[XFS] Remove m_nreadaheads

m_nreadaheads in the mount struct is never used; remove it and the various
macros assigned to it. Also remove a couple other unused macros in the
same areas.

Removes one user of xfs_physmem.

SGI-PV: 968563
SGI-Modid: xfs-linux-melb:xfs-kern:29322a

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>

fs/xfs/linux-2.6/xfs_lrw.h

@@ -71,11 +71,6 @@ extern void xfs_inval_cached_trace(struct xfs_iocore *,
 #define xfs_inval_cached_trace(io, offset, len, first, last)
 #endif
 
-/*
- * Maximum count of bmaps used by read and write paths.
- */
-#define	XFS_MAX_RW_NBMAPS	4
-
 extern int xfs_bmap(struct bhv_desc *, xfs_off_t, ssize_t, int,
 			struct xfs_iomap *, int *);
 extern int xfsbdstrat(struct xfs_mount *, struct xfs_buf *);

fs/xfs/xfs_mount.c

@@ -871,16 +871,6 @@ xfs_mountfs(
 		writeio_log = mp->m_writeio_log;
 	}
 
-	/*
-	 * Set the number of readahead buffers to use based on
-	 * physical memory size.
-	 */
-	if (xfs_physmem <= 4096)		/* <= 16MB */
-		mp->m_nreadaheads = XFS_RW_NREADAHEAD_16MB;
-	else if (xfs_physmem <= 8192)	/* <= 32MB */
-		mp->m_nreadaheads = XFS_RW_NREADAHEAD_32MB;
-	else
-		mp->m_nreadaheads = XFS_RW_NREADAHEAD_K32;
 	if (sbp->sb_blocklog > readio_log) {
 		mp->m_readio_log = sbp->sb_blocklog;
 	} else {

fs/xfs/xfs_mount.h

@@ -362,7 +362,6 @@ typedef struct xfs_mount {
 	__uint8_t		m_blkbb_log;	/* blocklog - BBSHIFT */
 	__uint8_t		m_agno_log;	/* log #ag's */
 	__uint8_t		m_agino_log;	/* #bits for agino in inum */
-	__uint8_t		m_nreadaheads;	/* #readahead buffers */
 	__uint16_t		m_inode_cluster_size;/* min inode buf size */
 	uint			m_blockmask;	/* sb_blocksize-1 */
 	uint			m_blockwsize;	/* sb_blocksize in words */

fs/xfs/xfs_rw.h

@@ -22,32 +22,6 @@ struct xfs_buf;
 struct xfs_inode;
 struct xfs_mount;
 
-/*
- * Maximum count of bmaps used by read and write paths.
- */
-#define	XFS_MAX_RW_NBMAPS	4
-
-/*
- * Counts of readahead buffers to use based on physical memory size.
- * None of these should be more than XFS_MAX_RW_NBMAPS.
- */
-#define	XFS_RW_NREADAHEAD_16MB	2
-#define	XFS_RW_NREADAHEAD_32MB	3
-#define	XFS_RW_NREADAHEAD_K32	4
-#define	XFS_RW_NREADAHEAD_K64	4
-
-/*
- * Maximum size of a buffer that we\'ll map.  Making this
- * too big will degrade performance due to the number of
- * pages which need to be gathered.  Making it too small
- * will prevent us from doing large I/O\'s to hardware that
- * needs it.
- *
- * This is currently set to 512 KB.
- */
-#define	XFS_MAX_BMAP_LEN_BB	1024
-#define	XFS_MAX_BMAP_LEN_BYTES	524288
-
 /*
  * Convert the given file system block to a disk block.
  * We have to treat it differently based on whether the