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udevadm: cleanup-db: don't delete information for kept db entries

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devices with the db_persist property won't be deleted during database
cleanup. This applies to dm and md devices in particular.
For such devices, we should also keep the files under /run/udev/links,
/run/udev/tags, and /run/udev/watch, to make sure that after restart,
udevd has the same information about the devices as it did before
the cleanup.

If we don't do this, a lower-priority device that is discovered in
the coldplug phase may take over symlinks from a device that persisted.
Not removing the watches also enables udevd to resume watching a device
after restart.

Signed-off-by: Martin Wilck <mwilck@suse.com>
This commit is contained in:
Martin Wilck 2022-01-20 14:31:45 +01:00
parent 28d6e85451
commit 7ec624147a
1 changed files with 59 additions and 3 deletions
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62
src/udev/udevadm-info.c
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@ -256,6 +256,62 @@ static void cleanup_dir(DIR *dir, mode_t mask, int depth) {
}
}
/*
* Assume that dir is a directory with file names matching udev data base
* entries for devices in /run/udev/data (such as "b8:16"), and removes
* all files except those that haven't been deleted in /run/udev/data
* (i.e. they were skipped during db cleanup because of the db_persist flag).
* Returns true if the directory is empty after cleanup.
*/
static bool cleanup_dir_after_db_cleanup(DIR *dir, DIR *datadir) {
unsigned int kept = 0;
assert(dir && datadir);
FOREACH_DIRENT_ALL(dent, dir, break) {
struct stat data_stats, link_stats;
if (dot_or_dot_dot(dent->d_name))
continue;
if (fstatat(dirfd(dir), dent->d_name, &link_stats, AT_SYMLINK_NOFOLLOW) < 0) {
if (errno != ENOENT)
kept++;
continue;
}
if (fstatat(dirfd(datadir), dent->d_name, &data_stats, 0) < 0)
(void) unlinkat(dirfd(dir), dent->d_name,
S_ISDIR(link_stats.st_mode) ? AT_REMOVEDIR : 0);
else
/* The entry still exists under /run/udev/data */
kept++;
}
return kept == 0;
}
static void cleanup_dirs_after_db_cleanup(DIR *dir, DIR *datadir) {
assert(dir && datadir);
FOREACH_DIRENT_ALL(dent, dir, break) {
struct stat stats;
if (dot_or_dot_dot(dent->d_name))
continue;
if (fstatat(dirfd(dir), dent->d_name, &stats, AT_SYMLINK_NOFOLLOW) < 0)
continue;
if (S_ISDIR(stats.st_mode)) {
_cleanup_closedir_ DIR *dir2 = NULL;
dir2 = fdopendir(openat(dirfd(dir), dent->d_name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC));
if (dir2 && cleanup_dir_after_db_cleanup(dir2, datadir))
(void) unlinkat(dirfd(dir), dent->d_name, AT_REMOVEDIR);
} else
(void) unlinkat(dirfd(dir), dent->d_name, 0);
}
}
static void cleanup_db(void) {
_cleanup_closedir_ DIR *dir1 = NULL, *dir2 = NULL, *dir3 = NULL, *dir4 = NULL, *dir5 = NULL;
@ -265,11 +321,11 @@ static void cleanup_db(void) {
dir2 = opendir("/run/udev/links");
if (dir2)
cleanup_dir(dir2, 0, 2);
cleanup_dirs_after_db_cleanup(dir2, dir1);
dir3 = opendir("/run/udev/tags");
if (dir3)
cleanup_dir(dir3, 0, 2);
cleanup_dirs_after_db_cleanup(dir3, dir1);
dir4 = opendir("/run/udev/static_node-tags");
if (dir4)
@ -277,7 +333,7 @@ static void cleanup_db(void) {
dir5 = opendir("/run/udev/watch");
if (dir5)
cleanup_dir(dir5, 0, 1);
cleanup_dir_after_db_cleanup(dir5, dir1);
}
static int query_device(QueryType query, sd_device* device) {