remove SWRITE* I/O types

These flags aren't real I/O types, but tell ll_rw_block to always
lock the buffer instead of giving up on a failed trylock.

Instead add a new write_dirty_buffer helper that implements this semantic
and use it from the existing SWRITE* callers.  Note that the ll_rw_block
code had a bug where it didn't promote WRITE_SYNC_PLUG properly, which
this patch fixes.

In the ufs code clean up the helper that used to call ll_rw_block
to mirror sync_dirty_buffer, which is the function it implements for
compound buffers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ufs/truncate.c b/fs/ufs/truncate.c
index 34d5cb1..a58f915 100644
--- a/fs/ufs/truncate.c
+++ b/fs/ufs/truncate.c
@@ -243,10 +243,8 @@
 		ubh_bforget(ind_ubh);
 		ind_ubh = NULL;
 	}
-	if (IS_SYNC(inode) && ind_ubh && ubh_buffer_dirty(ind_ubh)) {
-		ubh_ll_rw_block(SWRITE, ind_ubh);
-		ubh_wait_on_buffer (ind_ubh);
-	}
+	if (IS_SYNC(inode) && ind_ubh && ubh_buffer_dirty(ind_ubh))
+		ubh_sync_block(ind_ubh);
 	ubh_brelse (ind_ubh);
 	
 	UFSD("EXIT: ino %lu\n", inode->i_ino);
@@ -307,10 +305,8 @@
 		ubh_bforget(dind_bh);
 		dind_bh = NULL;
 	}
-	if (IS_SYNC(inode) && dind_bh && ubh_buffer_dirty(dind_bh)) {
-		ubh_ll_rw_block(SWRITE, dind_bh);
-		ubh_wait_on_buffer (dind_bh);
-	}
+	if (IS_SYNC(inode) && dind_bh && ubh_buffer_dirty(dind_bh))
+		ubh_sync_block(dind_bh);
 	ubh_brelse (dind_bh);
 	
 	UFSD("EXIT: ino %lu\n", inode->i_ino);
@@ -367,10 +363,8 @@
 		ubh_bforget(tind_bh);
 		tind_bh = NULL;
 	}
-	if (IS_SYNC(inode) && tind_bh && ubh_buffer_dirty(tind_bh)) {
-		ubh_ll_rw_block(SWRITE, tind_bh);
-		ubh_wait_on_buffer (tind_bh);
-	}
+	if (IS_SYNC(inode) && tind_bh && ubh_buffer_dirty(tind_bh))
+		ubh_sync_block(tind_bh);
 	ubh_brelse (tind_bh);
 	
 	UFSD("EXIT: ino %lu\n", inode->i_ino);