nilfs2: fix buffer head leak in nilfs_btnode_submit_block

nilfs_btnode_submit_block() refers to buffer head just before
returning from the function, but it releases the buffer head earlier
than that if nilfs_dat_translate() gets an error.

This has potential for oops in the erroneous case.  This fixes the
issue.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/nilfs2/btnode.c b/fs/nilfs2/btnode.c
index 447ce47a3306..0a6834bb278e 100644
--- a/fs/nilfs2/btnode.c
+++ b/fs/nilfs2/btnode.c
@@ -100,6 +100,7 @@ int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
 {
         struct buffer_head *bh;
         struct inode *inode = NILFS_BTNC_I(btnc);
+        struct page *page;
         int err;
 
         bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
@@ -107,6 +108,7 @@ int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
                 return -ENOMEM;
 
         err = -EEXIST; /* internal code */
+        page = bh->b_page;
 
         if (buffer_uptodate(bh) || buffer_dirty(bh))
                 goto found;
@@ -143,8 +145,8 @@ found:
         *pbh = bh;
 
 out_locked:
-        unlock_page(bh->b_page);
-        page_cache_release(bh->b_page);
+        unlock_page(page);
+        page_cache_release(page);
         return err;
 }