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util-linux/backport-libblkid-use-sys-to-read-all-block-devices.patch
wangchen2020 46b4dd2361 use /sys to read all block devices
2021-03-18 14:09:24 +08:00

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From 8d3f9430c59416e4c1eddc899578158a7a1ed414 Mon Sep 17 00:00:00 2001
From: Karel Zak <kzak@redhat.com>
Date: Wed, 7 Oct 2020 13:49:45 +0200
Subject: [PATCH] libblkid: use /sys to read all block devices
The old implementation uses /proc/partitions where devices are
filtered by kernel (missing devices with ext_range=1 and removable
devices).
The problem with the old implementation is whole-disk heuristic based
on device name, order of devices, etc.
The new implementation use the same code to read also removable
devices.
Addresses: https://github.com/karelzak/util-linux/issues/1151
Signed-off-by: Karel Zak <kzak@redhat.com>
---
lib/sysfs.c | 36 +++++---
libblkid/src/blkidP.h | 2 +-
libblkid/src/devname.c | 235 +++++++++++++++++++++----------------------------
3 files changed, 128 insertions(+), 145 deletions(-)
diff --git a/lib/sysfs.c b/lib/sysfs.c
index 5b4de2c..0c360ce 100644
--- a/lib/sysfs.c
+++ b/lib/sysfs.c
@@ -874,7 +874,7 @@ int sysfs_devname_is_hidden(const char *prefix, const char *name)
dev_t __sysfs_devname_to_devno(const char *prefix, const char *name, const char *parent)
{
char buf[PATH_MAX];
- char *_name = NULL; /* name as encoded in sysfs */
+ char *_name = NULL, *_parent = NULL; /* name as encoded in sysfs */
dev_t dev = 0;
int len;
@@ -901,19 +901,20 @@ dev_t __sysfs_devname_to_devno(const char *prefix, const char *name, const char
goto done;
sysfs_devname_dev_to_sys(_name);
- if (parent && strncmp("dm-", name, 3) != 0) {
- /*
- * Create path to /sys/block/<parent>/<name>/dev
- */
- char *_parent = strdup(parent);
-
+ if (parent) {
+ _parent = strdup(parent);
if (!_parent)
goto done;
+ }
+
+ if (parent && strncmp("dm-", name, 3) != 0) {
+ /*
+ * Create path to /sys/block/<parent>/<name>/dev
+ */
sysfs_devname_dev_to_sys(_parent);
len = snprintf(buf, sizeof(buf),
"%s" _PATH_SYS_BLOCK "/%s/%s/dev",
prefix, _parent, _name);
- free(_parent);
if (len < 0 || (size_t) len >= sizeof(buf))
goto done;
@@ -934,10 +935,22 @@ dev_t __sysfs_devname_to_devno(const char *prefix, const char *name, const char
goto done;
dev = read_devno(buf);
+ /*
+ * Read from /sys/block/<parent>/<partition>/dev
+ */
+ if (!dev && parent && startswith(name, parent)) {
+ len = snprintf(buf, sizeof(buf),
+ "%s" _PATH_SYS_BLOCK "/%s/%s/dev",
+ prefix, _parent, _name);
+ if (len < 0 || (size_t) len >= sizeof(buf))
+ goto done;
+ dev = read_devno(buf);
+ }
+
+ /*
+ * Read from /sys/block/<sysname>/device/dev
+ */
if (!dev) {
- /*
- * Read from /sys/block/<sysname>/device/dev
- */
len = snprintf(buf, sizeof(buf),
"%s" _PATH_SYS_BLOCK "/%s/device/dev",
prefix, _name);
@@ -947,6 +960,7 @@ dev_t __sysfs_devname_to_devno(const char *prefix, const char *name, const char
}
done:
free(_name);
+ free(_parent);
return dev;
}
diff --git a/libblkid/src/blkidP.h b/libblkid/src/blkidP.h
index 802a1b3..fe3736f 100644
--- a/libblkid/src/blkidP.h
+++ b/libblkid/src/blkidP.h
@@ -301,7 +301,7 @@ struct blkid_struct_cache
#define BLKID_PROBE_NONE 1
#define BLKID_ERR_IO 5
-#define BLKID_ERR_PROC 9
+#define BLKID_ERR_SYSFS 9
#define BLKID_ERR_MEM 12
#define BLKID_ERR_CACHE 14
#define BLKID_ERR_DEV 19
diff --git a/libblkid/src/devname.c b/libblkid/src/devname.c
index 8f2d89a..4b9df5a 100644
--- a/libblkid/src/devname.c
+++ b/libblkid/src/devname.c
@@ -39,6 +39,7 @@
#include "canonicalize.h" /* $(top_srcdir)/include */
#include "pathnames.h"
#include "sysfs.h"
+#include "fileutils.h"
/*
* Find a dev struct in the cache by device name, if available.
@@ -442,178 +443,146 @@ ubi_probe_all(blkid_cache cache, int only_if_new)
}
/*
- * Read the device data for all available block devices in the system.
+ * This function uses /sys to read all block devices in way compatible with
+ * /proc/partitions (like the original libblkid implementation)
*/
-static int probe_all(blkid_cache cache, int only_if_new)
+static int
+sysfs_probe_all(blkid_cache cache, int only_if_new, int only_removable)
{
- FILE *proc;
- char line[1024];
- char ptname0[128 + 1], ptname1[128 + 1], *ptname = NULL;
- char *ptnames[2];
- dev_t devs[2] = { 0, 0 };
- int iswhole[2] = { 0, 0 };
- int ma, mi;
- unsigned long long sz;
- int lens[2] = { 0, 0 };
- int which = 0, last = 0;
- struct list_head *p, *pnext;
+ DIR *sysfs;
+ struct dirent *dev;
- ptnames[0] = ptname0;
- ptnames[1] = ptname1;
+ sysfs = opendir(_PATH_SYS_BLOCK);
+ if (!sysfs)
+ return -BLKID_ERR_SYSFS;
- if (!cache)
- return -BLKID_ERR_PARAM;
+ /* scan /sys/block */
+ while ((dev = xreaddir(sysfs))) {
+ DIR *dir = NULL;
+ dev_t devno;
+ size_t nparts = 0;
+ unsigned int maxparts = 0, removable = 0;
+ struct dirent *part;
+ struct path_cxt *pc = NULL;
+ uint64_t size = 0;
- if (cache->bic_flags & BLKID_BIC_FL_PROBED &&
- time(NULL) - cache->bic_time < BLKID_PROBE_INTERVAL)
- return 0;
+ DBG(DEVNAME, ul_debug("checking %s", dev->d_name));
- blkid_read_cache(cache);
- evms_probe_all(cache, only_if_new);
-#ifdef VG_DIR
- lvm_probe_all(cache, only_if_new);
-#endif
- ubi_probe_all(cache, only_if_new);
+ devno = sysfs_devname_to_devno(dev->d_name);
+ if (!devno)
+ goto next;
+ pc = ul_new_sysfs_path(devno, NULL, NULL);
+ if (!pc)
+ goto next;
+
+ if (ul_path_read_u64(pc, &size, "size") != 0)
+ size = 0;
+ if (ul_path_read_u32(pc, &removable, "removable") != 0)
+ removable = 0;
+
+ /* ingnore empty devices */
+ if (!size)
+ goto next;
+
+ /* accept removeable if only removable requested */
+ if (only_removable) {
+ if (!removable)
+ goto next;
+
+ /* emulate /proc/partitions
+ * -- ignore empty devices and non-partitionable removable devices */
+ } else {
+ if (ul_path_read_u32(pc, &maxparts, "ext_range") != 0)
+ maxparts = 0;
+ if (!maxparts && removable)
+ goto next;
+ }
- proc = fopen(PROC_PARTITIONS, "r" UL_CLOEXECSTR);
- if (!proc)
- return -BLKID_ERR_PROC;
+ DBG(DEVNAME, ul_debug("read device name %s", dev->d_name));
- while (fgets(line, sizeof(line), proc)) {
- last = which;
- which ^= 1;
- ptname = ptnames[which];
+ dir = ul_path_opendir(pc, NULL);
+ if (!dir)
+ goto next;
- if (sscanf(line, " %d %d %llu %128[^\n ]",
- &ma, &mi, &sz, ptname) != 4)
- continue;
- devs[which] = makedev(ma, mi);
-
- DBG(DEVNAME, ul_debug("read device name %s", ptname));
-
- /* Skip whole disk devs unless they have no partitions.
- * If base name of device has changed, also
- * check previous dev to see if it didn't have a partn.
- * heuristic: partition name ends in a digit, & partition
- * names contain whole device name as substring.
- *
- * Skip extended partitions.
- * heuristic: size is 1
- */
+ /* read /sys/block/<name>/ do get partitions */
+ while ((part = xreaddir(dir))) {
+ dev_t partno;
- lens[which] = strlen(ptname);
- iswhole[which] = sysfs_devno_is_wholedisk(devs[which]);
+ if (!sysfs_blkdev_is_partition_dirent(dir, part, dev->d_name))
+ continue;
- /* probably partition, so check */
- if (!iswhole[which]) {
- DBG(DEVNAME, ul_debug(" Probe partition dev %s, devno 0x%04X",
- ptname, (unsigned int) devs[which]));
+ /* ignore extended partitions
+ * -- recount size to blocks like /proc/partitions */
+ if (ul_path_readf_u64(pc, &size, "%s/size", part->d_name) == 0
+ && (size >> 1) == 1)
+ continue;
+ partno = __sysfs_devname_to_devno(NULL, part->d_name, dev->d_name);
+ if (!partno)
+ continue;
- if (sz > 1)
- probe_one(cache, ptname, devs[which], 0,
- only_if_new, 0);
- lens[which] = 0; /* mark as checked */
+ DBG(DEVNAME, ul_debug(" Probe partition dev %s, devno 0x%04X",
+ part->d_name, (unsigned int) partno));
+ nparts++;
+ probe_one(cache, part->d_name, partno, 0, only_if_new, 0);
}
- /*
- * If last was a whole disk and we just found a partition
- * on it, remove the whole-disk dev from the cache if
- * it exists.
- */
- if (lens[last] && iswhole[last]
- && !strncmp(ptnames[last], ptname, lens[last])) {
+ if (!nparts) {
+ /* add non-partitioned whole disk to cache */
+ DBG(DEVNAME, ul_debug(" Probe whole dev %s, devno 0x%04X",
+ dev->d_name, (unsigned int) devno));
+ probe_one(cache, dev->d_name, devno, 0, only_if_new, 0);
+ } else {
+ /* remove partitioned whole-disk from cache */
+ struct list_head *p, *pnext;
list_for_each_safe(p, pnext, &cache->bic_devs) {
- blkid_dev tmp;
-
- /* find blkid dev for the whole-disk devno */
- tmp = list_entry(p, struct blkid_struct_dev,
- bid_devs);
- if (tmp->bid_devno == devs[last]) {
- DBG(DEVNAME, ul_debug(" freeing %s",
- tmp->bid_name));
+ blkid_dev tmp = list_entry(p, struct blkid_struct_dev,
+ bid_devs);
+ if (tmp->bid_devno == devno) {
+ DBG(DEVNAME, ul_debug(" freeing %s", tmp->bid_name));
blkid_free_dev(tmp);
cache->bic_flags |= BLKID_BIC_FL_CHANGED;
break;
}
}
- lens[last] = 0; /* mark as checked */
- }
- /*
- * If last was not checked because it looked like a whole-disk
- * dev, and the device's base name has changed,
- * check last as well.
- */
- if (lens[last] && strncmp(ptnames[last], ptname, lens[last]) != 0) {
- DBG(DEVNAME, ul_debug(" Probe whole dev %s, devno 0x%04X",
- ptnames[last], (unsigned int) devs[last]));
- probe_one(cache, ptnames[last], devs[last], 0,
- only_if_new, 0);
-
- lens[last] = 0; /* mark as checked */
}
+ next:
+ if (dir)
+ closedir(dir);
+ if (pc)
+ ul_unref_path(pc);
}
- /* Handle the last device if it wasn't partitioned */
- if (lens[which]) {
- DBG(DEVNAME, ul_debug(" Probe whole dev %s, devno 0x%04X",
- ptname, (unsigned int) devs[which]));
- probe_one(cache, ptname, devs[which], 0, only_if_new, 0);
- }
-
- fclose(proc);
- blkid_flush_cache(cache);
+ closedir(sysfs);
return 0;
}
-/* Don't use it by default -- it's pretty slow (because cdroms, floppy, ...)
+/*
+ * Read the device data for all available block devices in the system.
*/
-static int probe_all_removable(blkid_cache cache)
+static int probe_all(blkid_cache cache, int only_if_new)
{
- struct path_cxt *pc;
- DIR *dir;
- struct dirent *d;
-
if (!cache)
return -BLKID_ERR_PARAM;
- dir = opendir(_PATH_SYS_BLOCK);
- if (!dir)
- return -BLKID_ERR_PROC;
-
- pc = ul_new_path(NULL);
+ if (cache->bic_flags & BLKID_BIC_FL_PROBED &&
+ time(NULL) - cache->bic_time < BLKID_PROBE_INTERVAL)
+ return 0;
- while((d = readdir(dir))) {
- int removable = 0;
- dev_t devno;
+ blkid_read_cache(cache);
-#ifdef _DIRENT_HAVE_D_TYPE
- if (d->d_type != DT_UNKNOWN && d->d_type != DT_LNK)
- continue;
+ evms_probe_all(cache, only_if_new);
+#ifdef VG_DIR
+ lvm_probe_all(cache, only_if_new);
#endif
- if (d->d_name[0] == '.' &&
- ((d->d_name[1] == 0) ||
- ((d->d_name[1] == '.') && (d->d_name[2] == 0))))
- continue;
-
- devno = sysfs_devname_to_devno(d->d_name);
- if (!devno)
- continue;
-
- if (sysfs_blkdev_init_path(pc, devno, NULL) == 0
- && ul_path_read_s32(pc, &removable, "removable") != 0)
- removable = 0;
+ ubi_probe_all(cache, only_if_new);
- if (removable)
- probe_one(cache, d->d_name, devno, 0, 0, 1);
- }
+ sysfs_probe_all(cache, only_if_new, 0);
- ul_unref_path(pc);
- closedir(dir);
+ blkid_flush_cache(cache);
return 0;
}
-
/**
* blkid_probe_all:
* @cache: cache handler
@@ -677,7 +646,7 @@ int blkid_probe_all_removable(blkid_cache cache)
int ret;
DBG(PROBE, ul_debug("Begin blkid_probe_all_removable()"));
- ret = probe_all_removable(cache);
+ ret = sysfs_probe_all(cache, 0, 1);
DBG(PROBE, ul_debug("End blkid_probe_all_removable() [rc=%d]", ret));
return ret;
}
--
1.8.3.1
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