From 7e56b05058c8d2af2b5bc8b0b1475d9fdd6cd7dc Mon Sep 17 00:00:00 2001 From: Tony Hutter Date: Sat, 20 Feb 2021 20:17:45 -0800 Subject: [PATCH 19/38] Better zfs_get_enclosure_sysfs_path() enclosure support A multpathed disk will have several 'underlying' paths to the disk. For example, multipath disk 'dm-0' may be made up of paths: /dev/{sda,sdb,sdc,sdd}. On many enclosures those underlying sysfs paths will have a symlink back to their enclosure device entry (like 'enclosure_device0/slot1'). This is used by the statechange-led.sh script to set/clear the fault LED for a disk, and by 'zpool status -c'. However, on some enclosures, those underlying paths may not all have symlinks back to the enclosure device. Maybe only two out of four of them might. This patch updates zfs_get_enclosure_sysfs_path() to favor returning paths that have symlinks back to their enclosure devices, rather than just returning the first path. Reviewed-by: Brian Behlendorf Signed-off-by: Tony Hutter Closes #11617 --- lib/libzutil/os/linux/zutil_device_path_os.c | 252 +++++++++++-------- 1 file changed, 142 insertions(+), 110 deletions(-) diff --git a/lib/libzutil/os/linux/zutil_device_path_os.c b/lib/libzutil/os/linux/zutil_device_path_os.c index 36331fd72..1f767bb7a 100644 --- a/lib/libzutil/os/linux/zutil_device_path_os.c +++ b/lib/libzutil/os/linux/zutil_device_path_os.c @@ -154,15 +154,124 @@ zfs_strip_path(char *path) return (strrchr(path, '/') + 1); } +/* + * Given a dev name like "sda", return the full enclosure sysfs path to + * the disk. You can also pass in the name with "/dev" prepended + * to it (like /dev/sda). + * + * For example, disk "sda" in enclosure slot 1: + * dev: "sda" + * returns: "/sys/class/enclosure/1:0:3:0/Slot 1" + * + * 'dev' must be a non-devicemapper device. + * + * Returned string must be freed. + */ +char * +zfs_get_enclosure_sysfs_path(const char *dev_name) +{ + DIR *dp = NULL; + struct dirent *ep; + char buf[MAXPATHLEN]; + char *tmp1 = NULL; + char *tmp2 = NULL; + char *tmp3 = NULL; + char *path = NULL; + size_t size; + int tmpsize; + + if (dev_name == NULL) + return (NULL); + + /* If they preface 'dev' with a path (like "/dev") then strip it off */ + tmp1 = strrchr(dev_name, '/'); + if (tmp1 != NULL) + dev_name = tmp1 + 1; /* +1 since we want the chr after '/' */ + + tmpsize = asprintf(&tmp1, "/sys/block/%s/device", dev_name); + if (tmpsize == -1 || tmp1 == NULL) { + tmp1 = NULL; + goto end; + } + + dp = opendir(tmp1); + if (dp == NULL) { + tmp1 = NULL; /* To make free() at the end a NOP */ + goto end; + } + + /* + * Look though all sysfs entries in /sys/block//device for + * the enclosure symlink. + */ + while ((ep = readdir(dp))) { + /* Ignore everything that's not our enclosure_device link */ + if (strstr(ep->d_name, "enclosure_device") == NULL) + continue; + + if (asprintf(&tmp2, "%s/%s", tmp1, ep->d_name) == -1 || + tmp2 == NULL) + break; + + size = readlink(tmp2, buf, sizeof (buf)); + + /* Did readlink fail or crop the link name? */ + if (size == -1 || size >= sizeof (buf)) { + free(tmp2); + tmp2 = NULL; /* To make free() at the end a NOP */ + break; + } + + /* + * We got a valid link. readlink() doesn't terminate strings + * so we have to do it. + */ + buf[size] = '\0'; + + /* + * Our link will look like: + * + * "../../../../port-11:1:2/..STUFF../enclosure/1:0:3:0/SLOT 1" + * + * We want to grab the "enclosure/1:0:3:0/SLOT 1" part + */ + tmp3 = strstr(buf, "enclosure"); + if (tmp3 == NULL) + break; + + if (asprintf(&path, "/sys/class/%s", tmp3) == -1) { + /* If asprintf() fails, 'path' is undefined */ + path = NULL; + break; + } + + if (path == NULL) + break; + } + +end: + free(tmp2); + free(tmp1); + + if (dp != NULL) + closedir(dp); + + return (path); +} + /* * Allocate and return the underlying device name for a device mapper device. - * If a device mapper device maps to multiple devices, return the first device. * * For example, dm_name = "/dev/dm-0" could return "/dev/sda". Symlinks to a * DM device (like /dev/disk/by-vdev/A0) are also allowed. * - * Returns device name, or NULL on error or no match. If dm_name is not a DM - * device then return NULL. + * If the DM device has multiple underlying devices (like with multipath + * DM devices), then favor underlying devices that have a symlink back to their + * back to their enclosure device in sysfs. This will be useful for the + * zedlet scripts that toggle the fault LED. + * + * Returns an underlying device name, or NULL on error or no match. If dm_name + * is not a DM device then return NULL. * * NOTE: The returned name string must be *freed*. */ @@ -176,6 +285,8 @@ dm_get_underlying_path(const char *dm_name) char *path = NULL; char *dev_str; int size; + char *first_path = NULL; + char *enclosure_path; if (dm_name == NULL) return (NULL); @@ -204,13 +315,27 @@ dm_get_underlying_path(const char *dm_name) goto end; /* - * Return first entry (that isn't itself a directory) in the - * directory containing device-mapper dependent (underlying) - * devices. + * A device-mapper device can have multiple paths to it (multipath). + * Favor paths that have a symlink back to their enclosure device. + * We have to do this since some enclosures may only provide a symlink + * back for one underlying path to a disk and not the other. + * + * If no paths have links back to their enclosure, then just return the + * first path. */ while ((ep = readdir(dp))) { if (ep->d_type != DT_DIR) { /* skip "." and ".." dirs */ + if (!first_path) + first_path = strdup(ep->d_name); + + enclosure_path = + zfs_get_enclosure_sysfs_path(ep->d_name); + + if (!enclosure_path) + continue; + size = asprintf(&path, "/dev/%s", ep->d_name); + free(enclosure_path); break; } } @@ -220,6 +345,17 @@ end: closedir(dp); free(tmp); free(realp); + + if (!path) { + /* + * None of the underlying paths had a link back to their + * enclosure devices. Throw up out hands and return the first + * underlying path. + */ + size = asprintf(&path, "/dev/%s", first_path); + } + + free(first_path); return (path); } @@ -331,110 +467,6 @@ zfs_get_underlying_path(const char *dev_name) return (name); } -/* - * Given a dev name like "sda", return the full enclosure sysfs path to - * the disk. You can also pass in the name with "/dev" prepended - * to it (like /dev/sda). - * - * For example, disk "sda" in enclosure slot 1: - * dev: "sda" - * returns: "/sys/class/enclosure/1:0:3:0/Slot 1" - * - * 'dev' must be a non-devicemapper device. - * - * Returned string must be freed. - */ -char * -zfs_get_enclosure_sysfs_path(const char *dev_name) -{ - DIR *dp = NULL; - struct dirent *ep; - char buf[MAXPATHLEN]; - char *tmp1 = NULL; - char *tmp2 = NULL; - char *tmp3 = NULL; - char *path = NULL; - size_t size; - int tmpsize; - - if (dev_name == NULL) - return (NULL); - - /* If they preface 'dev' with a path (like "/dev") then strip it off */ - tmp1 = strrchr(dev_name, '/'); - if (tmp1 != NULL) - dev_name = tmp1 + 1; /* +1 since we want the chr after '/' */ - - tmpsize = asprintf(&tmp1, "/sys/block/%s/device", dev_name); - if (tmpsize == -1 || tmp1 == NULL) { - tmp1 = NULL; - goto end; - } - - dp = opendir(tmp1); - if (dp == NULL) { - tmp1 = NULL; /* To make free() at the end a NOP */ - goto end; - } - - /* - * Look though all sysfs entries in /sys/block//device for - * the enclosure symlink. - */ - while ((ep = readdir(dp))) { - /* Ignore everything that's not our enclosure_device link */ - if (strstr(ep->d_name, "enclosure_device") == NULL) - continue; - - if (asprintf(&tmp2, "%s/%s", tmp1, ep->d_name) == -1 || - tmp2 == NULL) - break; - - size = readlink(tmp2, buf, sizeof (buf)); - - /* Did readlink fail or crop the link name? */ - if (size == -1 || size >= sizeof (buf)) { - free(tmp2); - tmp2 = NULL; /* To make free() at the end a NOP */ - break; - } - - /* - * We got a valid link. readlink() doesn't terminate strings - * so we have to do it. - */ - buf[size] = '\0'; - - /* - * Our link will look like: - * - * "../../../../port-11:1:2/..STUFF../enclosure/1:0:3:0/SLOT 1" - * - * We want to grab the "enclosure/1:0:3:0/SLOT 1" part - */ - tmp3 = strstr(buf, "enclosure"); - if (tmp3 == NULL) - break; - - if (asprintf(&path, "/sys/class/%s", tmp3) == -1) { - /* If asprintf() fails, 'path' is undefined */ - path = NULL; - break; - } - - if (path == NULL) - break; - } - -end: - free(tmp2); - free(tmp1); - - if (dp != NULL) - closedir(dp); - - return (path); -} #ifdef HAVE_LIBUDEV -- 2.30.1