xref: /dragonfly/sys/vfs/ufs/ufs_readwrite.c (revision e91e64c7)
1 /*-
2  * Copyright (c) 1993
3  *	The Regents of the University of California.  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  * 3. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  *	@(#)ufs_readwrite.c	8.11 (Berkeley) 5/8/95
30  * $FreeBSD: src/sys/ufs/ufs/ufs_readwrite.c,v 1.65.2.14 2003/04/04 22:21:29 tegge Exp $
31  */
32 
33 #define	BLKSIZE(a, b, c)	blksize(a, b, c)
34 #define	FS			struct fs
35 #define	I_FS			i_fs
36 
37 #include <vm/vm.h>
38 #include <vm/vm_object.h>
39 #include <vm/vm_pager.h>
40 #include <vm/vm_map.h>
41 #include <vm/vnode_pager.h>
42 #include <sys/event.h>
43 #include <sys/vmmeter.h>
44 #include <sys/sysctl.h>
45 #include <vm/vm_page2.h>
46 
47 #define VN_KNOTE(vp, b) KNOTE(&vp->v_pollinfo.vpi_kqinfo.ki_note, (b))
48 
49 SYSCTL_DECL(_vfs_ffs);
50 
51 /*
52  * Vnode op for reading.
53  *
54  * ffs_read(struct vnode *a_vp, struct uio *a_uio, int a_ioflag,
55  *	    struct ucred *a_cred)
56  */
57 /* ARGSUSED */
58 int
ffs_read(struct vop_read_args * ap)59 ffs_read(struct vop_read_args *ap)
60 {
61 	struct vnode *vp;
62 	struct inode *ip;
63 	struct uio *uio;
64 	FS *fs;
65 	struct buf *bp;
66 	off_t bytesinfile;
67 	int xfersize, blkoffset;
68 	int error, orig_resid;
69 	int seqcount;
70 	int ioflag;
71 
72 	vp = ap->a_vp;
73 	seqcount = ap->a_ioflag >> IO_SEQSHIFT;
74 	ip = VTOI(vp);
75 	uio = ap->a_uio;
76 	ioflag = ap->a_ioflag;
77 #ifdef DIAGNOSTIC
78 	if (uio->uio_rw != UIO_READ)
79 		panic("ffs_read: mode");
80 
81 	if (vp->v_type == VLNK) {
82 		if ((int)ip->i_size < vp->v_mount->mnt_maxsymlinklen)
83 			panic("ffs_read: short symlink");
84 	} else if (vp->v_type != VREG && vp->v_type != VDIR)
85 		panic("ffs_read: type %d", vp->v_type);
86 #endif
87 	fs = ip->I_FS;
88 	if ((uint64_t)uio->uio_offset > fs->fs_maxfilesize)
89 		return (EFBIG);
90 
91 	orig_resid = uio->uio_resid;
92 	if (orig_resid <= 0)
93 		return (0);
94 
95 	bytesinfile = ip->i_size - uio->uio_offset;
96 	if (bytesinfile <= 0) {
97 		if ((vp->v_mount->mnt_flag & MNT_NOATIME) == 0)
98 			ip->i_flag |= IN_ACCESS;
99 		return 0;
100 	}
101 
102 	/*
103 	 * Ok so we couldn't do it all in one vm trick...
104 	 * so cycle around trying smaller bites..
105 	 */
106 	for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {
107 		if ((bytesinfile = ip->i_size - uio->uio_offset) <= 0)
108 			break;
109 
110 		error = ffs_blkatoff_ra(vp, uio->uio_offset, NULL,
111 					&bp, seqcount);
112 		if (error)
113 			break;
114 
115 		/*
116 		 * If IO_DIRECT then set B_DIRECT for the buffer.  This
117 		 * will cause us to attempt to release the buffer later on
118 		 * and will cause the buffer cache to attempt to free the
119 		 * underlying pages.
120 		 */
121 		if (ioflag & IO_DIRECT)
122 			bp->b_flags |= B_DIRECT;
123 
124 		/*
125 		 * We should only get non-zero b_resid when an I/O error
126 		 * has occurred, which should cause us to break above.
127 		 * However, if the short read did not cause an error,
128 		 * then we want to ensure that we do not uiomove bad
129 		 * or uninitialized data.
130 		 *
131 		 * XXX b_resid is only valid when an actual I/O has occured
132 		 * and may be incorrect if the buffer is B_CACHE or if the
133 		 * last op on the buffer was a failed write.  This KASSERT
134 		 * is a precursor to removing it from the UFS code.
135 		 */
136 		KASSERT(bp->b_resid == 0, ("bp->b_resid != 0"));
137 
138 		/*
139 		 * Calculate how much data we can copy
140 		 */
141 		blkoffset = blkoff(fs, uio->uio_offset);
142 		xfersize = bp->b_bufsize - blkoffset;
143 		if (xfersize > uio->uio_resid)
144 			xfersize = uio->uio_resid;
145 		if (xfersize > bytesinfile)
146 			xfersize = bytesinfile;
147 		if (xfersize <= 0) {
148 			panic("ufs_readwrite: impossible xfersize: %d",
149 			      xfersize);
150 		}
151 
152 		/*
153 		 * otherwise use the general form
154 		 */
155 		error = uiomovebp(bp, bp->b_data + blkoffset, xfersize, uio);
156 
157 		if (error)
158 			break;
159 
160 		if ((ioflag & (IO_VMIO|IO_DIRECT)) &&
161 		    (LIST_FIRST(&bp->b_dep) == NULL)) {
162 			/*
163 			 * If there are no dependencies, and it's VMIO,
164 			 * then we don't need the buf, mark it available
165 			 * for freeing. The VM has the data.
166 			 */
167 			bp->b_flags |= B_RELBUF;
168 			brelse(bp);
169 		} else {
170 			/*
171 			 * Otherwise let whoever
172 			 * made the request take care of
173 			 * freeing it. We just queue
174 			 * it onto another list.
175 			 */
176 			bqrelse(bp);
177 		}
178 	}
179 
180 	/*
181 	 * This can only happen in the case of an error
182 	 * because the loop above resets bp to NULL on each iteration
183 	 * and on normal completion has not set a new value into it.
184 	 * so it must have come from a 'break' statement
185 	 */
186 	if (bp != NULL) {
187 		if ((ioflag & (IO_VMIO|IO_DIRECT)) &&
188 		    (LIST_FIRST(&bp->b_dep) == NULL)) {
189 			bp->b_flags |= B_RELBUF;
190 			brelse(bp);
191 		} else {
192 			bqrelse(bp);
193 		}
194 	}
195 
196 	if ((error == 0 || uio->uio_resid != orig_resid) &&
197 	    (vp->v_mount->mnt_flag & MNT_NOATIME) == 0)
198 		ip->i_flag |= IN_ACCESS;
199 	return (error);
200 }
201 
202 /*
203  * Vnode op for writing.
204  *
205  * ffs_write(struct vnode *a_vp, struct uio *a_uio, int a_ioflag,
206  *	     struct ucred *a_cred)
207  */
208 int
ffs_write(struct vop_write_args * ap)209 ffs_write(struct vop_write_args *ap)
210 {
211 	struct vnode *vp;
212 	struct uio *uio;
213 	struct inode *ip;
214 	FS *fs;
215 	struct buf *bp;
216 	ufs_daddr_t lbn;
217 	off_t osize;
218 	off_t nsize;
219 	int seqcount;
220 	int blkoffset, error, extended, flags, ioflag, resid, size, xfersize;
221 	struct thread *td;
222 
223 	extended = 0;
224 	seqcount = ap->a_ioflag >> IO_SEQSHIFT;
225 	ioflag = ap->a_ioflag;
226 	uio = ap->a_uio;
227 	vp = ap->a_vp;
228 	ip = VTOI(vp);
229 
230 #ifdef DIAGNOSTIC
231 	if (uio->uio_rw != UIO_WRITE)
232 		panic("ffs_write: mode");
233 #endif
234 
235 	switch (vp->v_type) {
236 	case VREG:
237 		if (ioflag & IO_APPEND)
238 			uio->uio_offset = ip->i_size;
239 		if ((ip->i_flags & APPEND) && uio->uio_offset != ip->i_size)
240 			return (EPERM);
241 		/* FALLTHROUGH */
242 	case VLNK:
243 		break;
244 	case VDIR:
245 		panic("ffs_write: dir write");
246 		break;
247 	default:
248 		panic("ffs_write: type %p %d (%d,%d)", vp, (int)vp->v_type,
249 			(int)uio->uio_offset,
250 			(int)uio->uio_resid
251 		);
252 	}
253 
254 	fs = ip->I_FS;
255 	if (uio->uio_offset < 0 ||
256 	    (uint64_t)uio->uio_offset + uio->uio_resid > fs->fs_maxfilesize) {
257 		return (EFBIG);
258 	}
259 	/*
260 	 * Maybe this should be above the vnode op call, but so long as
261 	 * file servers have no limits, I don't think it matters.
262 	 */
263 	td = uio->uio_td;
264 	if (vp->v_type == VREG && td && td->td_proc &&
265 	    uio->uio_offset + uio->uio_resid >
266 	    td->td_proc->p_rlimit[RLIMIT_FSIZE].rlim_cur) {
267 		lwpsignal(td->td_proc, td->td_lwp, SIGXFSZ);
268 		return (EFBIG);
269 	}
270 
271 	resid = uio->uio_resid;
272 	osize = ip->i_size;
273 
274 	/*
275 	 * NOTE! These B_ flags are actually balloc-only flags, not buffer
276 	 * flags.  They are similar to the BA_ flags in fbsd.
277 	 */
278 	if (seqcount > B_SEQMAX)
279 		flags = B_SEQMAX << B_SEQSHIFT;
280 	else
281 		flags = seqcount << B_SEQSHIFT;
282 	if ((ioflag & IO_SYNC) && !DOINGASYNC(vp))
283 		flags |= B_SYNC;
284 
285 	if (uio->uio_segflg == UIO_NOCOPY)
286 		ip->i_flag |= IN_NOCOPYWRITE;
287 	else
288 		vclrflags(vp, VLASTWRITETS);
289 
290 	for (error = 0; uio->uio_resid > 0;) {
291 		lbn = lblkno(fs, uio->uio_offset);
292 		blkoffset = blkoff(fs, uio->uio_offset);
293 		xfersize = fs->fs_bsize - blkoffset;
294 		if (uio->uio_resid < xfersize)
295 			xfersize = uio->uio_resid;
296 
297 		if (uio->uio_offset + xfersize > ip->i_size) {
298 			nsize = uio->uio_offset + xfersize;
299 			nvnode_pager_setsize(vp, nsize,
300 				blkoffresize(fs, nsize), blkoff(fs, nsize));
301 		}
302 
303 #if 0
304 		/*
305 		 * If doing a dummy write to flush the buffer for a
306 		 * putpages we must perform a read-before-write to
307 		 * fill in any missing spots and clear any invalid
308 		 * areas.  Otherwise a multi-page buffer may not properly
309 		 * flush.
310 		 *
311 		 * We must clear any invalid areas
312 		 */
313 		if (uio->uio_segflg == UIO_NOCOPY) {
314 			error = ffs_blkatoff(vp, uio->uio_offset, NULL, &bp);
315 			if (error)
316 				break;
317 			bqrelse(bp);
318 		}
319 #endif
320 
321 		/*
322 		 * We must clear invalid areas.
323 		 */
324 		if (xfersize < fs->fs_bsize || uio->uio_segflg == UIO_NOCOPY)
325 			flags |= B_CLRBUF;
326 		else
327 			flags &= ~B_CLRBUF;
328 /* XXX is uio->uio_offset the right thing here? */
329 		error = VOP_BALLOC(vp, uio->uio_offset, xfersize,
330 				   ap->a_cred, flags, &bp);
331 		if (error != 0)
332 			break;
333 		/*
334 		 * If the buffer is not valid and we did not clear garbage
335 		 * out above, we have to do so here even though the write
336 		 * covers the entire buffer in order to avoid a mmap()/write
337 		 * race where another process may see the garbage prior to
338 		 * the uiomove() for a write replacing it.
339 		 */
340 		if ((bp->b_flags & B_CACHE) == 0 && (flags & B_CLRBUF) == 0)
341 			vfs_bio_clrbuf(bp);
342 		if (ioflag & IO_DIRECT)
343 			bp->b_flags |= B_DIRECT;
344 		if ((ioflag & (IO_SYNC|IO_INVAL)) == (IO_SYNC|IO_INVAL))
345 			bp->b_flags |= B_NOCACHE;
346 
347 		if (uio->uio_offset + xfersize > ip->i_size) {
348 			ip->i_size = uio->uio_offset + xfersize;
349 			extended = 1;
350 		}
351 
352 		size = BLKSIZE(fs, ip, lbn) - bp->b_resid;
353 		if (size < xfersize)
354 			xfersize = size;
355 
356 		error = uiomovebp(bp, bp->b_data + blkoffset, xfersize, uio);
357 		if ((ioflag & (IO_VMIO|IO_DIRECT)) &&
358 		    (LIST_FIRST(&bp->b_dep) == NULL)) {
359 			bp->b_flags |= B_RELBUF;
360 		}
361 
362 		/*
363 		 * If IO_SYNC each buffer is written synchronously.  Otherwise
364 		 * if we have a severe page deficiency write the buffer
365 		 * asynchronously.  Otherwise try to cluster, and if that
366 		 * doesn't do it then either do an async write (if O_DIRECT),
367 		 * or a delayed write (if not).
368 		 */
369 
370 		if (ioflag & IO_SYNC) {
371 			(void)bwrite(bp);
372 		} else if (vm_paging_severe() ||
373 			    buf_dirty_count_severe() ||
374 			    (ioflag & IO_ASYNC)) {
375 			bp->b_flags |= B_CLUSTEROK;
376 			bawrite(bp);
377 		} else if (xfersize + blkoffset == fs->fs_bsize) {
378 			if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERW) == 0) {
379 				bp->b_flags |= B_CLUSTEROK;
380 				cluster_write(bp, (off_t)ip->i_size, fs->fs_bsize, seqcount);
381 			} else {
382 				bawrite(bp);
383 			}
384 		} else if (ioflag & IO_DIRECT) {
385 			bp->b_flags |= B_CLUSTEROK;
386 			bawrite(bp);
387 		} else {
388 			bp->b_flags |= B_CLUSTEROK;
389 			bdwrite(bp);
390 		}
391 		if (error || xfersize == 0)
392 			break;
393 		ip->i_flag |= IN_CHANGE | IN_UPDATE;
394 	}
395 	/*
396 	 * If we successfully wrote any data, and we are not the superuser
397 	 * we clear the setuid and setgid bits as a precaution against
398 	 * tampering.
399 	 */
400 	if (resid > uio->uio_resid && ap->a_cred && ap->a_cred->cr_uid != 0)
401 		ip->i_mode &= ~(ISUID | ISGID);
402 	if (resid > uio->uio_resid)
403 		VN_KNOTE(vp, NOTE_WRITE | (extended ? NOTE_EXTEND : 0));
404 	if (error) {
405 		if (ioflag & IO_UNIT) {
406 			(void)ffs_truncate(vp, osize, ioflag & IO_SYNC,
407 					   ap->a_cred);
408 			uio->uio_offset -= resid - uio->uio_resid;
409 			uio->uio_resid = resid;
410 		}
411 	} else if (resid > uio->uio_resid && (ioflag & IO_SYNC)) {
412 		error = ffs_update(vp, 1);
413 	} else {
414 		ufs_itimes(vp);
415 	}
416 	if (uio->uio_segflg == UIO_NOCOPY)
417 		ip->i_flag &= ~IN_NOCOPYWRITE;
418 
419 	return (error);
420 }
421 
422