sbb[12] == 0x25) &&
(sbb[13]==1)) {
+			if (p->mpp)
+				p->mpp->failallpaths = 1;
+			MSG(c, "emc_clariion_checker: Path to inactive
snapshot.");
+			ret = PATH_DOWN;
+		}
+		else if (((sbb[2]&0xf)==2) && (sbb[12]==4) &&
(sbb[13]==3)) {
+			MSG(c, "emc_clariion_checker: Passive path is
healthy.");
+			ret = PATH_UP;	/* not ghost */
+		}
+		else
+			MSG(c, "emc_clariion_checker: Active path is
healthy.");
+	}
+	return ret;
 }
diff --git a/libcheckers/readsector0.c b/libcheckers/readsector0.c
index b0acec9..dd18528 100644
--- a/libcheckers/readsector0.c
+++ b/libcheckers/readsector0.c
@@ -34,8 +34,8 @@ void readsector0_free (struct checker * 
 	return;
 }
 
-static int
-sg_read (int sg_fd, unsigned char * buff)
+int
+sg_read (int sg_fd, unsigned char * buff, unsigned char * senseBuff)
 {
 	/* defaults */
 	int blocks = 1;
@@ -45,7 +45,6 @@ sg_read (int sg_fd, unsigned char * buff
 	int * diop = NULL;
 
 	unsigned char rdCmd[cdbsz];
-	unsigned char senseBuff[SENSE_BUFF_LEN];
 	struct sg_io_hdr io_hdr;
 	int res;
 	int rd_opcode[] = {0x8, 0x28, 0xa8, 0x88};
@@ -97,9 +96,10 @@ extern int
 readsector0 (struct checker * c)
 {
 	unsigned char buf[512];
+	unsigned char sbuf[SENSE_BUFF_LEN];
 	int ret;
 
-	ret = sg_read(c->fd, &buf[0]);
+	ret = sg_read(c->fd, &buf[0], &sbuf[0]);
 
 	switch (ret)
 	{
diff --git a/libmultipath/structs.h b/libmultipath/structs.h
index faa2b8f..049c82b 100644
--- a/libmultipath/structs.h
+++ b/libmultipath/structs.h
@@ -127,6 +127,7 @@ struct multipath {
 	int no_path_retry; /* number of retries after all paths are down
*/
 	int retry_tick;    /* remaining times for retries */
 	int minio;
+	int failallpaths;
 	unsigned long long size;
 	vector paths;
 	vector pg;