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shutdown: rework log_umount_blockers() a bit

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Let's go directly from opening /proc/ to opening /proc/$PID/fd/ instead
of indirectly via opening /proc/$PID/ first. Saves a syscall.

Also, add error logging about all unexpected errors.

Finally, drop redundant denylist for /proc/, /sys/, /dev/ prefix
checking, should be redundant, given the ealier check against the 'mnt'
prefix.
This commit is contained in:
Lennart Poettering
2022-08-24 11:55:14 +02:00
parent f11efcbeb1
commit 05768ae36b
1 changed files with 46 additions and 32 deletions
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78
src/shutdown/umount.c
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@@ -529,11 +529,12 @@ static bool nonunmountable_path(const char *path) {
}
static void log_umount_blockers(const char *mnt) {
_cleanup_free_ char *blockers = NULL;
int r;
_cleanup_closedir_ DIR *dir = opendir("/proc");
if (!dir)
return (void) log_warning_errno(errno, "opendir(/proc) failed: %m");
_cleanup_free_ char *blockers = NULL;
return (void) log_warning_errno(errno, "Failed to open /proc/: %m");
FOREACH_DIRENT_ALL(de, dir, break) {
if (!IN_SET(de->d_type, DT_DIR, DT_UNKNOWN))
@@ -543,37 +544,50 @@ static void log_umount_blockers(const char *mnt) {
if (parse_pid(de->d_name, &pid) < 0)
continue;
_cleanup_closedir_ DIR *pid_dir = xopendirat(dirfd(dir), de->d_name, 0);
if (!pid_dir)
_cleanup_free_ char *fdp = path_join(de->d_name, "fd");
if (!fdp)
return (void) log_oom();
_cleanup_closedir_ DIR *fd_dir = xopendirat(dirfd(dir), fdp, 0);
if (!fd_dir) {
if (errno != ENOENT) /* process gone by now? */
log_debug_errno(errno, "Failed to open /proc/%s/, ignoring: %m",fdp);
continue;
_cleanup_closedir_ DIR *fd_dir = xopendirat(dirfd(pid_dir), "fd", 0);
if (!fd_dir)
continue;
FOREACH_DIRENT(fd_de, fd_dir, break) {
_cleanup_free_ char *open_file = NULL, *comm = NULL;
if (readlinkat_malloc(dirfd(fd_dir), fd_de->d_name, &open_file) < 0)
continue;
if (!path_startswith(open_file, mnt))
continue;
if (PATH_STARTSWITH_SET(open_file, "/dev", "/sys", "/proc"))
continue;
if (get_process_comm(pid, &comm) < 0)
continue;
if (!strextend_with_separator(&blockers, ", ", comm))
return (void) log_oom();
if (!strextend(&blockers, "(", de->d_name, ")"))
return (void) log_oom();
break;
}
bool culprit = false;
FOREACH_DIRENT(fd_de, fd_dir, break) {
_cleanup_free_ char *open_file = NULL;
r = readlinkat_malloc(dirfd(fd_dir), fd_de->d_name, &open_file);
if (r < 0) {
if (r != -ENOENT) /* fd closed by now */
log_debug_errno(r, "Failed to read link /proc/%s/%s, ignoring: %m", fdp, fd_de->d_name);
continue;
}
if (path_startswith(open_file, mnt)) {
culprit = true;
break;
}
}
if (!culprit)
continue;
_cleanup_free_ char *comm = NULL;
r = get_process_comm(pid, &comm);
if (r < 0) {
if (r != -ESRCH) /* process gone by now */
log_debug_errno(r, "Failed to read process name of PID " PID_FMT ": %m", pid);
continue;
}
if (!strextend_with_separator(&blockers, ", ", comm))
return (void) log_oom();
if (!strextend(&blockers, "(", de->d_name, ")"))
return (void) log_oom();
}
if (blockers)