]> git.saurik.com Git - apple/xnu.git/blobdiff - bsd/vfs/vfs_cluster.c
xnu-344.tar.gz
[apple/xnu.git] / bsd / vfs / vfs_cluster.c
index 07f0dbbd57c4bd708e8c25f7af49055d0f7ab200..fc7004638c765aa2b8fc4fd865c898195f99e074 100644 (file)
@@ -1,5 +1,6 @@
+
 /*
- * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
  *
  * @APPLE_LICENSE_HEADER_START@
  * 
@@ -73,7 +74,6 @@
 #define CL_READ      0x01
 #define CL_ASYNC     0x02
 #define CL_COMMIT    0x04
-#define CL_NOMAP     0x08
 #define CL_PAGEOUT   0x10
 #define CL_AGE       0x20
 #define CL_DUMP      0x40
 #define CL_PAGEIN    0x100
 #define CL_DEV_MEMORY 0x200
 
+static void cluster_zero(upl_t upl, vm_offset_t   upl_offset,
+               int size, struct buf *bp);
+static int cluster_read_x(struct vnode *vp, struct uio *uio,
+               off_t filesize, int devblocksize, int flags);
+static int cluster_write_x(struct vnode *vp, struct uio *uio,
+               off_t oldEOF, off_t newEOF, off_t headOff,
+               off_t tailOff, int devblocksize, int flags);
+static int cluster_nocopy_read(struct vnode *vp, struct uio *uio,
+               off_t filesize, int devblocksize, int flags);
+static int cluster_nocopy_write(struct vnode *vp, struct uio *uio,
+               off_t newEOF, int devblocksize, int flags);
+static int cluster_phys_read(struct vnode *vp, struct uio *uio,
+               off_t filesize);
+static int cluster_phys_write(struct vnode *vp, struct uio *uio);
+static int cluster_push_x(struct vnode *vp, off_t EOF, daddr_t first, daddr_t last, int can_delay);
+static int cluster_try_push(struct vnode *vp, off_t newEOF, int can_delay, int push_all);
+
+
 /*
  * throttle the number of async writes that
  * can be outstanding on a single vnode
@@ -97,6 +115,7 @@ cluster_iodone(bp)
        int         total_size;
        int         total_resid;
        int         upl_offset;
+       int         zero_offset;
        upl_t       upl;
        struct buf *cbp;
        struct buf *cbp_head;
@@ -110,7 +129,7 @@ cluster_iodone(bp)
        cbp_head = (struct buf *)(bp->b_trans_head);
 
        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 20)) | DBG_FUNC_START,
-                    cbp_head, bp->b_lblkno, bp->b_bcount, bp->b_flags, 0);
+                    (int)cbp_head, bp->b_lblkno, bp->b_bcount, bp->b_flags, 0);
 
        for (cbp = cbp_head; cbp; cbp = cbp->b_trans_next) {
                /*
@@ -120,7 +139,7 @@ cluster_iodone(bp)
                if ( !(cbp->b_flags & B_DONE)) {
 
                        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 20)) | DBG_FUNC_END,
-                                    cbp_head, cbp, cbp->b_bcount, cbp->b_flags, 0);
+                                    (int)cbp_head, (int)cbp, cbp->b_bcount, cbp->b_flags, 0);
 
                        return 0;
                }
@@ -135,6 +154,7 @@ cluster_iodone(bp)
        b_flags    = cbp->b_flags;
        real_bp    = cbp->b_real_bp;
        vp         = cbp->b_vp;
+       zero_offset= cbp->b_validend;
 
        while (cbp) {
                if (cbp->b_vectorcount > 1)
@@ -156,6 +176,9 @@ cluster_iodone(bp)
                vp->v_flag &= ~VTHROTTLED;
                wakeup((caddr_t)&vp->v_numoutput);
        }
+       if (zero_offset)
+               cluster_zero(upl, zero_offset, PAGE_SIZE - (zero_offset & PAGE_MASK), real_bp);
+
        if ((b_flags & B_NEED_IODONE) && real_bp) {
                if (error) {
                        real_bp->b_flags |= B_ERROR;
@@ -175,7 +198,7 @@ cluster_iodone(bp)
                if (error || (b_flags & B_NOCACHE)) {
                        int upl_abort_code;
 
-                       if (b_flags & B_PAGEOUT)
+                       if ((b_flags & B_PAGEOUT) && (error != ENXIO)) /* transient error */
                                upl_abort_code = UPL_ABORT_FREE_ON_EMPTY;
                        else if (b_flags & B_PGIN)
                                upl_abort_code = UPL_ABORT_FREE_ON_EMPTY | UPL_ABORT_ERROR;
@@ -186,7 +209,7 @@ cluster_iodone(bp)
                                        upl_abort_code);
                        
                        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 20)) | DBG_FUNC_END,
-                                    upl, upl_offset - pg_offset, commit_size,
+                                    (int)upl, upl_offset - pg_offset, commit_size,
                                     0x80000000|upl_abort_code, 0);
 
                } else {
@@ -201,40 +224,45 @@ cluster_iodone(bp)
                                        upl_commit_flags);
 
                        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 20)) | DBG_FUNC_END,
-                                    upl, upl_offset - pg_offset, commit_size,
+                                    (int)upl, upl_offset - pg_offset, commit_size,
                                     upl_commit_flags, 0);
                }
        } else 
                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 20)) | DBG_FUNC_END,
-                            upl, upl_offset, 0, error, 0);
+                            (int)upl, upl_offset, 0, error, 0);
 
        return (error);
 }
 
 
 static void
-cluster_zero(upl, upl_offset, size, flags, bp)
+cluster_zero(upl, upl_offset, size, bp)
        upl_t         upl;
        vm_offset_t   upl_offset;
        int           size;
-       int           flags;
        struct buf   *bp;
 {
         vm_offset_t   io_addr = 0;
+       int           must_unmap = 0;
        kern_return_t kret;
 
-       if ( !(flags & CL_NOMAP)) {
+       KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 23)) | DBG_FUNC_NONE,
+                    upl_offset, size, (int)bp, 0, 0);
+
+       if (bp == NULL || bp->b_data == NULL) {
                kret = ubc_upl_map(upl, &io_addr);
                
                if (kret != KERN_SUCCESS)
                        panic("cluster_zero: ubc_upl_map() failed with (%d)", kret);
                if (io_addr == 0) 
                        panic("cluster_zero: ubc_upl_map() mapped 0");
+
+               must_unmap = 1;
        } else
                io_addr = (vm_offset_t)bp->b_data;
        bzero((caddr_t)(io_addr + upl_offset), size);
        
-       if ( !(flags & CL_NOMAP)) {
+       if (must_unmap) {
                kret = ubc_upl_unmap(upl);
 
                if (kret != KERN_SUCCESS)
@@ -243,28 +271,32 @@ cluster_zero(upl, upl_offset, size, flags, bp)
 }
 
 static int
-cluster_io(vp, upl, upl_offset, f_offset, size, flags, real_bp)
+cluster_io(vp, upl, upl_offset, f_offset, non_rounded_size, devblocksize, flags, real_bp)
        struct vnode *vp;
        upl_t         upl;
        vm_offset_t   upl_offset;
        off_t         f_offset;
-       int           size;
+       int           non_rounded_size;
+       int           devblocksize;
        int           flags;
        struct buf   *real_bp;
 {
        struct buf   *cbp;
        struct iovec *iovp;
+       u_int           size;
        int           io_flags;
        int           error = 0;
        int           retval = 0;
        struct buf   *cbp_head = 0;
        struct buf   *cbp_tail = 0;
        upl_page_info_t *pl;
+       int buf_count = 0;
        int pg_count;
        int pg_offset;
-       int max_iosize;
-       int max_vectors;
+       u_int max_iosize;
+       u_int max_vectors;
        int priv;
+       int zero_offset = 0;
 
        if (flags & CL_READ) {
                io_flags = (B_VECTORLIST | B_READ);
@@ -286,11 +318,16 @@ cluster_io(vp, upl, upl_offset, f_offset, size, flags, real_bp)
        if (flags & CL_PAGEIN)
                io_flags |= B_PGIN;
 
+       if (devblocksize)
+               size = (non_rounded_size + (devblocksize - 1)) & ~(devblocksize - 1);
+       else
+               size = non_rounded_size;
+
 
        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 22)) | DBG_FUNC_START,
                     (int)f_offset, size, upl_offset, flags, 0);
 
-       if ((flags & CL_READ) && ((upl_offset + size) & PAGE_MASK) && (!(flags & CL_NOZERO))) {
+       if ((flags & CL_READ) && ((upl_offset + non_rounded_size) & PAGE_MASK) && (!(flags & CL_NOZERO))) {
                /*
                 * then we are going to end up
                 * with a page that we can't complete (the file size wasn't a multiple
@@ -298,11 +335,7 @@ cluster_io(vp, upl, upl_offset, f_offset, size, flags, real_bp)
                 * so we'll go ahead and zero out the portion of the page we can't
                 * read in from the file
                 */
-               cluster_zero(upl, upl_offset + size, PAGE_SIZE - ((upl_offset + size) & PAGE_MASK), flags, real_bp);
-
-               KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 23)) | DBG_FUNC_NONE,
-                            upl_offset + size, PAGE_SIZE - ((upl_offset + size) & PAGE_MASK),
-                            flags, real_bp, 0);
+               zero_offset = upl_offset + non_rounded_size;
        }
        while (size) {
                size_t io_size;
@@ -326,7 +359,7 @@ cluster_io(vp, upl, upl_offset, f_offset, size, flags, real_bp)
                }
 
                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 24)) | DBG_FUNC_NONE,
-                            (int)f_offset, (int)blkno, io_size, 0, 0);
+                            (int)f_offset, (int)blkno, io_size, zero_offset, 0);
 
                if ( (!(flags & CL_READ) && (long)blkno == -1) || io_size == 0) {
                        if (flags & CL_PAGEOUT) {
@@ -375,19 +408,56 @@ cluster_io(vp, upl, upl_offset, f_offset, size, flags, real_bp)
                        pg_count = 1;
                }
                if ((flags & CL_READ) && (long)blkno == -1) {
+                       int bytes_to_zero;
+
                        /*
                         * if we're reading and blkno == -1, then we've got a
                         * 'hole' in the file that we need to deal with by zeroing
                         * out the affected area in the upl
                         */
-                       cluster_zero(upl, upl_offset, io_size, flags, real_bp);
-
-                       KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 23)) | DBG_FUNC_NONE,
-                                    upl_offset, io_size, flags, real_bp, 0);
+                       if (zero_offset && io_size == size) {
+                               /*
+                                * if this upl contains the EOF and it is not a multiple of PAGE_SIZE
+                                * than 'zero_offset' will be non-zero
+                                * if the 'hole' returned by VOP_CMAP extends all the way to the eof
+                                * (indicated by the io_size finishing off the I/O request for this UPL)
+                                * than we're not going to issue an I/O for the
+                                * last page in this upl... we need to zero both the hole and the tail
+                                * of the page beyond the EOF, since the delayed zero-fill won't kick in 
+                                */
+                               bytes_to_zero = (((upl_offset + io_size) + (PAGE_SIZE - 1)) & ~PAGE_MASK) - upl_offset;
 
-                       pg_count = (io_size - pg_offset) / PAGE_SIZE;
+                               zero_offset = 0;
+                       } else
+                               bytes_to_zero = io_size;
 
+                       cluster_zero(upl, upl_offset, bytes_to_zero, real_bp);
+                         
+                       if (cbp_head)
+                               /*
+                                * if there is a current I/O chain pending
+                                * then the first page of the group we just zero'd
+                                * will be handled by the I/O completion if the zero
+                                * fill started in the middle of the page
+                                */
+                               pg_count = (io_size - pg_offset) / PAGE_SIZE;
+                       else {
+                               /*
+                                * no pending I/O to pick up that first page
+                                * so, we have to make sure it gets committed
+                                * here.
+                                * set the pg_offset to 0 so that the upl_commit_range
+                                * starts with this page
+                                */
+                               pg_count = (io_size + pg_offset) / PAGE_SIZE;
+                               pg_offset = 0;
+                       }
                        if (io_size == size && ((upl_offset + io_size) & PAGE_MASK))
+                               /*
+                                * if we're done with the request for this UPL
+                                * then we have to make sure to commit the last page
+                                * even if we only partially zero-filled it
+                                */
                                pg_count++;
 
                        if (pg_count) {
@@ -395,9 +465,10 @@ cluster_io(vp, upl, upl_offset, f_offset, size, flags, real_bp)
                                        pg_resid = PAGE_SIZE - pg_offset;
                                else
                                        pg_resid = 0;
+
                                if (flags & CL_COMMIT)
                                        ubc_upl_commit_range(upl,
-                                                       upl_offset + pg_resid
+                                                       (upl_offset + pg_resid) & ~PAGE_MASK
                                                        pg_count * PAGE_SIZE,
                                                        UPL_COMMIT_CLEAR_DIRTY | UPL_COMMIT_FREE_ON_EMPTY);
                        }
@@ -405,9 +476,10 @@ cluster_io(vp, upl, upl_offset, f_offset, size, flags, real_bp)
                        f_offset   += io_size;
                        size       -= io_size;
 
-                       if (cbp_head && pg_count)
+                       if (cbp_head && pg_count) 
                                goto start_io;
                        continue;
+
                } else if (real_bp && (real_bp->b_blkno == real_bp->b_lblkno)) {
                        real_bp->b_blkno = blkno;
                }
@@ -541,18 +613,21 @@ cluster_io(vp, upl, upl_offset, f_offset, size, flags, real_bp)
                        cbp_tail = cbp;
                }
                (struct buf *)(cbp->b_trans_head) = cbp_head;
+               buf_count++;
 
                upl_offset += io_size;
                f_offset   += io_size;
                size       -= io_size;
 
-               if ( (!(upl_offset & PAGE_MASK) && !(flags & CL_DEV_MEMORY)) || size == 0) {
+               if ( (!(upl_offset & PAGE_MASK) && !(flags & CL_DEV_MEMORY) && ((flags & CL_ASYNC) || buf_count > 8)) || size == 0) {
                        /*
                         * if we have no more I/O to issue or
                         * the current I/O we've prepared fully
                         * completes the last page in this request
-                        * or it's been completed via a zero-fill
-                        * due to a 'hole' in the file
+                        * and it's either an ASYNC request or 
+                        * we've already accumulated more than 8 I/O's into
+                        * this transaction and it's not an I/O directed to 
+                        * special DEVICE memory
                         * then go ahead and issue the I/O
                         */
 start_io:              
@@ -566,8 +641,20 @@ start_io:
                        if (real_bp) {
                                cbp_head->b_flags |= B_NEED_IODONE;
                                cbp_head->b_real_bp = real_bp;
-                       }
+                       } else
+                               cbp_head->b_real_bp = (struct buf *)NULL;
 
+                       if (size == 0) {
+                               /*
+                                * we're about to issue the last I/O for this upl
+                                * if this was a read to the eof and the eof doesn't
+                                * finish on a page boundary, than we need to zero-fill
+                                * the rest of the page....
+                                */
+                               cbp_head->b_validend = zero_offset;
+                       } else
+                               cbp_head->b_validend = 0;
+                         
                        for (cbp = cbp_head; cbp;) {
                                struct buf * cbp_next;
 
@@ -575,7 +662,7 @@ start_io:
                                        cbp->b_vp->v_numoutput++;
 
                                cbp_next = cbp->b_trans_next;
-
+                               
                                (void) VOP_STRATEGY(cbp);
                                cbp = cbp_next;
                        }
@@ -584,12 +671,17 @@ start_io:
                                        biowait(cbp);
 
                                if (error = cluster_iodone(cbp_head)) {
-                                       retval = error;
+                                       if ((flags & CL_PAGEOUT) && (error == ENXIO))
+                                               retval = 0;     /* drop the error */
+                                       else
+                                               retval = error;
                                        error  = 0;
                                }
                        }
                        cbp_head = (struct buf *)0;
                        cbp_tail = (struct buf *)0;
+
+                       buf_count = 0;
                }
        }
        if (error) {
@@ -613,7 +705,7 @@ start_io:
                if (flags & CL_COMMIT) {
                        int upl_abort_code;
 
-                       if (flags & CL_PAGEOUT)
+                       if ((flags & CL_PAGEOUT) && (error != ENXIO)) /* transient error */
                                upl_abort_code = UPL_ABORT_FREE_ON_EMPTY;
                        else if (flags & CL_PAGEIN)
                            upl_abort_code = UPL_ABORT_FREE_ON_EMPTY | UPL_ABORT_ERROR;
@@ -624,7 +716,7 @@ start_io:
                                                upl_abort_code);
 
                        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 28)) | DBG_FUNC_NONE,
-                                    upl, upl_offset - pg_offset, abort_size, error, 0);
+                                    (int)upl, upl_offset - pg_offset, abort_size, error, 0);
                }
                if (real_bp) {
                        real_bp->b_flags |= B_ERROR;
@@ -650,14 +742,8 @@ cluster_rd_prefetch(vp, f_offset, size, filesize, devblocksize)
        off_t         filesize;
        int           devblocksize;
 {
-       upl_t         upl;
-       upl_page_info_t *pl;
-       int           pages_in_upl;
-       int           start_pg;
-       int           last_pg;
-       int           last_valid;
-       int           io_size;
-
+       int           pages_to_fetch;
+       int           skipped_pages;
 
        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 49)) | DBG_FUNC_START,
                     (int)f_offset, size, (int)filesize, 0, 0);
@@ -667,108 +753,29 @@ cluster_rd_prefetch(vp, f_offset, size, filesize, devblocksize)
                             (int)f_offset, 0, 0, 0, 0);
                return(0);
        }
-       if (ubc_page_op(vp, f_offset, 0, 0, 0) == KERN_SUCCESS) {
-               KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 49)) | DBG_FUNC_END,
-                            (int)f_offset, 0, 0, 0, 0);
-               return(1);
-       }
        if (size > (MAX_UPL_TRANSFER * PAGE_SIZE))
                size = MAX_UPL_TRANSFER * PAGE_SIZE;
        else
                size = (size + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1);
 
-       if ((off_t)size > (filesize - f_offset))
-               size = ((filesize - f_offset) + (devblocksize - 1)) & ~(devblocksize - 1);
+        if ((off_t)size > (filesize - f_offset))
+                size = filesize - f_offset;
        
-       pages_in_upl = (size + (PAGE_SIZE - 1)) / PAGE_SIZE;
-
-       ubc_create_upl(vp,
-                       f_offset,
-                       pages_in_upl * PAGE_SIZE,
-                               &upl, 
-                               &pl,
-                               UPL_FLAGS_NONE);
+       pages_to_fetch = (size + (PAGE_SIZE - 1)) / PAGE_SIZE;
 
-       if (upl == (upl_t) 0)
-               return(0);
-
-       /*
-        * scan from the beginning of the upl looking for the first
-        * non-valid page.... this will become the first page in
-        * the request we're going to make to 'cluster_io'... if all
-        * of the pages are valid, we won't call through to 'cluster_io'
-        */
-       for (start_pg = 0; start_pg < pages_in_upl; start_pg++) {
-               if (!upl_valid_page(pl, start_pg))
+       for (skipped_pages = 0; skipped_pages < pages_to_fetch; skipped_pages++) {
+               if (ubc_page_op(vp, f_offset, 0, 0, 0) != KERN_SUCCESS)
                        break;
+               f_offset += PAGE_SIZE;
+               size     -= PAGE_SIZE;
        }
-
-       /*
-        * scan from the starting invalid page looking for a valid
-        * page before the end of the upl is reached, if we 
-        * find one, then it will be the last page of the request to
-        * 'cluster_io'
-        */
-       for (last_pg = start_pg; last_pg < pages_in_upl; last_pg++) {
-               if (upl_valid_page(pl, last_pg))
-                       break;
-       }
-
-       /*
-        * if we find any more free valid pages at the tail of the upl
-        * than update maxra accordingly....
-        */
-       for (last_valid = last_pg; last_valid < pages_in_upl; last_valid++) {
-               if (!upl_valid_page(pl, last_valid))
-                       break;
-       }
-       if (start_pg < last_pg) {               
-               vm_offset_t   upl_offset;
-
-               /*
-                * we found a range of 'invalid' pages that must be filled
-                * 'size' has already been clipped to the LEOF
-                * make sure it's at least a multiple of the device block size
-                */
-               upl_offset = start_pg * PAGE_SIZE;
-               io_size    = (last_pg - start_pg) * PAGE_SIZE;
-
-               if ((upl_offset + io_size) > size) {
-                       io_size = size - upl_offset;
-
-                       KERNEL_DEBUG(0xd001000, upl_offset, size, io_size, 0, 0);
-               }
-               cluster_io(vp, upl, upl_offset, f_offset + upl_offset, io_size,
-                          CL_READ | CL_COMMIT | CL_ASYNC | CL_AGE, (struct buf *)0);
-       }
-       if (start_pg) {
-               /*
-                * start_pg of non-zero indicates we found some already valid pages
-                * at the beginning of the upl.... we need to release these without
-                * modifying there state
-                */
-               ubc_upl_abort_range(upl, 0, start_pg * PAGE_SIZE, UPL_ABORT_FREE_ON_EMPTY);
-
-               KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 50)) | DBG_FUNC_NONE,
-                            upl, 0, start_pg * PAGE_SIZE, 0, 0);
-       }
-       if (last_pg < pages_in_upl) {
-               /*
-                * the set of pages that we issued an I/O for did not extend all the
-                * way to the end of the upl... so just release them without modifying
-                * there state
-                */
-               ubc_upl_abort_range(upl, last_pg * PAGE_SIZE, (pages_in_upl - last_pg) * PAGE_SIZE,
-                               UPL_ABORT_FREE_ON_EMPTY);
-
-               KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 50)) | DBG_FUNC_NONE,
-                            upl, last_pg * PAGE_SIZE, (pages_in_upl - last_pg) * PAGE_SIZE, 0, 0);
-       }
+       if (skipped_pages < pages_to_fetch)
+               advisory_read(vp, filesize, f_offset, size, devblocksize);
 
        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 49)) | DBG_FUNC_END,
-                    (int)f_offset + (last_valid * PAGE_SIZE), 0, 0, 0, 0);
+                    (int)f_offset + (pages_to_fetch * PAGE_SIZE), skipped_pages, 0, 1, 0);
 
-       return(last_valid);
+       return (pages_to_fetch);
 }
 
 
@@ -795,7 +802,8 @@ cluster_rd_ahead(vp, b_lblkno, e_lblkno, filesize, devblocksize)
                return;
        }
 
-       if (vp->v_lastr == -1 || (b_lblkno != vp->v_lastr && b_lblkno != (vp->v_lastr + 1) && b_lblkno != (vp->v_maxra + 1))) {
+       if (vp->v_lastr == -1 || (b_lblkno != vp->v_lastr && b_lblkno != (vp->v_lastr + 1) &&
+                                (b_lblkno != (vp->v_maxra + 1) || vp->v_ralen == 0))) {
                vp->v_ralen = 0;
                vp->v_maxra = 0;
 
@@ -812,7 +820,7 @@ cluster_rd_ahead(vp, b_lblkno, e_lblkno, filesize, devblocksize)
                vp->v_ralen = min(max_pages, (e_lblkno + 1) - b_lblkno);
 
        if (e_lblkno < vp->v_maxra) {
-               if ((vp->v_maxra - e_lblkno) > (max_pages / 4)) {
+               if ((vp->v_maxra - e_lblkno) > max(max_pages / 16, 4)) {
 
                        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 48)) | DBG_FUNC_END,
                                     vp->v_ralen, vp->v_maxra, vp->v_lastr, 2, 0);
@@ -822,16 +830,17 @@ cluster_rd_ahead(vp, b_lblkno, e_lblkno, filesize, devblocksize)
        r_lblkno = max(e_lblkno, vp->v_maxra) + 1;
        f_offset = (off_t)r_lblkno * PAGE_SIZE_64;
 
-       size_of_prefetch = cluster_rd_prefetch(vp, f_offset, vp->v_ralen * PAGE_SIZE, filesize, devblocksize);
-
-       if (size_of_prefetch)
-               vp->v_maxra = r_lblkno + (size_of_prefetch - 1);
+       if (f_offset < filesize) {
+               size_of_prefetch = cluster_rd_prefetch(vp, f_offset, vp->v_ralen * PAGE_SIZE, filesize, devblocksize);
 
+               if (size_of_prefetch)
+                       vp->v_maxra = (r_lblkno + size_of_prefetch) - 1;
+       }
        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 48)) | DBG_FUNC_END,
                     vp->v_ralen, vp->v_maxra, vp->v_lastr, 3, 0);
 }
 
-
+int
 cluster_pageout(vp, upl, upl_offset, f_offset, size, filesize, devblocksize, flags)
        struct vnode *vp;
        upl_t         upl;
@@ -852,9 +861,6 @@ cluster_pageout(vp, upl, upl_offset, f_offset, size, filesize, devblocksize, fla
        if ((flags & UPL_NOCOMMIT) == 0) 
                local_flags |= CL_COMMIT;
 
-       if (upl == (upl_t) 0)
-               panic("cluster_pageout: can't handle NULL upl yet\n");
-
 
        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 52)) | DBG_FUNC_NONE,
                     (int)f_offset, size, (int)filesize, local_flags, 0);
@@ -869,8 +875,7 @@ cluster_pageout(vp, upl, upl_offset, f_offset, size, filesize, devblocksize, fla
 
         if (vp->v_mount->mnt_flag & MNT_RDONLY) {
                if (local_flags & CL_COMMIT)
-                       ubc_upl_abort_range(upl, upl_offset, size,
-                                               UPL_ABORT_FREE_ON_EMPTY);
+                       ubc_upl_abort_range(upl, upl_offset, size, UPL_ABORT_FREE_ON_EMPTY);
                return (EROFS);
        }
        /*
@@ -890,7 +895,7 @@ cluster_pageout(vp, upl, upl_offset, f_offset, size, filesize, devblocksize, fla
        if (size < max_size)
                io_size = size;
        else
-               io_size = (max_size + (devblocksize - 1)) & ~(devblocksize - 1);
+               io_size = max_size;
 
        pg_size = (io_size + (PAGE_SIZE - 1)) & ~PAGE_MASK;
 
@@ -904,11 +909,11 @@ cluster_pageout(vp, upl, upl_offset, f_offset, size, filesize, devblocksize, fla
                tsleep((caddr_t)&vp->v_numoutput, PRIBIO + 1, "cluster_pageout", 0);
        }
 
-       return (cluster_io(vp, upl, upl_offset, f_offset, io_size,
+       return (cluster_io(vp, upl, upl_offset, f_offset, io_size, devblocksize,
                           local_flags, (struct buf *)0));
 }
 
-
+int
 cluster_pagein(vp, upl, upl_offset, f_offset, size, filesize, devblocksize, flags)
        struct vnode *vp;
        upl_t         upl;
@@ -920,22 +925,19 @@ cluster_pagein(vp, upl, upl_offset, f_offset, size, filesize, devblocksize, flag
        int           flags;
 {
        u_int         io_size;
-       int           pg_size;
+       int           rounded_size;
         off_t         max_size;
        int           retval;
        int           local_flags = 0;
 
+       if (upl == NULL || size < 0)
+               panic("cluster_pagein: NULL upl passed in");
 
-       /*
-        * If they didn't ask for any data, then we are done...
-        * we can't issue an abort because we don't know how
-        * big the upl really is
-        */
-       if (size <= 0)
-               return (EINVAL);
-
+       if ((flags & UPL_IOSYNC) == 0)
+               local_flags |= CL_ASYNC;
        if ((flags & UPL_NOCOMMIT) == 0) 
-               local_flags = CL_COMMIT;
+               local_flags |= CL_COMMIT;
+
 
        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 56)) | DBG_FUNC_NONE,
                     (int)f_offset, size, (int)filesize, local_flags, 0);
@@ -947,10 +949,9 @@ cluster_pagein(vp, upl, upl_offset, f_offset, size, filesize, devblocksize, flag
         * or the size requested isn't a multiple of PAGE_SIZE
         */
        if (f_offset < 0 || f_offset >= filesize ||
-          (f_offset & PAGE_MASK_64) || (size & PAGE_MASK)) {
-               if (local_flags & CL_COMMIT)
-                       ubc_upl_abort_range(upl, upl_offset, size, 
-                                       UPL_ABORT_ERROR | UPL_ABORT_FREE_ON_EMPTY);
+          (f_offset & PAGE_MASK_64) || (size & PAGE_MASK) || (upl_offset & PAGE_MASK)) {
+               if (local_flags & CL_COMMIT)
+                       ubc_upl_abort_range(upl, upl_offset, size, UPL_ABORT_FREE_ON_EMPTY | UPL_ABORT_ERROR);
                return (EINVAL);
        }
        max_size = filesize - f_offset;
@@ -958,32 +959,16 @@ cluster_pagein(vp, upl, upl_offset, f_offset, size, filesize, devblocksize, flag
        if (size < max_size)
                io_size = size;
        else
-               io_size = (max_size + (devblocksize - 1)) & ~(devblocksize - 1);
+               io_size = max_size;
 
-       pg_size = (io_size + (PAGE_SIZE - 1)) & ~PAGE_MASK;
+       rounded_size = (io_size + (PAGE_SIZE - 1)) & ~PAGE_MASK;
 
-       if (upl == (upl_t) 0) {
-               ubc_create_upl( vp,
-                                               f_offset,
-                                               pg_size,
-                                               &upl,
-                                               NULL,
-                                               UPL_FLAGS_NONE);
-
-               if (upl == (upl_t) 0)
-                       return (EINVAL);
-
-               upl_offset = (vm_offset_t)0;
-               size = pg_size;
-       }
-       if (size > pg_size) {
-               if (local_flags & CL_COMMIT)
-                       ubc_upl_abort_range(upl, upl_offset + pg_size, size - pg_size,
-                                       UPL_ABORT_FREE_ON_EMPTY);
-       }
-
-       retval = cluster_io(vp, upl, upl_offset, f_offset, io_size,
-                           local_flags | CL_READ | CL_PAGEIN, (struct buf *)0);
+       if (size > rounded_size && (local_flags & CL_COMMIT))
+               ubc_upl_abort_range(upl, upl_offset + rounded_size,
+                                   size - (upl_offset + rounded_size), UPL_ABORT_FREE_ON_EMPTY | UPL_ABORT_ERROR);
+       
+       retval = cluster_io(vp, upl, upl_offset, f_offset, io_size, devblocksize,
+                          local_flags | CL_READ | CL_PAGEIN, (struct buf *)0);
 
        if (retval == 0) {
                int b_lblkno;
@@ -993,7 +978,7 @@ cluster_pagein(vp, upl, upl_offset, f_offset, size, filesize, devblocksize, flag
                e_lblkno = (int)
                        ((f_offset + ((off_t)io_size - 1)) / PAGE_SIZE_64);
 
-               if (!(flags & UPL_NORDAHEAD) && !(vp->v_flag & VRAOFF)) {
+               if (!(flags & UPL_NORDAHEAD) && !(vp->v_flag & VRAOFF) && rounded_size == PAGE_SIZE) {
                        /*
                         * we haven't read the last page in of the file yet
                         * so let's try to read ahead if we're in 
@@ -1006,26 +991,29 @@ cluster_pagein(vp, upl, upl_offset, f_offset, size, filesize, devblocksize, flag
        return (retval);
 }
 
-
+int
 cluster_bp(bp)
        struct buf *bp;
 {
         off_t  f_offset;
        int    flags;
 
+       KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 19)) | DBG_FUNC_START,
+                    (int)bp, bp->b_lblkno, bp->b_bcount, bp->b_flags, 0);
+
        if (bp->b_pagelist == (upl_t) 0)
                panic("cluster_bp: can't handle NULL upl yet\n");
        if (bp->b_flags & B_READ)
-               flags = CL_ASYNC | CL_NOMAP | CL_READ;
+               flags = CL_ASYNC | CL_READ;
        else
-               flags = CL_ASYNC | CL_NOMAP;
+               flags = CL_ASYNC;
 
        f_offset = ubc_blktooff(bp->b_vp, bp->b_lblkno);
 
-        return (cluster_io(bp->b_vp, bp->b_pagelist, 0, f_offset, bp->b_bcount, flags, bp));
+        return (cluster_io(bp->b_vp, bp->b_pagelist, 0, f_offset, bp->b_bcount, 0, flags, bp));
 }
 
-
+int
 cluster_write(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
        struct vnode *vp;
        struct uio   *uio;
@@ -1184,7 +1172,7 @@ cluster_write(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
        return(retval);
 }
 
-static
+static int
 cluster_nocopy_write(vp, uio, newEOF, devblocksize, flags)
        struct vnode *vp;
        struct uio   *uio;
@@ -1231,13 +1219,14 @@ cluster_nocopy_write(vp, uio, newEOF, devblocksize, flags)
          upl_needed_size = (upl_offset + io_size + (PAGE_SIZE -1)) & ~PAGE_MASK;
 
          KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 76)) | DBG_FUNC_START,
-                      (int)upl_offset, upl_needed_size, iov->iov_base, io_size, 0);
+                      (int)upl_offset, upl_needed_size, (int)iov->iov_base, io_size, 0);
 
          for (force_data_sync = 0; force_data_sync < 3; force_data_sync++)
            {
              pages_in_pl = 0;
              upl_size = upl_needed_size;
-             upl_flags = UPL_COPYOUT_FROM | UPL_NO_SYNC | UPL_CLEAN_IN_PLACE | UPL_SET_INTERNAL;
+             upl_flags = UPL_FILE_IO | UPL_COPYOUT_FROM | UPL_NO_SYNC |
+                         UPL_CLEAN_IN_PLACE | UPL_SET_INTERNAL;
 
              kret = vm_map_get_upl(current_map(),
                                    (vm_offset_t)iov->iov_base & ~PAGE_MASK,
@@ -1294,7 +1283,7 @@ cluster_nocopy_write(vp, uio, newEOF, devblocksize, flags)
            io_size = (upl_size - (int)upl_offset) & ~PAGE_MASK;
 
          KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 76)) | DBG_FUNC_END,
-                      (int)upl_offset, upl_size, iov->iov_base, io_size, 0);                  
+                      (int)upl_offset, upl_size, (int)iov->iov_base, io_size, 0);                     
 
          if (io_size == 0)
            {
@@ -1336,7 +1325,7 @@ cluster_nocopy_write(vp, uio, newEOF, devblocksize, flags)
                       (int)upl_offset, (int)uio->uio_offset, io_size, 0, 0);
 
          error = cluster_io(vp, upl, upl_offset, uio->uio_offset,
-                            io_size, 0, (struct buf *)0);
+                            io_size, devblocksize, 0, (struct buf *)0);
 
          if (error == 0) {
            /*
@@ -1371,7 +1360,7 @@ cluster_nocopy_write(vp, uio, newEOF, devblocksize, flags)
        return (error);
 }
 
-static
+static int
 cluster_phys_write(vp, uio)
        struct vnode *vp;
        struct uio   *uio;
@@ -1400,7 +1389,8 @@ cluster_phys_write(vp, uio)
 
        pages_in_pl = 0;
        upl_size = upl_needed_size;
-       upl_flags = UPL_COPYOUT_FROM | UPL_NO_SYNC | UPL_CLEAN_IN_PLACE | UPL_SET_INTERNAL;
+       upl_flags = UPL_FILE_IO | UPL_COPYOUT_FROM | UPL_NO_SYNC | 
+                   UPL_CLEAN_IN_PLACE | UPL_SET_INTERNAL;
 
        kret = vm_map_get_upl(current_map(),
                              (vm_offset_t)iov->iov_base & ~PAGE_MASK,
@@ -1428,7 +1418,7 @@ cluster_phys_write(vp, uio)
         */
 
        error = cluster_io(vp, upl, upl_offset, uio->uio_offset,
-                          io_size, CL_DEV_MEMORY, (struct buf *)0);
+                          io_size, 0, CL_DEV_MEMORY, (struct buf *)0);
 
        if (error == 0) {
          /*
@@ -1449,7 +1439,7 @@ cluster_phys_write(vp, uio)
        return (error);
 }
 
-static
+static int
 cluster_write_x(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
        struct vnode *vp;
        struct uio   *uio;
@@ -1469,7 +1459,6 @@ cluster_write_x(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
        int              start_offset;
        int              xfer_resid;
        int              io_size;
-       int              io_size_before_rounding;
        int              io_flags;
        vm_offset_t      io_address;
        int              io_offset;
@@ -1585,7 +1574,7 @@ cluster_write_x(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
                        panic("cluster_write: failed to get pagelist");
 
                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 41)) | DBG_FUNC_NONE,
-                       upl, (int)upl_f_offset, upl_size, start_offset, 0);
+                       (int)upl, (int)upl_f_offset, upl_size, start_offset, 0);
 
                if (start_offset && !upl_valid_page(pl, 0)) {
                        int   read_size;
@@ -1597,11 +1586,10 @@ cluster_write_x(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
                         */
                        read_size = PAGE_SIZE;
 
-                       if ((upl_f_offset + read_size) > newEOF) {
+                       if ((upl_f_offset + read_size) > newEOF)
                                read_size = newEOF - upl_f_offset;
-                               read_size = (read_size + (devblocksize - 1)) & ~(devblocksize - 1);
-                       }
-                       retval = cluster_io(vp, upl, 0, upl_f_offset, read_size,
+
+                       retval = cluster_io(vp, upl, 0, upl_f_offset, read_size, devblocksize,
                                            CL_READ, (struct buf *)0);
                        if (retval) {
                                /*
@@ -1611,10 +1599,10 @@ cluster_write_x(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
                                 * there state and mark the failed page in error
                                 */
                                ubc_upl_abort_range(upl, 0, PAGE_SIZE, UPL_ABORT_DUMP_PAGES);
-                               ubc_upl_abort(upl, 0);
+                               ubc_upl_abort_range(upl, 0, upl_size,  UPL_ABORT_FREE_ON_EMPTY);
 
                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 45)) | DBG_FUNC_NONE,
-                                            upl, 0, 0, retval, 0);
+                                            (int)upl, 0, 0, retval, 0);
                                break;
                        }
                }
@@ -1632,11 +1620,10 @@ cluster_write_x(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
 
                                read_size = PAGE_SIZE;
 
-                               if ((upl_f_offset + upl_offset + read_size) > newEOF) {
+                               if ((upl_f_offset + upl_offset + read_size) > newEOF)
                                        read_size = newEOF - (upl_f_offset + upl_offset);
-                                       read_size = (read_size + (devblocksize - 1)) & ~(devblocksize - 1);
-                               }
-                               retval = cluster_io(vp, upl, upl_offset, upl_f_offset + upl_offset, read_size,
+
+                               retval = cluster_io(vp, upl, upl_offset, upl_f_offset + upl_offset, read_size, devblocksize,
                                                    CL_READ, (struct buf *)0);
                                if (retval) {
                                        /*
@@ -1645,12 +1632,11 @@ cluster_write_x(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
                                         * need to release the rest of the pages in the upl without
                                         * modifying there state and mark the failed page in error
                                         */
-                                       ubc_upl_abort_range(upl, upl_offset, PAGE_SIZE,
-                                                       UPL_ABORT_DUMP_PAGES);
-                                       ubc_upl_abort(upl, 0);
+                                       ubc_upl_abort_range(upl, upl_offset, PAGE_SIZE, UPL_ABORT_DUMP_PAGES);
+                                       ubc_upl_abort_range(upl, 0,          upl_size,  UPL_ABORT_FREE_ON_EMPTY);
 
                                        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 45)) | DBG_FUNC_NONE,
-                                                    upl, 0, 0, retval, 0);
+                                                    (int)upl, 0, 0, retval, 0);
                                        break;
                                }
                        }
@@ -1667,21 +1653,32 @@ cluster_write_x(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
                        else
                                bytes_to_zero = xfer_resid;
 
-                       if ( !(flags & IO_NOZEROVALID)) {
+                       if ( !(flags & (IO_NOZEROVALID | IO_NOZERODIRTY))) {
                                bzero((caddr_t)(io_address + io_offset), bytes_to_zero);
 
                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 43)) | DBG_FUNC_NONE,
                                             (int)upl_f_offset + io_offset, bytes_to_zero,
-                                            (int)zero_cnt, xfer_resid, 0);
+                                            (int)io_offset, xfer_resid, 0);
                        } else {
+                               int zero_pg_index;
+
                                bytes_to_zero = min(bytes_to_zero, PAGE_SIZE - (int)(zero_off & PAGE_MASK_64));
+                               zero_pg_index = (int)((zero_off - upl_f_offset) / PAGE_SIZE_64);
+
+                               if ( !upl_valid_page(pl, zero_pg_index)) {
+                                       bzero((caddr_t)(io_address + io_offset), bytes_to_zero); 
+
+                                       KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 43)) | DBG_FUNC_NONE,
+                                                    (int)upl_f_offset + io_offset, bytes_to_zero,
+                                                    (int)io_offset, xfer_resid, 0);
 
-                               if ( !upl_valid_page(pl, (int)(zero_off / PAGE_SIZE_64))) {
+                               } else if ((flags & (IO_NOZERODIRTY | IO_NOZEROVALID)) == IO_NOZERODIRTY &&
+                                          !upl_dirty_page(pl, zero_pg_index)) {
                                        bzero((caddr_t)(io_address + io_offset), bytes_to_zero); 
 
                                        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 43)) | DBG_FUNC_NONE,
                                                     (int)upl_f_offset + io_offset, bytes_to_zero,
-                                                    (int)zero_cnt, xfer_resid, 0);
+                                                    (int)io_offset, xfer_resid, 0);
                                }
                        }
                        xfer_resid -= bytes_to_zero;
@@ -1697,13 +1694,15 @@ cluster_write_x(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
 
                        retval = uiomove((caddr_t)(io_address + io_offset), bytes_to_move, uio);
 
+
                        if (retval) {
                                if ((kret = ubc_upl_unmap(upl)) != KERN_SUCCESS)
                                        panic("cluster_write: kernel_upl_unmap failed\n");
-                               ubc_upl_abort(upl, UPL_ABORT_DUMP_PAGES);
+
+                               ubc_upl_abort_range(upl, 0, upl_size, UPL_ABORT_DUMP_PAGES | UPL_ABORT_FREE_ON_EMPTY);
 
                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 45)) | DBG_FUNC_NONE,
-                                            upl, 0, 0, retval, 0);
+                                            (int)upl, 0, 0, retval, 0);
                        } else {
                                uio_resid  -= bytes_to_move;
                                xfer_resid -= bytes_to_move;
@@ -1717,20 +1716,32 @@ cluster_write_x(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
                        else
                                bytes_to_zero = xfer_resid;
 
-                       if ( !(flags & IO_NOZEROVALID)) {
+                       if ( !(flags & (IO_NOZEROVALID | IO_NOZERODIRTY))) {
                                bzero((caddr_t)(io_address + io_offset), bytes_to_zero);
 
                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 43)) | DBG_FUNC_NONE,
                                             (int)upl_f_offset + io_offset,
-                                            bytes_to_zero, (int)zero_cnt1, xfer_resid, 0);
+                                            bytes_to_zero, (int)io_offset, xfer_resid, 0);
                        } else {
+                               int zero_pg_index;
+                       
                                bytes_to_zero = min(bytes_to_zero, PAGE_SIZE - (int)(zero_off1 & PAGE_MASK_64));
-                               if ( !upl_valid_page(pl, (int)(zero_off1 / PAGE_SIZE_64))) {
+                               zero_pg_index = (int)((zero_off1 - upl_f_offset) / PAGE_SIZE_64);
+
+                               if ( !upl_valid_page(pl, zero_pg_index)) {
                                        bzero((caddr_t)(io_address + io_offset), bytes_to_zero);
 
                                        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 43)) | DBG_FUNC_NONE,
                                                     (int)upl_f_offset + io_offset,
-                                                    bytes_to_zero, (int)zero_cnt1, xfer_resid, 0);
+                                                    bytes_to_zero, (int)io_offset, xfer_resid, 0);
+
+                               } else if ((flags & (IO_NOZERODIRTY | IO_NOZEROVALID)) == IO_NOZERODIRTY &&
+                                          !upl_dirty_page(pl, zero_pg_index)) {
+                                       bzero((caddr_t)(io_address + io_offset), bytes_to_zero);
+
+                                       KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 43)) | DBG_FUNC_NONE,
+                                                    (int)upl_f_offset + io_offset,
+                                                    bytes_to_zero, (int)io_offset, xfer_resid, 0);
                                }
                        }
                        xfer_resid -= bytes_to_zero;
@@ -1740,12 +1751,12 @@ cluster_write_x(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
                }
 
                if (retval == 0) {
-                       int must_push;
+                       int cl_index;
                        int can_delay;
 
                        io_size += start_offset;
 
-                       if ((upl_f_offset + io_size) == newEOF && io_size < upl_size) {
+                       if ((upl_f_offset + io_size) >= newEOF && io_size < upl_size) {
                                /*
                                 * if we're extending the file with this write
                                 * we'll zero fill the rest of the page so that
@@ -1761,138 +1772,181 @@ cluster_write_x(vp, uio, oldEOF, newEOF, headOff, tailOff, devblocksize, flags)
                        if ((kret = ubc_upl_unmap(upl)) != KERN_SUCCESS)
                                panic("cluster_write: kernel_upl_unmap failed\n");
 
-                       io_size_before_rounding = io_size;
-
-                       if (io_size & (devblocksize - 1))
-                               io_size = (io_size + (devblocksize - 1)) & ~(devblocksize - 1);
+                       if (flags & IO_SYNC)
+                               /*
+                                * if the IO_SYNC flag is set than we need to 
+                                * bypass any clusters and immediately issue
+                                * the I/O
+                                */
+                               goto issue_io;
 
-                       must_push = 0;
-                       can_delay = 0;
+                       if (vp->v_clen == 0)
+                               /*
+                                * no clusters currently present
+                                */
+                               goto start_new_cluster;
 
-                       if (vp->v_clen) {
-                               int newsize;
+                       /*
+                        * keep track of the overall dirty page
+                        * range we've developed
+                        * in case we have to fall back to the
+                        * VHASDIRTY method of flushing
+                        */
+                       if (vp->v_flag & VHASDIRTY)
+                               goto delay_io;
 
+                       for (cl_index = 0; cl_index < vp->v_clen; cl_index++) {
                                /*
                                 * we have an existing cluster... see if this write will extend it nicely
                                 */
-                               if (start_blkno >= vp->v_cstart) {
-                                       if (last_blkno <= (vp->v_cstart + vp->v_clen)) {
+                               if (start_blkno >= vp->v_clusters[cl_index].start_pg) {
+                                       /*
+                                        * the current write starts at or after the current cluster
+                                        */
+                                       if (last_blkno <= (vp->v_clusters[cl_index].start_pg + MAX_UPL_TRANSFER)) {
                                                /*
                                                 * we have a write that fits entirely
                                                 * within the existing cluster limits
                                                 */
-                                               if (last_blkno >= vp->v_lastw) {
+                                               if (last_blkno > vp->v_clusters[cl_index].last_pg)
                                                        /*
-                                                        * if we're extending the dirty region within the cluster
-                                                        * we need to update the cluster info... we check for blkno
-                                                        * equality because we may be extending the file with a 
-                                                        * partial write.... this in turn changes our idea of how
-                                                        * much data to write out (v_ciosiz) for the last page
+                                                        * update our idea of where the cluster ends
                                                         */
-                                                       vp->v_lastw = last_blkno;
-                                                       newsize = io_size + ((start_blkno - vp->v_cstart) * PAGE_SIZE);
-
-                                                       if (newsize > vp->v_ciosiz)
-                                                               vp->v_ciosiz = newsize;
-                                               }
-                                               can_delay = 1;
-                                               goto finish_io;
+                                                       vp->v_clusters[cl_index].last_pg = last_blkno;
+                                               break;
                                        }
-                                       if (start_blkno < (vp->v_cstart + vp->v_clen)) {
+                                       if (start_blkno < (vp->v_clusters[cl_index].start_pg + MAX_UPL_TRANSFER)) {
                                                /*
                                                 * we have a write that starts in the middle of the current cluster
                                                 * but extends beyond the cluster's limit
                                                 * we'll clip the current cluster if we actually
-                                                * overlap with the new write and then push it out
+                                                * overlap with the new write
                                                 * and start a new cluster with the current write
                                                 */
-                                                if (vp->v_lastw > start_blkno) {
-                                                       vp->v_lastw = start_blkno;
-                                                       vp->v_ciosiz = (vp->v_lastw - vp->v_cstart) * PAGE_SIZE;
-                                                }
+                                                if (vp->v_clusters[cl_index].last_pg > start_blkno)
+                                                       vp->v_clusters[cl_index].last_pg = start_blkno;
                                        }
                                        /*
                                         * we also get here for the case where the current write starts
                                         * beyond the limit of the existing cluster
+                                        *
+                                        * in either case, we'll check the remaining clusters before 
+                                        * starting a new one
                                         */
-                                       must_push = 1;
-                                       goto check_delay;
-                               }
-                               /*
-                                * the current write starts in front of the current cluster
-                                */
-                               if (last_blkno > vp->v_cstart) {
+                               } else {
                                        /*
-                                        * the current write extends into the existing cluster
+                                        * the current write starts in front of the current cluster
                                         */
-                                       if ((vp->v_lastw - start_blkno) > vp->v_clen) {
+                                       if ((vp->v_clusters[cl_index].last_pg - start_blkno) <=  MAX_UPL_TRANSFER) {
                                                /*
-                                                * if we were to combine this write with the current cluster
-                                                * we would exceed the cluster size limit....
-                                                * clip the current cluster by moving the start position
-                                                * to where the current write ends, and then push it
-                                                */
-                                               vp->v_ciosiz -= (last_blkno - vp->v_cstart) * PAGE_SIZE;
-                                               vp->v_cstart = last_blkno;
-
-                                               /*
-                                                * round up the io_size to the nearest page size
-                                                * since we've coalesced with at least 1 pre-existing
-                                                * page in the current cluster... this write may have ended in the
-                                                * middle of the page which would cause io_size to give us an
-                                                * inaccurate view of how much I/O we actually need to do
+                                                * we can just merge the old cluster
+                                                * with the new request and leave it
+                                                * in the cache
                                                 */
-                                               io_size = (io_size + (PAGE_SIZE - 1)) & ~PAGE_MASK;
+                                               vp->v_clusters[cl_index].start_pg = start_blkno;
 
-                                               must_push = 1;
-                                               goto check_delay;
+                                               if (last_blkno > vp->v_clusters[cl_index].last_pg) {
+                                                       /*
+                                                        * the current write completely
+                                                        * envelops the existing cluster
+                                                        */
+                                                       vp->v_clusters[cl_index].last_pg = last_blkno;
+                                               }
+                                               break;
                                        }
+
                                        /*
-                                        * we can coalesce the current write with the existing cluster
-                                        * adjust the cluster info to reflect this
+                                        * if we were to combine this write with the current cluster
+                                        * we would exceed the cluster size limit.... so,
+                                        * let's see if there's any overlap of the new I/O with
+                                        * the existing cluster...
+                                        * 
                                         */
-                                       if (last_blkno > vp->v_lastw) {
+                                       if (last_blkno > vp->v_clusters[cl_index].start_pg)
                                                /*
-                                                * the current write completey overlaps
-                                                * the existing cluster
+                                                * the current write extends into the existing cluster
+                                                * clip the current cluster by moving the start position
+                                                * to where the current write ends
                                                 */
-                                               vp->v_lastw = last_blkno;
-                                               vp->v_ciosiz = io_size;
-                                       } else {
-                                               vp->v_ciosiz += (vp->v_cstart - start_blkno) * PAGE_SIZE;
-
-                                               if (io_size > vp->v_ciosiz)
-                                                       vp->v_ciosiz = io_size;
-                                       }
-                                       vp->v_cstart = start_blkno;
-                                       can_delay = 1;
-                                       goto finish_io;
+                                               vp->v_clusters[cl_index].start_pg = last_blkno;
+                                       /*
+                                        * if we get here, there was no way to merge
+                                        * the new I/O with this cluster and
+                                        * keep it under our maximum cluster length
+                                        * we'll check the remaining clusters before starting a new one
+                                        */
                                }
-                               /*
-                                * this I/O range is entirely in front of the current cluster
-                                * so we need to push the current cluster out before beginning
+                       }
+                       if (cl_index < vp->v_clen)
+                               /*
+                                * we found an existing cluster that we
+                                * could merger this I/O into
+                                */
+                               goto delay_io;
+
+                       if (vp->v_clen < MAX_CLUSTERS && !(vp->v_flag & VNOCACHE_DATA))
+                               /*
+                                * we didn't find an existing cluster to
+                                * merge into, but there's room to start
                                 * a new one
                                 */
-                               must_push = 1;
-                       }
-check_delay:
-                       if (must_push)
-                               cluster_push(vp);
+                               goto start_new_cluster;
 
-                       if (io_size_before_rounding < (MAX_UPL_TRANSFER * PAGE_SIZE) && !(flags & IO_SYNC)) {
-                               vp->v_clen = MAX_UPL_TRANSFER;
+                       /*
+                        * no exisitng cluster to merge with and no
+                        * room to start a new one... we'll try 
+                        * pushing the existing ones... if none of
+                        * them are able to be pushed, we'll have
+                        * to fall back on the VHASDIRTY mechanism
+                        * cluster_try_push will set v_clen to the
+                        * number of remaining clusters if it is
+                        * unable to push all of them
+                        */
+                       if (vp->v_flag & VNOCACHE_DATA)
+                               can_delay = 0;
+                       else
+                               can_delay = 1;
+
+                       if (cluster_try_push(vp, newEOF, can_delay, 0) == 0) {
+                               vp->v_flag |= VHASDIRTY;
+                               goto delay_io;
+                       }
+start_new_cluster:
+                       if (vp->v_clen == 0) {
+                               vp->v_ciosiz = devblocksize;
                                vp->v_cstart = start_blkno;
                                vp->v_lastw  = last_blkno;
-                               vp->v_ciosiz = io_size;
-                               
-                               can_delay = 1;
                        }
-finish_io:
-                       if (can_delay) {
-                               ubc_upl_commit_range(upl, 0, upl_size,
-                                                    UPL_COMMIT_SET_DIRTY | UPL_COMMIT_FREE_ON_EMPTY);
-                               continue;
+                       vp->v_clusters[vp->v_clen].start_pg = start_blkno;
+                       vp->v_clusters[vp->v_clen].last_pg  = last_blkno;
+                       vp->v_clen++;
+delay_io:
+                       /*
+                        * make sure we keep v_cstart and v_lastw up to 
+                        * date in case we have to fall back on the
+                        * V_HASDIRTY mechanism (or we've already entered it)
+                        */
+                       if (start_blkno < vp->v_cstart)
+                               vp->v_cstart = start_blkno;
+                       if (last_blkno > vp->v_lastw)
+                               vp->v_lastw = last_blkno;
+
+                       ubc_upl_commit_range(upl, 0, upl_size, UPL_COMMIT_SET_DIRTY | UPL_COMMIT_INACTIVATE | UPL_COMMIT_FREE_ON_EMPTY);
+                       continue;
+issue_io:
+                       /*
+                        * in order to maintain some semblance of coherency with mapped writes
+                        * we need to write the cluster back out as a multiple of the PAGESIZE
+                        * unless the cluster encompasses the last page of the file... in this
+                        * case we'll round out to the nearest device block boundary
+                        */
+                       io_size = upl_size;
+
+                       if ((upl_f_offset + io_size) > newEOF) {
+                               io_size = newEOF - upl_f_offset;
+                               io_size = (io_size + (devblocksize - 1)) & ~(devblocksize - 1);
                        }
+
                        if (flags & IO_SYNC)
                                io_flags = CL_COMMIT | CL_AGE;
                        else
@@ -1905,7 +1959,7 @@ finish_io:
                                vp->v_flag |= VTHROTTLED;
                                tsleep((caddr_t)&vp->v_numoutput, PRIBIO + 1, "cluster_write", 0);
                        }       
-                       retval = cluster_io(vp, upl, 0, upl_f_offset, io_size,
+                       retval = cluster_io(vp, upl, 0, upl_f_offset, io_size, devblocksize,
                                            io_flags, (struct buf *)0);
                }
        }
@@ -1915,6 +1969,7 @@ finish_io:
        return (retval);
 }
 
+int
 cluster_read(vp, uio, filesize, devblocksize, flags)
        struct vnode *vp;
        struct uio   *uio;
@@ -2061,7 +2116,7 @@ cluster_read(vp, uio, filesize, devblocksize, flags)
        return(retval);
 }
 
-static
+static int
 cluster_read_x(vp, uio, filesize, devblocksize, flags)
        struct vnode *vp;
        struct uio   *uio;
@@ -2108,7 +2163,7 @@ cluster_read_x(vp, uio, filesize, devblocksize, flags)
                        io_size = uio->uio_resid;
                else
                        io_size = max_size;
-#ifdef ppc
+
                if (uio->uio_segflg == UIO_USERSPACE && !(vp->v_flag & VNOCACHE_DATA)) {
                        segflg = uio->uio_segflg;
 
@@ -2170,14 +2225,13 @@ cluster_read_x(vp, uio, filesize, devblocksize, flags)
                        }
                        max_size = filesize - uio->uio_offset;
                }
-#endif
                upl_size = (start_offset + io_size + (PAGE_SIZE - 1)) & ~PAGE_MASK;
                if (upl_size > (MAX_UPL_TRANSFER * PAGE_SIZE))
                        upl_size = MAX_UPL_TRANSFER * PAGE_SIZE;
                pages_in_upl = upl_size / PAGE_SIZE;
 
                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 33)) | DBG_FUNC_START,
-                            upl, (int)upl_f_offset, upl_size, start_offset, 0);
+                            (int)upl, (int)upl_f_offset, upl_size, start_offset, 0);
 
                kret = ubc_create_upl(vp, 
                                                upl_f_offset,
@@ -2189,7 +2243,7 @@ cluster_read_x(vp, uio, filesize, devblocksize, flags)
                        panic("cluster_read: failed to get pagelist");
 
                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 33)) | DBG_FUNC_END,
-                            upl, (int)upl_f_offset, upl_size, start_offset, 0);
+                            (int)upl, (int)upl_f_offset, upl_size, start_offset, 0);
 
                /*
                 * scan from the beginning of the upl looking for the first
@@ -2223,16 +2277,15 @@ cluster_read_x(vp, uio, filesize, devblocksize, flags)
                        upl_offset = start_pg * PAGE_SIZE;
                        io_size    = (last_pg - start_pg) * PAGE_SIZE;
 
-                       if ((upl_f_offset + upl_offset + io_size) > filesize) {
+                       if ((upl_f_offset + upl_offset + io_size) > filesize)
                                io_size = filesize - (upl_f_offset + upl_offset);
-                               io_size = (io_size + (devblocksize - 1)) & ~(devblocksize - 1);
-                       }
+
                        /*
                         * issue a synchronous read to cluster_io
                         */
 
                        error = cluster_io(vp, upl, upl_offset, upl_f_offset + upl_offset,
-                                          io_size, CL_READ, (struct buf *)0);
+                                          io_size, devblocksize, CL_READ, (struct buf *)0);
                }
                if (error == 0) {
                        /*
@@ -2279,7 +2332,6 @@ cluster_read_x(vp, uio, filesize, devblocksize, flags)
                                        cluster_rd_ahead(vp, b_lblkno, e_lblkno, filesize, devblocksize);
                                vp->v_lastr = e_lblkno;
                        }
-#ifdef ppc
                        if (uio->uio_segflg == UIO_USERSPACE) {
                                int       offset;
 
@@ -2313,8 +2365,8 @@ cluster_read_x(vp, uio, filesize, devblocksize, flags)
                                             (int)uio->uio_offset, val_size, uio->uio_resid, 0, 0);
 
                                uio->uio_segflg = segflg;
-                       } else
-#endif
+                       }
+                       else
                        {
                                if ((kret = ubc_upl_map(upl, &io_address)) != KERN_SUCCESS)
                                        panic("cluster_read: ubc_upl_map() failed\n");
@@ -2334,7 +2386,7 @@ cluster_read_x(vp, uio, filesize, devblocksize, flags)
                        io_size = (last_pg - start_pg) * PAGE_SIZE;
 
                        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 35)) | DBG_FUNC_START,
-                                    upl, start_pg * PAGE_SIZE, io_size, error, 0);
+                                    (int)upl, start_pg * PAGE_SIZE, io_size, error, 0);
 
                        if (error || (vp->v_flag & VNOCACHE_DATA))
                                ubc_upl_abort_range(upl, start_pg * PAGE_SIZE, io_size,
@@ -2346,7 +2398,7 @@ cluster_read_x(vp, uio, filesize, devblocksize, flags)
                                                | UPL_COMMIT_INACTIVATE);
 
                        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 35)) | DBG_FUNC_END,
-                                    upl, start_pg * PAGE_SIZE, io_size, error, 0);
+                                    (int)upl, start_pg * PAGE_SIZE, io_size, error, 0);
                }
                if ((last_pg - start_pg) < pages_in_upl) {
                        int cur_pg;
@@ -2358,10 +2410,10 @@ cluster_read_x(vp, uio, filesize, devblocksize, flags)
                         * there state
                         */
                        if (error)
-                               ubc_upl_abort(upl, 0);
+                               ubc_upl_abort_range(upl, 0, upl_size, UPL_ABORT_FREE_ON_EMPTY);
                        else {
                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 35)) | DBG_FUNC_START,
-                                            upl, -1, pages_in_upl - (last_pg - start_pg), 0, 0);
+                                            (int)upl, -1, pages_in_upl - (last_pg - start_pg), 0, 0);
 
                                if (start_pg) {
                                        /*
@@ -2411,11 +2463,12 @@ cluster_read_x(vp, uio, filesize, devblocksize, flags)
                                         * that we didn't issue an I/O for, just release them
                                         * unchanged
                                         */
-                                       ubc_upl_abort(upl, 0);
+                                       ubc_upl_abort_range(upl, uio_last * PAGE_SIZE,
+                                                           (pages_in_upl - uio_last) * PAGE_SIZE, UPL_ABORT_FREE_ON_EMPTY);
                                }
 
                                KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 35)) | DBG_FUNC_END,
-                                       upl, -1, -1, 0, 0);
+                                       (int)upl, -1, -1, 0, 0);
                        }
                }
                if (retval == 0)
@@ -2425,7 +2478,7 @@ cluster_read_x(vp, uio, filesize, devblocksize, flags)
        return (retval);
 }
 
-static
+static int
 cluster_nocopy_read(vp, uio, filesize, devblocksize, flags)
        struct vnode *vp;
        struct uio   *uio;
@@ -2558,13 +2611,13 @@ cluster_nocopy_read(vp, uio, filesize, devblocksize, flags)
          upl_needed_size = (upl_offset + io_size + (PAGE_SIZE -1)) & ~PAGE_MASK;
 
          KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 72)) | DBG_FUNC_START,
-                      (int)upl_offset, upl_needed_size, iov->iov_base, io_size, 0);
+                      (int)upl_offset, upl_needed_size, (int)iov->iov_base, io_size, 0);
 
          for (force_data_sync = 0; force_data_sync < 3; force_data_sync++)
            {
              pages_in_pl = 0;
              upl_size = upl_needed_size;
-             upl_flags = UPL_NO_SYNC | UPL_CLEAN_IN_PLACE | UPL_SET_INTERNAL;
+             upl_flags = UPL_FILE_IO | UPL_NO_SYNC | UPL_CLEAN_IN_PLACE | UPL_SET_INTERNAL;
 
              kret = vm_map_get_upl(current_map(),
                                    (vm_offset_t)iov->iov_base & ~PAGE_MASK,
@@ -2628,10 +2681,10 @@ cluster_nocopy_read(vp, uio, filesize, devblocksize, flags)
           */
 
          KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 73)) | DBG_FUNC_START,
-                      upl, (int)upl_offset, (int)start_upl_f_offset, io_size, 0);
+                      (int)upl, (int)upl_offset, (int)start_upl_f_offset, io_size, 0);
 
          error = cluster_io(vp, upl, upl_offset, start_upl_f_offset,
-                            io_size, CL_READ| CL_NOZERO, (struct buf *)0);
+                            io_size, devblocksize, CL_READ| CL_NOZERO, (struct buf *)0);
 
          if (error == 0) {
            /*
@@ -2653,7 +2706,7 @@ cluster_nocopy_read(vp, uio, filesize, devblocksize, flags)
          }
 
          KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 73)) | DBG_FUNC_END,
-                      upl, (int)uio->uio_offset, (int)uio->uio_resid, error, 0);
+                      (int)upl, (int)uio->uio_offset, (int)uio->uio_resid, error, 0);
 
          if (retval == 0)
            retval = error;
@@ -2668,7 +2721,7 @@ cluster_nocopy_read(vp, uio, filesize, devblocksize, flags)
 }
 
 
-static
+static int
 cluster_phys_read(vp, uio, filesize)
        struct vnode *vp;
        struct uio   *uio;
@@ -2706,7 +2759,7 @@ cluster_phys_read(vp, uio, filesize)
 
        pages_in_pl = 0;
        upl_size = upl_needed_size;
-       upl_flags = UPL_NO_SYNC | UPL_CLEAN_IN_PLACE | UPL_SET_INTERNAL;
+       upl_flags = UPL_FILE_IO | UPL_NO_SYNC | UPL_CLEAN_IN_PLACE | UPL_SET_INTERNAL;
 
        kret = vm_map_get_upl(current_map(),
                              (vm_offset_t)iov->iov_base & ~PAGE_MASK,
@@ -2732,7 +2785,7 @@ cluster_phys_read(vp, uio, filesize)
         */
 
        error = cluster_io(vp, upl, upl_offset, uio->uio_offset,
-                          io_size,  CL_READ| CL_NOZERO | CL_DEV_MEMORY, (struct buf *)0);
+                          io_size, 0, CL_READ| CL_NOZERO | CL_DEV_MEMORY, (struct buf *)0);
 
        if (error == 0)
          {
@@ -2758,6 +2811,7 @@ cluster_phys_read(vp, uio, filesize)
  * generate advisory I/O's in the largest chunks possible
  * the completed pages will be released into the VM cache
  */
+int
 advisory_read(vp, filesize, f_offset, resid, devblocksize)
        struct vnode *vp;
        off_t         filesize;
@@ -2778,7 +2832,7 @@ advisory_read(vp, filesize, f_offset, resid, devblocksize)
        int              io_size;
        kern_return_t    kret;
        int              retval = 0;
-
+       int              issued_io;
 
        if (!UBCINFOEXISTS(vp))
                return(EINVAL);
@@ -2814,88 +2868,83 @@ advisory_read(vp, filesize, f_offset, resid, devblocksize)
                                                upl_size,
                                                &upl,
                                                &pl,
-                                               UPL_FLAGS_NONE);
+                                               UPL_RET_ONLY_ABSENT);
                if (kret != KERN_SUCCESS)
-                       panic("advisory_read: failed to get pagelist");
-
-
-               KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 61)) | DBG_FUNC_NONE,
-                            upl, (int)upl_f_offset, upl_size, start_offset, 0);
+                       return(retval);
+               issued_io = 0;
 
                /*
-                * scan from the beginning of the upl looking for the first
-                * non-valid page.... this will become the first page in
-                * the request we're going to make to 'cluster_io'... if all
-                * of the pages are valid, we won't call through to 'cluster_io'
+                * before we start marching forward, we must make sure we end on 
+                * a present page, otherwise we will be working with a freed
+                * upl
                 */
-               for (start_pg = 0; start_pg < pages_in_upl; start_pg++) {
-                       if (!upl_valid_page(pl, start_pg))
-                               break;
+               for (last_pg = pages_in_upl - 1; last_pg >= 0; last_pg--) {
+                       if (upl_page_present(pl, last_pg))
+                               break;
                }
+               pages_in_upl = last_pg + 1;
 
-               /*
-                * scan from the starting invalid page looking for a valid
-                * page before the end of the upl is reached, if we 
-                * find one, then it will be the last page of the request to
-                * 'cluster_io'
-                */
-               for (last_pg = start_pg; last_pg < pages_in_upl; last_pg++) {
-                       if (upl_valid_page(pl, last_pg))
-                               break;
-               }
 
-               if (start_pg < last_pg) {               
+               KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 61)) | DBG_FUNC_NONE,
+                            (int)upl, (int)upl_f_offset, upl_size, start_offset, 0);
+
+
+               for (last_pg = 0; last_pg < pages_in_upl; ) {
                        /*
-                        * we found a range of 'invalid' pages that must be filled
-                        * if the last page in this range is the last page of the file
-                        * we may have to clip the size of it to keep from reading past
-                        * the end of the last physical block associated with the file
+                        * scan from the beginning of the upl looking for the first
+                        * page that is present.... this will become the first page in
+                        * the request we're going to make to 'cluster_io'... if all
+                        * of the pages are absent, we won't call through to 'cluster_io'
                         */
-                       upl_offset = start_pg * PAGE_SIZE;
-                       io_size    = (last_pg - start_pg) * PAGE_SIZE;
-
-                       if ((upl_f_offset + upl_offset + io_size) > filesize) {
-                               io_size = filesize - (upl_f_offset + upl_offset);
-                               io_size = (io_size + (devblocksize - 1)) & ~(devblocksize - 1);
+                       for (start_pg = last_pg; start_pg < pages_in_upl; start_pg++) {
+                               if (upl_page_present(pl, start_pg))
+                                       break;
                        }
-                       /*
-                        * issue an asynchronous read to cluster_io
-                        */
-                       retval = cluster_io(vp, upl, upl_offset, upl_f_offset + upl_offset, io_size,
-                                         CL_ASYNC | CL_READ | CL_COMMIT | CL_AGE, (struct buf *)0);
-               }
-               if (start_pg) {
-                       /*
-                        * start_pg of non-zero indicates we found some already valid pages
-                        * at the beginning of the upl.... we need to release these without
-                        * modifying there state
-                        */
-                       ubc_upl_abort_range(upl, 0, start_pg * PAGE_SIZE,
-                                       UPL_ABORT_FREE_ON_EMPTY);
 
-                       KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 62)) | DBG_FUNC_NONE,
-                                   upl, 0, start_pg * PAGE_SIZE, 0, 0);
-               }
-               if (last_pg < pages_in_upl) {
                        /*
-                        * the set of pages that we issued an I/O for did not extend all the
-                        * way to the end of the upl..so just release them without modifying
-                        * there state
+                        * scan from the starting present page looking for an absent
+                        * page before the end of the upl is reached, if we 
+                        * find one, then it will terminate the range of pages being
+                        * presented to 'cluster_io'
                         */
-                       ubc_upl_abort_range(upl, last_pg * PAGE_SIZE, (pages_in_upl - last_pg) * PAGE_SIZE,
-                                       UPL_ABORT_FREE_ON_EMPTY);
+                       for (last_pg = start_pg; last_pg < pages_in_upl; last_pg++) {
+                               if (!upl_page_present(pl, last_pg))
+                                       break;
+                       }
+
+                       if (last_pg > start_pg) {               
+                               /*
+                                * we found a range of pages that must be filled
+                                * if the last page in this range is the last page of the file
+                                * we may have to clip the size of it to keep from reading past
+                                * the end of the last physical block associated with the file
+                                */
+                               upl_offset = start_pg * PAGE_SIZE;
+                               io_size    = (last_pg - start_pg) * PAGE_SIZE;
+
+                               if ((upl_f_offset + upl_offset + io_size) > filesize)
+                                       io_size = filesize - (upl_f_offset + upl_offset);
+
+                               /*
+                                * issue an asynchronous read to cluster_io
+                                */
+                               retval = cluster_io(vp, upl, upl_offset, upl_f_offset + upl_offset, io_size, devblocksize,
+                                                   CL_ASYNC | CL_READ | CL_COMMIT | CL_AGE, (struct buf *)0);
 
-                       KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 63)) | DBG_FUNC_NONE,
-                                    upl, last_pg * PAGE_SIZE,
-                                    (pages_in_upl - last_pg) * PAGE_SIZE, 0, 0);
+                               issued_io = 1;
+                       }
                }
-               io_size = (last_pg * PAGE_SIZE) - start_offset;
+               if (issued_io == 0)
+                       ubc_upl_abort(upl, 0);
+
+               io_size = upl_size - start_offset;
                
                if (io_size > resid)
                        io_size = resid;
                f_offset += io_size;
                resid    -= io_size;
        }
+
        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 60)) | DBG_FUNC_END,
                     (int)f_offset, resid, retval, 0, 0);
 
@@ -2903,8 +2952,172 @@ advisory_read(vp, filesize, f_offset, resid, devblocksize)
 }
 
 
+int
 cluster_push(vp)
         struct vnode *vp;
+{
+        int  retval;
+
+       if (!UBCINFOEXISTS(vp) || vp->v_clen == 0) {
+               vp->v_flag &= ~VHASDIRTY;
+               return(0);
+       }
+
+       KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 53)) | DBG_FUNC_START,
+                    vp->v_flag & VHASDIRTY, vp->v_clen, 0, 0, 0);
+
+       if (vp->v_flag & VHASDIRTY) {
+               daddr_t start_pg;
+               daddr_t last_pg;
+               daddr_t end_pg;
+
+               start_pg = vp->v_cstart;
+               end_pg   = vp->v_lastw;
+
+               vp->v_flag &= ~VHASDIRTY;
+               vp->v_clen = 0;
+
+               while (start_pg < end_pg) {
+                       last_pg = start_pg + MAX_UPL_TRANSFER;
+
+                       if (last_pg > end_pg)
+                               last_pg = end_pg;
+
+                       cluster_push_x(vp, ubc_getsize(vp), start_pg, last_pg, 0);
+
+                       start_pg = last_pg;
+               }
+               return (1);
+       }
+       retval = cluster_try_push(vp, ubc_getsize(vp), 0, 1);
+
+       KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 53)) | DBG_FUNC_END,
+                    vp->v_flag & VHASDIRTY, vp->v_clen, retval, 0, 0);
+
+       return (retval);
+}
+
+
+static int
+cluster_try_push(vp, EOF, can_delay, push_all)
+        struct vnode *vp;
+       off_t  EOF;
+       int    can_delay;
+       int    push_all;
+{
+        int cl_index;
+       int cl_index1;
+       int min_index;
+        int cl_len;
+       int cl_total;
+       int cl_pushed;
+       struct v_cluster l_clusters[MAX_CLUSTERS];
+
+       /*
+        * make a local 'sorted' copy of the clusters
+        * and clear vp->v_clen so that new clusters can
+        * be developed
+        */
+       for (cl_index = 0; cl_index < vp->v_clen; cl_index++) {
+               for (min_index = -1, cl_index1 = 0; cl_index1 < vp->v_clen; cl_index1++) {
+                       if (vp->v_clusters[cl_index1].start_pg == vp->v_clusters[cl_index1].last_pg)
+                               continue;
+                       if (min_index == -1)
+                               min_index = cl_index1;
+                       else if (vp->v_clusters[cl_index1].start_pg < vp->v_clusters[min_index].start_pg)
+                               min_index = cl_index1;
+               }
+               if (min_index == -1)
+                       break;
+               l_clusters[cl_index].start_pg = vp->v_clusters[min_index].start_pg;
+               l_clusters[cl_index].last_pg  = vp->v_clusters[min_index].last_pg;
+
+               vp->v_clusters[min_index].start_pg = vp->v_clusters[min_index].last_pg;
+       }
+       cl_len     = cl_index;
+       vp->v_clen = 0;
+
+       for (cl_pushed = 0, cl_index = 0; cl_index < cl_len; cl_index++) {
+               /*
+                * try to push each cluster in turn...  cluster_push_x may not
+                * push the cluster if can_delay is TRUE and the cluster doesn't
+                * meet the critera for an immediate push
+                */
+               if (cluster_push_x(vp, EOF, l_clusters[cl_index].start_pg, l_clusters[cl_index].last_pg, can_delay)) {
+                       l_clusters[cl_index].start_pg = 0;
+                       l_clusters[cl_index].last_pg  = 0;
+
+                       cl_pushed++;
+
+                       if (push_all == 0)
+                               break;
+               }
+       }
+       if (cl_len > cl_pushed) {
+              /*
+               * we didn't push all of the clusters, so
+               * lets try to merge them back in to the vnode
+               */
+               if ((MAX_CLUSTERS - vp->v_clen) < (cl_len - cl_pushed)) {
+                       /*
+                        * we picked up some new clusters while we were trying to
+                        * push the old ones (I don't think this can happen because
+                        * I'm holding the lock, but just in case)... the sum of the
+                        * leftovers plus the new cluster count exceeds our ability
+                        * to represent them, so fall back to the VHASDIRTY mechanism
+                        */
+                       for (cl_index = 0; cl_index < cl_len; cl_index++) {
+                               if (l_clusters[cl_index].start_pg == l_clusters[cl_index].last_pg)
+                                       continue;
+
+                               if (l_clusters[cl_index].start_pg < vp->v_cstart)
+                                       vp->v_cstart = l_clusters[cl_index].start_pg;
+                               if (l_clusters[cl_index].last_pg > vp->v_lastw)
+                                       vp->v_lastw = l_clusters[cl_index].last_pg;
+                       }
+                       vp->v_flag |= VHASDIRTY;
+               } else {
+                       /*
+                        * we've got room to merge the leftovers back in
+                        * just append them starting at the next 'hole'
+                        * represented by vp->v_clen
+                        */
+                       for (cl_index = 0, cl_index1 = vp->v_clen; cl_index < cl_len; cl_index++) {
+                               if (l_clusters[cl_index].start_pg == l_clusters[cl_index].last_pg)
+                                       continue;
+
+                               vp->v_clusters[cl_index1].start_pg = l_clusters[cl_index].start_pg;
+                               vp->v_clusters[cl_index1].last_pg  = l_clusters[cl_index].last_pg;
+
+                               if (cl_index1 == 0) {
+                                       vp->v_cstart = l_clusters[cl_index].start_pg;
+                                       vp->v_lastw  = l_clusters[cl_index].last_pg;
+                               } else {
+                                       if (l_clusters[cl_index].start_pg < vp->v_cstart)
+                                               vp->v_cstart = l_clusters[cl_index].start_pg;
+                                       if (l_clusters[cl_index].last_pg > vp->v_lastw)
+                                               vp->v_lastw = l_clusters[cl_index].last_pg;
+                               }
+                               cl_index1++;
+                       }
+                       /*
+                        * update the cluster count
+                        */
+                       vp->v_clen = cl_index1;
+               }
+       }
+       return(MAX_CLUSTERS - vp->v_clen);
+}
+
+
+
+static int
+cluster_push_x(vp, EOF, first, last, can_delay)
+        struct vnode *vp;
+       off_t  EOF;
+       daddr_t first;
+       daddr_t last;
+       int    can_delay;
 {
        upl_page_info_t *pl;
        upl_t            upl;
@@ -2920,28 +3133,62 @@ cluster_push(vp)
        kern_return_t    kret;
 
 
-       if (!UBCINFOEXISTS(vp))
-               return(0);
+       KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 51)) | DBG_FUNC_START,
+                    vp->v_clen, first, last, EOF, 0);
+
+       if ((pages_in_upl = last - first) == 0) {
+               KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 51)) | DBG_FUNC_END, 1, 0, 0, 0, 0);
 
-        if (vp->v_clen == 0 || (pages_in_upl = vp->v_lastw - vp->v_cstart) == 0)
-               return (0);
+               return (1);
+       }
        upl_size = pages_in_upl * PAGE_SIZE;
-       upl_f_offset = ((off_t)vp->v_cstart) * PAGE_SIZE_64;
-       size = vp->v_ciosiz;
-       vp->v_clen = 0;
+       upl_f_offset = ((off_t)first) * PAGE_SIZE_64;
 
-       if (size > upl_size || (upl_size - size) > PAGE_SIZE)
-               panic("cluster_push: v_ciosiz doesn't match size of cluster\n");
+       if (upl_f_offset + upl_size >= EOF) {
+
+               if (upl_f_offset >= EOF) {
+                       /*
+                        * must have truncated the file and missed 
+                        * clearing a dangling cluster (i.e. it's completely
+                        * beyond the new EOF
+                        */
+                       KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 51)) | DBG_FUNC_END, 1, 1, 0, 0, 0);
+
+                       return(1);
+               }
+               size = EOF - upl_f_offset;
 
+               upl_size = (size + (PAGE_SIZE - 1) ) & ~(PAGE_SIZE - 1);
+               pages_in_upl = upl_size / PAGE_SIZE;
+       } else {
+               if (can_delay && (pages_in_upl < (MAX_UPL_TRANSFER - (MAX_UPL_TRANSFER / 2))))
+                       return(0);
+               size = upl_size;
+       }
        kret = ubc_create_upl(vp, 
                                upl_f_offset,
                                upl_size,
                                &upl,
-                                       &pl,
-                                       UPL_FLAGS_NONE);
+                               &pl,
+                               UPL_RET_ONLY_DIRTY);
        if (kret != KERN_SUCCESS)
                panic("cluster_push: failed to get pagelist");
 
+       if (can_delay) {
+               int  num_of_dirty;
+       
+               for (num_of_dirty = 0, start_pg = 0; start_pg < pages_in_upl; start_pg++) {
+                       if (upl_valid_page(pl, start_pg) && upl_dirty_page(pl, start_pg))
+                               num_of_dirty++;
+               }
+               if (num_of_dirty < pages_in_upl / 2) {
+                       ubc_upl_abort_range(upl, 0, upl_size, UPL_ABORT_FREE_ON_EMPTY);
+
+                       KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 51)) | DBG_FUNC_END, 0, 2, num_of_dirty, (pages_in_upl / 2), 0);
+
+                       return(0);
+               }
+       }
        last_pg = 0;
 
        while (size) {
@@ -2978,9 +3225,11 @@ cluster_push(vp)
                        vp->v_flag |= VTHROTTLED;
                        tsleep((caddr_t)&vp->v_numoutput, PRIBIO + 1, "cluster_push", 0);
                }
-               cluster_io(vp, upl, upl_offset, upl_f_offset + upl_offset, io_size, io_flags, (struct buf *)0);
+               cluster_io(vp, upl, upl_offset, upl_f_offset + upl_offset, io_size, vp->v_ciosiz, io_flags, (struct buf *)0);
 
                size -= io_size;
        }
+       KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 51)) | DBG_FUNC_END, 1, 3, 0, 0, 0);
+
        return(1);
 }