ocfs2: trylock in ocfs2_readpage()

Similarly to the page lock / cluster lock inversion in ocfs2_readpage, we
can deadlock on ip_alloc_sem. We can down_read_trylock() instead and just
return AOP_TRUNCATED_PAGE if the operation fails.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 8e7cafb5fc6c..30306707b2ca 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -222,7 +222,10 @@ static int ocfs2_readpage(struct file *file, struct page *page)
                 goto out;
         }
 
-        down_read(&OCFS2_I(inode)->ip_alloc_sem);
+        if (down_read_trylock(&OCFS2_I(inode)->ip_alloc_sem) == 0) {
+                ret = AOP_TRUNCATED_PAGE;
+                goto out_meta_unlock;
+        }
 
         /*
          * i_size might have just been updated as we grabed the meta lock.  We
@@ -258,6 +261,7 @@ static int ocfs2_readpage(struct file *file, struct page *page)
         ocfs2_data_unlock(inode, 0);
 out_alloc:
         up_read(&OCFS2_I(inode)->ip_alloc_sem);
+out_meta_unlock:
         ocfs2_meta_unlock(inode, 0);
 out:
         if (unlock)