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authorJan Kara <jack@suse.cz>2018-09-27 13:23:32 +0200
committerDan Williams <dan.j.williams@intel.com>2018-09-27 10:56:15 -0700
commitf52afc93cd018fe6910133a05d44671192d1aeb0 (patch)
tree32137752634c7f3c0f4efecfc91d64551bed047c
parent6bf4ca7fbc85d80446ac01c0d1d77db4d91a6d84 (diff)
downloadlinux-f52afc93cd018fe6910133a05d44671192d1aeb0.tar.gz
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>
-rw-r--r--fs/dax.c1
1 files changed, 1 insertions, 0 deletions
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;
 		}