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/balloc.c b/fs/ufs/balloc.c
index 048484f..46f7a80 100644
--- a/fs/ufs/balloc.c
+++ b/fs/ufs/balloc.c
@@ -114,10 +114,8 @@
 	
 	ubh_mark_buffer_dirty (USPI_UBH(uspi));
 	ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
-	if (sb->s_flags & MS_SYNCHRONOUS) {
-		ubh_ll_rw_block(SWRITE, UCPI_UBH(ucpi));
-		ubh_wait_on_buffer (UCPI_UBH(ucpi));
-	}
+	if (sb->s_flags & MS_SYNCHRONOUS)
+		ubh_sync_block(UCPI_UBH(ucpi));
 	sb->s_dirt = 1;
 	
 	unlock_super (sb);
@@ -207,10 +205,8 @@
 
 	ubh_mark_buffer_dirty (USPI_UBH(uspi));
 	ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
-	if (sb->s_flags & MS_SYNCHRONOUS) {
-		ubh_ll_rw_block(SWRITE, UCPI_UBH(ucpi));
-		ubh_wait_on_buffer (UCPI_UBH(ucpi));
-	}
+	if (sb->s_flags & MS_SYNCHRONOUS)
+		ubh_sync_block(UCPI_UBH(ucpi));
 
 	if (overflow) {
 		fragment += count;
@@ -558,10 +554,8 @@
 	
 	ubh_mark_buffer_dirty (USPI_UBH(uspi));
 	ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
-	if (sb->s_flags & MS_SYNCHRONOUS) {
-		ubh_ll_rw_block(SWRITE, UCPI_UBH(ucpi));
-		ubh_wait_on_buffer (UCPI_UBH(ucpi));
-	}
+	if (sb->s_flags & MS_SYNCHRONOUS)
+		ubh_sync_block(UCPI_UBH(ucpi));
 	sb->s_dirt = 1;
 
 	UFSD("EXIT, fragment %llu\n", (unsigned long long)fragment);
@@ -680,10 +674,8 @@
 succed:
 	ubh_mark_buffer_dirty (USPI_UBH(uspi));
 	ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
-	if (sb->s_flags & MS_SYNCHRONOUS) {
-		ubh_ll_rw_block(SWRITE, UCPI_UBH(ucpi));
-		ubh_wait_on_buffer (UCPI_UBH(ucpi));
-	}
+	if (sb->s_flags & MS_SYNCHRONOUS)
+		ubh_sync_block(UCPI_UBH(ucpi));
 	sb->s_dirt = 1;
 
 	result += cgno * uspi->s_fpg;