Commit f2e95355 authored Jun 13, 2017 by Jan Kara

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: 7e49b6f2
Signed-off-by: Jan Kara <jack@suse.cz>

parent 146c4ad6

fs/udf/inode.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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);
		}

Admin message