Add support for reading directly from file to userland buffer when the

O_DIRECT descriptor status flag is set and both offset and length is a
multiple of the physical media sector size.

2 files changed, 511 insertions, 0 deletions

diff --git a/sys/ufs/ffs/ffs_rawread.c b/sys/ufs/ffs/ffs_rawread.c
new file mode 100644
index 0000000..1fc66e6
--- /dev/null
+++ b/sys/ufs/ffs/ffs_rawread.c
@@ -0,0 +1,498 @@
+/*-
+ * Copyright (c) 2000-2003 Tor Egge
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/fcntl.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <sys/proc.h>
+#include <sys/mount.h>
+#include <sys/namei.h>
+#include <sys/vnode.h>
+#include <sys/conf.h>
+#include <sys/filio.h>
+#include <sys/ttycom.h>
+#include <sys/bio.h>
+#include <sys/buf.h>
+#include <ufs/ufs/quota.h>
+#include <ufs/ufs/inode.h>
+#include <ufs/ffs/fs.h>
+
+#include <machine/limits.h>
+#include <vm/vm.h>
+#include <vm/vm_extern.h>
+#include <vm/vm_object.h>
+#include <sys/kernel.h>
+#include <sys/sysctl.h>
+
+static int ffs_rawread_readahead(struct vnode *vp,
+				 caddr_t udata,
+				 off_t offset,
+				 size_t len,
+				 struct thread *td,
+				 struct buf *bp,
+				 caddr_t sa);
+static int ffs_rawread_main(struct vnode *vp,
+			    struct uio *uio);
+
+static int ffs_rawread_sync(struct vnode *vp, struct thread *td);
+
+int ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone);
+
+void ffs_rawread_setup(void);
+
+static void ffs_rawreadwakeup(struct buf *bp);
+
+
+SYSCTL_DECL(_vfs_ffs);
+
+static int ffsrawbufcnt = 4;
+SYSCTL_INT(_vfs_ffs, OID_AUTO, ffsrawbufcnt, CTLFLAG_RD, &ffsrawbufcnt, 0,
+	   "Buffers available for raw reads");
+
+static int allowrawread = 1;
+SYSCTL_INT(_vfs_ffs, OID_AUTO, allowrawread, CTLFLAG_RW, &allowrawread, 0,
+	   "Flag to enable raw reads");
+
+static int rawreadahead = 1;
+SYSCTL_INT(_vfs_ffs, OID_AUTO, rawreadahead, CTLFLAG_RW, &rawreadahead, 0,
+	   "Flag to enable readahead for long raw reads");
+
+
+void
+ffs_rawread_setup(void)
+{
+	ffsrawbufcnt = (nswbuf > 100 ) ? (nswbuf - (nswbuf >> 4)) : nswbuf - 8;
+}
+
+
+static int
+ffs_rawread_sync(struct vnode *vp, struct thread *td)
+{
+	int spl;
+	int error;
+	int upgraded;
+
+	GIANT_REQUIRED;
+	/* Check for dirty mmap, pending writes and dirty buffers */
+	spl = splbio();
+	VI_LOCK(vp);
+	if (vp->v_numoutput > 0 ||
+	    !TAILQ_EMPTY(&vp->v_dirtyblkhd) ||
+	    (vp->v_iflag & VI_OBJDIRTY) != 0) {
+		splx(spl);
+		VI_UNLOCK(vp);
+		
+		if (VOP_ISLOCKED(vp, td) != LK_EXCLUSIVE) {
+			upgraded = 1;
+			/* Upgrade to exclusive lock, this might block */
+			VOP_LOCK(vp, LK_UPGRADE | LK_NOPAUSE, td);
+		} else
+			upgraded = 0;
+			
+		
+		/* Attempt to msync mmap() regions to clean dirty mmap */ 
+		VI_LOCK(vp);
+		if ((vp->v_iflag & VI_OBJDIRTY) != 0) {
+			struct vm_object *obj;
+			VI_UNLOCK(vp);
+			if (VOP_GETVOBJECT(vp, &obj) == 0)
+				vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
+			VI_LOCK(vp);
+		}
+
+		/* Wait for pending writes to complete */
+		spl = splbio();
+		while (vp->v_numoutput) {
+			vp->v_iflag |= VI_BWAIT;
+			error = msleep((caddr_t)&vp->v_numoutput,
+				       VI_MTX(vp),
+				       PRIBIO + 1,
+				       "rawrdfls", 0);
+			if (error != 0) {
+				splx(spl);
+				VI_UNLOCK(vp);
+				if (upgraded != 0)
+					VOP_LOCK(vp, LK_DOWNGRADE, td);
+				return (error);
+			}
+		}
+		/* Flush dirty buffers */
+		if (!TAILQ_EMPTY(&vp->v_dirtyblkhd)) {
+			splx(spl);
+			VI_UNLOCK(vp);
+			if ((error = VOP_FSYNC(vp, NOCRED, MNT_WAIT, td)) != 0) {
+				if (upgraded != 0)
+					VOP_LOCK(vp, LK_DOWNGRADE, td);
+				return (error);
+			}
+			VI_LOCK(vp);
+			spl = splbio();
+			if (vp->v_numoutput > 0 ||
+			    !TAILQ_EMPTY(&vp->v_dirtyblkhd))
+				panic("ffs_rawread_sync: dirty bufs");
+		}
+		splx(spl);
+		VI_UNLOCK(vp);
+		if (upgraded != 0)
+			VOP_LOCK(vp, LK_DOWNGRADE, td);
+	} else {
+		splx(spl);
+		VI_UNLOCK(vp);
+	}
+	return 0;
+}
+
+
+static int
+ffs_rawread_readahead(struct vnode *vp,
+		      caddr_t udata,
+		      off_t offset,
+		      size_t len,
+		      struct thread *td,
+		      struct buf *bp,
+		      caddr_t sa)
+{
+	int error;
+	u_int iolen;
+	off_t blockno;
+	int blockoff;
+	int bsize;
+	struct vnode *dp;
+	int bforwards;
+	
+	GIANT_REQUIRED;
+	bsize = vp->v_mount->mnt_stat.f_iosize;
+	
+	iolen = ((vm_offset_t) udata) & PAGE_MASK;
+	bp->b_bcount = len;
+	if (bp->b_bcount + iolen > bp->b_kvasize) {
+		bp->b_bcount = bp->b_kvasize;
+		if (iolen != 0)
+			bp->b_bcount -= PAGE_SIZE;
+	}
+	bp->b_flags = B_PHYS;
+	bp->b_iocmd = BIO_READ;
+	bp->b_iodone = ffs_rawreadwakeup;
+	bp->b_data = udata;
+	bp->b_saveaddr = sa;
+	bp->b_offset = offset;
+	blockno = bp->b_offset / bsize;
+	blockoff = (bp->b_offset % bsize) / DEV_BSIZE;
+	if ((daddr_t) blockno != blockno) {
+		return EINVAL; /* blockno overflow */
+	}
+	
+	bp->b_lblkno = bp->b_blkno = blockno;
+	if (!useracc(bp->b_data, bp->b_bcount, VM_PROT_WRITE)) {
+		return EFAULT;
+	}
+	
+	error = VOP_BMAP(vp, bp->b_lblkno, &dp, &bp->b_blkno, &bforwards,
+			 NULL);
+	if (error != 0) {
+		return error;
+	}
+	if (bp->b_blkno == -1) {
+
+		/* Fill holes with NULs to preserve semantics */
+		
+		if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
+			bp->b_bcount = bsize - blockoff * DEV_BSIZE;
+		bp->b_bufsize = bp->b_bcount;
+		
+		if (vmapbuf(bp) < 0)
+			return EFAULT;
+		
+		if (ticks - PCPU_GET(switchticks) >= hogticks)
+			uio_yield();
+		bzero(bp->b_data, bp->b_bufsize);
+
+		/* Mark operation completed (similar to bufdone()) */
+
+		bp->b_resid = 0;
+		bp->b_flags |= B_DONE;
+		return 0;
+	}
+	
+	if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards))
+		bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE;
+	bp->b_bufsize = bp->b_bcount;
+	bp->b_blkno += blockoff;
+	bp->b_dev = dp->v_rdev;
+	
+	vmapbuf(bp);
+	if (vmapbuf < 0)
+		return EFAULT;
+	
+	if (dp->v_type == VCHR)
+		(void) VOP_SPECSTRATEGY(dp, bp);
+	else
+		(void) VOP_STRATEGY(dp, bp);
+	return 0;
+}
+
+
+static int
+ffs_rawread_main(struct vnode *vp,
+		 struct uio *uio)
+{
+	int error, nerror;
+	struct buf *bp, *nbp, *tbp;
+	caddr_t sa, nsa, tsa;
+	u_int iolen;
+	int spl;
+	caddr_t udata;
+	long resid;
+	off_t offset;
+	struct thread *td;
+	
+	GIANT_REQUIRED;
+	td = uio->uio_td ? uio->uio_td : curthread;
+	udata = uio->uio_iov->iov_base;
+	resid = uio->uio_resid;
+	offset = uio->uio_offset;
+
+	/*
+	 * keep the process from being swapped
+	 */
+	PHOLD(td->td_proc);
+	
+	error = 0;
+	nerror = 0;
+	
+	bp = NULL;
+	nbp = NULL;
+	sa = NULL;
+	nsa = NULL;
+	
+	while (resid > 0) {
+		
+		if (bp == NULL) { /* Setup first read */
+			/* XXX: Leave some bufs for swap */
+			bp = getpbuf(&ffsrawbufcnt);
+			sa = bp->b_data;
+			bp->b_vp = vp; 
+			bp->b_error = 0;
+			error = ffs_rawread_readahead(vp, udata, offset,
+						     resid, td, bp, sa);
+			if (error != 0)
+				break;
+			
+			if (resid > bp->b_bufsize) { /* Setup fist readahead */
+				/* XXX: Leave bufs for swap */
+				if (rawreadahead != 0) 
+					nbp = trypbuf(&ffsrawbufcnt);
+				else
+					nbp = NULL;
+				if (nbp != NULL) {
+					nsa = nbp->b_data;
+					nbp->b_vp = vp;
+					nbp->b_error = 0;
+					
+					nerror = ffs_rawread_readahead(vp, 
+								       udata +
+								       bp->b_bufsize,
+								       offset +
+								       bp->b_bufsize,
+								       resid -
+								       bp->b_bufsize,
+								       td,
+								       nbp,
+								       nsa);
+					if (nerror) {
+						relpbuf(nbp, &ffsrawbufcnt);
+						nbp = NULL;
+					}
+				}
+			}
+		}
+		
+		spl = splbio();
+		while ((bp->b_flags & B_DONE) == 0) {
+			tsleep((caddr_t)bp, PRIBIO, "rawrd", 0);
+		}
+		splx(spl);
+		
+		vunmapbuf(bp);
+		
+		iolen = bp->b_bcount - bp->b_resid;
+		if (iolen == 0 && (bp->b_ioflags & BIO_ERROR) == 0) {
+			nerror = 0;	/* Ignore possible beyond EOF error */
+			break; /* EOF */
+		}
+		
+		if ((bp->b_ioflags & BIO_ERROR) != 0) {
+			error = bp->b_error;
+			break;
+		}
+		resid -= iolen;
+		udata += iolen;
+		offset += iolen;
+		if (iolen < bp->b_bufsize) {
+			/* Incomplete read.  Try to read remaining part */
+			error = ffs_rawread_readahead(vp,
+						      udata,
+						      offset,
+						      bp->b_bufsize - iolen,
+						      td,
+						      bp,
+						      sa);
+			if (error != 0)
+				break;
+		} else if (nbp != NULL) { /* Complete read with readahead */
+			
+			tbp = bp;
+			bp = nbp;
+			nbp = tbp;
+			
+			tsa = sa;
+			sa = nsa;
+			nsa = tsa;
+			
+			if (resid <= bp->b_bufsize) { /* No more readaheads */
+				relpbuf(nbp, &ffsrawbufcnt);
+				nbp = NULL;
+			} else { /* Setup next readahead */
+				nerror = ffs_rawread_readahead(vp,
+							       udata +
+							       bp->b_bufsize,
+							       offset +
+							       bp->b_bufsize,
+							       resid -
+							       bp->b_bufsize,
+							       td,
+							       nbp,
+							       nsa);
+				if (nerror != 0) {
+					relpbuf(nbp, &ffsrawbufcnt);
+					nbp = NULL;
+				}
+			}
+		} else if (nerror != 0) {/* Deferred Readahead error */
+			break;		
+		}  else if (resid > 0) { /* More to read, no readahead */
+			error = ffs_rawread_readahead(vp, udata, offset,
+						      resid, td, bp, sa);
+			if (error != 0)
+				break;
+		}
+	}
+	
+	if (bp != NULL)
+		relpbuf(bp, &ffsrawbufcnt);
+	if (nbp != NULL) {			/* Run down readahead buffer */
+		spl = splbio();
+		while ((nbp->b_flags & B_DONE) == 0) {
+			tsleep((caddr_t)nbp, PRIBIO, "rawrd", 0);
+		}
+		splx(spl);
+		vunmapbuf(nbp);
+		relpbuf(nbp, &ffsrawbufcnt);
+	}
+	
+	if (error == 0)
+		error = nerror;
+	PRELE(td->td_proc);
+	uio->uio_iov->iov_base = udata;
+	uio->uio_resid = resid;
+	uio->uio_offset = offset;
+	return error;
+}
+
+
+int
+ffs_rawread(struct vnode *vp,
+	    struct uio *uio,
+	    int *workdone)
+{
+	if (allowrawread != 0 &&
+	    uio->uio_iovcnt == 1 && 
+	    uio->uio_segflg == UIO_USERSPACE &&
+	    uio->uio_resid == uio->uio_iov->iov_len &&
+	    (((uio->uio_td != NULL) ? uio->uio_td : curthread)->td_flags &
+	     TDF_DEADLKTREAT) == 0) {
+		int secsize;		/* Media sector size */
+		off_t filebytes;	/* Bytes left of file */
+		int blockbytes;		/* Bytes left of file in full blocks */
+		int partialbytes;	/* Bytes in last partial block */
+		int skipbytes;		/* Bytes not to read in ffs_rawread */
+		struct inode *ip;
+		int error;
+		
+
+		/* Only handle sector aligned reads */
+		ip = VTOI(vp);
+		secsize = ip->i_devvp->v_rdev->si_bsize_phys;
+		if ((uio->uio_offset & (secsize - 1)) == 0 &&
+		    (uio->uio_resid & (secsize - 1)) == 0) {
+			
+			/* Sync dirty pages and buffers if needed */
+			error = ffs_rawread_sync(vp,
+						 (uio->uio_td != NULL) ?
+						 uio->uio_td : curthread);
+			if (error != 0)
+				return error;
+			
+			/* Check for end of file */
+			if (ip->i_size > uio->uio_offset) {
+				filebytes = ip->i_size - uio->uio_offset;
+
+				/* No special eof handling needed ? */
+				if (uio->uio_resid <= filebytes) {
+					*workdone = 1;
+					return ffs_rawread_main(vp, uio);
+				}
+				
+				partialbytes = ((unsigned int) ip->i_size) %
+					ip->i_fs->fs_bsize;
+				blockbytes = (int) filebytes - partialbytes;
+				if (blockbytes > 0) {
+					skipbytes = uio->uio_resid -
+						blockbytes;
+					uio->uio_resid = blockbytes;
+					error = ffs_rawread_main(vp, uio);
+					uio->uio_resid += skipbytes;
+					if (error != 0)
+						return error;
+					/* Read remaining part using buffer */
+				}
+			}
+		}
+	}
+	*workdone = 0;
+	return 0;
+}
+
+
+static void
+ffs_rawreadwakeup(struct buf *bp)
+{
+	wakeup((caddr_t) bp);
+}
diff --git a/sys/ufs/ffs/ffs_vnops.c b/sys/ufs/ffs/ffs_vnops.c
index 8aa3db4..8742a5b 100644
--- a/sys/ufs/ffs/ffs_vnops.c
+++ b/sys/ufs/ffs/ffs_vnops.c
@@ -76,7 +76,11 @@
 
 #include <ufs/ffs/fs.h>
 #include <ufs/ffs/ffs_extern.h>
+#include "opt_directio.h"
 
+#ifdef DIRECTIO
+extern int	ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone);
+#endif
 static int	ffs_fsync(struct vop_fsync_args *);
 static int	ffs_getpages(struct vop_getpages_args *);
 static int	ffs_read(struct vop_read_args *);
@@ -349,6 +353,15 @@ ffs_read(ap)
 #else
 		panic("ffs_read+IO_EXT");
 #endif
+#ifdef DIRECTIO
+	if ((ioflag & IO_DIRECT) != 0) {
+		int workdone;
+
+		error = ffs_rawread(vp, uio, &workdone);
+		if (error != 0 || workdone != 0)
+			return error;
+	}
+#endif
 
 	GIANT_REQUIRED;