A mulitpath device can only be reloaded read/write when all paths are
read/write. Also, whenever a read-only scsi device is rescanned, the
scsi subsystem will first unconditionally issue a uevent with DISK_RO=0
before checking the read-only status, and if it the device is still
read-only, issuing another uevent with DISK_RO=1. These uevents cause
pointless reloads when read-only paths are rescanned. To avoid this,
first check if the path is being changed to the existing multipath
read-only state. If the state is the same, do nothing. If it's
different, check to see if all paths are read/write before changing a
multipath device from read-only to read/write. If the multipath device
read-only state is unknown, assume that it needs to be reloaded.
Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
---
libmultipath/libmultipath.version | 1 +
libmultipath/sysfs.c | 22 ++++++++++++++++++++++
libmultipath/sysfs.h | 1 +
multipathd/main.c | 26 +++++++++++++++++++++++++-
4 files changed, 49 insertions(+), 1 deletion(-)
diff --git a/libmultipath/libmultipath.version b/libmultipath/libmultipath.version
index 9c7ffa71..7562ec16 100644
--- a/libmultipath/libmultipath.version
+++ b/libmultipath/libmultipath.version
@@ -205,6 +205,7 @@ global:
strlcpy;
sync_map_state;
sysfs_attr_set_value;
+ sysfs_get_ro;
sysfs_get_size;
sysfs_is_multipathed;
timespeccmp;
diff --git a/libmultipath/sysfs.c b/libmultipath/sysfs.c
index f45dbee1..26f28739 100644
--- a/libmultipath/sysfs.c
+++ b/libmultipath/sysfs.c
@@ -236,6 +236,28 @@ sysfs_get_size (struct path *pp, unsigned long long * size)
return 0;
}
+int
+sysfs_get_ro (struct path *pp)
+{
+ int ro;
+ char buff[3]; /* Either "0\n\0" or "1\n\0" */
+
+ if (!pp->udev)
+ return -1;
+
+ if (sysfs_attr_get_value(pp->udev, "ro", buff, sizeof(buff)) <= 0) {
+ condlog(3, "%s: Cannot read ro attribute in sysfs", pp->dev);
+ return -1;
+ }
+
+ if (sscanf(buff, "%d\n", &ro) != 1 || ro < 0 || ro > 1) {
+ condlog(3, "%s: Cannot parse ro attribute", pp->dev);
+ return -1;
+ }
+
+ return ro;
+}
+
int sysfs_check_holders(char * check_devt, char * new_devt)
{
unsigned int major, new_minor, table_minor;
diff --git a/libmultipath/sysfs.h b/libmultipath/sysfs.h
index 72b39ab2..c948c467 100644
--- a/libmultipath/sysfs.h
+++ b/libmultipath/sysfs.h
@@ -13,6 +13,7 @@ ssize_t sysfs_attr_get_value(struct udev_device *dev, const char *attr_name,
ssize_t sysfs_bin_attr_get_value(struct udev_device *dev, const char *attr_name,
unsigned char * value, size_t value_len);
int sysfs_get_size (struct path *pp, unsigned long long * size);
+int sysfs_get_ro(struct path *pp);
int sysfs_check_holders(char * check_devt, char * new_devt);
bool sysfs_is_multipathed(struct path *pp, bool set_wwid);
#endif
diff --git a/multipathd/main.c b/multipathd/main.c
index 5cb70575..b00171f6 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -1440,6 +1440,30 @@ finish_path_init(struct path *pp, struct vectors * vecs)
return -1;
}
+static bool
+needs_ro_update(struct multipath *mpp, int ro)
+{
+ struct pathgroup * pgp;
+ struct path * pp;
+ unsigned int i, j;
+
+ if (!mpp || ro < 0)
+ return false;
+ if (!mpp->dmi)
+ return true;
+ if (mpp->dmi->read_only == ro)
+ return false;
+ if (ro == 1)
+ return true;
+ vector_foreach_slot (mpp->pg, pgp, i) {
+ vector_foreach_slot (pgp->paths, pp, j) {
+ if (sysfs_get_ro(pp) == 1)
+ return false;
+ }
+ }
+ return true;
+}
+
static int
uev_update_path (struct uevent *uev, struct vectors * vecs)
{
@@ -1512,7 +1536,7 @@ uev_update_path (struct uevent *uev, struct vectors * vecs)
}
ro = uevent_get_disk_ro(uev);
- if (mpp && ro >= 0) {
+ if (needs_ro_update(mpp, ro)) {
condlog(2, "%s: update path write_protect to '%d' (uevent)", uev->kernel, ro);
if (mpp->wait_for_udev)
--
2.17.2
--
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