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