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 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