1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * NILFS B-tree node cache
4 *
5 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
6 *
7 * Originally written by Seiji Kihara.
8 * Fully revised by Ryusuke Konishi for stabilization and simplification.
9 *
10 */
11
12#include <linux/types.h>
13#include <linux/buffer_head.h>
14#include <linux/mm.h>
15#include <linux/backing-dev.h>
16#include <linux/gfp.h>
17#include "nilfs.h"
18#include "mdt.h"
19#include "dat.h"
20#include "page.h"
21#include "btnode.h"
22
23
24/**
25 * nilfs_init_btnc_inode - initialize B-tree node cache inode
26 * @btnc_inode: inode to be initialized
27 *
28 * nilfs_init_btnc_inode() sets up an inode for B-tree node cache.
29 */
30void nilfs_init_btnc_inode(struct inode *btnc_inode)
31{
32 struct nilfs_inode_info *ii = NILFS_I(inode: btnc_inode);
33
34 btnc_inode->i_mode = S_IFREG;
35 ii->i_flags = 0;
36 memset(&ii->i_bmap_data, 0, sizeof(struct nilfs_bmap));
37 mapping_set_gfp_mask(m: btnc_inode->i_mapping, GFP_NOFS);
38}
39
40void nilfs_btnode_cache_clear(struct address_space *btnc)
41{
42 invalidate_mapping_pages(mapping: btnc, start: 0, end: -1);
43 truncate_inode_pages(btnc, 0);
44}
45
46struct buffer_head *
47nilfs_btnode_create_block(struct address_space *btnc, __u64 blocknr)
48{
49 struct inode *inode = btnc->host;
50 struct buffer_head *bh;
51
52 bh = nilfs_grab_buffer(inode, btnc, blocknr, BIT(BH_NILFS_Node));
53 if (unlikely(!bh))
54 return NULL;
55
56 if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
57 buffer_dirty(bh))) {
58 brelse(bh);
59 BUG();
60 }
61 memset(bh->b_data, 0, i_blocksize(inode));
62 bh->b_bdev = inode->i_sb->s_bdev;
63 bh->b_blocknr = blocknr;
64 set_buffer_mapped(bh);
65 set_buffer_uptodate(bh);
66
67 unlock_page(page: bh->b_page);
68 put_page(page: bh->b_page);
69 return bh;
70}
71
72int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
73 sector_t pblocknr, blk_opf_t opf,
74 struct buffer_head **pbh, sector_t *submit_ptr)
75{
76 struct buffer_head *bh;
77 struct inode *inode = btnc->host;
78 struct page *page;
79 int err;
80
81 bh = nilfs_grab_buffer(inode, btnc, blocknr, BIT(BH_NILFS_Node));
82 if (unlikely(!bh))
83 return -ENOMEM;
84
85 err = -EEXIST; /* internal code */
86 page = bh->b_page;
87
88 if (buffer_uptodate(bh) || buffer_dirty(bh))
89 goto found;
90
91 if (pblocknr == 0) {
92 pblocknr = blocknr;
93 if (inode->i_ino != NILFS_DAT_INO) {
94 struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
95
96 /* blocknr is a virtual block number */
97 err = nilfs_dat_translate(nilfs->ns_dat, blocknr,
98 &pblocknr);
99 if (unlikely(err)) {
100 brelse(bh);
101 goto out_locked;
102 }
103 }
104 }
105
106 if (opf & REQ_RAHEAD) {
107 if (pblocknr != *submit_ptr + 1 || !trylock_buffer(bh)) {
108 err = -EBUSY; /* internal code */
109 brelse(bh);
110 goto out_locked;
111 }
112 } else { /* opf == REQ_OP_READ */
113 lock_buffer(bh);
114 }
115 if (buffer_uptodate(bh)) {
116 unlock_buffer(bh);
117 err = -EEXIST; /* internal code */
118 goto found;
119 }
120 set_buffer_mapped(bh);
121 bh->b_bdev = inode->i_sb->s_bdev;
122 bh->b_blocknr = pblocknr; /* set block address for read */
123 bh->b_end_io = end_buffer_read_sync;
124 get_bh(bh);
125 submit_bh(opf, bh);
126 bh->b_blocknr = blocknr; /* set back to the given block address */
127 *submit_ptr = pblocknr;
128 err = 0;
129found:
130 *pbh = bh;
131
132out_locked:
133 unlock_page(page);
134 put_page(page);
135 return err;
136}
137
138/**
139 * nilfs_btnode_delete - delete B-tree node buffer
140 * @bh: buffer to be deleted
141 *
142 * nilfs_btnode_delete() invalidates the specified buffer and delete the page
143 * including the buffer if the page gets unbusy.
144 */
145void nilfs_btnode_delete(struct buffer_head *bh)
146{
147 struct address_space *mapping;
148 struct page *page = bh->b_page;
149 pgoff_t index = page_index(page);
150 int still_dirty;
151
152 get_page(page);
153 lock_page(page);
154 wait_on_page_writeback(page);
155
156 nilfs_forget_buffer(bh);
157 still_dirty = PageDirty(page);
158 mapping = page->mapping;
159 unlock_page(page);
160 put_page(page);
161
162 if (!still_dirty && mapping)
163 invalidate_inode_pages2_range(mapping, start: index, end: index);
164}
165
166/**
167 * nilfs_btnode_prepare_change_key
168 * prepare to move contents of the block for old key to one of new key.
169 * the old buffer will not be removed, but might be reused for new buffer.
170 * it might return -ENOMEM because of memory allocation errors,
171 * and might return -EIO because of disk read errors.
172 */
173int nilfs_btnode_prepare_change_key(struct address_space *btnc,
174 struct nilfs_btnode_chkey_ctxt *ctxt)
175{
176 struct buffer_head *obh, *nbh;
177 struct inode *inode = btnc->host;
178 __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
179 int err;
180
181 if (oldkey == newkey)
182 return 0;
183
184 obh = ctxt->bh;
185 ctxt->newbh = NULL;
186
187 if (inode->i_blkbits == PAGE_SHIFT) {
188 struct page *opage = obh->b_page;
189 lock_page(page: opage);
190retry:
191 /* BUG_ON(oldkey != obh->b_folio->index); */
192 if (unlikely(oldkey != opage->index))
193 NILFS_PAGE_BUG(opage,
194 "invalid oldkey %lld (newkey=%lld)",
195 (unsigned long long)oldkey,
196 (unsigned long long)newkey);
197
198 xa_lock_irq(&btnc->i_pages);
199 err = __xa_insert(&btnc->i_pages, index: newkey, entry: opage, GFP_NOFS);
200 xa_unlock_irq(&btnc->i_pages);
201 /*
202 * Note: page->index will not change to newkey until
203 * nilfs_btnode_commit_change_key() will be called.
204 * To protect the page in intermediate state, the page lock
205 * is held.
206 */
207 if (!err)
208 return 0;
209 else if (err != -EBUSY)
210 goto failed_unlock;
211
212 err = invalidate_inode_pages2_range(mapping: btnc, start: newkey, end: newkey);
213 if (!err)
214 goto retry;
215 /* fallback to copy mode */
216 unlock_page(page: opage);
217 }
218
219 nbh = nilfs_btnode_create_block(btnc, blocknr: newkey);
220 if (!nbh)
221 return -ENOMEM;
222
223 BUG_ON(nbh == obh);
224 ctxt->newbh = nbh;
225 return 0;
226
227 failed_unlock:
228 unlock_page(page: obh->b_page);
229 return err;
230}
231
232/**
233 * nilfs_btnode_commit_change_key
234 * commit the change_key operation prepared by prepare_change_key().
235 */
236void nilfs_btnode_commit_change_key(struct address_space *btnc,
237 struct nilfs_btnode_chkey_ctxt *ctxt)
238{
239 struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;
240 __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
241 struct page *opage;
242
243 if (oldkey == newkey)
244 return;
245
246 if (nbh == NULL) { /* blocksize == pagesize */
247 opage = obh->b_page;
248 if (unlikely(oldkey != opage->index))
249 NILFS_PAGE_BUG(opage,
250 "invalid oldkey %lld (newkey=%lld)",
251 (unsigned long long)oldkey,
252 (unsigned long long)newkey);
253 mark_buffer_dirty(bh: obh);
254
255 xa_lock_irq(&btnc->i_pages);
256 __xa_erase(&btnc->i_pages, index: oldkey);
257 __xa_set_mark(&btnc->i_pages, index: newkey, PAGECACHE_TAG_DIRTY);
258 xa_unlock_irq(&btnc->i_pages);
259
260 opage->index = obh->b_blocknr = newkey;
261 unlock_page(page: opage);
262 } else {
263 nilfs_copy_buffer(nbh, obh);
264 mark_buffer_dirty(bh: nbh);
265
266 nbh->b_blocknr = newkey;
267 ctxt->bh = nbh;
268 nilfs_btnode_delete(bh: 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 */
276void 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 xa_erase_irq(xa: &btnc->i_pages, index: newkey);
287 unlock_page(page: ctxt->bh->b_page);
288 } else {
289 /*
290 * When canceling a buffer that a prepare operation has
291 * allocated to copy a node block to another location, use
292 * nilfs_btnode_delete() to initialize and release the buffer
293 * so that the buffer flags will not be in an inconsistent
294 * state when it is reallocated.
295 */
296 nilfs_btnode_delete(bh: nbh);
297 }
298}
299

source code of linux/fs/nilfs2/btnode.c