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gfs2: Add GL_NOPID flag for process-independent glock holders 

Add a GL_NOPID flag to indicate that once a glock holder has been acquired, it
won't be associated with the current process anymore.  This is useful for iopen
and flock glocks which are associated with open files, as well as journal glock
holders and similar which are associated with the filesystem.

Once GL_NOPID is used for all applicable glocks (see the next patches),
processes will no longer be falsely reported as holding glocks which they are
not actually holding in the glocks dump file.  Unlike before, when a process is
reported as having "(ended)", this will indicate an actual bug.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Andreas Gruenbacher 2022-04-05 22:07:30 +02:00
parent 56535dc695
commit cbe6d2576e
2 changed files with 32 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
fs/gfs2/glock.c
View File

@ -1467,6 +1467,15 @@ void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
va_end(args);
}
static inline bool pid_is_meaningful(const struct gfs2_holder *gh)
{
if (!(gh->gh_flags & GL_NOPID))
return true;
if (gh->gh_state == LM_ST_UNLOCKED)
return true;
return false;
}
/**
* add_to_queue - Add a holder to the wait queue (but look for recursion)
* @gh: the holder structure to add
@ -1503,10 +1512,17 @@ __acquires(&gl->gl_lockref.lock)
}
list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
(gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK) &&
!test_bit(HIF_MAY_DEMOTE, &gh2->gh_iflags)))
goto trap_recursive;
if (likely(gh2->gh_owner_pid != gh->gh_owner_pid))
continue;
if (gh->gh_gl->gl_ops->go_type == LM_TYPE_FLOCK)
continue;
if (test_bit(HIF_MAY_DEMOTE, &gh2->gh_iflags))
continue;
if (!pid_is_meaningful(gh2))
continue;
goto trap_recursive;
}
list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
if (try_futile &&
!(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
fail:
@ -2321,19 +2337,24 @@ static const char *hflags2str(char *buf, u16 flags, unsigned long iflags)
static void dump_holder(struct seq_file *seq, const struct gfs2_holder *gh,
const char *fs_id_buf)
{
struct task_struct *gh_owner = NULL;
const char *comm = "(none)";
pid_t owner_pid = 0;
char flags_buf[32];
rcu_read_lock();
if (gh->gh_owner_pid)
if (pid_is_meaningful(gh)) {
struct task_struct *gh_owner;
comm = "(ended)";
owner_pid = pid_nr(gh->gh_owner_pid);
gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
if (gh_owner)
comm = gh_owner->comm;
}
gfs2_print_dbg(seq, "%s H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
fs_id_buf, state2str(gh->gh_state),
hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
gh->gh_error,
gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
gh_owner ? gh_owner->comm : "(ended)",
(void *)gh->gh_ip);
gh->gh_error, (long)owner_pid, comm, (void *)gh->gh_ip);
rcu_read_unlock();
}

1
fs/gfs2/glock.h
View File

@ -91,6 +91,7 @@ enum {
#define GL_ASYNC 0x0040
#define GL_EXACT 0x0080
#define GL_SKIP 0x0100
#define GL_NOPID 0x0200
#define GL_NOCACHE 0x0400
/*