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Linux/fs/nilfs2/btnode.c

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  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, BIT(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, i_blocksize(inode));
 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, int mode_flags,
 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, BIT(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_flags & REQ_RAHEAD) {
 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, mode_flags, 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 

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