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