[PATCH 26/27] xfs: cleanup I/O-related buffer flags

Christoph Hellwig
2011-07-01T09:46:11Z

[-- Attachment #1: xfs-buf-cleanup-flags --]
[-- Type: text/plain, Size: 7874 bytes --]

Remove the unused and misnamed _XBF_RUN_QUEUES flag, rename XBF_LOG_BUFFER
to the more fitting XBF_SYNCIO, and split XBF_ORDERED into XBF_FUA and
XBF_FLUSH to allow more fine grained control over the bio flags. Also
cleanup processing of the flags in _xfs_buf_ioapply to make more sense,
and renumber the sparse flag number space to group flags by purpose.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: xfs/fs/xfs/linux-2.6/xfs_buf.c
===================================================================
--- xfs.orig/fs/xfs/linux-2.6/xfs_buf.c 2011-06-29 14:04:28.084452749 +0200
+++ xfs/fs/xfs/linux-2.6/xfs_buf.c 2011-06-29 14:27:00.987123445 +0200
@@ -592,10 +592,8 @@ _xfs_buf_read(
ASSERT(!(flags & (XBF_DELWRI|XBF_WRITE)));
ASSERT(bp->b_bn != XFS_BUF_DADDR_NULL);

- bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_DELWRI | \
- XBF_READ_AHEAD | _XBF_RUN_QUEUES);
- bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | \
- XBF_READ_AHEAD | _XBF_RUN_QUEUES);
+ bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_DELWRI | XBF_READ_AHEAD);
+ bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);

status = xfs_buf_iorequest(bp);
if (status || XFS_BUF_ISERROR(bp) || (flags & XBF_ASYNC))
@@ -1211,23 +1209,21 @@ _xfs_buf_ioapply(
total_nr_pages = bp->b_page_count;
map_i = 0;

- if (bp->b_flags & XBF_ORDERED) {
- ASSERT(!(bp->b_flags & XBF_READ));
- rw = WRITE_FLUSH_FUA;
- } else if (bp->b_flags & XBF_LOG_BUFFER) {
- ASSERT(!(bp->b_flags & XBF_READ_AHEAD));
- bp->b_flags &= ~_XBF_RUN_QUEUES;
- rw = (bp->b_flags & XBF_WRITE) ? WRITE_SYNC : READ_SYNC;
- } else if (bp->b_flags & _XBF_RUN_QUEUES) {
- ASSERT(!(bp->b_flags & XBF_READ_AHEAD));
- bp->b_flags &= ~_XBF_RUN_QUEUES;
- rw = (bp->b_flags & XBF_WRITE) ? WRITE_META : READ_META;
+ if (bp->b_flags & XBF_WRITE) {
+ if (bp->b_flags & XBF_SYNCIO)
+ rw = WRITE_SYNC;
+ else
+ rw = WRITE;
+ if (bp->b_flags & XBF_FUA)
+ rw |= REQ_FUA;
+ if (bp->b_flags & XBF_FLUSH)
+ rw |= REQ_FLUSH;
+ } else if (bp->b_flags & XBF_READ_AHEAD) {
+ rw = READA;
} else {
- rw = (bp->b_flags & XBF_WRITE) ? WRITE :
- (bp->b_flags & XBF_READ_AHEAD) ? READA : READ;
+ rw = READ;
}

-
next_chunk:
atomic_inc(&bp->b_io_remaining);
nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);
@@ -1689,8 +1685,7 @@ xfs_buf_delwri_split(
break;
}

- bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q|
- _XBF_RUN_QUEUES);
+ bp->b_flags &= ~(XBF_DELWRI | _XBF_DELWRI_Q);
bp->b_flags |= XBF_WRITE;
list_move_tail(&bp->b_list, list);
trace_xfs_buf_delwri_split(bp, _RET_IP_);
Index: xfs/fs/xfs/linux-2.6/xfs_buf.h
===================================================================
--- xfs.orig/fs/xfs/linux-2.6/xfs_buf.h 2011-06-29 14:03:57.994615760 +0200
+++ xfs/fs/xfs/linux-2.6/xfs_buf.h 2011-06-29 14:18:16.806629842 +0200
@@ -46,43 +46,46 @@ typedef enum {

#define XBF_READ (1 << 0) /* buffer intended for reading from device */
#define XBF_WRITE (1 << 1) /* buffer intended for writing to device */
-#define XBF_MAPPED (1 << 2) /* buffer mapped (b_addr valid) */
+#define XBF_READ_AHEAD (1 << 2) /* asynchronous read-ahead */
+#define XBF_MAPPED (1 << 3) /* buffer mapped (b_addr valid) */
#define XBF_ASYNC (1 << 4) /* initiator will not wait for completion */
#define XBF_DONE (1 << 5) /* all pages in the buffer uptodate */
#define XBF_DELWRI (1 << 6) /* buffer has dirty pages */
#define XBF_STALE (1 << 7) /* buffer has been staled, do not find it */
-#define XBF_ORDERED (1 << 11)/* use ordered writes */
-#define XBF_READ_AHEAD (1 << 12)/* asynchronous read-ahead */
-#define XBF_LOG_BUFFER (1 << 13)/* this is a buffer used for the log */
+
+/* I/O hints for the BIO layer */
+#define XBF_SYNCIO (1 << 10)/* treat this buffer as synchronous I/O */
+#define XBF_FUA (1 << 11)/* force cache write through mode */
+#define XBF_FLUSH (1 << 12)/* flush the disk cache before a write */

/* flags used only as arguments to access routines */
-#define XBF_LOCK (1 << 14)/* lock requested */
-#define XBF_TRYLOCK (1 << 15)/* lock requested, but do not wait */
-#define XBF_DONT_BLOCK (1 << 16)/* do not block in current thread */
+#define XBF_LOCK (1 << 15)/* lock requested */
+#define XBF_TRYLOCK (1 << 16)/* lock requested, but do not wait */
+#define XBF_DONT_BLOCK (1 << 17)/* do not block in current thread */

/* flags used only internally */
-#define _XBF_PAGES (1 << 18)/* backed by refcounted pages */
-#define _XBF_RUN_QUEUES (1 << 19)/* run block device task queue */
-#define _XBF_KMEM (1 << 20)/* backed by heap memory */
-#define _XBF_DELWRI_Q (1 << 21)/* buffer on delwri queue */
+#define _XBF_PAGES (1 << 20)/* backed by refcounted pages */
+#define _XBF_KMEM (1 << 21)/* backed by heap memory */
+#define _XBF_DELWRI_Q (1 << 22)/* buffer on delwri queue */

typedef unsigned int xfs_buf_flags_t;

#define XFS_BUF_FLAGS \
{ XBF_READ, "READ" }, \
{ XBF_WRITE, "WRITE" }, \
+ { XBF_READ_AHEAD, "READ_AHEAD" }, \
{ XBF_MAPPED, "MAPPED" }, \
{ XBF_ASYNC, "ASYNC" }, \
{ XBF_DONE, "DONE" }, \
{ XBF_DELWRI, "DELWRI" }, \
{ XBF_STALE, "STALE" }, \
- { XBF_ORDERED, "ORDERED" }, \
- { XBF_READ_AHEAD, "READ_AHEAD" }, \
+ { XBF_SYNCIO, "SYNCIO" }, \
+ { XBF_FUA, "FUA" }, \
+ { XBF_FLUSH, "FLUSH" }, \
{ XBF_LOCK, "LOCK" }, /* should never be set */\
{ XBF_TRYLOCK, "TRYLOCK" }, /* ditto */\
{ XBF_DONT_BLOCK, "DONT_BLOCK" }, /* ditto */\
{ _XBF_PAGES, "PAGES" }, \
- { _XBF_RUN_QUEUES, "RUN_QUEUES" }, \
{ _XBF_KMEM, "KMEM" }, \
{ _XBF_DELWRI_Q, "DELWRI_Q" }

@@ -230,8 +233,9 @@ extern void xfs_buf_terminate(void);

#define XFS_BUF_BFLAGS(bp) ((bp)->b_flags)
-#define XFS_BUF_ZEROFLAGS(bp) ((bp)->b_flags &= \
- ~(XBF_READ|XBF_WRITE|XBF_ASYNC|XBF_DELWRI|XBF_ORDERED))
+#define XFS_BUF_ZEROFLAGS(bp) \
+ ((bp)->b_flags &= ~(XBF_READ|XBF_WRITE|XBF_ASYNC|XBF_DELWRI| \
+ XBF_SYNCIO|XBF_FUA|XBF_FLUSH))

void xfs_buf_stale(struct xfs_buf *bp);
#define XFS_BUF_STALE(bp) xfs_buf_stale(bp);
@@ -263,10 +267,6 @@ void xfs_buf_stale(struct xfs_buf *bp);
#define XFS_BUF_UNASYNC(bp) ((bp)->b_flags &= ~XBF_ASYNC)
#define XFS_BUF_ISASYNC(bp) ((bp)->b_flags & XBF_ASYNC)

-#define XFS_BUF_ORDERED(bp) ((bp)->b_flags |= XBF_ORDERED)
-#define XFS_BUF_UNORDERED(bp) ((bp)->b_flags &= ~XBF_ORDERED)
-#define XFS_BUF_ISORDERED(bp) ((bp)->b_flags & XBF_ORDERED)
-
#define XFS_BUF_HOLD(bp) xfs_buf_hold(bp)
#define XFS_BUF_READ(bp) ((bp)->b_flags |= XBF_READ)
#define XFS_BUF_UNREAD(bp) ((bp)->b_flags &= ~XBF_READ)
Index: xfs/fs/xfs/xfs_log.c
===================================================================
--- xfs.orig/fs/xfs/xfs_log.c 2011-06-29 14:04:18.587837528 +0200
+++ xfs/fs/xfs/xfs_log.c 2011-06-29 19:45:20.176987585 +0200
@@ -1268,7 +1268,6 @@ xlog_bdstrat(
return 0;
}

- bp->b_flags |= _XBF_RUN_QUEUES;
xfs_buf_iorequest(bp);
return 0;
}
@@ -1369,7 +1368,7 @@ xlog_sync(xlog_t *log,
XFS_BUF_ZEROFLAGS(bp);
XFS_BUF_BUSY(bp);
XFS_BUF_ASYNC(bp);
- bp->b_flags |= XBF_LOG_BUFFER;
+ bp->b_flags |= XBF_SYNCIO;

if (log->l_mp->m_flags & XFS_MOUNT_BARRIER) {
/*
@@ -1380,7 +1379,7 @@ xlog_sync(xlog_t *log,
*/
if (log->l_mp->m_logdev_targp != log->l_mp->m_ddev_targp)
xfs_blkdev_issue_flush(log->l_mp->m_ddev_targp);
- XFS_BUF_ORDERED(bp);
+ bp->b_flags |= XBF_FUA | XBF_FLUSH;
}

ASSERT(XFS_BUF_ADDR(bp) <= log->l_logBBsize-1);
@@ -1413,9 +1412,9 @@ xlog_sync(xlog_t *log,
XFS_BUF_ZEROFLAGS(bp);
XFS_BUF_BUSY(bp);
XFS_BUF_ASYNC(bp);
- bp->b_flags |= XBF_LOG_BUFFER;
+ bp->b_flags |= XBF_SYNCIO;
if (log->l_mp->m_flags & XFS_MOUNT_BARRIER)
- XFS_BUF_ORDERED(bp);
+ bp->b_flags |= XBF_FUA | XBF_FLUSH;
dptr = XFS_BUF_PTR(bp);
/*
* Bump the cycle numbers at the start of each block