release/src-rt-6.x.4708/linux/linux-2.6.36/fs/reiserfs/tail_conversion.c

   1 /*
   2  * Copyright 1999 Hans Reiser, see reiserfs/README for licensing and copyright details
   3  */
   4
   5 #include <linux/time.h>
   6 #include <linux/pagemap.h>
   7 #include <linux/buffer_head.h>
   8 #include <linux/reiserfs_fs.h>
   9
  10 /* access to tail : when one is going to read tail it must make sure, that is not running.
  11  direct2indirect and indirect2direct can not run concurrently */
  12
  13 /* Converts direct items to an unformatted node. Panics if file has no
  14    tail. -ENOSPC if no disk space for conversion */
  15 /* path points to first direct item of the file regarless of how many of
  16    them are there */
  17 int direct2indirect(struct reiserfs_transaction_handle *th, struct inode *inode,
  18                     struct treepath *path, struct buffer_head *unbh,
  19                     loff_t tail_offset)
  20 {
  21         struct super_block *sb = inode->i_sb;
  22         struct buffer_head *up_to_date_bh;
  23         struct item_head *p_le_ih = PATH_PITEM_HEAD(path);
  24         unsigned long total_tail = 0;
  25         struct cpu_key end_key; /* Key to search for the last byte of the
  26                                    converted item. */
  27         struct item_head ind_ih;        /* new indirect item to be inserted or
  28                                            key of unfm pointer to be pasted */
  29         int blk_size, retval;   /* returned value for reiserfs_insert_item and clones */
  30         unp_t unfm_ptr;         /* Handle on an unformatted node
  31                                    that will be inserted in the
  32                                    tree. */
  33
  34         BUG_ON(!th->t_trans_id);
  35
  36         REISERFS_SB(sb)->s_direct2indirect++;
  37
  38         blk_size = sb->s_blocksize;
  39
  40         /* and key to search for append or insert pointer to the new
  41            unformatted node. */
  42         copy_item_head(&ind_ih, p_le_ih);
  43         set_le_ih_k_offset(&ind_ih, tail_offset);
  44         set_le_ih_k_type(&ind_ih, TYPE_INDIRECT);
  45
  46         /* Set the key to search for the place for new unfm pointer */
  47         make_cpu_key(&end_key, inode, tail_offset, TYPE_INDIRECT, 4);
  48
  49         if (search_for_position_by_key(sb, &end_key, path) == POSITION_FOUND) {
  50                 reiserfs_error(sb, "PAP-14030",
  51                                "pasted or inserted byte exists in "
  52                                "the tree %K. Use fsck to repair.", &end_key);
  53                 pathrelse(path);
  54                 return -EIO;
  55         }
  56
  57         p_le_ih = PATH_PITEM_HEAD(path);
  58
  59         unfm_ptr = cpu_to_le32(unbh->b_blocknr);
  60
  61         if (is_statdata_le_ih(p_le_ih)) {
  62                 /* Insert new indirect item. */
  63                 set_ih_free_space(&ind_ih, 0);  /* delete at nearest future */
  64                 put_ih_item_len(&ind_ih, UNFM_P_SIZE);
  65                 PATH_LAST_POSITION(path)++;
  66                 retval =
  67                     reiserfs_insert_item(th, path, &end_key, &ind_ih, inode,
  68                                          (char *)&unfm_ptr);
  69         } else {
  70                 /* Paste into last indirect item of an object. */
  71                 retval = reiserfs_paste_into_item(th, path, &end_key, inode,
  72                                                     (char *)&unfm_ptr,
  73                                                     UNFM_P_SIZE);
  74         }
  75         if (retval) {
  76                 return retval;
  77         }
  78         // note: from here there are two keys which have matching first
  79         // three key components. They only differ by the fourth one.
  80
  81         /* Set the key to search for the direct items of the file */
  82         make_cpu_key(&end_key, inode, max_reiserfs_offset(inode), TYPE_DIRECT,
  83                      4);
  84
  85         /* Move bytes from the direct items to the new unformatted node
  86            and delete them. */
  87         while (1) {
  88                 int tail_size;
  89
  90                 /* end_key.k_offset is set so, that we will always have found
  91                    last item of the file */
  92                 if (search_for_position_by_key(sb, &end_key, path) ==
  93                     POSITION_FOUND)
  94                         reiserfs_panic(sb, "PAP-14050",
  95                                        "direct item (%K) not found", &end_key);
  96                 p_le_ih = PATH_PITEM_HEAD(path);
  97                 RFALSE(!is_direct_le_ih(p_le_ih),
  98                        "vs-14055: direct item expected(%K), found %h",
  99                        &end_key, p_le_ih);
 100                 tail_size = (le_ih_k_offset(p_le_ih) & (blk_size - 1))
 101                     + ih_item_len(p_le_ih) - 1;
 102
 103                 /* we only send the unbh pointer if the buffer is not up to date.
 104                  ** this avoids overwriting good data from writepage() with old data
 105                  ** from the disk or buffer cache
 106                  ** Special case: unbh->b_page will be NULL if we are coming through
 107                  ** DIRECT_IO handler here.
 108                  */
 109                 if (!unbh->b_page || buffer_uptodate(unbh)
 110                     || PageUptodate(unbh->b_page)) {
 111                         up_to_date_bh = NULL;
 112                 } else {
 113                         up_to_date_bh = unbh;
 114                 }
 115                 retval = reiserfs_delete_item(th, path, &end_key, inode,
 116                                                 up_to_date_bh);
 117
 118                 total_tail += retval;
 119                 if (tail_size == retval)
 120                         // done: file does not have direct items anymore
 121                         break;
 122
 123         }
 124         /* if we've copied bytes from disk into the page, we need to zero
 125          ** out the unused part of the block (it was not up to date before)
 126          */
 127         if (up_to_date_bh) {
 128                 unsigned pgoff =
 129                     (tail_offset + total_tail - 1) & (PAGE_CACHE_SIZE - 1);
 130                 char *kaddr = kmap_atomic(up_to_date_bh->b_page, KM_USER0);
 131                 memset(kaddr + pgoff, 0, blk_size - total_tail);
 132                 kunmap_atomic(kaddr, KM_USER0);
 133         }
 134
 135         REISERFS_I(inode)->i_first_direct_byte = U32_MAX;
 136
 137         return 0;
 138 }
 139
 140 /* stolen from fs/buffer.c */
 141 void reiserfs_unmap_buffer(struct buffer_head *bh)
 142 {
 143         lock_buffer(bh);
 144         if (buffer_journaled(bh) || buffer_journal_dirty(bh)) {
 145                 BUG();
 146         }
 147         clear_buffer_dirty(bh);
 148         /* Remove the buffer from whatever list it belongs to. We are mostly
 149            interested in removing it from per-sb j_dirty_buffers list, to avoid
 150            BUG() on attempt to write not mapped buffer */
 151         if ((!list_empty(&bh->b_assoc_buffers) || bh->b_private) && bh->b_page) {
 152                 struct inode *inode = bh->b_page->mapping->host;
 153                 struct reiserfs_journal *j = SB_JOURNAL(inode->i_sb);
 154                 spin_lock(&j->j_dirty_buffers_lock);
 155                 list_del_init(&bh->b_assoc_buffers);
 156                 reiserfs_free_jh(bh);
 157                 spin_unlock(&j->j_dirty_buffers_lock);
 158         }
 159         clear_buffer_mapped(bh);
 160         clear_buffer_req(bh);
 161         clear_buffer_new(bh);
 162         bh->b_bdev = NULL;
 163         unlock_buffer(bh);
 164 }
 165
 166 /* this first locks inode (neither reads nor sync are permitted),
 167    reads tail through page cache, insert direct item. When direct item
 168    inserted successfully inode is left locked. Return value is always
 169    what we expect from it (number of cut bytes). But when tail remains
 170    in the unformatted node, we set mode to SKIP_BALANCING and unlock
 171    inode */
 172 int indirect2direct(struct reiserfs_transaction_handle *th,
 173                     struct inode *inode, struct page *page,
 174                     struct treepath *path,      /* path to the indirect item. */
 175                     const struct cpu_key *item_key,     /* Key to look for
 176                                                          * unformatted node
 177                                                          * pointer to be cut. */
 178                     loff_t n_new_file_size,     /* New file size. */
 179                     char *mode)
 180 {
 181         struct super_block *sb = inode->i_sb;
 182         struct item_head s_ih;
 183         unsigned long block_size = sb->s_blocksize;
 184         char *tail;
 185         int tail_len, round_tail_len;
 186         loff_t pos, pos1;       /* position of first byte of the tail */
 187         struct cpu_key key;
 188
 189         BUG_ON(!th->t_trans_id);
 190
 191         REISERFS_SB(sb)->s_indirect2direct++;
 192
 193         *mode = M_SKIP_BALANCING;
 194
 195         /* store item head path points to. */
 196         copy_item_head(&s_ih, PATH_PITEM_HEAD(path));
 197
 198         tail_len = (n_new_file_size & (block_size - 1));
 199         if (get_inode_sd_version(inode) == STAT_DATA_V2)
 200                 round_tail_len = ROUND_UP(tail_len);
 201         else
 202                 round_tail_len = tail_len;
 203
 204         pos =
 205             le_ih_k_offset(&s_ih) - 1 + (ih_item_len(&s_ih) / UNFM_P_SIZE -
 206                                          1) * sb->s_blocksize;
 207         pos1 = pos;
 208
 209         // we are protected by i_mutex. The tail can not disapper, not
 210         // append can be done either
 211         // we are in truncate or packing tail in file_release
 212
 213         tail = (char *)kmap(page);      /* this can schedule */
 214
 215         if (path_changed(&s_ih, path)) {
 216                 /* re-search indirect item */
 217                 if (search_for_position_by_key(sb, item_key, path)
 218                     == POSITION_NOT_FOUND)
 219                         reiserfs_panic(sb, "PAP-5520",
 220                                        "item to be converted %K does not exist",
 221                                        item_key);
 222                 copy_item_head(&s_ih, PATH_PITEM_HEAD(path));
 223 #ifdef CONFIG_REISERFS_CHECK
 224                 pos = le_ih_k_offset(&s_ih) - 1 +
 225                     (ih_item_len(&s_ih) / UNFM_P_SIZE -
 226                      1) * sb->s_blocksize;
 227                 if (pos != pos1)
 228                         reiserfs_panic(sb, "vs-5530", "tail position "
 229                                        "changed while we were reading it");
 230 #endif
 231         }
 232
 233         /* Set direct item header to insert. */
 234         make_le_item_head(&s_ih, NULL, get_inode_item_key_version(inode),
 235                           pos1 + 1, TYPE_DIRECT, round_tail_len,
 236                           0xffff /*ih_free_space */ );
 237
 238         /* we want a pointer to the first byte of the tail in the page.
 239          ** the page was locked and this part of the page was up to date when
 240          ** indirect2direct was called, so we know the bytes are still valid
 241          */
 242         tail = tail + (pos & (PAGE_CACHE_SIZE - 1));
 243
 244         PATH_LAST_POSITION(path)++;
 245
 246         key = *item_key;
 247         set_cpu_key_k_type(&key, TYPE_DIRECT);
 248         key.key_length = 4;
 249         /* Insert tail as new direct item in the tree */
 250         if (reiserfs_insert_item(th, path, &key, &s_ih, inode,
 251                                  tail ? tail : NULL) < 0) {
 252                 /* No disk memory. So we can not convert last unformatted node
 253                    to the direct item.  In this case we used to adjust
 254                    indirect items's ih_free_space. Now ih_free_space is not
 255                    used, it would be ideal to write zeros to corresponding
 256                    unformatted node. For now i_size is considered as guard for
 257                    going out of file size */
 258                 kunmap(page);
 259                 return block_size - round_tail_len;
 260         }
 261         kunmap(page);
 262
 263         /* make sure to get the i_blocks changes from reiserfs_insert_item */
 264         reiserfs_update_sd(th, inode);
 265
 266         // note: we have now the same as in above direct2indirect
 267         // conversion: there are two keys which have matching first three
 268         // key components. They only differ by the fouhth one.
 269
 270         /* We have inserted new direct item and must remove last
 271            unformatted node. */
 272         *mode = M_CUT;
 273
 274         /* we store position of first direct item in the in-core inode */
 275         /* mark_file_with_tail (inode, pos1 + 1); */
 276         REISERFS_I(inode)->i_first_direct_byte = pos1 + 1;
 277
 278         return block_size - round_tail_len;
 279 }