ffs_rawread.c revision 200770 
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
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/sys/ufs/ffs/ffs_rawread.c 200770 2009-12-21 12:29:38Z kib $");
29
30#include <sys/param.h>
31#include <sys/systm.h>
32#include <sys/fcntl.h>
33#include <sys/file.h>
34#include <sys/stat.h>
35#include <sys/proc.h>
36#include <sys/limits.h>
37#include <sys/mount.h>
38#include <sys/namei.h>
39#include <sys/vnode.h>
40#include <sys/conf.h>
41#include <sys/filio.h>
42#include <sys/ttycom.h>
43#include <sys/bio.h>
44#include <sys/buf.h>
45#include <ufs/ufs/extattr.h>
46#include <ufs/ufs/quota.h>
47#include <ufs/ufs/inode.h>
48#include <ufs/ufs/ufsmount.h>
49#include <ufs/ufs/ufs_extern.h>
50#include <ufs/ffs/fs.h>
51#include <ufs/ffs/ffs_extern.h>
52
53#include <vm/vm.h>
54#include <vm/vm_extern.h>
55#include <vm/vm_object.h>
56#include <sys/kernel.h>
57#include <sys/sysctl.h>
58
59static int ffs_rawread_readahead(struct vnode *vp,
60				 caddr_t udata,
61				 off_t offset,
62				 size_t len,
63				 struct thread *td,
64				 struct buf *bp,
65				 caddr_t sa);
66static int ffs_rawread_main(struct vnode *vp,
67			    struct uio *uio);
68
69static int ffs_rawread_sync(struct vnode *vp);
70
71int ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone);
72
73void ffs_rawread_setup(void);
74
75SYSCTL_DECL(_vfs_ffs);
76
77static int ffsrawbufcnt = 4;
78SYSCTL_INT(_vfs_ffs, OID_AUTO, ffsrawbufcnt, CTLFLAG_RD, &ffsrawbufcnt, 0,
79	   "Buffers available for raw reads");
80
81static int allowrawread = 1;
82SYSCTL_INT(_vfs_ffs, OID_AUTO, allowrawread, CTLFLAG_RW, &allowrawread, 0,
83	   "Flag to enable raw reads");
84
85static int rawreadahead = 1;
86SYSCTL_INT(_vfs_ffs, OID_AUTO, rawreadahead, CTLFLAG_RW, &rawreadahead, 0,
87	   "Flag to enable readahead for long raw reads");
88
89
90void
91ffs_rawread_setup(void)
92{
93	ffsrawbufcnt = (nswbuf > 100 ) ? (nswbuf - (nswbuf >> 4)) : nswbuf - 8;
94}
95
96
97static int
98ffs_rawread_sync(struct vnode *vp)
99{
100	int error;
101	int upgraded;
102	struct bufobj *bo;
103	struct mount *mp;
104	vm_object_t obj;
105
106	/* Check for dirty mmap, pending writes and dirty buffers */
107	bo = &vp->v_bufobj;
108	BO_LOCK(bo);
109	VI_LOCK(vp);
110	if (bo->bo_numoutput > 0 ||
111	    bo->bo_dirty.bv_cnt > 0 ||
112	    ((obj = vp->v_object) != NULL &&
113	     (obj->flags & OBJ_MIGHTBEDIRTY) != 0)) {
114		VI_UNLOCK(vp);
115		BO_UNLOCK(bo);
116
117		if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
118			if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE)
119				upgraded = 1;
120			else
121				upgraded = 0;
122			VOP_UNLOCK(vp, 0);
123			(void) vn_start_write(vp, &mp, V_WAIT);
124			VOP_LOCK(vp, LK_EXCLUSIVE);
125		} else if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE) {
126			upgraded = 1;
127			/* Upgrade to exclusive lock, this might block */
128			VOP_LOCK(vp, LK_UPGRADE);
129		} else
130			upgraded = 0;
131
132
133		VI_LOCK(vp);
134		/* Check if vnode was reclaimed while unlocked. */
135		if ((vp->v_iflag & VI_DOOMED) != 0) {
136			VI_UNLOCK(vp);
137			if (upgraded != 0)
138				VOP_LOCK(vp, LK_DOWNGRADE);
139			vn_finished_write(mp);
140			return (EIO);
141		}
142		/* Attempt to msync mmap() regions to clean dirty mmap */
143		if ((obj = vp->v_object) != NULL &&
144		    (obj->flags & OBJ_MIGHTBEDIRTY) != 0) {
145			VI_UNLOCK(vp);
146			VM_OBJECT_LOCK(obj);
147			vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
148			VM_OBJECT_UNLOCK(obj);
149		} else
150			VI_UNLOCK(vp);
151
152		/* Wait for pending writes to complete */
153		BO_LOCK(bo);
154		error = bufobj_wwait(&vp->v_bufobj, 0, 0);
155		if (error != 0) {
156			/* XXX: can't happen with a zero timeout ??? */
157			BO_UNLOCK(bo);
158			if (upgraded != 0)
159				VOP_LOCK(vp, LK_DOWNGRADE);
160			vn_finished_write(mp);
161			return (error);
162		}
163		/* Flush dirty buffers */
164		if (bo->bo_dirty.bv_cnt > 0) {
165			BO_UNLOCK(bo);
166			if ((error = ffs_syncvnode(vp, MNT_WAIT)) != 0) {
167				if (upgraded != 0)
168					VOP_LOCK(vp, LK_DOWNGRADE);
169				vn_finished_write(mp);
170				return (error);
171			}
172			BO_LOCK(bo);
173			if (bo->bo_numoutput > 0 || bo->bo_dirty.bv_cnt > 0)
174				panic("ffs_rawread_sync: dirty bufs");
175		}
176		BO_UNLOCK(bo);
177		if (upgraded != 0)
178			VOP_LOCK(vp, LK_DOWNGRADE);
179		vn_finished_write(mp);
180	} else {
181		VI_UNLOCK(vp);
182		BO_UNLOCK(bo);
183	}
184	return 0;
185}
186
187
188static int
189ffs_rawread_readahead(struct vnode *vp,
190		      caddr_t udata,
191		      off_t offset,
192		      size_t len,
193		      struct thread *td,
194		      struct buf *bp,
195		      caddr_t sa)
196{
197	int error;
198	u_int iolen;
199	off_t blockno;
200	int blockoff;
201	int bsize;
202	struct vnode *dp;
203	int bforwards;
204	struct inode *ip;
205	ufs2_daddr_t blkno;
206
207	bsize = vp->v_mount->mnt_stat.f_iosize;
208
209	ip = VTOI(vp);
210	dp = ip->i_devvp;
211
212	iolen = ((vm_offset_t) udata) & PAGE_MASK;
213	bp->b_bcount = len;
214	if (bp->b_bcount + iolen > bp->b_kvasize) {
215		bp->b_bcount = bp->b_kvasize;
216		if (iolen != 0)
217			bp->b_bcount -= PAGE_SIZE;
218	}
219	bp->b_flags = 0;	/* XXX necessary ? */
220	bp->b_iocmd = BIO_READ;
221	bp->b_iodone = bdone;
222	bp->b_data = udata;
223	bp->b_saveaddr = sa;
224	blockno = offset / bsize;
225	blockoff = (offset % bsize) / DEV_BSIZE;
226	if ((daddr_t) blockno != blockno) {
227		return EINVAL; /* blockno overflow */
228	}
229
230	bp->b_lblkno = bp->b_blkno = blockno;
231
232	error = ufs_bmaparray(vp, bp->b_lblkno, &blkno, NULL, &bforwards, NULL);
233	if (error != 0)
234		return error;
235	if (blkno == -1) {
236
237		/* Fill holes with NULs to preserve semantics */
238
239		if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
240			bp->b_bcount = bsize - blockoff * DEV_BSIZE;
241		bp->b_bufsize = bp->b_bcount;
242
243		if (vmapbuf(bp) < 0)
244			return EFAULT;
245
246		if (ticks - PCPU_GET(switchticks) >= hogticks)
247			uio_yield();
248		bzero(bp->b_data, bp->b_bufsize);
249
250		/* Mark operation completed (similar to bufdone()) */
251
252		bp->b_resid = 0;
253		bp->b_flags |= B_DONE;
254		return 0;
255	}
256	bp->b_blkno = blkno + blockoff;
257	bp->b_offset = bp->b_iooffset = (blkno + blockoff) * DEV_BSIZE;
258
259	if (bp->b_bcount + blockoff * DEV_BSIZE > bsize * (1 + bforwards))
260		bp->b_bcount = bsize * (1 + bforwards) - blockoff * DEV_BSIZE;
261	bp->b_bufsize = bp->b_bcount;
262
263	if (vmapbuf(bp) < 0)
264		return EFAULT;
265
266	BO_STRATEGY(&dp->v_bufobj, bp);
267	return 0;
268}
269
270
271static int
272ffs_rawread_main(struct vnode *vp,
273		 struct uio *uio)
274{
275	int error, nerror;
276	struct buf *bp, *nbp, *tbp;
277	caddr_t sa, nsa, tsa;
278	u_int iolen;
279	int spl;
280	caddr_t udata;
281	long resid;
282	off_t offset;
283	struct thread *td;
284
285	td = uio->uio_td ? uio->uio_td : curthread;
286	udata = uio->uio_iov->iov_base;
287	resid = uio->uio_resid;
288	offset = uio->uio_offset;
289
290	/*
291	 * keep the process from being swapped
292	 */
293	PHOLD(td->td_proc);
294
295	error = 0;
296	nerror = 0;
297
298	bp = NULL;
299	nbp = NULL;
300	sa = NULL;
301	nsa = NULL;
302
303	while (resid > 0) {
304
305		if (bp == NULL) { /* Setup first read */
306			/* XXX: Leave some bufs for swap */
307			bp = getpbuf(&ffsrawbufcnt);
308			sa = bp->b_data;
309			pbgetvp(vp, bp);
310			error = ffs_rawread_readahead(vp, udata, offset,
311						     resid, td, bp, sa);
312			if (error != 0)
313				break;
314
315			if (resid > bp->b_bufsize) { /* Setup fist readahead */
316				/* XXX: Leave bufs for swap */
317				if (rawreadahead != 0)
318					nbp = trypbuf(&ffsrawbufcnt);
319				else
320					nbp = NULL;
321				if (nbp != NULL) {
322					nsa = nbp->b_data;
323					pbgetvp(vp, nbp);
324
325					nerror = ffs_rawread_readahead(vp,
326								       udata +
327								       bp->b_bufsize,
328								       offset +
329								       bp->b_bufsize,
330								       resid -
331								       bp->b_bufsize,
332								       td,
333								       nbp,
334								       nsa);
335					if (nerror) {
336						pbrelvp(nbp);
337						relpbuf(nbp, &ffsrawbufcnt);
338						nbp = NULL;
339					}
340				}
341			}
342		}
343
344		spl = splbio();
345		bwait(bp, PRIBIO, "rawrd");
346		splx(spl);
347
348		vunmapbuf(bp);
349
350		iolen = bp->b_bcount - bp->b_resid;
351		if (iolen == 0 && (bp->b_ioflags & BIO_ERROR) == 0) {
352			nerror = 0;	/* Ignore possible beyond EOF error */
353			break; /* EOF */
354		}
355
356		if ((bp->b_ioflags & BIO_ERROR) != 0) {
357			error = bp->b_error;
358			break;
359		}
360		resid -= iolen;
361		udata += iolen;
362		offset += iolen;
363		if (iolen < bp->b_bufsize) {
364			/* Incomplete read.  Try to read remaining part */
365			error = ffs_rawread_readahead(vp,
366						      udata,
367						      offset,
368						      bp->b_bufsize - iolen,
369						      td,
370						      bp,
371						      sa);
372			if (error != 0)
373				break;
374		} else if (nbp != NULL) { /* Complete read with readahead */
375
376			tbp = bp;
377			bp = nbp;
378			nbp = tbp;
379
380			tsa = sa;
381			sa = nsa;
382			nsa = tsa;
383
384			if (resid <= bp->b_bufsize) { /* No more readaheads */
385				pbrelvp(nbp);
386				relpbuf(nbp, &ffsrawbufcnt);
387				nbp = NULL;
388			} else { /* Setup next readahead */
389				nerror = ffs_rawread_readahead(vp,
390							       udata +
391							       bp->b_bufsize,
392							       offset +
393							       bp->b_bufsize,
394							       resid -
395							       bp->b_bufsize,
396							       td,
397							       nbp,
398							       nsa);
399				if (nerror != 0) {
400					pbrelvp(nbp);
401					relpbuf(nbp, &ffsrawbufcnt);
402					nbp = NULL;
403				}
404			}
405		} else if (nerror != 0) {/* Deferred Readahead error */
406			break;
407		}  else if (resid > 0) { /* More to read, no readahead */
408			error = ffs_rawread_readahead(vp, udata, offset,
409						      resid, td, bp, sa);
410			if (error != 0)
411				break;
412		}
413	}
414
415	if (bp != NULL) {
416		pbrelvp(bp);
417		relpbuf(bp, &ffsrawbufcnt);
418	}
419	if (nbp != NULL) {			/* Run down readahead buffer */
420		spl = splbio();
421		bwait(nbp, PRIBIO, "rawrd");
422		splx(spl);
423		vunmapbuf(nbp);
424		pbrelvp(nbp);
425		relpbuf(nbp, &ffsrawbufcnt);
426	}
427
428	if (error == 0)
429		error = nerror;
430	PRELE(td->td_proc);
431	uio->uio_iov->iov_base = udata;
432	uio->uio_resid = resid;
433	uio->uio_offset = offset;
434	return error;
435}
436
437
438int
439ffs_rawread(struct vnode *vp,
440	    struct uio *uio,
441	    int *workdone)
442{
443	if (allowrawread != 0 &&
444	    uio->uio_iovcnt == 1 &&
445	    uio->uio_segflg == UIO_USERSPACE &&
446	    uio->uio_resid == uio->uio_iov->iov_len &&
447	    (((uio->uio_td != NULL) ? uio->uio_td : curthread)->td_pflags &
448	     TDP_DEADLKTREAT) == 0) {
449		int secsize;		/* Media sector size */
450		off_t filebytes;	/* Bytes left of file */
451		int blockbytes;		/* Bytes left of file in full blocks */
452		int partialbytes;	/* Bytes in last partial block */
453		int skipbytes;		/* Bytes not to read in ffs_rawread */
454		struct inode *ip;
455		int error;
456
457
458		/* Only handle sector aligned reads */
459		ip = VTOI(vp);
460		secsize = ip->i_devvp->v_bufobj.bo_bsize;
461		if ((uio->uio_offset & (secsize - 1)) == 0 &&
462		    (uio->uio_resid & (secsize - 1)) == 0) {
463
464			/* Sync dirty pages and buffers if needed */
465			error = ffs_rawread_sync(vp);
466			if (error != 0)
467				return error;
468
469			/* Check for end of file */
470			if (ip->i_size > uio->uio_offset) {
471				filebytes = ip->i_size - uio->uio_offset;
472
473				/* No special eof handling needed ? */
474				if (uio->uio_resid <= filebytes) {
475					*workdone = 1;
476					return ffs_rawread_main(vp, uio);
477				}
478
479				partialbytes = ((unsigned int) ip->i_size) %
480					ip->i_fs->fs_bsize;
481				blockbytes = (int) filebytes - partialbytes;
482				if (blockbytes > 0) {
483					skipbytes = uio->uio_resid -
484						blockbytes;
485					uio->uio_resid = blockbytes;
486					error = ffs_rawread_main(vp, uio);
487					uio->uio_resid += skipbytes;
488					if (error != 0)
489						return error;
490					/* Read remaining part using buffer */
491				}
492			}
493		}
494	}
495	*workdone = 0;
496	return 0;
497}
498