procfs: remove sparse errors in proc_devtree.c
[linux-2.6] / fs / nilfs2 / btnode.c
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 "nilfs.h"
31 #include "mdt.h"
32 #include "dat.h"
33 #include "page.h"
34 #include "btnode.h"
35
36
37 void nilfs_btnode_cache_init_once(struct address_space *btnc)
38 {
39         INIT_RADIX_TREE(&btnc->page_tree, GFP_ATOMIC);
40         spin_lock_init(&btnc->tree_lock);
41         INIT_LIST_HEAD(&btnc->private_list);
42         spin_lock_init(&btnc->private_lock);
43
44         spin_lock_init(&btnc->i_mmap_lock);
45         INIT_RAW_PRIO_TREE_ROOT(&btnc->i_mmap);
46         INIT_LIST_HEAD(&btnc->i_mmap_nonlinear);
47 }
48
49 static struct address_space_operations def_btnode_aops = {
50         .sync_page              = block_sync_page,
51 };
52
53 void nilfs_btnode_cache_init(struct address_space *btnc,
54                              struct backing_dev_info *bdi)
55 {
56         btnc->host = NULL;  /* can safely set to host inode ? */
57         btnc->flags = 0;
58         mapping_set_gfp_mask(btnc, GFP_NOFS);
59         btnc->assoc_mapping = NULL;
60         btnc->backing_dev_info = bdi;
61         btnc->a_ops = &def_btnode_aops;
62 }
63
64 void nilfs_btnode_cache_clear(struct address_space *btnc)
65 {
66         invalidate_mapping_pages(btnc, 0, -1);
67         truncate_inode_pages(btnc, 0);
68 }
69
70 int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
71                               sector_t pblocknr, struct buffer_head **pbh,
72                               int newblk)
73 {
74         struct buffer_head *bh;
75         struct inode *inode = NILFS_BTNC_I(btnc);
76         int err;
77
78         bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
79         if (unlikely(!bh))
80                 return -ENOMEM;
81
82         err = -EEXIST; /* internal code */
83         if (newblk) {
84                 if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
85                              buffer_dirty(bh))) {
86                         brelse(bh);
87                         BUG();
88                 }
89                 bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
90                 bh->b_blocknr = blocknr;
91                 set_buffer_mapped(bh);
92                 set_buffer_uptodate(bh);
93                 goto found;
94         }
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 =
103                                 nilfs_dat_inode(NILFS_I_NILFS(inode));
104
105                         /* blocknr is a virtual block number */
106                         err = nilfs_dat_translate(dat, blocknr, &pblocknr);
107                         if (unlikely(err)) {
108                                 brelse(bh);
109                                 goto out_locked;
110                         }
111                 }
112         }
113         lock_buffer(bh);
114         if (buffer_uptodate(bh)) {
115                 unlock_buffer(bh);
116                 err = -EEXIST; /* internal code */
117                 goto found;
118         }
119         set_buffer_mapped(bh);
120         bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
121         bh->b_blocknr = pblocknr; /* set block address for read */
122         bh->b_end_io = end_buffer_read_sync;
123         get_bh(bh);
124         submit_bh(READ, bh);
125         bh->b_blocknr = blocknr; /* set back to the given block address */
126         err = 0;
127 found:
128         *pbh = bh;
129
130 out_locked:
131         unlock_page(bh->b_page);
132         page_cache_release(bh->b_page);
133         return err;
134 }
135
136 int nilfs_btnode_get(struct address_space *btnc, __u64 blocknr,
137                      sector_t pblocknr, struct buffer_head **pbh, int newblk)
138 {
139         struct buffer_head *bh;
140         int err;
141
142         err = nilfs_btnode_submit_block(btnc, blocknr, pblocknr, pbh, newblk);
143         if (err == -EEXIST) /* internal code (cache hit) */
144                 return 0;
145         if (unlikely(err))
146                 return err;
147
148         bh = *pbh;
149         wait_on_buffer(bh);
150         if (!buffer_uptodate(bh)) {
151                 brelse(bh);
152                 return -EIO;
153         }
154         return 0;
155 }
156
157 /**
158  * nilfs_btnode_delete - delete B-tree node buffer
159  * @bh: buffer to be deleted
160  *
161  * nilfs_btnode_delete() invalidates the specified buffer and delete the page
162  * including the buffer if the page gets unbusy.
163  */
164 void nilfs_btnode_delete(struct buffer_head *bh)
165 {
166         struct address_space *mapping;
167         struct page *page = bh->b_page;
168         pgoff_t index = page_index(page);
169         int still_dirty;
170
171         page_cache_get(page);
172         lock_page(page);
173         wait_on_page_writeback(page);
174
175         nilfs_forget_buffer(bh);
176         still_dirty = PageDirty(page);
177         mapping = page->mapping;
178         unlock_page(page);
179         page_cache_release(page);
180
181         if (!still_dirty && mapping)
182                 invalidate_inode_pages2_range(mapping, index, index);
183 }
184
185 /**
186  * nilfs_btnode_prepare_change_key
187  *  prepare to move contents of the block for old key to one of new key.
188  *  the old buffer will not be removed, but might be reused for new buffer.
189  *  it might return -ENOMEM because of memory allocation errors,
190  *  and might return -EIO because of disk read errors.
191  */
192 int nilfs_btnode_prepare_change_key(struct address_space *btnc,
193                                     struct nilfs_btnode_chkey_ctxt *ctxt)
194 {
195         struct buffer_head *obh, *nbh;
196         struct inode *inode = NILFS_BTNC_I(btnc);
197         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
198         int err;
199
200         if (oldkey == newkey)
201                 return 0;
202
203         obh = ctxt->bh;
204         ctxt->newbh = NULL;
205
206         if (inode->i_blkbits == PAGE_CACHE_SHIFT) {
207                 lock_page(obh->b_page);
208                 /*
209                  * We cannot call radix_tree_preload for the kernels older
210                  * than 2.6.23, because it is not exported for modules.
211                  */
212                 err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
213                 if (err)
214                         goto failed_unlock;
215                 /* BUG_ON(oldkey != obh->b_page->index); */
216                 if (unlikely(oldkey != obh->b_page->index))
217                         NILFS_PAGE_BUG(obh->b_page,
218                                        "invalid oldkey %lld (newkey=%lld)",
219                                        (unsigned long long)oldkey,
220                                        (unsigned long long)newkey);
221
222 retry:
223                 spin_lock_irq(&btnc->tree_lock);
224                 err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page);
225                 spin_unlock_irq(&btnc->tree_lock);
226                 /*
227                  * Note: page->index will not change to newkey until
228                  * nilfs_btnode_commit_change_key() will be called.
229                  * To protect the page in intermediate state, the page lock
230                  * is held.
231                  */
232                 radix_tree_preload_end();
233                 if (!err)
234                         return 0;
235                 else if (err != -EEXIST)
236                         goto failed_unlock;
237
238                 err = invalidate_inode_pages2_range(btnc, newkey, newkey);
239                 if (!err)
240                         goto retry;
241                 /* fallback to copy mode */
242                 unlock_page(obh->b_page);
243         }
244
245         err = nilfs_btnode_get(btnc, newkey, 0, &nbh, 1);
246         if (likely(!err)) {
247                 BUG_ON(nbh == obh);
248                 ctxt->newbh = nbh;
249         }
250         return err;
251
252  failed_unlock:
253         unlock_page(obh->b_page);
254         return err;
255 }
256
257 /**
258  * nilfs_btnode_commit_change_key
259  *  commit the change_key operation prepared by prepare_change_key().
260  */
261 void nilfs_btnode_commit_change_key(struct address_space *btnc,
262                                     struct nilfs_btnode_chkey_ctxt *ctxt)
263 {
264         struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;
265         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
266         struct page *opage;
267
268         if (oldkey == newkey)
269                 return;
270
271         if (nbh == NULL) {      /* blocksize == pagesize */
272                 opage = obh->b_page;
273                 if (unlikely(oldkey != opage->index))
274                         NILFS_PAGE_BUG(opage,
275                                        "invalid oldkey %lld (newkey=%lld)",
276                                        (unsigned long long)oldkey,
277                                        (unsigned long long)newkey);
278                 if (!test_set_buffer_dirty(obh) && TestSetPageDirty(opage))
279                         BUG();
280
281                 spin_lock_irq(&btnc->tree_lock);
282                 radix_tree_delete(&btnc->page_tree, oldkey);
283                 radix_tree_tag_set(&btnc->page_tree, newkey,
284                                    PAGECACHE_TAG_DIRTY);
285                 spin_unlock_irq(&btnc->tree_lock);
286
287                 opage->index = obh->b_blocknr = newkey;
288                 unlock_page(opage);
289         } else {
290                 nilfs_copy_buffer(nbh, obh);
291                 nilfs_btnode_mark_dirty(nbh);
292
293                 nbh->b_blocknr = newkey;
294                 ctxt->bh = nbh;
295                 nilfs_btnode_delete(obh); /* will decrement bh->b_count */
296         }
297 }
298
299 /**
300  * nilfs_btnode_abort_change_key
301  *  abort the change_key operation prepared by prepare_change_key().
302  */
303 void nilfs_btnode_abort_change_key(struct address_space *btnc,
304                                    struct nilfs_btnode_chkey_ctxt *ctxt)
305 {
306         struct buffer_head *nbh = ctxt->newbh;
307         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
308
309         if (oldkey == newkey)
310                 return;
311
312         if (nbh == NULL) {      /* blocksize == pagesize */
313                 spin_lock_irq(&btnc->tree_lock);
314                 radix_tree_delete(&btnc->page_tree, newkey);
315                 spin_unlock_irq(&btnc->tree_lock);
316                 unlock_page(ctxt->bh->b_page);
317         } else
318                 brelse(nbh);
319 }