xref: /openbmc/linux/fs/ocfs2/buffer_head_io.c (revision 9ac8d3fb)
1 /* -*- mode: c; c-basic-offset: 8; -*-
2  * vim: noexpandtab sw=8 ts=8 sts=0:
3  *
4  * io.c
5  *
6  * Buffer cache handling
7  *
8  * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
9  *
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public
12  * License as published by the Free Software Foundation; either
13  * version 2 of the License, or (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18  * General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public
21  * License along with this program; if not, write to the
22  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
23  * Boston, MA 021110-1307, USA.
24  */
25 
26 #include <linux/fs.h>
27 #include <linux/types.h>
28 #include <linux/slab.h>
29 #include <linux/highmem.h>
30 
31 #include <cluster/masklog.h>
32 
33 #include "ocfs2.h"
34 
35 #include "alloc.h"
36 #include "inode.h"
37 #include "journal.h"
38 #include "uptodate.h"
39 
40 #include "buffer_head_io.h"
41 
42 int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh,
43 		      struct inode *inode)
44 {
45 	int ret = 0;
46 
47 	mlog_entry("(bh->b_blocknr = %llu, inode=%p)\n",
48 		   (unsigned long long)bh->b_blocknr, inode);
49 
50 	BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO);
51 	BUG_ON(buffer_jbd(bh));
52 
53 	/* No need to check for a soft readonly file system here. non
54 	 * journalled writes are only ever done on system files which
55 	 * can get modified during recovery even if read-only. */
56 	if (ocfs2_is_hard_readonly(osb)) {
57 		ret = -EROFS;
58 		goto out;
59 	}
60 
61 	mutex_lock(&OCFS2_I(inode)->ip_io_mutex);
62 
63 	lock_buffer(bh);
64 	set_buffer_uptodate(bh);
65 
66 	/* remove from dirty list before I/O. */
67 	clear_buffer_dirty(bh);
68 
69 	get_bh(bh); /* for end_buffer_write_sync() */
70 	bh->b_end_io = end_buffer_write_sync;
71 	submit_bh(WRITE, bh);
72 
73 	wait_on_buffer(bh);
74 
75 	if (buffer_uptodate(bh)) {
76 		ocfs2_set_buffer_uptodate(inode, bh);
77 	} else {
78 		/* We don't need to remove the clustered uptodate
79 		 * information for this bh as it's not marked locally
80 		 * uptodate. */
81 		ret = -EIO;
82 		put_bh(bh);
83 	}
84 
85 	mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
86 out:
87 	mlog_exit(ret);
88 	return ret;
89 }
90 
91 int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
92 			   unsigned int nr, struct buffer_head *bhs[])
93 {
94 	int status = 0;
95 	unsigned int i;
96 	struct buffer_head *bh;
97 
98 	if (!nr) {
99 		mlog(ML_BH_IO, "No buffers will be read!\n");
100 		goto bail;
101 	}
102 
103 	for (i = 0 ; i < nr ; i++) {
104 		if (bhs[i] == NULL) {
105 			bhs[i] = sb_getblk(osb->sb, block++);
106 			if (bhs[i] == NULL) {
107 				status = -EIO;
108 				mlog_errno(status);
109 				goto bail;
110 			}
111 		}
112 		bh = bhs[i];
113 
114 		if (buffer_jbd(bh)) {
115 			mlog(ML_ERROR,
116 			     "trying to sync read a jbd "
117 			     "managed bh (blocknr = %llu), skipping\n",
118 			     (unsigned long long)bh->b_blocknr);
119 			continue;
120 		}
121 
122 		if (buffer_dirty(bh)) {
123 			/* This should probably be a BUG, or
124 			 * at least return an error. */
125 			mlog(ML_ERROR,
126 			     "trying to sync read a dirty "
127 			     "buffer! (blocknr = %llu), skipping\n",
128 			     (unsigned long long)bh->b_blocknr);
129 			continue;
130 		}
131 
132 		lock_buffer(bh);
133 		if (buffer_jbd(bh)) {
134 			mlog(ML_ERROR,
135 			     "block %llu had the JBD bit set "
136 			     "while I was in lock_buffer!",
137 			     (unsigned long long)bh->b_blocknr);
138 			BUG();
139 		}
140 
141 		clear_buffer_uptodate(bh);
142 		get_bh(bh); /* for end_buffer_read_sync() */
143 		bh->b_end_io = end_buffer_read_sync;
144 		submit_bh(READ, bh);
145 	}
146 
147 	for (i = nr; i > 0; i--) {
148 		bh = bhs[i - 1];
149 
150 		if (buffer_jbd(bh)) {
151 			mlog(ML_ERROR,
152 			     "the journal got the buffer while it was "
153 			     "locked for io! (blocknr = %llu)\n",
154 			     (unsigned long long)bh->b_blocknr);
155 			BUG();
156 		}
157 
158 		wait_on_buffer(bh);
159 		if (!buffer_uptodate(bh)) {
160 			/* Status won't be cleared from here on out,
161 			 * so we can safely record this and loop back
162 			 * to cleanup the other buffers. */
163 			status = -EIO;
164 			put_bh(bh);
165 			bhs[i - 1] = NULL;
166 		}
167 	}
168 
169 bail:
170 	return status;
171 }
172 
173 int ocfs2_read_blocks(struct inode *inode, u64 block, int nr,
174 		      struct buffer_head *bhs[], int flags)
175 {
176 	int status = 0;
177 	int i, ignore_cache = 0;
178 	struct buffer_head *bh;
179 
180 	mlog_entry("(inode=%p, block=(%llu), nr=(%d), flags=%d)\n",
181 		   inode, (unsigned long long)block, nr, flags);
182 
183 	BUG_ON(!inode);
184 	BUG_ON((flags & OCFS2_BH_READAHEAD) &&
185 	       (flags & OCFS2_BH_IGNORE_CACHE));
186 
187 	if (bhs == NULL) {
188 		status = -EINVAL;
189 		mlog_errno(status);
190 		goto bail;
191 	}
192 
193 	if (nr < 0) {
194 		mlog(ML_ERROR, "asked to read %d blocks!\n", nr);
195 		status = -EINVAL;
196 		mlog_errno(status);
197 		goto bail;
198 	}
199 
200 	if (nr == 0) {
201 		mlog(ML_BH_IO, "No buffers will be read!\n");
202 		status = 0;
203 		goto bail;
204 	}
205 
206 	mutex_lock(&OCFS2_I(inode)->ip_io_mutex);
207 	for (i = 0 ; i < nr ; i++) {
208 		if (bhs[i] == NULL) {
209 			bhs[i] = sb_getblk(inode->i_sb, block++);
210 			if (bhs[i] == NULL) {
211 				mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
212 				status = -EIO;
213 				mlog_errno(status);
214 				goto bail;
215 			}
216 		}
217 		bh = bhs[i];
218 		ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);
219 
220 		/* There are three read-ahead cases here which we need to
221 		 * be concerned with. All three assume a buffer has
222 		 * previously been submitted with OCFS2_BH_READAHEAD
223 		 * and it hasn't yet completed I/O.
224 		 *
225 		 * 1) The current request is sync to disk. This rarely
226 		 *    happens these days, and never when performance
227 		 *    matters - the code can just wait on the buffer
228 		 *    lock and re-submit.
229 		 *
230 		 * 2) The current request is cached, but not
231 		 *    readahead. ocfs2_buffer_uptodate() will return
232 		 *    false anyway, so we'll wind up waiting on the
233 		 *    buffer lock to do I/O. We re-check the request
234 		 *    with after getting the lock to avoid a re-submit.
235 		 *
236 		 * 3) The current request is readahead (and so must
237 		 *    also be a caching one). We short circuit if the
238 		 *    buffer is locked (under I/O) and if it's in the
239 		 *    uptodate cache. The re-check from #2 catches the
240 		 *    case that the previous read-ahead completes just
241 		 *    before our is-it-in-flight check.
242 		 */
243 
244 		if (!ignore_cache && !ocfs2_buffer_uptodate(inode, bh)) {
245 			mlog(ML_UPTODATE,
246 			     "bh (%llu), inode %llu not uptodate\n",
247 			     (unsigned long long)bh->b_blocknr,
248 			     (unsigned long long)OCFS2_I(inode)->ip_blkno);
249 			/* We're using ignore_cache here to say
250 			 * "go to disk" */
251 			ignore_cache = 1;
252 		}
253 
254 		/* XXX: Can we ever get this and *not* have the cached
255 		 * flag set? */
256 		if (buffer_jbd(bh)) {
257 			if (ignore_cache)
258 				mlog(ML_BH_IO, "trying to sync read a jbd "
259 					       "managed bh (blocknr = %llu)\n",
260 				     (unsigned long long)bh->b_blocknr);
261 			continue;
262 		}
263 
264 		if (ignore_cache) {
265 			if (buffer_dirty(bh)) {
266 				/* This should probably be a BUG, or
267 				 * at least return an error. */
268 				mlog(ML_BH_IO, "asking me to sync read a dirty "
269 					       "buffer! (blocknr = %llu)\n",
270 				     (unsigned long long)bh->b_blocknr);
271 				continue;
272 			}
273 
274 			/* A read-ahead request was made - if the
275 			 * buffer is already under read-ahead from a
276 			 * previously submitted request than we are
277 			 * done here. */
278 			if ((flags & OCFS2_BH_READAHEAD)
279 			    && ocfs2_buffer_read_ahead(inode, bh))
280 				continue;
281 
282 			lock_buffer(bh);
283 			if (buffer_jbd(bh)) {
284 #ifdef CATCH_BH_JBD_RACES
285 				mlog(ML_ERROR, "block %llu had the JBD bit set "
286 					       "while I was in lock_buffer!",
287 				     (unsigned long long)bh->b_blocknr);
288 				BUG();
289 #else
290 				unlock_buffer(bh);
291 				continue;
292 #endif
293 			}
294 
295 			/* Re-check ocfs2_buffer_uptodate() as a
296 			 * previously read-ahead buffer may have
297 			 * completed I/O while we were waiting for the
298 			 * buffer lock. */
299 			if (!(flags & OCFS2_BH_IGNORE_CACHE)
300 			    && !(flags & OCFS2_BH_READAHEAD)
301 			    && ocfs2_buffer_uptodate(inode, bh)) {
302 				unlock_buffer(bh);
303 				continue;
304 			}
305 
306 			clear_buffer_uptodate(bh);
307 			get_bh(bh); /* for end_buffer_read_sync() */
308 			bh->b_end_io = end_buffer_read_sync;
309 			submit_bh(READ, bh);
310 			continue;
311 		}
312 	}
313 
314 	status = 0;
315 
316 	for (i = (nr - 1); i >= 0; i--) {
317 		bh = bhs[i];
318 
319 		if (!(flags & OCFS2_BH_READAHEAD)) {
320 			/* We know this can't have changed as we hold the
321 			 * inode sem. Avoid doing any work on the bh if the
322 			 * journal has it. */
323 			if (!buffer_jbd(bh))
324 				wait_on_buffer(bh);
325 
326 			if (!buffer_uptodate(bh)) {
327 				/* Status won't be cleared from here on out,
328 				 * so we can safely record this and loop back
329 				 * to cleanup the other buffers. Don't need to
330 				 * remove the clustered uptodate information
331 				 * for this bh as it's not marked locally
332 				 * uptodate. */
333 				status = -EIO;
334 				put_bh(bh);
335 				bhs[i] = NULL;
336 				continue;
337 			}
338 		}
339 
340 		/* Always set the buffer in the cache, even if it was
341 		 * a forced read, or read-ahead which hasn't yet
342 		 * completed. */
343 		ocfs2_set_buffer_uptodate(inode, bh);
344 	}
345 	mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
346 
347 	mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n",
348 	     (unsigned long long)block, nr,
349 	     ((flags & OCFS2_BH_IGNORE_CACHE) || ignore_cache) ? "no" : "yes",
350 	     flags);
351 
352 bail:
353 
354 	mlog_exit(status);
355 	return status;
356 }
357 
358 /* Check whether the blkno is the super block or one of the backups. */
359 static void ocfs2_check_super_or_backup(struct super_block *sb,
360 					sector_t blkno)
361 {
362 	int i;
363 	u64 backup_blkno;
364 
365 	if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
366 		return;
367 
368 	for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
369 		backup_blkno = ocfs2_backup_super_blkno(sb, i);
370 		if (backup_blkno == blkno)
371 			return;
372 	}
373 
374 	BUG();
375 }
376 
377 /*
378  * Write super block and backups doesn't need to collaborate with journal,
379  * so we don't need to lock ip_io_mutex and inode doesn't need to bea passed
380  * into this function.
381  */
382 int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
383 				struct buffer_head *bh)
384 {
385 	int ret = 0;
386 
387 	mlog_entry_void();
388 
389 	BUG_ON(buffer_jbd(bh));
390 	ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
391 
392 	if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
393 		ret = -EROFS;
394 		goto out;
395 	}
396 
397 	lock_buffer(bh);
398 	set_buffer_uptodate(bh);
399 
400 	/* remove from dirty list before I/O. */
401 	clear_buffer_dirty(bh);
402 
403 	get_bh(bh); /* for end_buffer_write_sync() */
404 	bh->b_end_io = end_buffer_write_sync;
405 	submit_bh(WRITE, bh);
406 
407 	wait_on_buffer(bh);
408 
409 	if (!buffer_uptodate(bh)) {
410 		ret = -EIO;
411 		put_bh(bh);
412 	}
413 
414 out:
415 	mlog_exit(ret);
416 	return ret;
417 }
418