From cbe6d2576e2cf7571e781439728ad31bdfd9dfcb Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Tue, 5 Apr 2022 22:07:30 +0200 Subject: 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 --- fs/gfs2/glock.c | 41 +++++++++++++++++++++++++++++++---------- fs/gfs2/glock.h | 1 + 2 files changed, 32 insertions(+), 10 deletions(-) (limited to 'fs/gfs2') diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 533ec772166d..f80fba5d1d4d 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -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(); } diff --git a/fs/gfs2/glock.h b/fs/gfs2/glock.h index c0ae9100a0bc..e764ebeba54c 100644 --- a/fs/gfs2/glock.h +++ b/fs/gfs2/glock.h @@ -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 /* -- cgit v1.2.3-59-g8ed1b