mirror of https://github.com/openzfs/zfs.git
Read the /etc/hostid file directly.
Deprecate the /usr/bin/hostid call by reading the /etc/hostid file directly. Add the spl_hostid_path parameter to override the default /etc/hostid path. Rename the set_hostid() function to hostid_exec() to better reflect actual behavior and complement the new hostid_read() function. Use HW_INVALID_HOSTID as the spl_hostid sentinel value because zero seems to be a valid gethostid() result on Linux.
This commit is contained in:
Darik Horn
Brian Behlendorf
parent
bf0c60c060
commit
0d54dcb566
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@ -30,4 +30,8 @@
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/* to hold a decimal or hex */
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/* hostid string */
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/* Supplemental definitions for Linux. */
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#define HW_HOSTID_PATH "/etc/hostid" /* binary configuration file */
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#define HW_HOSTID_MASK 0xFFFFFFFF /* significant hostid bits */
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#endif /* SPL_SYSTEMINFO_H */
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@ -27,7 +27,7 @@
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#include <sys/sysmacros.h>
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#include <sys/systeminfo.h>
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#include <sys/vmsystm.h>
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#include <sys/vnode.h>
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#include <sys/kobj.h>
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#include <sys/kmem.h>
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#include <sys/mutex.h>
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#include <sys/rwlock.h>
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@ -52,7 +52,7 @@
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char spl_version[16] = "SPL v" SPL_META_VERSION;
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EXPORT_SYMBOL(spl_version);
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unsigned long spl_hostid = 0;
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unsigned long spl_hostid = HW_INVALID_HOSTID;
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EXPORT_SYMBOL(spl_hostid);
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module_param(spl_hostid, ulong, 0644);
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MODULE_PARM_DESC(spl_hostid, "The system hostid.");
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@ -364,6 +364,100 @@ struct new_utsname *__utsname(void)
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}
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EXPORT_SYMBOL(__utsname);
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/*
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* Read the unique system identifier from the /etc/hostid file.
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*
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* The behavior of /usr/bin/hostid on Linux systems with the
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* regular eglibc and coreutils is:
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*
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* 1. Generate the value if the /etc/hostid file does not exist
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* or if the /etc/hostid file is less than four bytes in size.
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*
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* 2. If the /etc/hostid file is at least 4 bytes, then return
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* the first four bytes [0..3] in native endian order.
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*
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* 3. Always ignore bytes [4..] if they exist in the file.
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*
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* Only the first four bytes are significant, even on systems that
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* have a 64-bit word size.
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*
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* See:
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*
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* eglibc: sysdeps/unix/sysv/linux/gethostid.c
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* coreutils: src/hostid.c
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*
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* Notes:
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*
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* The /etc/hostid file on Solaris is a text file that often reads:
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*
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* # DO NOT EDIT
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* "0123456789"
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*
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* Directly copying this file to Linux results in a constant
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* hostid of 4f442023 because the default comment constitutes
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* the first four bytes of the file.
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*
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*/
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char *spl_hostid_path = HW_HOSTID_PATH;
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module_param(spl_hostid_path, charp, 0444);
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MODULE_PARM_DESC(spl_hostid_path, "The system hostid file (/etc/hostid)");
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static int
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hostid_read(void)
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{
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int result;
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uint64_t size;
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struct _buf *file;
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unsigned long hostid = 0;
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file = kobj_open_file(spl_hostid_path);
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if (file == (struct _buf *)-1) {
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printk(KERN_WARNING
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"SPL: The %s file is not found.\n",
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spl_hostid_path);
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return -1;
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}
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result = kobj_get_filesize(file, &size);
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if (result != 0) {
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printk(KERN_WARNING
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"SPL: kobj_get_filesize returned %i on %s\n",
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result, spl_hostid_path);
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kobj_close_file(file);
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return -2;
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}
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if (size < sizeof(HW_HOSTID_MASK)) {
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printk(KERN_WARNING
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"SPL: Ignoring the %s file because it is %llu bytes; "
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"expecting %lu bytes instead.\n",
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spl_hostid_path, size, sizeof(HW_HOSTID_MASK));
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kobj_close_file(file);
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return -3;
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}
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/* Read directly into the variable like eglibc does. */
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/* Short reads are okay; native behavior is preserved. */
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result = kobj_read_file(file, (char *)&hostid, sizeof(hostid), 0);
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if (result < 0) {
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printk(KERN_WARNING
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"SPL: kobj_read_file returned %i on %s\n",
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result, spl_hostid_path);
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kobj_close_file(file);
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return -4;
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}
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/* Mask down to 32 bits like coreutils does. */
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spl_hostid = hostid & HW_HOSTID_MASK;
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kobj_close_file(file);
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return 0;
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}
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#define GET_HOSTID_CMD \
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"exec 0</dev/null " \
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" 1>/proc/sys/kernel/spl/hostid " \
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@ -371,7 +465,7 @@ EXPORT_SYMBOL(__utsname);
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"hostid"
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static int
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set_hostid(void)
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hostid_exec(void)
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{
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char *argv[] = { "/bin/sh",
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"-c",
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@ -486,8 +580,14 @@ __init spl_init(void)
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if ((rc = zlib_init()))
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SGOTO(out9, rc);
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/* Get the hostid if it was not passed as a module parameter. */
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if (spl_hostid == 0 && (rc = set_hostid()))
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/*
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* Get the hostid if it was not passed as a module parameter. Try
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* reading the /etc/hostid file directly, and then fall back to calling
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* the /usr/bin/hostid utility.
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*/
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if (spl_hostid == HW_INVALID_HOSTID
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&& (rc = hostid_read()) && (rc = hostid_exec()))
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SGOTO(out10, rc = -EADDRNOTAVAIL);
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#ifndef HAVE_KALLSYMS_LOOKUP_NAME
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