Hi,
this patch removes the assumption that device directories in /sys are
always real directories. With the work-in-progress unification of all
sysfs devices, they will show up as symlinks pointing into a single
device tree if the kernel does not set CONFIG_SYSFS_DEPRECATED.
It also adds direct support for a future "block as a class", which will
not have any hierarchy to recurse to find all block devices.
$ diffstat lvm2-future-proof-sysfs.patch
filter-sysfs.c | 91 +++++++++++++++++++++++++++++++++++----------------------
1 file changed, 56 insertions(+), 35 deletions(-)
Thanks,
Kay
--- lib/filters/filter-sysfs.c.orig 2007-08-11 11:51:59.000000000 +0200
+++ lib/filters/filter-sysfs.c 2007-08-12 15:23:21.000000000 +0200
@@ -20,12 +20,14 @@
#include <dirent.h>
-static int _locate_sysfs_blocks(const char *proc, char *path, size_t len)
+static int _locate_sysfs_blocks(const char *proc, char *path, size_t len,
+ int *sys_depth)
{
char proc_mounts[PATH_MAX];
- int r = 0;
FILE *fp;
char *split[4], buffer[PATH_MAX + 16];
+ const char *sys_mnt = NULL;
+ struct stat info;
if (!*proc) {
log_verbose("No proc filesystem found: skipping sysfs filter");
@@ -46,10 +48,7 @@
while (fgets(buffer, sizeof(buffer), fp)) {
if (dm_split_words(buffer, 4, 0, split) == 4 &&
!strcmp(split[2], "sysfs")) {
- if (dm_snprintf(path, len, "%s/%s", split[1],
- "block") >= 0) {
- r = 1;
- }
+ sys_mnt = split[1];
break;
}
}
@@ -57,7 +56,34 @@
if (fclose(fp))
log_sys_error("fclose", proc_mounts);
- return r;
+ if (!sys_mnt) {
+ log_error("Failed to find sysfs mount point");
+ return 0;
+ }
+
+ if (dm_snprintf(path, len, "%s/%s", sys_mnt,
+ "subsystem/block/devices") >= 0) {
+ if (stat(path, &info) >= 0) {
+ *sys_depth = 0;
+ return 1;
+ }
+ }
+
+ if (dm_snprintf(path, len, "%s/%s", sys_mnt, "class/block") >= 0) {
+ if (stat(path, &info) >= 0) {
+ *sys_depth = 0;
+ return 1;
+ }
+ }
+
+ if (dm_snprintf(path, len, "%s/%s", sys_mnt, "block") >= 0) {
+ if (stat(path, &info) >= 0) {
+ *sys_depth = 1;
+ return 1;
+ }
+ }
+
+ return 0;
}
/*----------------------------------------------------------------
@@ -72,11 +98,13 @@
struct dev_set {
struct dm_pool *mem;
const char *sys_block;
+ int sys_depth;
int initialised;
struct entry *slots[SET_BUCKETS];
};
-static struct dev_set *_dev_set_create(struct dm_pool *mem, const char *sys_block)
+static struct dev_set *_dev_set_create(struct dm_pool *mem,
+ const char *sys_block, int sys_depth)
{
struct dev_set *ds;
@@ -85,6 +113,7 @@
ds->mem = mem;
ds->sys_block = dm_pool_strdup(mem, sys_block);
+ ds->sys_depth = sys_depth;
ds->initialised = 0;
return ds;
@@ -168,13 +197,13 @@
/*
* Recurse through sysfs directories, inserting any devs found.
*/
-static int _read_devs(struct dev_set *ds, const char *dir)
+static int _read_devs(struct dev_set *ds, const char *dir, int sysfs_depth)
{
struct dirent *d;
DIR *dr;
- unsigned char dtype;
struct stat info;
char path[PATH_MAX];
+ char file[PATH_MAX];
dev_t dev = { 0 };
int r = 1;
@@ -194,31 +223,22 @@
continue;
}
- dtype = d->d_type;
-
- if (dtype == DT_UNKNOWN) {
- if (lstat(path, &info) >= 0) {
- if (S_ISLNK(info.st_mode))
- dtype = DT_LNK;
- else if (S_ISDIR(info.st_mode))
- dtype = DT_DIR;
- else if (S_ISREG(info.st_mode))
- dtype = DT_REG;
- }
+ /* devices have a "dev" file */
+ if (dm_snprintf(file, sizeof(file), "%s/dev", path) < 0) {
+ log_error("sysfs path name too long: %s in %s",
+ d->d_name, dir);
+ continue;
}
- if (dtype == DT_DIR) {
- if (!_read_devs(ds, path)) {
- r = 0;
- break;
- }
+ if (stat(file, &info) >= 0) {
+ /* * recurse if we found a device and expect subdirs */
+ if (sysfs_depth > 0)
+ _read_devs(ds, path, sysfs_depth - 1);
+
+ /* add the device we have found */
+ if (_read_dev(file, &dev))
+ _set_insert(ds, dev);
}
-
- if ((dtype == DT_REG && !strcmp(d->d_name, "dev")))
- if (!_read_dev(path, &dev) || !_set_insert(ds, dev)) {
- r = 0;
- break;
- }
}
if (closedir(dr))
@@ -229,7 +249,7 @@
static int _init_devs(struct dev_set *ds)
{
- if (!_read_devs(ds, ds->sys_block)) {
+ if (!_read_devs(ds, ds->sys_block, ds->sys_depth)) {
ds->initialised = -1;
return 0;
}
@@ -267,11 +287,12 @@
struct dev_filter *sysfs_filter_create(const char *proc)
{
char sys_block[PATH_MAX];
+ int sys_depth;
struct dm_pool *mem;
struct dev_set *ds;
struct dev_filter *f;
- if (!_locate_sysfs_blocks(proc, sys_block, sizeof(sys_block)))
+ if (!_locate_sysfs_blocks(proc, sys_block, sizeof(sys_block), &sys_depth))
return NULL;
if (!(mem = dm_pool_create("sysfs", 256))) {
@@ -279,7 +300,7 @@
return NULL;
}
- if (!(ds = _dev_set_create(mem, sys_block))) {
+ if (!(ds = _dev_set_create(mem, sys_block, sys_depth))) {
log_error("sysfs dev_set creation failed");
goto bad;
}
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