writeback: get rid of wbc->for_writepages

It's only set, it's never checked. Kill it.

Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

fs/afs/write.c

@@ -712,7 +712,6 @@ int afs_writeback_all(struct afs_vnode *vnode)
 		.bdi		= mapping->backing_dev_info,
 		.sync_mode	= WB_SYNC_ALL,
 		.nr_to_write	= LONG_MAX,
-		.for_writepages = 1,
 		.range_cyclic	= 1,
 	};
 	int ret;

fs/btrfs/ordered-data.c

@@ -740,7 +740,6 @@ int btrfs_fdatawrite_range(struct address_space *mapping, loff_t start,
 		.nr_to_write = mapping->nrpages * 2,
 		.range_start = start,
 		.range_end = end,
-		.for_writepages = 1,
 	};
 	return btrfs_writepages(mapping, &wbc);
 }

fs/jbd2/commit.c

@@ -220,7 +220,6 @@ static int journal_submit_inode_data_buffers(struct address_space *mapping)
 		.nr_to_write = mapping->nrpages * 2,
 		.range_start = 0,
 		.range_end = i_size_read(mapping->host),
-		.for_writepages = 1,
 	};
 
 	ret = generic_writepages(mapping, &wbc);

fs/nfs/write.c

@@ -1490,7 +1490,6 @@ static int nfs_write_mapping(struct address_space *mapping, int how)
 		.nr_to_write = LONG_MAX,
 		.range_start = 0,
 		.range_end = LLONG_MAX,
-		.for_writepages = 1,
 	};
 
 	return __nfs_write_mapping(mapping, &wbc, how);