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Better zfs_get_enclosure_sysfs_path() enclosure support

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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 <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #11617
This commit is contained in:
Tony Hutter 2021-02-20 20:17:45 -08:00
parent bdd43a2396
commit 88a3751e67
1 changed files with 142 additions and 110 deletions
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252
lib/libzutil/os/linux/zutil_device_path_os.c
View File

@ -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/<dev>/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/<dev>/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