Prev: [PATCH 04/11] block: remove spurious uses of REQ_HARDBARRIER
Next: [PATCH 01/11] block/loop: queue ordered mode should be DRAIN_FLUSH
From: Tejun Heo on 12 Aug 2010 08:50
Propagate deprecation of REQ_HARDBARRIER and new REQ_FLUSH/FUA
interface to upper layers.

* WRITE_BARRIER is marked deprecated and WRITE_FLUSH, WRITE_FUA and
WRITE_FLUSH_FUA are added.

* REQ_COMMON_MASK now includes REQ_FLUSH | REQ_FUA so that they are
copied from bio to request.

* BH_Ordered is marked deprecated and BH_Flush and BH_FUA are added.

Signed-off-by: Tejun Heo <tj(a)kernel.org>
Cc: Christoph Hellwig <hch(a)infradead.org>
---
fs/buffer.c | 27 ++++++++++++++++-----------
include/linux/blk_types.h | 2 +-
include/linux/buffer_head.h | 8 ++++++--
include/linux/fs.h | 20 +++++++++++++-------
4 files changed, 36 insertions(+), 21 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index d54812b..ec32fbb 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3019,18 +3019,23 @@ int submit_bh(int rw, struct buffer_head * bh)
BUG_ON(buffer_delay(bh));
BUG_ON(buffer_unwritten(bh));

- /*
- * Mask in barrier bit for a write (could be either a WRITE or a
- * WRITE_SYNC
- */
- if (buffer_ordered(bh) && (rw & WRITE))
- rw |= WRITE_BARRIER;
+ if (rw & WRITE) {
+ /* ordered is deprecated, will be removed */
+ if (buffer_ordered(bh))
+ rw |= WRITE_BARRIER;

- /*
- * Only clear out a write error when rewriting
- */
- if (test_set_buffer_req(bh) && (rw & WRITE))
- clear_buffer_write_io_error(bh);
+ if (buffer_flush(bh))
+ rw |= WRITE_FLUSH;
+
+ if (buffer_fua(bh))
+ rw |= WRITE_FUA;
+
+ /*
+ * Only clear out a write error when rewriting
+ */
+ if (test_set_buffer_req(bh))
+ clear_buffer_write_io_error(bh);
+ }

/*
* from here on down, it's all bio -- do the initial mapping,
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 8e9887d..6609fc0 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -164,7 +164,7 @@ enum rq_flag_bits {
(REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)
#define REQ_COMMON_MASK \
(REQ_WRITE | REQ_FAILFAST_MASK | REQ_HARDBARRIER | REQ_SYNC | \
- REQ_META| REQ_DISCARD | REQ_NOIDLE)
+ REQ_META | REQ_DISCARD | REQ_NOIDLE | REQ_FLUSH | REQ_FUA)

#define REQ_UNPLUG (1 << __REQ_UNPLUG)
#define REQ_RAHEAD (1 << __REQ_RAHEAD)
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 1b9ba19..498bd8b 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -32,8 +32,10 @@ enum bh_state_bits {
BH_Delay, /* Buffer is not yet allocated on disk */
BH_Boundary, /* Block is followed by a discontiguity */
BH_Write_EIO, /* I/O error on write */
- BH_Ordered, /* ordered write */
- BH_Eopnotsupp, /* operation not supported (barrier) */
+ BH_Ordered, /* DEPRECATED: ordered write */
+ BH_Eopnotsupp, /* DEPRECATED: operation not supported (barrier) */
+ BH_Flush, /* Flush device cache before executing IO */
+ BH_FUA, /* Data should be on non-volatile media on completion */
BH_Unwritten, /* Buffer is allocated on disk but not written */
BH_Quiet, /* Buffer Error Prinks to be quiet */

@@ -126,6 +128,8 @@ BUFFER_FNS(Delay, delay)
BUFFER_FNS(Boundary, boundary)
BUFFER_FNS(Write_EIO, write_io_error)
BUFFER_FNS(Ordered, ordered)
+BUFFER_FNS(Flush, flush)
+BUFFER_FNS(FUA, fua)
BUFFER_FNS(Eopnotsupp, eopnotsupp)
BUFFER_FNS(Unwritten, unwritten)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 4ebd8eb..6e30b0b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -138,13 +138,13 @@ struct inodes_stat_t {
* SWRITE_SYNC
* SWRITE_SYNC_PLUG Like WRITE_SYNC/WRITE_SYNC_PLUG, but locks the buffer.
* See SWRITE.
- * WRITE_BARRIER Like WRITE_SYNC, but tells the block layer that all
- * previously submitted writes must be safely on storage
- * before this one is started. Also guarantees that when
- * this write is complete, it itself is also safely on
- * storage. Prevents reordering of writes on both sides
- * of this IO.
- *
+ * WRITE_BARRIER DEPRECATED. Always fails. Use FLUSH/FUA instead.
+ * WRITE_FLUSH Like WRITE_SYNC but with preceding cache flush.
+ * WRITE_FUA Like WRITE_SYNC but data is guaranteed to be on
+ * non-volatile media on completion.
+ * WRITE_FLUSH_FUA Combination of WRITE_FLUSH and FUA. The IO is preceded
+ * by a cache flush and data is guaranteed to be on
+ * non-volatile media on completion.
*/
#define RW_MASK REQ_WRITE
#define RWA_MASK REQ_RAHEAD
@@ -162,6 +162,12 @@ struct inodes_stat_t {
#define WRITE_META (WRITE | REQ_META)
#define WRITE_BARRIER (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG | \
REQ_HARDBARRIER)
+#define WRITE_FLUSH (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG | \
+ REQ_FLUSH)
+#define WRITE_FUA (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG | \
+ REQ_FUA)
+#define WRITE_FLUSH_FUA (WRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG | \
+ REQ_FLUSH | REQ_FUA)
#define SWRITE_SYNC_PLUG (SWRITE | REQ_SYNC | REQ_NOIDLE)
#define SWRITE_SYNC (SWRITE | REQ_SYNC | REQ_NOIDLE | REQ_UNPLUG)

--
1.7.1

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