xref: /openbmc/linux/fs/nilfs2/btnode.c (revision 565d76cb)
1 /*
2  * btnode.c - NILFS B-tree node cache
3  *
4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
19  *
20  * This file was originally written by Seiji Kihara <kihara@osrg.net>
21  * and fully revised by Ryusuke Konishi <ryusuke@osrg.net> for
22  * stabilization and simplification.
23  *
24  */
25 
26 #include <linux/types.h>
27 #include <linux/buffer_head.h>
28 #include <linux/mm.h>
29 #include <linux/backing-dev.h>
30 #include <linux/gfp.h>
31 #include "nilfs.h"
32 #include "mdt.h"
33 #include "dat.h"
34 #include "page.h"
35 #include "btnode.h"
36 
37 
38 static const struct address_space_operations def_btnode_aops = {
39 	.sync_page		= block_sync_page,
40 };
41 
42 void nilfs_btnode_cache_init(struct address_space *btnc,
43 			     struct backing_dev_info *bdi)
44 {
45 	nilfs_mapping_init(btnc, bdi, &def_btnode_aops);
46 }
47 
48 void nilfs_btnode_cache_clear(struct address_space *btnc)
49 {
50 	invalidate_mapping_pages(btnc, 0, -1);
51 	truncate_inode_pages(btnc, 0);
52 }
53 
54 struct buffer_head *
55 nilfs_btnode_create_block(struct address_space *btnc, __u64 blocknr)
56 {
57 	struct inode *inode = NILFS_BTNC_I(btnc);
58 	struct buffer_head *bh;
59 
60 	bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
61 	if (unlikely(!bh))
62 		return NULL;
63 
64 	if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
65 		     buffer_dirty(bh))) {
66 		brelse(bh);
67 		BUG();
68 	}
69 	memset(bh->b_data, 0, 1 << inode->i_blkbits);
70 	bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
71 	bh->b_blocknr = blocknr;
72 	set_buffer_mapped(bh);
73 	set_buffer_uptodate(bh);
74 
75 	unlock_page(bh->b_page);
76 	page_cache_release(bh->b_page);
77 	return bh;
78 }
79 
80 int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
81 			      sector_t pblocknr, int mode,
82 			      struct buffer_head **pbh, sector_t *submit_ptr)
83 {
84 	struct buffer_head *bh;
85 	struct inode *inode = NILFS_BTNC_I(btnc);
86 	struct page *page;
87 	int err;
88 
89 	bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
90 	if (unlikely(!bh))
91 		return -ENOMEM;
92 
93 	err = -EEXIST; /* internal code */
94 	page = bh->b_page;
95 
96 	if (buffer_uptodate(bh) || buffer_dirty(bh))
97 		goto found;
98 
99 	if (pblocknr == 0) {
100 		pblocknr = blocknr;
101 		if (inode->i_ino != NILFS_DAT_INO) {
102 			struct inode *dat = NILFS_I_NILFS(inode)->ns_dat;
103 
104 			/* blocknr is a virtual block number */
105 			err = nilfs_dat_translate(dat, blocknr, &pblocknr);
106 			if (unlikely(err)) {
107 				brelse(bh);
108 				goto out_locked;
109 			}
110 		}
111 	}
112 
113 	if (mode == READA) {
114 		if (pblocknr != *submit_ptr + 1 || !trylock_buffer(bh)) {
115 			err = -EBUSY; /* internal code */
116 			brelse(bh);
117 			goto out_locked;
118 		}
119 	} else { /* mode == READ */
120 		lock_buffer(bh);
121 	}
122 	if (buffer_uptodate(bh)) {
123 		unlock_buffer(bh);
124 		err = -EEXIST; /* internal code */
125 		goto found;
126 	}
127 	set_buffer_mapped(bh);
128 	bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
129 	bh->b_blocknr = pblocknr; /* set block address for read */
130 	bh->b_end_io = end_buffer_read_sync;
131 	get_bh(bh);
132 	submit_bh(mode, bh);
133 	bh->b_blocknr = blocknr; /* set back to the given block address */
134 	*submit_ptr = pblocknr;
135 	err = 0;
136 found:
137 	*pbh = bh;
138 
139 out_locked:
140 	unlock_page(page);
141 	page_cache_release(page);
142 	return err;
143 }
144 
145 /**
146  * nilfs_btnode_delete - delete B-tree node buffer
147  * @bh: buffer to be deleted
148  *
149  * nilfs_btnode_delete() invalidates the specified buffer and delete the page
150  * including the buffer if the page gets unbusy.
151  */
152 void nilfs_btnode_delete(struct buffer_head *bh)
153 {
154 	struct address_space *mapping;
155 	struct page *page = bh->b_page;
156 	pgoff_t index = page_index(page);
157 	int still_dirty;
158 
159 	page_cache_get(page);
160 	lock_page(page);
161 	wait_on_page_writeback(page);
162 
163 	nilfs_forget_buffer(bh);
164 	still_dirty = PageDirty(page);
165 	mapping = page->mapping;
166 	unlock_page(page);
167 	page_cache_release(page);
168 
169 	if (!still_dirty && mapping)
170 		invalidate_inode_pages2_range(mapping, index, index);
171 }
172 
173 /**
174  * nilfs_btnode_prepare_change_key
175  *  prepare to move contents of the block for old key to one of new key.
176  *  the old buffer will not be removed, but might be reused for new buffer.
177  *  it might return -ENOMEM because of memory allocation errors,
178  *  and might return -EIO because of disk read errors.
179  */
180 int nilfs_btnode_prepare_change_key(struct address_space *btnc,
181 				    struct nilfs_btnode_chkey_ctxt *ctxt)
182 {
183 	struct buffer_head *obh, *nbh;
184 	struct inode *inode = NILFS_BTNC_I(btnc);
185 	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
186 	int err;
187 
188 	if (oldkey == newkey)
189 		return 0;
190 
191 	obh = ctxt->bh;
192 	ctxt->newbh = NULL;
193 
194 	if (inode->i_blkbits == PAGE_CACHE_SHIFT) {
195 		lock_page(obh->b_page);
196 		/*
197 		 * We cannot call radix_tree_preload for the kernels older
198 		 * than 2.6.23, because it is not exported for modules.
199 		 */
200 retry:
201 		err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
202 		if (err)
203 			goto failed_unlock;
204 		/* BUG_ON(oldkey != obh->b_page->index); */
205 		if (unlikely(oldkey != obh->b_page->index))
206 			NILFS_PAGE_BUG(obh->b_page,
207 				       "invalid oldkey %lld (newkey=%lld)",
208 				       (unsigned long long)oldkey,
209 				       (unsigned long long)newkey);
210 
211 		spin_lock_irq(&btnc->tree_lock);
212 		err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page);
213 		spin_unlock_irq(&btnc->tree_lock);
214 		/*
215 		 * Note: page->index will not change to newkey until
216 		 * nilfs_btnode_commit_change_key() will be called.
217 		 * To protect the page in intermediate state, the page lock
218 		 * is held.
219 		 */
220 		radix_tree_preload_end();
221 		if (!err)
222 			return 0;
223 		else if (err != -EEXIST)
224 			goto failed_unlock;
225 
226 		err = invalidate_inode_pages2_range(btnc, newkey, newkey);
227 		if (!err)
228 			goto retry;
229 		/* fallback to copy mode */
230 		unlock_page(obh->b_page);
231 	}
232 
233 	nbh = nilfs_btnode_create_block(btnc, newkey);
234 	if (!nbh)
235 		return -ENOMEM;
236 
237 	BUG_ON(nbh == obh);
238 	ctxt->newbh = nbh;
239 	return 0;
240 
241  failed_unlock:
242 	unlock_page(obh->b_page);
243 	return err;
244 }
245 
246 /**
247  * nilfs_btnode_commit_change_key
248  *  commit the change_key operation prepared by prepare_change_key().
249  */
250 void nilfs_btnode_commit_change_key(struct address_space *btnc,
251 				    struct nilfs_btnode_chkey_ctxt *ctxt)
252 {
253 	struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;
254 	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
255 	struct page *opage;
256 
257 	if (oldkey == newkey)
258 		return;
259 
260 	if (nbh == NULL) {	/* blocksize == pagesize */
261 		opage = obh->b_page;
262 		if (unlikely(oldkey != opage->index))
263 			NILFS_PAGE_BUG(opage,
264 				       "invalid oldkey %lld (newkey=%lld)",
265 				       (unsigned long long)oldkey,
266 				       (unsigned long long)newkey);
267 		nilfs_btnode_mark_dirty(obh);
268 
269 		spin_lock_irq(&btnc->tree_lock);
270 		radix_tree_delete(&btnc->page_tree, oldkey);
271 		radix_tree_tag_set(&btnc->page_tree, newkey,
272 				   PAGECACHE_TAG_DIRTY);
273 		spin_unlock_irq(&btnc->tree_lock);
274 
275 		opage->index = obh->b_blocknr = newkey;
276 		unlock_page(opage);
277 	} else {
278 		nilfs_copy_buffer(nbh, obh);
279 		nilfs_btnode_mark_dirty(nbh);
280 
281 		nbh->b_blocknr = newkey;
282 		ctxt->bh = nbh;
283 		nilfs_btnode_delete(obh); /* will decrement bh->b_count */
284 	}
285 }
286 
287 /**
288  * nilfs_btnode_abort_change_key
289  *  abort the change_key operation prepared by prepare_change_key().
290  */
291 void nilfs_btnode_abort_change_key(struct address_space *btnc,
292 				   struct nilfs_btnode_chkey_ctxt *ctxt)
293 {
294 	struct buffer_head *nbh = ctxt->newbh;
295 	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
296 
297 	if (oldkey == newkey)
298 		return;
299 
300 	if (nbh == NULL) {	/* blocksize == pagesize */
301 		spin_lock_irq(&btnc->tree_lock);
302 		radix_tree_delete(&btnc->page_tree, newkey);
303 		spin_unlock_irq(&btnc->tree_lock);
304 		unlock_page(ctxt->bh->b_page);
305 	} else
306 		brelse(nbh);
307 }
308