xref: /openbmc/linux/fs/nilfs2/btnode.c (revision 0edbfea5)
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  * Originally written by Seiji Kihara.
17  * Fully revised by Ryusuke Konishi for stabilization and simplification.
18  *
19  */
20 
21 #include <linux/types.h>
22 #include <linux/buffer_head.h>
23 #include <linux/mm.h>
24 #include <linux/backing-dev.h>
25 #include <linux/gfp.h>
26 #include "nilfs.h"
27 #include "mdt.h"
28 #include "dat.h"
29 #include "page.h"
30 #include "btnode.h"
31 
32 void nilfs_btnode_cache_clear(struct address_space *btnc)
33 {
34 	invalidate_mapping_pages(btnc, 0, -1);
35 	truncate_inode_pages(btnc, 0);
36 }
37 
38 struct buffer_head *
39 nilfs_btnode_create_block(struct address_space *btnc, __u64 blocknr)
40 {
41 	struct inode *inode = NILFS_BTNC_I(btnc);
42 	struct buffer_head *bh;
43 
44 	bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
45 	if (unlikely(!bh))
46 		return NULL;
47 
48 	if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
49 		     buffer_dirty(bh))) {
50 		brelse(bh);
51 		BUG();
52 	}
53 	memset(bh->b_data, 0, 1 << inode->i_blkbits);
54 	bh->b_bdev = inode->i_sb->s_bdev;
55 	bh->b_blocknr = blocknr;
56 	set_buffer_mapped(bh);
57 	set_buffer_uptodate(bh);
58 
59 	unlock_page(bh->b_page);
60 	put_page(bh->b_page);
61 	return bh;
62 }
63 
64 int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
65 			      sector_t pblocknr, int mode,
66 			      struct buffer_head **pbh, sector_t *submit_ptr)
67 {
68 	struct buffer_head *bh;
69 	struct inode *inode = NILFS_BTNC_I(btnc);
70 	struct page *page;
71 	int err;
72 
73 	bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
74 	if (unlikely(!bh))
75 		return -ENOMEM;
76 
77 	err = -EEXIST; /* internal code */
78 	page = bh->b_page;
79 
80 	if (buffer_uptodate(bh) || buffer_dirty(bh))
81 		goto found;
82 
83 	if (pblocknr == 0) {
84 		pblocknr = blocknr;
85 		if (inode->i_ino != NILFS_DAT_INO) {
86 			struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
87 
88 			/* blocknr is a virtual block number */
89 			err = nilfs_dat_translate(nilfs->ns_dat, blocknr,
90 						  &pblocknr);
91 			if (unlikely(err)) {
92 				brelse(bh);
93 				goto out_locked;
94 			}
95 		}
96 	}
97 
98 	if (mode == READA) {
99 		if (pblocknr != *submit_ptr + 1 || !trylock_buffer(bh)) {
100 			err = -EBUSY; /* internal code */
101 			brelse(bh);
102 			goto out_locked;
103 		}
104 	} else { /* mode == READ */
105 		lock_buffer(bh);
106 	}
107 	if (buffer_uptodate(bh)) {
108 		unlock_buffer(bh);
109 		err = -EEXIST; /* internal code */
110 		goto found;
111 	}
112 	set_buffer_mapped(bh);
113 	bh->b_bdev = inode->i_sb->s_bdev;
114 	bh->b_blocknr = pblocknr; /* set block address for read */
115 	bh->b_end_io = end_buffer_read_sync;
116 	get_bh(bh);
117 	submit_bh(mode, bh);
118 	bh->b_blocknr = blocknr; /* set back to the given block address */
119 	*submit_ptr = pblocknr;
120 	err = 0;
121 found:
122 	*pbh = bh;
123 
124 out_locked:
125 	unlock_page(page);
126 	put_page(page);
127 	return err;
128 }
129 
130 /**
131  * nilfs_btnode_delete - delete B-tree node buffer
132  * @bh: buffer to be deleted
133  *
134  * nilfs_btnode_delete() invalidates the specified buffer and delete the page
135  * including the buffer if the page gets unbusy.
136  */
137 void nilfs_btnode_delete(struct buffer_head *bh)
138 {
139 	struct address_space *mapping;
140 	struct page *page = bh->b_page;
141 	pgoff_t index = page_index(page);
142 	int still_dirty;
143 
144 	get_page(page);
145 	lock_page(page);
146 	wait_on_page_writeback(page);
147 
148 	nilfs_forget_buffer(bh);
149 	still_dirty = PageDirty(page);
150 	mapping = page->mapping;
151 	unlock_page(page);
152 	put_page(page);
153 
154 	if (!still_dirty && mapping)
155 		invalidate_inode_pages2_range(mapping, index, index);
156 }
157 
158 /**
159  * nilfs_btnode_prepare_change_key
160  *  prepare to move contents of the block for old key to one of new key.
161  *  the old buffer will not be removed, but might be reused for new buffer.
162  *  it might return -ENOMEM because of memory allocation errors,
163  *  and might return -EIO because of disk read errors.
164  */
165 int nilfs_btnode_prepare_change_key(struct address_space *btnc,
166 				    struct nilfs_btnode_chkey_ctxt *ctxt)
167 {
168 	struct buffer_head *obh, *nbh;
169 	struct inode *inode = NILFS_BTNC_I(btnc);
170 	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
171 	int err;
172 
173 	if (oldkey == newkey)
174 		return 0;
175 
176 	obh = ctxt->bh;
177 	ctxt->newbh = NULL;
178 
179 	if (inode->i_blkbits == PAGE_SHIFT) {
180 		lock_page(obh->b_page);
181 		/*
182 		 * We cannot call radix_tree_preload for the kernels older
183 		 * than 2.6.23, because it is not exported for modules.
184 		 */
185 retry:
186 		err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
187 		if (err)
188 			goto failed_unlock;
189 		/* BUG_ON(oldkey != obh->b_page->index); */
190 		if (unlikely(oldkey != obh->b_page->index))
191 			NILFS_PAGE_BUG(obh->b_page,
192 				       "invalid oldkey %lld (newkey=%lld)",
193 				       (unsigned long long)oldkey,
194 				       (unsigned long long)newkey);
195 
196 		spin_lock_irq(&btnc->tree_lock);
197 		err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page);
198 		spin_unlock_irq(&btnc->tree_lock);
199 		/*
200 		 * Note: page->index will not change to newkey until
201 		 * nilfs_btnode_commit_change_key() will be called.
202 		 * To protect the page in intermediate state, the page lock
203 		 * is held.
204 		 */
205 		radix_tree_preload_end();
206 		if (!err)
207 			return 0;
208 		else if (err != -EEXIST)
209 			goto failed_unlock;
210 
211 		err = invalidate_inode_pages2_range(btnc, newkey, newkey);
212 		if (!err)
213 			goto retry;
214 		/* fallback to copy mode */
215 		unlock_page(obh->b_page);
216 	}
217 
218 	nbh = nilfs_btnode_create_block(btnc, newkey);
219 	if (!nbh)
220 		return -ENOMEM;
221 
222 	BUG_ON(nbh == obh);
223 	ctxt->newbh = nbh;
224 	return 0;
225 
226  failed_unlock:
227 	unlock_page(obh->b_page);
228 	return err;
229 }
230 
231 /**
232  * nilfs_btnode_commit_change_key
233  *  commit the change_key operation prepared by prepare_change_key().
234  */
235 void nilfs_btnode_commit_change_key(struct address_space *btnc,
236 				    struct nilfs_btnode_chkey_ctxt *ctxt)
237 {
238 	struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;
239 	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
240 	struct page *opage;
241 
242 	if (oldkey == newkey)
243 		return;
244 
245 	if (nbh == NULL) {	/* blocksize == pagesize */
246 		opage = obh->b_page;
247 		if (unlikely(oldkey != opage->index))
248 			NILFS_PAGE_BUG(opage,
249 				       "invalid oldkey %lld (newkey=%lld)",
250 				       (unsigned long long)oldkey,
251 				       (unsigned long long)newkey);
252 		mark_buffer_dirty(obh);
253 
254 		spin_lock_irq(&btnc->tree_lock);
255 		radix_tree_delete(&btnc->page_tree, oldkey);
256 		radix_tree_tag_set(&btnc->page_tree, newkey,
257 				   PAGECACHE_TAG_DIRTY);
258 		spin_unlock_irq(&btnc->tree_lock);
259 
260 		opage->index = obh->b_blocknr = newkey;
261 		unlock_page(opage);
262 	} else {
263 		nilfs_copy_buffer(nbh, obh);
264 		mark_buffer_dirty(nbh);
265 
266 		nbh->b_blocknr = newkey;
267 		ctxt->bh = nbh;
268 		nilfs_btnode_delete(obh); /* will decrement bh->b_count */
269 	}
270 }
271 
272 /**
273  * nilfs_btnode_abort_change_key
274  *  abort the change_key operation prepared by prepare_change_key().
275  */
276 void nilfs_btnode_abort_change_key(struct address_space *btnc,
277 				   struct nilfs_btnode_chkey_ctxt *ctxt)
278 {
279 	struct buffer_head *nbh = ctxt->newbh;
280 	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
281 
282 	if (oldkey == newkey)
283 		return;
284 
285 	if (nbh == NULL) {	/* blocksize == pagesize */
286 		spin_lock_irq(&btnc->tree_lock);
287 		radix_tree_delete(&btnc->page_tree, newkey);
288 		spin_unlock_irq(&btnc->tree_lock);
289 		unlock_page(ctxt->bh->b_page);
290 	} else
291 		brelse(nbh);
292 }
293