This is an addendum to the patch to remove the erroneous seq |= 1 in volume lookup loop. Switch to using scoped_seqlock_read() as suggested by Oleg Nesterov[1]. Signed-off-by: David Howells Reviewed-by: Oleg Nesterov cc: Marc Dionne cc: Li RongQing cc: linux-afs@lists.infradead.org Link: https://lore.kernel.org/r/aifaeKvz3KemfzaS@redhat.com/ [1] --- fs/afs/callback.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/fs/afs/callback.c b/fs/afs/callback.c index 833ac3178ddc..dd7a407ea368 100644 --- a/fs/afs/callback.c +++ b/fs/afs/callback.c @@ -113,16 +113,12 @@ static struct afs_volume *afs_lookup_volume_rcu(struct afs_cell *cell, { struct afs_volume *volume = NULL; struct rb_node *p; - int seq = 1; - for (;;) { + scoped_seqlock_read(&cell->volume_lock, ss_lock) { /* Unfortunately, rbtree walking doesn't give reliable results * under just the RCU read lock, so we have to check for * changes. */ - seq++; /* 2 on the 1st/lockless path, otherwise odd */ - read_seqbegin_or_lock(&cell->volume_lock, &seq); - p = rcu_dereference_raw(cell->volumes.rb_node); while (p) { volume = rb_entry(p, struct afs_volume, cell_node); @@ -138,11 +134,8 @@ static struct afs_volume *afs_lookup_volume_rcu(struct afs_cell *cell, if (volume && afs_try_get_volume(volume, afs_volume_trace_get_callback)) break; - if (!need_seqretry(&cell->volume_lock, seq)) - break; } - done_seqretry(&cell->volume_lock, seq); return volume; }