ffs_rawread.c revision 112724 
1/*-
2 * Copyright (c) 2000-2003 Tor Egge
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/sys/ufs/ffs/ffs_rawread.c 112724 2003-03-27 20:48:34Z tegge $
27 */
28
29#include <sys/param.h>
30#include <sys/systm.h>
31#include <sys/fcntl.h>
32#include <sys/file.h>
33#include <sys/stat.h>
34#include <sys/proc.h>
35#include <sys/mount.h>
36#include <sys/namei.h>
37#include <sys/vnode.h>
38#include <sys/conf.h>
39#include <sys/filio.h>
40#include <sys/ttycom.h>
41#include <sys/bio.h>
42#include <sys/buf.h>
43#include <ufs/ufs/quota.h>
44#include <ufs/ufs/inode.h>
45#include <ufs/ffs/fs.h>
46
47#include <machine/limits.h>
48#include <vm/vm.h>
49#include <vm/vm_extern.h>
50#include <vm/vm_object.h>
51#include <sys/kernel.h>
52#include <sys/sysctl.h>
53
54static int ffs_rawread_readahead(struct vnode *vp,
55				 caddr_t udata,
56				 off_t offset,
57				 size_t len,
58				 struct thread *td,
59				 struct buf *bp,
60				 caddr_t sa);
61static int ffs_rawread_main(struct vnode *vp,
62			    struct uio *uio);
63
64static int ffs_rawread_sync(struct vnode *vp, struct thread *td);
65
66int ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone);
67
68void ffs_rawread_setup(void);
69
70static void ffs_rawreadwakeup(struct buf *bp);
71
72
73SYSCTL_DECL(_vfs_ffs);
74
75static int ffsrawbufcnt = 4;
76SYSCTL_INT(_vfs_ffs, OID_AUTO, ffsrawbufcnt, CTLFLAG_RD, &ffsrawbufcnt, 0,
77	   "Buffers available for raw reads");
78
79static int allowrawread = 1;
80SYSCTL_INT(_vfs_ffs, OID_AUTO, allowrawread, CTLFLAG_RW, &allowrawread, 0,
81	   "Flag to enable raw reads");
82
83static int rawreadahead = 1;
84SYSCTL_INT(_vfs_ffs, OID_AUTO, rawreadahead, CTLFLAG_RW, &rawreadahead, 0,
85	   "Flag to enable readahead for long raw reads");
86
87
88void
89ffs_rawread_setup(void)
90{
91	ffsrawbufcnt = (nswbuf > 100 ) ? (nswbuf - (nswbuf >> 4)) : nswbuf - 8;
92}
93
94
95static int
96ffs_rawread_sync(struct vnode *vp, struct thread *td)
97{
98	int spl;
99	int error;
100	int upgraded;
101
102	GIANT_REQUIRED;
103	/* Check for dirty mmap, pending writes and dirty buffers */
104	spl = splbio();
105	VI_LOCK(vp);
106	if (vp->v_numoutput > 0 ||
107	    !TAILQ_EMPTY(&vp->v_dirtyblkhd) ||
108	    (vp->v_iflag & VI_OBJDIRTY) != 0) {
109		splx(spl);
110		VI_UNLOCK(vp);
111
112		if (VOP_ISLOCKED(vp, td) != LK_EXCLUSIVE) {
113			upgraded = 1;
114			/* Upgrade to exclusive lock, this might block */
115			VOP_LOCK(vp, LK_UPGRADE | LK_NOPAUSE, td);
116		} else
117			upgraded = 0;
118
119
120		/* Attempt to msync mmap() regions to clean dirty mmap */
121		VI_LOCK(vp);
122		if ((vp->v_iflag & VI_OBJDIRTY) != 0) {
123			struct vm_object *obj;
124			VI_UNLOCK(vp);
125			if (VOP_GETVOBJECT(vp, &obj) == 0)
126				vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
127			VI_LOCK(vp);
128		}
129
130		/* Wait for pending writes to complete */
131		spl = splbio();
132		while (vp->v_numoutput) {
133			vp->v_iflag |= VI_BWAIT;
134			error = msleep((caddr_t)&vp->v_numoutput,
135				       VI_MTX(vp),
136				       PRIBIO + 1,
137				       "rawrdfls", 0);
138			if (error != 0) {
139				splx(spl);
140				VI_UNLOCK(vp);
141				if (upgraded != 0)
142					VOP_LOCK(vp, LK_DOWNGRADE, td);
143				return (error);
144			}
145		}
146		/* Flush dirty buffers */
147		if (!TAILQ_EMPTY(&vp->v_dirtyblkhd)) {
148			splx(spl);
149			VI_UNLOCK(vp);
150			if ((error = VOP_FSYNC(vp, NOCRED, MNT_WAIT, td)) != 0) {
151				if (upgraded != 0)
152					VOP_LOCK(vp, LK_DOWNGRADE, td);
153				return (error);
154			}
155			VI_LOCK(vp);
156			spl = splbio();
157			if (vp->v_numoutput > 0 ||
158			    !TAILQ_EMPTY(&vp->v_dirtyblkhd))
159				panic("ffs_rawread_sync: dirty bufs");
160		}
161		splx(spl);
162		VI_UNLOCK(vp);
163		if (upgraded != 0)
164			VOP_LOCK(vp, LK_DOWNGRADE, td);
165	} else {
166		splx(spl);
167		VI_UNLOCK(vp);
168	}
169	return 0;
170}
171
172
173static int
174ffs_rawread_readahead(struct vnode *vp,
175		      caddr_t udata,
176		      off_t offset,
177		      size_t len,
178		      struct thread *td,
179		      struct buf *bp,
180		      caddr_t sa)
181{
182	int error;
183	u_int iolen;
184	off_t blockno;
185	int blockoff;
186	int bsize;
187	struct vnode *dp;
188	int bforwards;
189
190	GIANT_REQUIRED;
191	bsize = vp->v_mount->mnt_stat.f_iosize;
192
193	iolen = ((vm_offset_t) udata) & PAGE_MASK;
194	bp->b_bcount = len;
195	if (bp->b_bcount + iolen > bp->b_kvasize) {
196		bp->b_bcount = bp->b_kvasize;
197		if (iolen != 0)
198			bp->b_bcount -= PAGE_SIZE;
199	}
200	bp->b_flags = B_PHYS;
201	bp->b_iocmd = BIO_READ;
202	bp->b_iodone = ffs_rawreadwakeup;
203	bp->b_data = udata;
204	bp->b_saveaddr = sa;
205	bp->b_offset = offset;
206	blockno = bp->b_offset / bsize;
207	blockoff = (bp->b_offset % bsize) / DEV_BSIZE;
208	if ((daddr_t) blockno != blockno) {
209		return EINVAL; /* blockno overflow */
210	}
211
212	bp->b_lblkno = bp->b_blkno = blockno;
213	if (!useracc(bp->b_data, bp->b_bcount, VM_PROT_WRITE)) {
214		return EFAULT;
215	}
216
217	error = VOP_BMAP(vp, bp->b_lblkno, &dp, &bp->b_blkno, &bforwards,
218			 NULL);
219	if (error != 0) {
220		return error;
221	}
222	if (bp->b_blkno == -1) {
223
224		/* Fill holes with NULs to preserve semantics */
225
226		if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
227			bp->b_bcount = bsize - blockoff * DEV_BSIZE;
228		bp->b_bufsize = bp->b_bcount;
229
230		if (vmapbuf(bp) < 0)
231			return EFAULT;
232
233		if (ticks - PCPU_GET(switchticks) >= hogticks)
234			uio_yield();
235		bzero(bp->b_data, bp->b_bufsize);
236
237		/* Mark operation completed (similar to bufdone()) */
238
239		bp->b_resid = 0;
240		bp->b_flags |= B_DONE;
241		return 0;
242	}
243
244	if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards))
245		bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE;
246	bp->b_bufsize = bp->b_bcount;
247	bp->b_blkno += blockoff;
248	bp->b_dev = dp->v_rdev;
249
250	if (vmapbuf(bp) < 0)
251		return EFAULT;
252
253	if (dp->v_type == VCHR)
254		(void) VOP_SPECSTRATEGY(dp, bp);
255	else
256		(void) VOP_STRATEGY(dp, bp);
257	return 0;
258}
259
260
261static int
262ffs_rawread_main(struct vnode *vp,
263		 struct uio *uio)
264{
265	int error, nerror;
266	struct buf *bp, *nbp, *tbp;
267	caddr_t sa, nsa, tsa;
268	u_int iolen;
269	int spl;
270	caddr_t udata;
271	long resid;
272	off_t offset;
273	struct thread *td;
274
275	GIANT_REQUIRED;
276	td = uio->uio_td ? uio->uio_td : curthread;
277	udata = uio->uio_iov->iov_base;
278	resid = uio->uio_resid;
279	offset = uio->uio_offset;
280
281	/*
282	 * keep the process from being swapped
283	 */
284	PHOLD(td->td_proc);
285
286	error = 0;
287	nerror = 0;
288
289	bp = NULL;
290	nbp = NULL;
291	sa = NULL;
292	nsa = NULL;
293
294	while (resid > 0) {
295
296		if (bp == NULL) { /* Setup first read */
297			/* XXX: Leave some bufs for swap */
298			bp = getpbuf(&ffsrawbufcnt);
299			sa = bp->b_data;
300			bp->b_vp = vp;
301			bp->b_error = 0;
302			error = ffs_rawread_readahead(vp, udata, offset,
303						     resid, td, bp, sa);
304			if (error != 0)
305				break;
306
307			if (resid > bp->b_bufsize) { /* Setup fist readahead */
308				/* XXX: Leave bufs for swap */
309				if (rawreadahead != 0)
310					nbp = trypbuf(&ffsrawbufcnt);
311				else
312					nbp = NULL;
313				if (nbp != NULL) {
314					nsa = nbp->b_data;
315					nbp->b_vp = vp;
316					nbp->b_error = 0;
317
318					nerror = ffs_rawread_readahead(vp,
319								       udata +
320								       bp->b_bufsize,
321								       offset +
322								       bp->b_bufsize,
323								       resid -
324								       bp->b_bufsize,
325								       td,
326								       nbp,
327								       nsa);
328					if (nerror) {
329						relpbuf(nbp, &ffsrawbufcnt);
330						nbp = NULL;
331					}
332				}
333			}
334		}
335
336		spl = splbio();
337		bwait(bp, PRIBIO, "rawrd");
338		splx(spl);
339
340		vunmapbuf(bp);
341
342		iolen = bp->b_bcount - bp->b_resid;
343		if (iolen == 0 && (bp->b_ioflags & BIO_ERROR) == 0) {
344			nerror = 0;	/* Ignore possible beyond EOF error */
345			break; /* EOF */
346		}
347
348		if ((bp->b_ioflags & BIO_ERROR) != 0) {
349			error = bp->b_error;
350			break;
351		}
352		resid -= iolen;
353		udata += iolen;
354		offset += iolen;
355		if (iolen < bp->b_bufsize) {
356			/* Incomplete read.  Try to read remaining part */
357			error = ffs_rawread_readahead(vp,
358						      udata,
359						      offset,
360						      bp->b_bufsize - iolen,
361						      td,
362						      bp,
363						      sa);
364			if (error != 0)
365				break;
366		} else if (nbp != NULL) { /* Complete read with readahead */
367
368			tbp = bp;
369			bp = nbp;
370			nbp = tbp;
371
372			tsa = sa;
373			sa = nsa;
374			nsa = tsa;
375
376			if (resid <= bp->b_bufsize) { /* No more readaheads */
377				relpbuf(nbp, &ffsrawbufcnt);
378				nbp = NULL;
379			} else { /* Setup next readahead */
380				nerror = ffs_rawread_readahead(vp,
381							       udata +
382							       bp->b_bufsize,
383							       offset +
384							       bp->b_bufsize,
385							       resid -
386							       bp->b_bufsize,
387							       td,
388							       nbp,
389							       nsa);
390				if (nerror != 0) {
391					relpbuf(nbp, &ffsrawbufcnt);
392					nbp = NULL;
393				}
394			}
395		} else if (nerror != 0) {/* Deferred Readahead error */
396			break;
397		}  else if (resid > 0) { /* More to read, no readahead */
398			error = ffs_rawread_readahead(vp, udata, offset,
399						      resid, td, bp, sa);
400			if (error != 0)
401				break;
402		}
403	}
404
405	if (bp != NULL)
406		relpbuf(bp, &ffsrawbufcnt);
407	if (nbp != NULL) {			/* Run down readahead buffer */
408		spl = splbio();
409		bwait(nbp, PRIBIO, "rawrd");
410		splx(spl);
411		vunmapbuf(nbp);
412		relpbuf(nbp, &ffsrawbufcnt);
413	}
414
415	if (error == 0)
416		error = nerror;
417	PRELE(td->td_proc);
418	uio->uio_iov->iov_base = udata;
419	uio->uio_resid = resid;
420	uio->uio_offset = offset;
421	return error;
422}
423
424
425int
426ffs_rawread(struct vnode *vp,
427	    struct uio *uio,
428	    int *workdone)
429{
430	if (allowrawread != 0 &&
431	    uio->uio_iovcnt == 1 &&
432	    uio->uio_segflg == UIO_USERSPACE &&
433	    uio->uio_resid == uio->uio_iov->iov_len &&
434	    (((uio->uio_td != NULL) ? uio->uio_td : curthread)->td_flags &
435	     TDF_DEADLKTREAT) == 0) {
436		int secsize;		/* Media sector size */
437		off_t filebytes;	/* Bytes left of file */
438		int blockbytes;		/* Bytes left of file in full blocks */
439		int partialbytes;	/* Bytes in last partial block */
440		int skipbytes;		/* Bytes not to read in ffs_rawread */
441		struct inode *ip;
442		int error;
443
444
445		/* Only handle sector aligned reads */
446		ip = VTOI(vp);
447		secsize = ip->i_devvp->v_rdev->si_bsize_phys;
448		if ((uio->uio_offset & (secsize - 1)) == 0 &&
449		    (uio->uio_resid & (secsize - 1)) == 0) {
450
451			/* Sync dirty pages and buffers if needed */
452			error = ffs_rawread_sync(vp,
453						 (uio->uio_td != NULL) ?
454						 uio->uio_td : curthread);
455			if (error != 0)
456				return error;
457
458			/* Check for end of file */
459			if (ip->i_size > uio->uio_offset) {
460				filebytes = ip->i_size - uio->uio_offset;
461
462				/* No special eof handling needed ? */
463				if (uio->uio_resid <= filebytes) {
464					*workdone = 1;
465					return ffs_rawread_main(vp, uio);
466				}
467
468				partialbytes = ((unsigned int) ip->i_size) %
469					ip->i_fs->fs_bsize;
470				blockbytes = (int) filebytes - partialbytes;
471				if (blockbytes > 0) {
472					skipbytes = uio->uio_resid -
473						blockbytes;
474					uio->uio_resid = blockbytes;
475					error = ffs_rawread_main(vp, uio);
476					uio->uio_resid += skipbytes;
477					if (error != 0)
478						return error;
479					/* Read remaining part using buffer */
480				}
481			}
482		}
483	}
484	*workdone = 0;
485	return 0;
486}
487
488
489static void
490ffs_rawreadwakeup(struct buf *bp)
491{
492	bdone(bp);
493}
494