From f52afc93cd018fe6910133a05d44671192d1aeb0 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Thu, 27 Sep 2018 13:23:32 +0200
Subject: dax: Fix deadlock in dax_lock_mapping_entry()
When dax_lock_mapping_entry() has to sleep to obtain entry lock, it will
fail to unlock mapping->i_pages spinlock and thus immediately deadlock
against itself when retrying to grab the entry lock again. Fix the
problem by unlocking mapping->i_pages before retrying.
Fixes: c2a7d2a11552 ("filesystem-dax: Introduce dax_lock_mapping_entry()")
Reported-by: Barret Rhoden <brho@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
fs/dax.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/dax.c b/fs/dax.c
index f32d7125ad0f..e4ef8af31aa6 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -447,6 +447,7 @@ bool dax_lock_mapping_entry(struct page *page)
xa_unlock_irq(&mapping->i_pages);
break;
} else if (IS_ERR(entry)) {
+ xa_unlock_irq(&mapping->i_pages);
WARN_ON_ONCE(PTR_ERR(entry) != -EAGAIN);
continue;
}
--
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