xref: /freebsd/sys/ufs/ffs/ffs_rawread.c (revision 3f0164abf32b9b761e0a2cb4bdca3a8b84f156d4)
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("$FreeBSD$");
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 <sys/rwlock.h>
46 #include <ufs/ufs/extattr.h>
47 #include <ufs/ufs/quota.h>
48 #include <ufs/ufs/inode.h>
49 #include <ufs/ufs/ufsmount.h>
50 #include <ufs/ufs/ufs_extern.h>
51 #include <ufs/ffs/fs.h>
52 #include <ufs/ffs/ffs_extern.h>
53 
54 #include <vm/vm.h>
55 #include <vm/vm_extern.h>
56 #include <vm/vm_object.h>
57 #include <sys/kernel.h>
58 #include <sys/sysctl.h>
59 
60 static int ffs_rawread_readahead(struct vnode *vp,
61 				 caddr_t udata,
62 				 off_t offset,
63 				 size_t len,
64 				 struct thread *td,
65 				 struct buf *bp,
66 				 caddr_t sa);
67 static int ffs_rawread_main(struct vnode *vp,
68 			    struct uio *uio);
69 
70 static int ffs_rawread_sync(struct vnode *vp);
71 
72 int ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone);
73 
74 void ffs_rawread_setup(void);
75 
76 SYSCTL_DECL(_vfs_ffs);
77 
78 static int ffsrawbufcnt = 4;
79 SYSCTL_INT(_vfs_ffs, OID_AUTO, ffsrawbufcnt, CTLFLAG_RD, &ffsrawbufcnt, 0,
80 	   "Buffers available for raw reads");
81 
82 static int allowrawread = 1;
83 SYSCTL_INT(_vfs_ffs, OID_AUTO, allowrawread, CTLFLAG_RW, &allowrawread, 0,
84 	   "Flag to enable raw reads");
85 
86 static int rawreadahead = 1;
87 SYSCTL_INT(_vfs_ffs, OID_AUTO, rawreadahead, CTLFLAG_RW, &rawreadahead, 0,
88 	   "Flag to enable readahead for long raw reads");
89 
90 
91 void
92 ffs_rawread_setup(void)
93 {
94 	ffsrawbufcnt = (nswbuf > 100 ) ? (nswbuf - (nswbuf >> 4)) : nswbuf - 8;
95 }
96 
97 
98 static int
99 ffs_rawread_sync(struct vnode *vp)
100 {
101 	int error;
102 	int upgraded;
103 	struct bufobj *bo;
104 	struct mount *mp;
105 	vm_object_t obj;
106 
107 	/* Check for dirty mmap, pending writes and dirty buffers */
108 	bo = &vp->v_bufobj;
109 	BO_LOCK(bo);
110 	VI_LOCK(vp);
111 	if (bo->bo_numoutput > 0 ||
112 	    bo->bo_dirty.bv_cnt > 0 ||
113 	    ((obj = vp->v_object) != NULL &&
114 	     (obj->flags & OBJ_MIGHTBEDIRTY) != 0)) {
115 		VI_UNLOCK(vp);
116 		BO_UNLOCK(bo);
117 
118 		if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
119 			if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE)
120 				upgraded = 1;
121 			else
122 				upgraded = 0;
123 			VOP_UNLOCK(vp, 0);
124 			(void) vn_start_write(vp, &mp, V_WAIT);
125 			VOP_LOCK(vp, LK_EXCLUSIVE);
126 		} else if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE) {
127 			upgraded = 1;
128 			/* Upgrade to exclusive lock, this might block */
129 			VOP_LOCK(vp, LK_UPGRADE);
130 		} else
131 			upgraded = 0;
132 
133 
134 		VI_LOCK(vp);
135 		/* Check if vnode was reclaimed while unlocked. */
136 		if ((vp->v_iflag & VI_DOOMED) != 0) {
137 			VI_UNLOCK(vp);
138 			if (upgraded != 0)
139 				VOP_LOCK(vp, LK_DOWNGRADE);
140 			vn_finished_write(mp);
141 			return (EIO);
142 		}
143 		/* Attempt to msync mmap() regions to clean dirty mmap */
144 		if ((obj = vp->v_object) != NULL &&
145 		    (obj->flags & OBJ_MIGHTBEDIRTY) != 0) {
146 			VI_UNLOCK(vp);
147 			VM_OBJECT_WLOCK(obj);
148 			vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
149 			VM_OBJECT_WUNLOCK(obj);
150 		} else
151 			VI_UNLOCK(vp);
152 
153 		/* Wait for pending writes to complete */
154 		BO_LOCK(bo);
155 		error = bufobj_wwait(&vp->v_bufobj, 0, 0);
156 		if (error != 0) {
157 			/* XXX: can't happen with a zero timeout ??? */
158 			BO_UNLOCK(bo);
159 			if (upgraded != 0)
160 				VOP_LOCK(vp, LK_DOWNGRADE);
161 			vn_finished_write(mp);
162 			return (error);
163 		}
164 		/* Flush dirty buffers */
165 		if (bo->bo_dirty.bv_cnt > 0) {
166 			BO_UNLOCK(bo);
167 			if ((error = ffs_syncvnode(vp, MNT_WAIT, 0)) != 0) {
168 				if (upgraded != 0)
169 					VOP_LOCK(vp, LK_DOWNGRADE);
170 				vn_finished_write(mp);
171 				return (error);
172 			}
173 			BO_LOCK(bo);
174 			if (bo->bo_numoutput > 0 || bo->bo_dirty.bv_cnt > 0)
175 				panic("ffs_rawread_sync: dirty bufs");
176 		}
177 		BO_UNLOCK(bo);
178 		if (upgraded != 0)
179 			VOP_LOCK(vp, LK_DOWNGRADE);
180 		vn_finished_write(mp);
181 	} else {
182 		VI_UNLOCK(vp);
183 		BO_UNLOCK(bo);
184 	}
185 	return 0;
186 }
187 
188 
189 static int
190 ffs_rawread_readahead(struct vnode *vp,
191 		      caddr_t udata,
192 		      off_t offset,
193 		      size_t len,
194 		      struct thread *td,
195 		      struct buf *bp,
196 		      caddr_t sa)
197 {
198 	int error;
199 	u_int iolen;
200 	off_t blockno;
201 	int blockoff;
202 	int bsize;
203 	struct vnode *dp;
204 	int bforwards;
205 	struct inode *ip;
206 	ufs2_daddr_t blkno;
207 
208 	bsize = vp->v_mount->mnt_stat.f_iosize;
209 
210 	ip = VTOI(vp);
211 	dp = ip->i_devvp;
212 
213 	iolen = ((vm_offset_t) udata) & PAGE_MASK;
214 	bp->b_bcount = len;
215 	if (bp->b_bcount + iolen > bp->b_kvasize) {
216 		bp->b_bcount = bp->b_kvasize;
217 		if (iolen != 0)
218 			bp->b_bcount -= PAGE_SIZE;
219 	}
220 	bp->b_flags = 0;	/* XXX necessary ? */
221 	bp->b_iocmd = BIO_READ;
222 	bp->b_iodone = bdone;
223 	bp->b_data = udata;
224 	bp->b_saveaddr = sa;
225 	blockno = offset / bsize;
226 	blockoff = (offset % bsize) / DEV_BSIZE;
227 	if ((daddr_t) blockno != blockno) {
228 		return EINVAL; /* blockno overflow */
229 	}
230 
231 	bp->b_lblkno = bp->b_blkno = blockno;
232 
233 	error = ufs_bmaparray(vp, bp->b_lblkno, &blkno, NULL, &bforwards, NULL);
234 	if (error != 0)
235 		return error;
236 	if (blkno == -1) {
237 
238 		/* Fill holes with NULs to preserve semantics */
239 
240 		if (bp->b_bcount + blockoff * DEV_BSIZE > bsize)
241 			bp->b_bcount = bsize - blockoff * DEV_BSIZE;
242 		bp->b_bufsize = bp->b_bcount;
243 
244 		if (vmapbuf(bp, 1) < 0)
245 			return EFAULT;
246 
247 		maybe_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, 1) < 0)
264 		return EFAULT;
265 
266 	BO_STRATEGY(&dp->v_bufobj, bp);
267 	return 0;
268 }
269 
270 
271 static int
272 ffs_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 
438 int
439 ffs_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