fs/omfs/file.c

   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/module.h>
   8 #include <linux/fs.h>
   9 #include <linux/buffer_head.h>
  10 #include <linux/mpage.h>
  11 #include "omfs.h"
  12
  13 static u32 omfs_max_extents(struct omfs_sb_info *sbi, int offset)
  14 {
  15         return (sbi->s_sys_blocksize - offset -
  16                 sizeof(struct omfs_extent)) /
  17                 sizeof(struct omfs_extent_entry) + 1;
  18 }
  19
  20 void omfs_make_empty_table(struct buffer_head *bh, int offset)
  21 {
  22         struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];
  23
  24         oe->e_next = ~cpu_to_be64(0ULL);
  25         oe->e_extent_count = cpu_to_be32(1),
  26         oe->e_fill = cpu_to_be32(0x22),
  27         oe->e_entry.e_cluster = ~cpu_to_be64(0ULL);
  28         oe->e_entry.e_blocks = ~cpu_to_be64(0ULL);
  29 }
  30
  31 int omfs_shrink_inode(struct inode *inode)
  32 {
  33         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
  34         struct omfs_extent *oe;
  35         struct omfs_extent_entry *entry;
  36         struct buffer_head *bh;
  37         u64 next, last;
  38         u32 extent_count;
  39         u32 max_extents;
  40         int ret;
  41
  42         /* traverse extent table, freeing each entry that is greater
  43          * than inode->i_size;
  44          */
  45         next = inode->i_ino;
  46
  47         /* only support truncate -> 0 for now */
  48         ret = -EIO;
  49         if (inode->i_size != 0)
  50                 goto out;
  51
  52         bh = omfs_bread(inode->i_sb, next);
  53         if (!bh)
  54                 goto out;
  55
  56         oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
  57         max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
  58
  59         for (;;) {
  60
  61                 if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
  62                         goto out_brelse;
  63
  64                 extent_count = be32_to_cpu(oe->e_extent_count);
  65
  66                 if (extent_count > max_extents)
  67                         goto out_brelse;
  68
  69                 last = next;
  70                 next = be64_to_cpu(oe->e_next);
  71                 entry = &oe->e_entry;
  72
  73                 /* ignore last entry as it is the terminator */
  74                 for (; extent_count > 1; extent_count--) {
  75                         u64 start, count;
  76                         start = be64_to_cpu(entry->e_cluster);
  77                         count = be64_to_cpu(entry->e_blocks);
  78
  79                         omfs_clear_range(inode->i_sb, start, (int) count);
  80                         entry++;
  81                 }
  82                 omfs_make_empty_table(bh, (char *) oe - bh->b_data);
  83                 mark_buffer_dirty(bh);
  84                 brelse(bh);
  85
  86                 if (last != inode->i_ino)
  87                         omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);
  88
  89                 if (next == ~0)
  90                         break;
  91
  92                 bh = omfs_bread(inode->i_sb, next);
  93                 if (!bh)
  94                         goto out;
  95                 oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
  96                 max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
  97         }
  98         ret = 0;
  99 out:
 100         return ret;
 101 out_brelse:
 102         brelse(bh);
 103         return ret;
 104 }
 105
 106 static void omfs_truncate(struct inode *inode)
 107 {
 108         omfs_shrink_inode(inode);
 109         mark_inode_dirty(inode);
 110 }
 111
 112 /*
 113  * Add new blocks to the current extent, or create new entries/continuations
 114  * as necessary.
 115  */
 116 static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
 117                         u64 *ret_block)
 118 {
 119         struct omfs_extent_entry *terminator;
 120         struct omfs_extent_entry *entry = &oe->e_entry;
 121         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
 122         u32 extent_count = be32_to_cpu(oe->e_extent_count);
 123         u64 new_block = 0;
 124         u32 max_count;
 125         int new_count;
 126         int ret = 0;
 127
 128         /* reached the end of the extent table with no blocks mapped.
 129          * there are three possibilities for adding: grow last extent,
 130          * add a new extent to the current extent table, and add a
 131          * continuation inode.  in last two cases need an allocator for
 132          * sbi->s_cluster_size
 133          */
 134
 135         /* TODO: handle holes */
 136
 137         /* should always have a terminator */
 138         if (extent_count < 1)
 139                 return -EIO;
 140
 141         /* trivially grow current extent, if next block is not taken */
 142         terminator = entry + extent_count - 1;
 143         if (extent_count > 1) {
 144                 entry = terminator-1;
 145                 new_block = be64_to_cpu(entry->e_cluster) +
 146                         be64_to_cpu(entry->e_blocks);
 147
 148                 if (omfs_allocate_block(inode->i_sb, new_block)) {
 149                         entry->e_blocks =
 150                                 cpu_to_be64(be64_to_cpu(entry->e_blocks) + 1);
 151                         terminator->e_blocks = ~(cpu_to_be64(
 152                                 be64_to_cpu(~terminator->e_blocks) + 1));
 153                         goto out;
 154                 }
 155         }
 156         max_count = omfs_max_extents(sbi, OMFS_EXTENT_START);
 157
 158         /* TODO: add a continuation block here */
 159         if (be32_to_cpu(oe->e_extent_count) > max_count-1)
 160                 return -EIO;
 161
 162         /* try to allocate a new cluster */
 163         ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
 164                 &new_block, &new_count);
 165         if (ret)
 166                 goto out_fail;
 167
 168         /* copy terminator down an entry */
 169         entry = terminator;
 170         terminator++;
 171         memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
 172
 173         entry->e_cluster = cpu_to_be64(new_block);
 174         entry->e_blocks = cpu_to_be64((u64) new_count);
 175
 176         terminator->e_blocks = ~(cpu_to_be64(
 177                 be64_to_cpu(~terminator->e_blocks) + (u64) new_count));
 178
 179         /* write in new entry */
 180         oe->e_extent_count = cpu_to_be32(1 + be32_to_cpu(oe->e_extent_count));
 181
 182 out:
 183         *ret_block = new_block;
 184 out_fail:
 185         return ret;
 186 }
 187
 188 /*
 189  * Scans across the directory table for a given file block number.
 190  * If block not found, return 0.
 191  */
 192 static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
 193                         sector_t block, int count, int *left)
 194 {
 195         /* count > 1 because of terminator */
 196         sector_t searched = 0;
 197         for (; count > 1; count--) {
 198                 int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
 199                         be64_to_cpu(ent->e_blocks));
 200
 201                 if (block >= searched  &&
 202                     block < searched + numblocks) {
 203                         /*
 204                          * found it at cluster + (block - searched)
 205                          * numblocks - (block - searched) is remainder
 206                          */
 207                         *left = numblocks - (block - searched);
 208                         return clus_to_blk(OMFS_SB(inode->i_sb),
 209                                 be64_to_cpu(ent->e_cluster)) +
 210                                 block - searched;
 211                 }
 212                 searched += numblocks;
 213                 ent++;
 214         }
 215         return 0;
 216 }
 217
 218 static int omfs_get_block(struct inode *inode, sector_t block,
 219                           struct buffer_head *bh_result, int create)
 220 {
 221         struct buffer_head *bh;
 222         sector_t next, offset;
 223         int ret;
 224         u64 uninitialized_var(new_block);
 225         u32 max_extents;
 226         int extent_count;
 227         struct omfs_extent *oe;
 228         struct omfs_extent_entry *entry;
 229         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
 230         int max_blocks = bh_result->b_size >> inode->i_blkbits;
 231         int remain;
 232
 233         ret = -EIO;
 234         bh = omfs_bread(inode->i_sb, inode->i_ino);
 235         if (!bh)
 236                 goto out;
 237
 238         oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
 239         max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
 240         next = inode->i_ino;
 241
 242         for (;;) {
 243
 244                 if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
 245                         goto out_brelse;
 246
 247                 extent_count = be32_to_cpu(oe->e_extent_count);
 248                 next = be64_to_cpu(oe->e_next);
 249                 entry = &oe->e_entry;
 250
 251                 if (extent_count > max_extents)
 252                         goto out_brelse;
 253
 254                 offset = find_block(inode, entry, block, extent_count, &remain);
 255                 if (offset > 0) {
 256                         ret = 0;
 257                         map_bh(bh_result, inode->i_sb, offset);
 258                         if (remain > max_blocks)
 259                                 remain = max_blocks;
 260                         bh_result->b_size = (remain << inode->i_blkbits);
 261                         goto out_brelse;
 262                 }
 263                 if (next == ~0)
 264                         break;
 265
 266                 brelse(bh);
 267                 bh = omfs_bread(inode->i_sb, next);
 268                 if (!bh)
 269                         goto out;
 270                 oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
 271                 max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
 272         }
 273         if (create) {
 274                 ret = omfs_grow_extent(inode, oe, &new_block);
 275                 if (ret == 0) {
 276                         mark_buffer_dirty(bh);
 277                         mark_inode_dirty(inode);
 278                         map_bh(bh_result, inode->i_sb,
 279                                         clus_to_blk(sbi, new_block));
 280                 }
 281         }
 282 out_brelse:
 283         brelse(bh);
 284 out:
 285         return ret;
 286 }
 287
 288 static int omfs_readpage(struct file *file, struct page *page)
 289 {
 290         return block_read_full_page(page, omfs_get_block);
 291 }
 292
 293 static int omfs_readpages(struct file *file, struct address_space *mapping,
 294                 struct list_head *pages, unsigned nr_pages)
 295 {
 296         return mpage_readpages(mapping, pages, nr_pages, omfs_get_block);
 297 }
 298
 299 static int omfs_writepage(struct page *page, struct writeback_control *wbc)
 300 {
 301         return block_write_full_page(page, omfs_get_block, wbc);
 302 }
 303
 304 static int
 305 omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 306 {
 307         return mpage_writepages(mapping, wbc, omfs_get_block);
 308 }
 309
 310 static int omfs_write_begin(struct file *file, struct address_space *mapping,
 311                         loff_t pos, unsigned len, unsigned flags,
 312                         struct page **pagep, void **fsdata)
 313 {
 314         int ret;
 315
 316         ret = block_write_begin(mapping, pos, len, flags, pagep,
 317                                 omfs_get_block);
 318         if (unlikely(ret)) {
 319                 loff_t isize = mapping->host->i_size;
 320                 if (pos + len > isize)
 321                         vmtruncate(mapping->host, isize);
 322         }
 323
 324         return ret;
 325 }
 326
 327 static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
 328 {
 329         return generic_block_bmap(mapping, block, omfs_get_block);
 330 }
 331
 332 const struct file_operations omfs_file_operations = {
 333         .llseek = generic_file_llseek,
 334         .read = do_sync_read,
 335         .write = do_sync_write,
 336         .aio_read = generic_file_aio_read,
 337         .aio_write = generic_file_aio_write,
 338         .mmap = generic_file_mmap,
 339         .fsync = generic_file_fsync,
 340         .splice_read = generic_file_splice_read,
 341 };
 342
 343 static int omfs_setattr(struct dentry *dentry, struct iattr *attr)
 344 {
 345         struct inode *inode = dentry->d_inode;
 346         int error;
 347
 348         error = inode_change_ok(inode, attr);
 349         if (error)
 350                 return error;
 351
 352         if ((attr->ia_valid & ATTR_SIZE) &&
 353             attr->ia_size != i_size_read(inode)) {
 354                 error = vmtruncate(inode, attr->ia_size);
 355                 if (error)
 356                         return error;
 357         }
 358
 359         setattr_copy(inode, attr);
 360         mark_inode_dirty(inode);
 361         return 0;
 362 }
 363
 364 const struct inode_operations omfs_file_inops = {
 365         .setattr = omfs_setattr,
 366         .truncate = omfs_truncate
 367 };
 368
 369 const struct address_space_operations omfs_aops = {
 370         .readpage = omfs_readpage,
 371         .readpages = omfs_readpages,
 372         .writepage = omfs_writepage,
 373         .writepages = omfs_writepages,
 374         .write_begin = omfs_write_begin,
 375         .write_end = generic_write_end,
 376         .bmap = omfs_bmap,
 377 };
 378