1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #pragma ident "%Z%%M% %I% %E% SMI"
28
29 #include <sys/systm.h>
30 #include <sys/types.h>
31 #include <sys/vnode.h>
32 #include <sys/file.h>
33 #include <sys/buf.h>
34 #include <sys/ddi.h>
35 #include <sys/errno.h>
36 #include <sys/cmn_err.h>
37 #include <sys/fs/ufs_inode.h>
38 #include <sys/fs/ufs_filio.h>
39 #include <sys/fs/ufs_snap.h>
40 #include <sys/fssnap_if.h>
41 #include <sys/sysmacros.h>
42 #include <sys/modctl.h>
43 #include <sys/fs/ufs_bio.h>
44 #include <sys/debug.h>
45 #include <sys/kmem.h>
46 #include <sys/inttypes.h>
47 #include <sys/vfs.h>
48 #include <sys/disp.h>
49 #include <sys/atomic.h>
50 #include <sys/conf.h>
51 #include <sys/param.h>
52 #include <sys/policy.h>
53
54 static int ufs_snap_init_backfile(int *, int, vnode_t ***, struct ufsvfs *);
55 static void release_backing_vnodes(vnode_t ***, int);
56 static int ufs_snap_find_candidates(void *, struct ufsvfs *, int);
57
58 /*
59 * Create a snapshot on a file system
60 */
61 int
ufs_snap_create(struct vnode * vp,struct fiosnapcreate_multi * fiosnapp,cred_t * cr)62 ufs_snap_create(struct vnode *vp, struct fiosnapcreate_multi *fiosnapp,
63 cred_t *cr)
64 {
65 int error = 0;
66 struct ufsvfs *ufsvfsp = VTOI(vp)->i_ufsvfs;
67 struct fs *fs = ufsvfsp->vfs_fs;
68 vnode_t **bfvpp = NULL;
69 struct lockfs lf;
70 void *snapid = NULL;
71
72 u_offset_t nchunks;
73 uint_t chunksize, fragsperchunk;
74
75 /*
76 * Only privilege processes can create a snapshot for now. This
77 * would be better if it was based on the permissions of the device
78 * file.
79 */
80 if (secpolicy_fs_config(cr, ufsvfsp->vfs_vfs) != 0)
81 return (EPERM);
82
83 /*
84 * There is no reason to make a snapshot of a read-only file system
85 */
86 if (fs->fs_ronly) {
87 fiosnapp->error = FIOCOW_EREADONLY;
88 return (EROFS);
89 }
90
91 /*
92 * Initialize the backing files to store old data. This assumes any
93 * preallocation and setup has been done already.
94 * ufs_snap_init_backfile() allocates and returns a pointer to
95 * a null-terminated array of vnodes in bfvpp.
96 */
97 error = ufs_snap_init_backfile(fiosnapp->backfiledesc,
98 fiosnapp->backfilecount, &bfvpp, ufsvfsp);
99 if (error) {
100 fiosnapp->error = FIOCOW_EBACKFILE;
101 return (error);
102 }
103
104 /*
105 * File system must be write locked to prevent updates while
106 * the snapshot is being established.
107 */
108 if ((error = ufs_fiolfss(vp, &lf)) != 0) {
109 release_backing_vnodes(&bfvpp, fiosnapp->backfilecount);
110 return (error);
111 }
112
113 if (!LOCKFS_IS_ULOCK(&lf)) {
114 release_backing_vnodes(&bfvpp, fiosnapp->backfilecount);
115 fiosnapp->error = FIOCOW_EULOCK;
116 return (EINVAL);
117 }
118
119 lf.lf_lock = LOCKFS_WLOCK;
120 lf.lf_flags = 0;
121 lf.lf_comment = NULL;
122 if ((error = ufs_fiolfs(vp, &lf, 1)) != 0) {
123 release_backing_vnodes(&bfvpp, fiosnapp->backfilecount);
124 fiosnapp->error = FIOCOW_EWLOCK;
125 return (EINVAL);
126 }
127
128 /*
129 * File system must be fairly consistent to enable snapshots
130 */
131 if (fs->fs_clean != FSACTIVE &&
132 fs->fs_clean != FSSTABLE &&
133 fs->fs_clean != FSCLEAN &&
134 fs->fs_clean != FSLOG) {
135 fiosnapp->error = FIOCOW_ECLEAN;
136 error = EINVAL;
137 goto unlockout;
138 }
139
140 /*
141 * Only one snapshot is allowed per file system, so error if
142 * a snapshot is already enabled.
143 */
144 if (ufsvfsp->vfs_snapshot) {
145 fiosnapp->error = FIOCOW_EBUSY;
146 error = EBUSY;
147 goto unlockout;
148 }
149
150 /* Tell bio.c how to call our strategy routine. XXX ugly hack */
151 if (bio_snapshot_strategy == NULL)
152 bio_snapshot_strategy =
153 (void (*) (void *, buf_t *))fssnap_strategy;
154
155 /*
156 * use chunk size that is passed in, or the file system
157 * block size if it is zero. For most cases, the file system
158 * block size will be reasonably efficient. A larger
159 * chunksize uses less memory but may potentially induce more
160 * I/O copying the larger chunks aside.
161 */
162 if (fiosnapp->chunksize != 0)
163 chunksize = fiosnapp->chunksize;
164 else
165 chunksize = fs->fs_bsize * 4;
166
167
168 /*
169 * compute the number of chunks in this whole file system. Since
170 * the UFS allocation bitmaps are in units of fragments, we first
171 * compute the number of fragments per chunk. Things work out
172 * nicer if the chunk size is a power-of-two multiple of the
173 * fragment size.
174 */
175 if ((chunksize < fs->fs_fsize) || (chunksize % fs->fs_fsize != 0)) {
176 fiosnapp->error = FIOCOW_ECHUNKSZ;
177 error = EINVAL;
178 goto unlockout;
179 }
180 fragsperchunk = chunksize >> fs->fs_fshift;
181 nchunks = (fs->fs_size + fragsperchunk) / fragsperchunk;
182
183 /*
184 * Create and initialize snapshot state and allocate/initialize
185 * translation table. This does the real work of taking the snapshot.
186 */
187 snapid = fssnap_create(nchunks, chunksize, fiosnapp->maxsize, vp,
188 fiosnapp->backfilecount, bfvpp, fiosnapp->backfilename,
189 fiosnapp->backfilesize);
190 if (snapid == NULL) {
191 fiosnapp->error = FIOCOW_ECREATE;
192 error = EINVAL;
193 goto unlockout;
194 }
195
196 error = ufs_snap_find_candidates(snapid, ufsvfsp, chunksize);
197 fiosnapp->snapshotnumber = fssnap_create_done(snapid);
198
199 if (error) {
200 cmn_err(CE_WARN, "ufs_snap_create: failed scanning bitmaps, "
201 "error = %d.", error);
202 fiosnapp->error = FIOCOW_EBITMAP;
203 goto unlockout;
204 }
205
206 ufsvfsp->vfs_snapshot = snapid;
207
208 unlockout:
209 /*
210 * Unlock the file system
211 */
212 lf.lf_lock = LOCKFS_ULOCK;
213 lf.lf_flags = 0;
214 if ((ufs_fiolfs(vp, &lf, 1) != 0) && !error) {
215 fiosnapp->error = FIOCOW_ENOULOCK;
216 error = EINVAL;
217 } else {
218 fiosnapp->error = 0;
219 }
220
221 /* clean up the snapshot if an error occurred. */
222 if (error && snapid != NULL)
223 (void) fssnap_delete(&snapid);
224 else if (error && bfvpp != NULL)
225 release_backing_vnodes(&bfvpp, fiosnapp->backfilecount);
226
227 return (error);
228 }
229
230 static int
ufs_snap_init_backfile(int * filedesc,int count,vnode_t *** vppp,struct ufsvfs * ufsvfsp)231 ufs_snap_init_backfile(int *filedesc, int count, vnode_t ***vppp,
232 struct ufsvfs *ufsvfsp)
233 {
234 file_t *fp;
235 vnode_t **vpp;
236 int i;
237
238 vpp = (vnode_t **)kmem_zalloc((count + 1) * sizeof (vnode_t *),
239 KM_SLEEP);
240 *vppp = vpp;
241 for (i = 0; i < count; i++) {
242 if ((fp = getf(*filedesc)) == NULL) {
243 release_backing_vnodes(vppp, count);
244 *vppp = NULL;
245 return (EBADF);
246 }
247
248 ASSERT(fp->f_vnode != NULL);
249 VN_HOLD(fp->f_vnode);
250
251 *vpp = fp->f_vnode;
252 releasef(*filedesc);
253 filedesc++;
254
255 /* make sure the backing file is on a different file system */
256 if ((*vpp)->v_vfsp == ufsvfsp->vfs_vfs) {
257 release_backing_vnodes(vppp, count);
258 *vppp = NULL;
259 return (EINVAL);
260 }
261 vpp++;
262 }
263 return (0);
264 }
265
266 static void
release_backing_vnodes(vnode_t *** bvppp,int count)267 release_backing_vnodes(vnode_t ***bvppp, int count)
268 {
269 vnode_t **vpp;
270
271 vpp = *bvppp;
272 while (*vpp) {
273 VN_RELE(*vpp);
274 *vpp++ = NULL;
275 }
276 kmem_free(*bvppp, (count + 1) * sizeof (vnode_t *));
277 *bvppp = NULL;
278 }
279
280 static int
ufs_snap_find_candidates(void * snapid,struct ufsvfs * ufsvfsp,int chunksize)281 ufs_snap_find_candidates(void *snapid, struct ufsvfs *ufsvfsp, int chunksize)
282 {
283 struct fs *fs = ufsvfsp->vfs_fs;
284 struct buf *cgbp; /* cylinder group buffer */
285 struct cg *cgp; /* cylinder group data */
286 ulong_t cg;
287 ulong_t cgbase;
288 ulong_t chunk;
289 uchar_t *blksfree;
290
291 ulong_t curfrag;
292 int error = 0;
293
294 /*
295 * read through each ufs cylinder group and fetch the fragment
296 * allocation bitmap. UFS indicates a fragment is allocated by
297 * a zero bit (not a one bit) in the fragment offset.
298 */
299 cgbase = 0LL;
300 for (cg = 0; cg < fs->fs_ncg; cg++) {
301 /* read the cylinder group in */
302 cgbp = BREAD(ufsvfsp->vfs_dev,
303 (daddr_t)fsbtodb(fs, cgtod(fs, cg)), (int)fs->fs_cgsize);
304 if ((error = geterror(cgbp)) != 0) {
305 brelse(cgbp);
306 goto errout;
307 }
308 cgp = cgbp->b_un.b_cg;
309
310 /* check the magic number */
311 if (cgp->cg_magic != CG_MAGIC) {
312 cmn_err(CE_WARN, "ufs_snap_find_candidates: cg %lu "
313 "magic number (0x%x) does not match expected "
314 "magic number (0x%x)", cg, cgp->cg_magic, CG_MAGIC);
315 error = EIO;
316 goto errout;
317 }
318
319 blksfree = cg_blksfree(cgp);
320
321 /*
322 * go through the allocation bitmap and set the
323 * corresponding bit in the candidate map.
324 */
325 for (curfrag = 0; curfrag < cgp->cg_ndblk; curfrag++) {
326 if (isclr(blksfree, curfrag)) {
327 /*
328 * this assumes chunksize is a multiple of
329 * the fragment size
330 */
331 chunk = (ulong_t)((cgbase + curfrag) /
332 (chunksize >> fs->fs_fshift));
333
334 fssnap_set_candidate(snapid, chunk);
335 /*
336 * no need to scan the rest of this chunk since
337 * it is already marked, so skip to the next
338 */
339 curfrag += ((chunksize >> fs->fs_fshift) -
340 ((cgbase + curfrag) %
341 (chunksize >> fs->fs_fshift))) - 1;
342 }
343 }
344
345 cgbase += cgp->cg_ndblk;
346 ASSERT(cgbase <= fs->fs_size);
347 brelse(cgbp);
348 } /* cylinder group loop */
349
350 ASSERT(cgbase == fs->fs_size);
351
352 errout:
353 return (error);
354 }
355
356
357 int
ufs_snap_delete(struct vnode * vp,struct fiosnapdelete * fiosnapp,cred_t * cr)358 ufs_snap_delete(struct vnode *vp, struct fiosnapdelete *fiosnapp, cred_t *cr)
359 {
360 struct ufsvfs *ufsvfsp = VTOI(vp)->i_ufsvfs;
361 struct fs *fs = ufsvfsp->vfs_fs;
362
363 /*
364 * Initialize fields in the user's buffer
365 */
366 fiosnapp->error = 0;
367
368 /*
369 * No snapshot exists, we're done.
370 */
371 if (ufsvfsp->vfs_snapshot == NULL)
372 return (ENOENT);
373
374 /*
375 * must have sufficient privileges.
376 */
377 if (secpolicy_fs_config(cr, ufsvfsp->vfs_vfs) != 0)
378 return (EPERM);
379
380 /*
381 * Readonly file system
382 */
383 if (fs->fs_ronly) {
384 fiosnapp->error = FIOCOW_EREADONLY;
385 return (EROFS);
386 }
387
388 /* free the data structures and clear the vfs_snapshot field. */
389 fiosnapp->snapshotnumber = fssnap_delete(&ufsvfsp->vfs_snapshot);
390
391 if (fiosnapp->snapshotnumber == -1)
392 return (EINVAL);
393
394 return (0);
395 }
396