ocfs2: snapshot the dentry name while tracing file release

ocfs2_file_release() passes the live dentry name and length to a trace
event while holding oi->ip_lock. This lock protects the open count and
delays RCU reclamation of external names, but it does not serialize name
changes during rename. The dentry can switch between inline and external
names, and a separately loaded length can describe a different name.

The ocfs2__file_ops event sizes and copies its __string separately.
A concurrently rewritten inline name need not remain consistent between
those operations. External names can also be selected at this call site;
the existing spinlock critical section protects their allocation lifetime,
while a snapshot additionally pairs a stable name with its length.

Take a name snapshot before acquiring oi->ip_lock and release it after
dropping the lock. Keep the trace call and open-count argument inside
the original critical section. Cache the event-enabled check so the
snapshot stays paired even if tracing is toggled meanwhile.

Link: https://lore.kernel.org/pm-ocfs2-objects-candidate-0088-v7-6324344256f0c3b1c3d8-2@gmail.com
Fixes: 468eedde23d6 ("ocfs2: Remove mlog(0) from fs/ocfs2/file.c")
Signed-off-by: Cen Zhang <zzzccc427@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Assisted-by: LLM
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Heming Zhao <heming.zhao@suse.com>
Cc: Jia-Ju Bai <baijiaju1990@gmail.com>
Cc: <jjzuming@gmail.com>
Cc: <stable@vger.kernel.org>

0 files changed, 0 insertions, 0 deletions