Recent kernels have an 'access_state' attribute which allows us to read the asymmetric access state directly from sysfs.
Signed-off-by: Hannes Reinecke <[email protected]> --- libmultipath/discovery.c | 33 +++++++++++++++++++++++++++++ libmultipath/discovery.h | 2 ++ libmultipath/prio.h | 1 + libmultipath/prioritizers/Makefile | 3 ++- libmultipath/prioritizers/sysfs.c | 43 ++++++++++++++++++++++++++++++++++++++ libmultipath/propsel.c | 6 +++++- multipath/multipath.conf.5 | 14 ++++++++++++- 7 files changed, 99 insertions(+), 3 deletions(-) create mode 100644 libmultipath/prioritizers/sysfs.c diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c index a364056..4a4b828 100644 --- a/libmultipath/discovery.c +++ b/libmultipath/discovery.c @@ -208,6 +208,8 @@ declare_sysfs_get_str(devtype); declare_sysfs_get_str(vendor); declare_sysfs_get_str(model); declare_sysfs_get_str(rev); +declare_sysfs_get_str(access_state); +declare_sysfs_get_str(preferred_path); ssize_t sysfs_get_vpd (struct udev_device * udev, int pg, @@ -483,6 +485,37 @@ int sysfs_get_iscsi_ip_address(struct path *pp, char *ip_address) return 1; } +int +sysfs_get_asymmetric_access_state(struct path *pp, char *buff, int buflen) +{ + struct udev_device *parent = pp->udev; + char value[16], *eptr; + unsigned int preferred; + + while (parent) { + const char *subsys = udev_device_get_subsystem(parent); + if (subsys && !strncmp(subsys, "scsi", 4)) + break; + parent = udev_device_get_parent(parent); + } + + if (!parent) + return -1; + + if (sysfs_get_access_state(parent, buff, buflen) <= 0) + return -1; + + if (sysfs_get_preferred_path(parent, value, 16) <= 0) + return 0; + + preferred = strtoul(value, &eptr, 0); + if (value == eptr || preferred == ULONG_MAX) { + /* Parse error, ignore */ + return 0; + } + return preferred; +} + static void sysfs_set_rport_tmo(struct multipath *mpp, struct path *pp) { diff --git a/libmultipath/discovery.h b/libmultipath/discovery.h index 5931bc6..b45c802 100644 --- a/libmultipath/discovery.h +++ b/libmultipath/discovery.h @@ -47,6 +47,8 @@ int sysfs_get_host_pci_name(struct path *pp, char *pci_name); int sysfs_get_iscsi_ip_address(struct path *pp, char *ip_address); ssize_t sysfs_get_vpd (struct udev_device * udev, int pg, unsigned char * buff, size_t len); +int sysfs_get_asymmetric_access_state(struct path *pp, + char *buff, int buflen); /* * discovery bitmask diff --git a/libmultipath/prio.h b/libmultipath/prio.h index 495688f..65abf54 100644 --- a/libmultipath/prio.h +++ b/libmultipath/prio.h @@ -29,6 +29,7 @@ struct path; #define PRIO_RDAC "rdac" #define PRIO_DATACORE "datacore" #define PRIO_WEIGHTED_PATH "weightedpath" +#define PRIO_SYSFS "sysfs" /* * Value used to mark the fact prio was not defined diff --git a/libmultipath/prioritizers/Makefile b/libmultipath/prioritizers/Makefile index 6cfac88..0d1857f 100644 --- a/libmultipath/prioritizers/Makefile +++ b/libmultipath/prioritizers/Makefile @@ -15,7 +15,8 @@ LIBS = \ libpriodatacore.so \ libpriohds.so \ libprioweightedpath.so \ - libprioiet.so + libprioiet.so \ + libpriosysfs.so CFLAGS += -I.. diff --git a/libmultipath/prioritizers/sysfs.c b/libmultipath/prioritizers/sysfs.c new file mode 100644 index 0000000..35a5c83 --- /dev/null +++ b/libmultipath/prioritizers/sysfs.c @@ -0,0 +1,43 @@ +/* + * sysfs.c + * + * Copyright(c) 2016 Hannes Reinecke, SUSE Linux GmbH + */ + +#include <stdio.h> + +#include "structs.h" +#include "discovery.h" +#include "prio.h" + +static const struct { + unsigned char value; + char *name; +} sysfs_access_state_map[] = { + { 50, "active/optimized" }, + { 10, "active/non-optimized" }, + { 5, "lba-dependent" }, + { 1, "standby" }, +}; + +int getprio (struct path * pp, char * args) +{ + int prio = 0, rc, i; + char buff[512]; + + rc = sysfs_get_asymmetric_access_state(pp, buff, 512); + if (rc < 0) + return PRIO_UNDEF; + prio = 0; + for (i = 0; i < 4; i++) { + if (!strncmp(buff, sysfs_access_state_map[i].name, + strlen(sysfs_access_state_map[i].name))) { + prio = sysfs_access_state_map[i].value; + break; + } + } + if (rc > 0) + prio += 80; + + return prio; +} diff --git a/libmultipath/propsel.c b/libmultipath/propsel.c index 8abe360..b0182de 100644 --- a/libmultipath/propsel.c +++ b/libmultipath/propsel.c @@ -374,6 +374,7 @@ detect_prio(struct path * pp) int ret; struct prio *p = &pp->prio; int tpgs = 0; + char buff[512]; if ((tpgs = get_target_port_group_support(pp->fd)) <= 0) return; @@ -383,7 +384,10 @@ detect_prio(struct path * pp) return; if (get_asymmetric_access_state(pp->fd, ret) < 0) return; - prio_get(p, PRIO_ALUA, DEFAULT_PRIO_ARGS); + if (sysfs_get_asymmetric_access_state(pp, buff, 512) < 0) + prio_get(p, PRIO_ALUA, DEFAULT_PRIO_ARGS); + else + prio_get(p, PRIO_SYSFS, DEFAULT_PRIO_ARGS); } #define set_prio(src, msg) \ diff --git a/multipath/multipath.conf.5 b/multipath/multipath.conf.5 index 2ff88c4..aaaa01b 100644 --- a/multipath/multipath.conf.5 +++ b/multipath/multipath.conf.5 @@ -203,6 +203,10 @@ Generate the path priority for NetApp arrays. .B rdac Generate the path priority for LSI/Engenio/NetApp E-Series RDAC controller. .TP +.B sysfs +Use the sysfs attributes access_state and preferred_path to generate the +path priority. +.TP .B hp_sw Generate the path priority for Compaq/HP controller in active/standby mode. @@ -449,8 +453,16 @@ If set to .I yes , multipath will try to detect if the device supports ALUA. If so, the device will automatically use the +.I sysfs +prioritizer if the required sysfs attributes +.I access_state +and +.I preferred_path +are supported, or the .I alua -prioritizer. If not, the prioritizer will be selected as usual. Default is +prioritizer if not. If set to +.I no +, the prioritizer will be selected as usual. Default is .I no .TP .B force_sync -- 2.6.6 -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
