130 lines
3.8 KiB
Diff
130 lines
3.8 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Benjamin Marzinski <bmarzins@redhat.com>
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Date: Mon, 15 Nov 2021 10:54:35 -0600
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Subject: [PATCH] multipathd: avoid unnecessary path read-only reloads
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A mulitpath device can only be reloaded read/write when all paths are
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read/write. Also, whenever a read-only device is rescanned, the scsi
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subsystem will first unconditionally issue a uevent with DISK_RO=0
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before checking the read-only status, and if it the device is still
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read-only, issuing another uevent with DISK_RO=1. These uevents cause
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pointless reloads when read-only paths are rescanned. To avoid this,
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check to see if all paths are read/write before changing a multipath
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device from read-only to read/write.
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Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
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---
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libmultipath/libmultipath.version | 5 +++++
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libmultipath/sysfs.c | 22 ++++++++++++++++++++++
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libmultipath/sysfs.h | 1 +
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multipathd/main.c | 31 ++++++++++++++++++++++++++++++-
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4 files changed, 58 insertions(+), 1 deletion(-)
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diff --git a/libmultipath/libmultipath.version b/libmultipath/libmultipath.version
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index eb5b5b55..dd1b4122 100644
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--- a/libmultipath/libmultipath.version
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+++ b/libmultipath/libmultipath.version
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@@ -287,3 +287,8 @@ global:
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local:
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*;
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};
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+
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+LIBMULTIPATH_9.1.0 {
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+global:
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+ sysfs_get_ro;
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+} LIBMULTIPATH_9.0.0;
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diff --git a/libmultipath/sysfs.c b/libmultipath/sysfs.c
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index 9ff145f2..24c12b6a 100644
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--- a/libmultipath/sysfs.c
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+++ b/libmultipath/sysfs.c
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@@ -236,6 +236,28 @@ sysfs_get_size (struct path *pp, unsigned long long * size)
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return 0;
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}
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+int
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+sysfs_get_ro (struct path *pp)
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+{
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+ int ro;
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+ char buff[3]; /* Either "0\n\0" or "1\n\0" */
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+
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+ if (!pp->udev)
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+ return -1;
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+
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+ if (sysfs_attr_get_value(pp->udev, "ro", buff, sizeof(buff)) <= 0) {
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+ condlog(3, "%s: Cannot read ro attribute in sysfs", pp->dev);
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+ return -1;
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+ }
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+
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+ if (sscanf(buff, "%d\n", &ro) != 1 || ro < 0 || ro > 1) {
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+ condlog(3, "%s: Cannot parse ro attribute", pp->dev);
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+ return -1;
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+ }
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+
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+ return ro;
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+}
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+
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int sysfs_check_holders(char * check_devt, char * new_devt)
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{
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unsigned int major, new_minor, table_minor;
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diff --git a/libmultipath/sysfs.h b/libmultipath/sysfs.h
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index 72b39ab2..c948c467 100644
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--- a/libmultipath/sysfs.h
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+++ b/libmultipath/sysfs.h
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@@ -13,6 +13,7 @@ ssize_t sysfs_attr_get_value(struct udev_device *dev, const char *attr_name,
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ssize_t sysfs_bin_attr_get_value(struct udev_device *dev, const char *attr_name,
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unsigned char * value, size_t value_len);
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int sysfs_get_size (struct path *pp, unsigned long long * size);
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+int sysfs_get_ro(struct path *pp);
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int sysfs_check_holders(char * check_devt, char * new_devt);
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bool sysfs_is_multipathed(struct path *pp, bool set_wwid);
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#endif
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diff --git a/multipathd/main.c b/multipathd/main.c
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index 1defeaf1..6145e512 100644
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--- a/multipathd/main.c
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+++ b/multipathd/main.c
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@@ -1324,6 +1324,35 @@ fail:
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return REMOVE_PATH_MAP_ERROR;
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}
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+static bool
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+needs_ro_update(struct multipath *mpp, int ro)
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+{
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+ struct pathgroup * pgp;
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+ struct path * pp;
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+ unsigned int i, j;
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+ struct dm_info *dmi = NULL;
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+
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+ if (!mpp || ro < 0)
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+ return false;
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+ dm_get_info(mpp->alias, &dmi);
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+ if (!dmi) /* assume we do need to reload the device */
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+ return true;
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+ if (dmi->read_only == ro) {
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+ free(dmi);
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+ return false;
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+ }
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+ free(dmi);
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+ if (ro == 1)
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+ return true;
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+ vector_foreach_slot (mpp->pg, pgp, i) {
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+ vector_foreach_slot (pgp->paths, pp, j) {
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+ if (sysfs_get_ro(pp) == 1)
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+ return false;
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+ }
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+ }
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+ return true;
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+}
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+
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static int
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uev_update_path (struct uevent *uev, struct vectors * vecs)
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{
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@@ -1388,7 +1417,7 @@ uev_update_path (struct uevent *uev, struct vectors * vecs)
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}
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ro = uevent_get_disk_ro(uev);
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- if (mpp && ro >= 0) {
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+ if (needs_ro_update(mpp, ro)) {
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condlog(2, "%s: update path write_protect to '%d' (uevent)", uev->kernel, ro);
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if (mpp->wait_for_udev)
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