udf: Fix deadlock between writeback and udf_setsize()

udf_setsize() called truncate_setsize() with i_data_sem held. Thus
truncate_pagecache() called from truncate_setsize() could lock a page
under i_data_sem which can deadlock as page lock ranks below
i_data_sem - e. g. writeback can hold page lock and try to acquire
i_data_sem to map a block.

Fix the problem by moving truncate_setsize() calls from under
i_data_sem. It is safe for us to change i_size without holding
i_data_sem as all the places that depend on i_size being stable already
hold inode_lock.

CC: stable@vger.kernel.org
Fixes: 7e49b6f2480cb9a9e7322a91592e56a5c85361f5
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index 98c510e17203..18fdb9d90812 100644
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -1222,8 +1222,8 @@ int udf_setsize(struct inode *inode, loff_t newsize)
                         return err;
                 }
 set_size:
-                truncate_setsize(inode, newsize);
                 up_write(&iinfo->i_data_sem);
+                truncate_setsize(inode, newsize);
         } else {
                 if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
                         down_write(&iinfo->i_data_sem);
@@ -1240,9 +1240,9 @@ set_size:
                                           udf_get_block);
                 if (err)
                         return err;
+                truncate_setsize(inode, newsize);
                 down_write(&iinfo->i_data_sem);
                 udf_clear_extent_cache(inode);
-                truncate_setsize(inode, newsize);
                 udf_truncate_extents(inode);
                 up_write(&iinfo->i_data_sem);
         }