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 xa_lock_irq(&btnc->i_pages); 197 err = radix_tree_insert(&btnc->i_pages, newkey, obh->b_page); 198 xa_unlock_irq(&btnc->i_pages); 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 xa_lock_irq(&btnc->i_pages); 255 radix_tree_delete(&btnc->i_pages, oldkey); 256 radix_tree_tag_set(&btnc->i_pages, newkey, 257 PAGECACHE_TAG_DIRTY); 258 xa_unlock_irq(&btnc->i_pages); 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 xa_lock_irq(&btnc->i_pages); 287 radix_tree_delete(&btnc->i_pages, newkey); 288 xa_unlock_irq(&btnc->i_pages); 289 unlock_page(ctxt->bh->b_page); 290 } else 291 brelse(nbh); 292 } 293