From 3fd5d3ad35dc44aaf0f28d60cc0eb75887bff54d Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Wed, 28 Mar 2018 12:05:35 +0200 Subject: [PATCH] gfs2: Stop using rhashtable_walk_peek Function rhashtable_walk_peek is problematic because there is no guarantee that the glock previously returned still exists; when that key is deleted, rhashtable_walk_peek can end up returning a different key, which will cause an inconsistent glock dump. Fix this by keeping track of the current glock in the seq file iterator functions instead. Signed-off-by: Andreas Gruenbacher Signed-off-by: Bob Peterson --- fs/gfs2/glock.c | 47 ++++++++++++++++++++++++++++------------------- 1 file changed, 28 insertions(+), 19 deletions(-) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 82fb558..097bd3c 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1923,28 +1923,37 @@ void gfs2_glock_exit(void) static void gfs2_glock_iter_next(struct gfs2_glock_iter *gi, loff_t n) { - if (n == 0) - gi->gl = rhashtable_walk_peek(&gi->hti); - else { - gi->gl = rhashtable_walk_next(&gi->hti); - n--; + struct gfs2_glock *gl = gi->gl; + + if (gl) { + if (n == 0) + return; + if (!lockref_put_not_zero(&gl->gl_lockref)) + gfs2_glock_queue_put(gl); } for (;;) { - if (IS_ERR_OR_NULL(gi->gl)) { - if (!gi->gl) - return; - if (PTR_ERR(gi->gl) != -EAGAIN) { - gi->gl = NULL; - return; + gl = rhashtable_walk_next(&gi->hti); + if (IS_ERR_OR_NULL(gl)) { + if (gl == ERR_PTR(-EAGAIN)) { + n = 1; + continue; } - n = 0; - } else if (gi->sdp == gi->gl->gl_name.ln_sbd && - !__lockref_is_dead(&gi->gl->gl_lockref)) { - if (!n--) - break; + gl = NULL; + break; + } + if (gl->gl_name.ln_sbd != gi->sdp) + continue; + if (n <= 1) { + if (!lockref_get_not_dead(&gl->gl_lockref)) + continue; + break; + } else { + if (__lockref_is_dead(&gl->gl_lockref)) + continue; + n--; } - gi->gl = rhashtable_walk_next(&gi->hti); } + gi->gl = gl; } static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos) @@ -1988,7 +1997,6 @@ static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr) { struct gfs2_glock_iter *gi = seq->private; - gi->gl = NULL; rhashtable_walk_stop(&gi->hti); } @@ -2076,7 +2084,8 @@ static int gfs2_glocks_release(struct inode *inode, struct file *file) struct seq_file *seq = file->private_data; struct gfs2_glock_iter *gi = seq->private; - gi->gl = NULL; + if (gi->gl) + gfs2_glock_put(gi->gl); rhashtable_walk_exit(&gi->hti); return seq_release_private(inode, file); } -- 2.7.4