1 /* 2 * OMFS (as used by RIO Karma) file operations. 3 * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com> 4 * Released under GPL v2. 5 */ 6 7 #include <linux/version.h> 8 #include <linux/module.h> 9 #include <linux/fs.h> 10 #include <linux/buffer_head.h> 11 #include <linux/mpage.h> 12 #include "omfs.h" 13 14 static u32 omfs_max_extents(struct omfs_sb_info *sbi, int offset) 15 { 16 return (sbi->s_sys_blocksize - offset - 17 sizeof(struct omfs_extent)) / 18 sizeof(struct omfs_extent_entry) + 1; 19 } 20 21 void omfs_make_empty_table(struct buffer_head *bh, int offset) 22 { 23 struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset]; 24 25 oe->e_next = ~cpu_to_be64(0ULL); 26 oe->e_extent_count = cpu_to_be32(1), 27 oe->e_fill = cpu_to_be32(0x22), 28 oe->e_entry.e_cluster = ~cpu_to_be64(0ULL); 29 oe->e_entry.e_blocks = ~cpu_to_be64(0ULL); 30 } 31 32 int omfs_shrink_inode(struct inode *inode) 33 { 34 struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb); 35 struct omfs_extent *oe; 36 struct omfs_extent_entry *entry; 37 struct buffer_head *bh; 38 u64 next, last; 39 u32 extent_count; 40 u32 max_extents; 41 int ret; 42 43 /* traverse extent table, freeing each entry that is greater 44 * than inode->i_size; 45 */ 46 next = inode->i_ino; 47 48 /* only support truncate -> 0 for now */ 49 ret = -EIO; 50 if (inode->i_size != 0) 51 goto out; 52 53 bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next)); 54 if (!bh) 55 goto out; 56 57 oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]); 58 max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START); 59 60 for (;;) { 61 62 if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next)) 63 goto out_brelse; 64 65 extent_count = be32_to_cpu(oe->e_extent_count); 66 67 if (extent_count > max_extents) 68 goto out_brelse; 69 70 last = next; 71 next = be64_to_cpu(oe->e_next); 72 entry = &oe->e_entry; 73 74 /* ignore last entry as it is the terminator */ 75 for (; extent_count > 1; extent_count--) { 76 u64 start, count; 77 start = be64_to_cpu(entry->e_cluster); 78 count = be64_to_cpu(entry->e_blocks); 79 80 omfs_clear_range(inode->i_sb, start, (int) count); 81 entry++; 82 } 83 omfs_make_empty_table(bh, (char *) oe - bh->b_data); 84 mark_buffer_dirty(bh); 85 brelse(bh); 86 87 if (last != inode->i_ino) 88 omfs_clear_range(inode->i_sb, last, sbi->s_mirrors); 89 90 if (next == ~0) 91 break; 92 93 bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next)); 94 if (!bh) 95 goto out; 96 oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]); 97 max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT); 98 } 99 ret = 0; 100 out: 101 return ret; 102 out_brelse: 103 brelse(bh); 104 return ret; 105 } 106 107 static void omfs_truncate(struct inode *inode) 108 { 109 omfs_shrink_inode(inode); 110 mark_inode_dirty(inode); 111 } 112 113 /* 114 * Add new blocks to the current extent, or create new entries/continuations 115 * as necessary. 116 */ 117 static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe, 118 u64 *ret_block) 119 { 120 struct omfs_extent_entry *terminator; 121 struct omfs_extent_entry *entry = &oe->e_entry; 122 struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb); 123 u32 extent_count = be32_to_cpu(oe->e_extent_count); 124 u64 new_block = 0; 125 u32 max_count; 126 int new_count; 127 int ret = 0; 128 129 /* reached the end of the extent table with no blocks mapped. 130 * there are three possibilities for adding: grow last extent, 131 * add a new extent to the current extent table, and add a 132 * continuation inode. in last two cases need an allocator for 133 * sbi->s_cluster_size 134 */ 135 136 /* TODO: handle holes */ 137 138 /* should always have a terminator */ 139 if (extent_count < 1) 140 return -EIO; 141 142 /* trivially grow current extent, if next block is not taken */ 143 terminator = entry + extent_count - 1; 144 if (extent_count > 1) { 145 entry = terminator-1; 146 new_block = be64_to_cpu(entry->e_cluster) + 147 be64_to_cpu(entry->e_blocks); 148 149 if (omfs_allocate_block(inode->i_sb, new_block)) { 150 entry->e_blocks = 151 cpu_to_be64(be64_to_cpu(entry->e_blocks) + 1); 152 terminator->e_blocks = ~(cpu_to_be64( 153 be64_to_cpu(~terminator->e_blocks) + 1)); 154 goto out; 155 } 156 } 157 max_count = omfs_max_extents(sbi, OMFS_EXTENT_START); 158 159 /* TODO: add a continuation block here */ 160 if (be32_to_cpu(oe->e_extent_count) > max_count-1) 161 return -EIO; 162 163 /* try to allocate a new cluster */ 164 ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize, 165 &new_block, &new_count); 166 if (ret) 167 goto out_fail; 168 169 /* copy terminator down an entry */ 170 entry = terminator; 171 terminator++; 172 memcpy(terminator, entry, sizeof(struct omfs_extent_entry)); 173 174 entry->e_cluster = cpu_to_be64(new_block); 175 entry->e_blocks = cpu_to_be64((u64) new_count); 176 177 terminator->e_blocks = ~(cpu_to_be64( 178 be64_to_cpu(~terminator->e_blocks) + (u64) new_count)); 179 180 /* write in new entry */ 181 oe->e_extent_count = cpu_to_be32(1 + be32_to_cpu(oe->e_extent_count)); 182 183 out: 184 *ret_block = new_block; 185 out_fail: 186 return ret; 187 } 188 189 /* 190 * Scans across the directory table for a given file block number. 191 * If block not found, return 0. 192 */ 193 static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent, 194 sector_t block, int count, int *left) 195 { 196 /* count > 1 because of terminator */ 197 sector_t searched = 0; 198 for (; count > 1; count--) { 199 int numblocks = clus_to_blk(OMFS_SB(inode->i_sb), 200 be64_to_cpu(ent->e_blocks)); 201 202 if (block >= searched && 203 block < searched + numblocks) { 204 /* 205 * found it at cluster + (block - searched) 206 * numblocks - (block - searched) is remainder 207 */ 208 *left = numblocks - (block - searched); 209 return clus_to_blk(OMFS_SB(inode->i_sb), 210 be64_to_cpu(ent->e_cluster)) + 211 block - searched; 212 } 213 searched += numblocks; 214 ent++; 215 } 216 return 0; 217 } 218 219 static int omfs_get_block(struct inode *inode, sector_t block, 220 struct buffer_head *bh_result, int create) 221 { 222 struct buffer_head *bh; 223 sector_t next, offset; 224 int ret; 225 u64 new_block; 226 u32 max_extents; 227 int extent_count; 228 struct omfs_extent *oe; 229 struct omfs_extent_entry *entry; 230 struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb); 231 int max_blocks = bh_result->b_size >> inode->i_blkbits; 232 int remain; 233 234 ret = -EIO; 235 bh = sb_bread(inode->i_sb, clus_to_blk(sbi, inode->i_ino)); 236 if (!bh) 237 goto out; 238 239 oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]); 240 max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START); 241 next = inode->i_ino; 242 243 for (;;) { 244 245 if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next)) 246 goto out_brelse; 247 248 extent_count = be32_to_cpu(oe->e_extent_count); 249 next = be64_to_cpu(oe->e_next); 250 entry = &oe->e_entry; 251 252 if (extent_count > max_extents) 253 goto out_brelse; 254 255 offset = find_block(inode, entry, block, extent_count, &remain); 256 if (offset > 0) { 257 ret = 0; 258 map_bh(bh_result, inode->i_sb, offset); 259 if (remain > max_blocks) 260 remain = max_blocks; 261 bh_result->b_size = (remain << inode->i_blkbits); 262 goto out_brelse; 263 } 264 if (next == ~0) 265 break; 266 267 brelse(bh); 268 bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next)); 269 if (!bh) 270 goto out; 271 oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]); 272 max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT); 273 } 274 if (create) { 275 ret = omfs_grow_extent(inode, oe, &new_block); 276 if (ret == 0) { 277 mark_buffer_dirty(bh); 278 mark_inode_dirty(inode); 279 map_bh(bh_result, inode->i_sb, 280 clus_to_blk(sbi, new_block)); 281 } 282 } 283 out_brelse: 284 brelse(bh); 285 out: 286 return ret; 287 } 288 289 static int omfs_readpage(struct file *file, struct page *page) 290 { 291 return block_read_full_page(page, omfs_get_block); 292 } 293 294 static int omfs_readpages(struct file *file, struct address_space *mapping, 295 struct list_head *pages, unsigned nr_pages) 296 { 297 return mpage_readpages(mapping, pages, nr_pages, omfs_get_block); 298 } 299 300 static int omfs_writepage(struct page *page, struct writeback_control *wbc) 301 { 302 return block_write_full_page(page, omfs_get_block, wbc); 303 } 304 305 static int 306 omfs_writepages(struct address_space *mapping, struct writeback_control *wbc) 307 { 308 return mpage_writepages(mapping, wbc, omfs_get_block); 309 } 310 311 static int omfs_write_begin(struct file *file, struct address_space *mapping, 312 loff_t pos, unsigned len, unsigned flags, 313 struct page **pagep, void **fsdata) 314 { 315 *pagep = NULL; 316 return block_write_begin(file, mapping, pos, len, flags, 317 pagep, fsdata, omfs_get_block); 318 } 319 320 static sector_t omfs_bmap(struct address_space *mapping, sector_t block) 321 { 322 return generic_block_bmap(mapping, block, omfs_get_block); 323 } 324 325 const struct file_operations omfs_file_operations = { 326 .llseek = generic_file_llseek, 327 .read = do_sync_read, 328 .write = do_sync_write, 329 .aio_read = generic_file_aio_read, 330 .aio_write = generic_file_aio_write, 331 .mmap = generic_file_mmap, 332 .fsync = generic_file_fsync, 333 .splice_read = generic_file_splice_read, 334 }; 335 336 const struct inode_operations omfs_file_inops = { 337 .truncate = omfs_truncate 338 }; 339 340 const struct address_space_operations omfs_aops = { 341 .readpage = omfs_readpage, 342 .readpages = omfs_readpages, 343 .writepage = omfs_writepage, 344 .writepages = omfs_writepages, 345 .sync_page = block_sync_page, 346 .write_begin = omfs_write_begin, 347 .write_end = generic_write_end, 348 .bmap = omfs_bmap, 349 }; 350 351