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         /* FIXME: we could avoid this */
  50         if (search_for_position_by_key(sb, &end_key, path) == POSITION_FOUND) {
  51                 reiserfs_error(sb, "PAP-14030",
  52                                "pasted or inserted byte exists in "
  53                                "the tree %K. Use fsck to repair.", &end_key);
  54                 pathrelse(path);
  55                 return -EIO;
  56         }
  57
  58         p_le_ih = PATH_PITEM_HEAD(path);
  59
  60         unfm_ptr = cpu_to_le32(unbh->b_blocknr);
  61
  62         if (is_statdata_le_ih(p_le_ih)) {
  63                 /* Insert new indirect item. */
  64                 set_ih_free_space(&ind_ih, 0);  /* delete at nearest future */
  65                 put_ih_item_len(&ind_ih, UNFM_P_SIZE);
  66                 PATH_LAST_POSITION(path)++;
  67                 retval =
  68                     reiserfs_insert_item(th, path, &end_key, &ind_ih, inode,
  69                                          (char *)&unfm_ptr);
  70         } else {
  71                 /* Paste into last indirect item of an object. */
  72                 retval = reiserfs_paste_into_item(th, path, &end_key, inode,
  73                                                     (char *)&unfm_ptr,
  74                                                     UNFM_P_SIZE);
  75         }
  76         if (retval) {
  77                 return retval;
  78         }
  79         // note: from here there are two keys which have matching first
  80         // three key components. They only differ by the fourth one.
  81
  82         /* Set the key to search for the direct items of the file */
  83         make_cpu_key(&end_key, inode, max_reiserfs_offset(inode), TYPE_DIRECT,
  84                      4);
  85
  86         /* Move bytes from the direct items to the new unformatted node
  87            and delete them. */
  88         while (1) {
  89                 int tail_size;
  90
  91                 /* end_key.k_offset is set so, that we will always have found
  92                    last item of the file */
  93                 if (search_for_position_by_key(sb, &end_key, path) ==
  94                     POSITION_FOUND)
  95                         reiserfs_panic(sb, "PAP-14050",
  96                                        "direct item (%K) not found", &end_key);
  97                 p_le_ih = PATH_PITEM_HEAD(path);
  98                 RFALSE(!is_direct_le_ih(p_le_ih),
  99                        "vs-14055: direct item expected(%K), found %h",
 100                        &end_key, p_le_ih);
 101                 tail_size = (le_ih_k_offset(p_le_ih) & (blk_size - 1))
 102                     + ih_item_len(p_le_ih) - 1;
 103
 104                 /* we only send the unbh pointer if the buffer is not up to date.
 105                  ** this avoids overwriting good data from writepage() with old data
 106                  ** from the disk or buffer cache
 107                  ** Special case: unbh->b_page will be NULL if we are coming through
 108                  ** DIRECT_IO handler here.
 109                  */
 110                 if (!unbh->b_page || buffer_uptodate(unbh)
 111                     || PageUptodate(unbh->b_page)) {
 112                         up_to_date_bh = NULL;
 113                 } else {
 114                         up_to_date_bh = unbh;
 115                 }
 116                 retval = reiserfs_delete_item(th, path, &end_key, inode,
 117                                                 up_to_date_bh);
 118
 119                 total_tail += retval;
 120                 if (tail_size == retval)
 121                         // done: file does not have direct items anymore
 122                         break;
 123
 124         }
 125         /* if we've copied bytes from disk into the page, we need to zero
 126          ** out the unused part of the block (it was not up to date before)
 127          */
 128         if (up_to_date_bh) {
 129                 unsigned pgoff =
 130                     (tail_offset + total_tail - 1) & (PAGE_CACHE_SIZE - 1);
 131                 char *kaddr = kmap_atomic(up_to_date_bh->b_page, KM_USER0);
 132                 memset(kaddr + pgoff, 0, blk_size - total_tail);
 133                 kunmap_atomic(kaddr, KM_USER0);
 134         }
 135
 136         REISERFS_I(inode)->i_first_direct_byte = U32_MAX;
 137
 138         return 0;
 139 }
 140
 141 /* stolen from fs/buffer.c */
 142 void reiserfs_unmap_buffer(struct buffer_head *bh)
 143 {
 144         lock_buffer(bh);
 145         if (buffer_journaled(bh) || buffer_journal_dirty(bh)) {
 146                 BUG();
 147         }
 148         clear_buffer_dirty(bh);
 149         /* Remove the buffer from whatever list it belongs to. We are mostly
 150            interested in removing it from per-sb j_dirty_buffers list, to avoid
 151            BUG() on attempt to write not mapped buffer */
 152         if ((!list_empty(&bh->b_assoc_buffers) || bh->b_private) && bh->b_page) {
 153                 struct inode *inode = bh->b_page->mapping->host;
 154                 struct reiserfs_journal *j = SB_JOURNAL(inode->i_sb);
 155                 spin_lock(&j->j_dirty_buffers_lock);
 156                 list_del_init(&bh->b_assoc_buffers);
 157                 reiserfs_free_jh(bh);
 158                 spin_unlock(&j->j_dirty_buffers_lock);
 159         }
 160         clear_buffer_mapped(bh);
 161         clear_buffer_req(bh);
 162         clear_buffer_new(bh);
 163         bh->b_bdev = NULL;
 164         unlock_buffer(bh);
 165 }
 166
 167 /* this first locks inode (neither reads nor sync are permitted),
 168    reads tail through page cache, insert direct item. When direct item
 169    inserted successfully inode is left locked. Return value is always
 170    what we expect from it (number of cut bytes). But when tail remains
 171    in the unformatted node, we set mode to SKIP_BALANCING and unlock
 172    inode */
 173 int indirect2direct(struct reiserfs_transaction_handle *th,
 174                     struct inode *inode, struct page *page,
 175                     struct treepath *path,      /* path to the indirect item. */
 176                     const struct cpu_key *item_key,     /* Key to look for
 177                                                          * unformatted node
 178                                                          * pointer to be cut. */
 179                     loff_t n_new_file_size,     /* New file size. */
 180                     char *mode)
 181 {
 182         struct super_block *sb = inode->i_sb;
 183         struct item_head s_ih;
 184         unsigned long block_size = sb->s_blocksize;
 185         char *tail;
 186         int tail_len, round_tail_len;
 187         loff_t pos, pos1;       /* position of first byte of the tail */
 188         struct cpu_key key;
 189
 190         BUG_ON(!th->t_trans_id);
 191
 192         REISERFS_SB(sb)->s_indirect2direct++;
 193
 194         *mode = M_SKIP_BALANCING;
 195
 196         /* store item head path points to. */
 197         copy_item_head(&s_ih, PATH_PITEM_HEAD(path));
 198
 199         tail_len = (n_new_file_size & (block_size - 1));
 200         if (get_inode_sd_version(inode) == STAT_DATA_V2)
 201                 round_tail_len = ROUND_UP(tail_len);
 202         else
 203                 round_tail_len = tail_len;
 204
 205         pos =
 206             le_ih_k_offset(&s_ih) - 1 + (ih_item_len(&s_ih) / UNFM_P_SIZE -
 207                                          1) * sb->s_blocksize;
 208         pos1 = pos;
 209
 210         // we are protected by i_mutex. The tail can not disapper, not
 211         // append can be done either
 212         // we are in truncate or packing tail in file_release
 213
 214         tail = (char *)kmap(page);      /* this can schedule */
 215
 216         if (path_changed(&s_ih, path)) {
 217                 /* re-search indirect item */
 218                 if (search_for_position_by_key(sb, item_key, path)
 219                     == POSITION_NOT_FOUND)
 220                         reiserfs_panic(sb, "PAP-5520",
 221                                        "item to be converted %K does not exist",
 222                                        item_key);
 223                 copy_item_head(&s_ih, PATH_PITEM_HEAD(path));
 224 #ifdef CONFIG_REISERFS_CHECK
 225                 pos = le_ih_k_offset(&s_ih) - 1 +
 226                     (ih_item_len(&s_ih) / UNFM_P_SIZE -
 227                      1) * sb->s_blocksize;
 228                 if (pos != pos1)
 229                         reiserfs_panic(sb, "vs-5530", "tail position "
 230                                        "changed while we were reading it");
 231 #endif
 232         }
 233
 234         /* Set direct item header to insert. */
 235         make_le_item_head(&s_ih, NULL, get_inode_item_key_version(inode),
 236                           pos1 + 1, TYPE_DIRECT, round_tail_len,
 237                           0xffff /*ih_free_space */ );
 238
 239         /* we want a pointer to the first byte of the tail in the page.
 240          ** the page was locked and this part of the page was up to date when
 241          ** indirect2direct was called, so we know the bytes are still valid
 242          */
 243         tail = tail + (pos & (PAGE_CACHE_SIZE - 1));
 244
 245         PATH_LAST_POSITION(path)++;
 246
 247         key = *item_key;
 248         set_cpu_key_k_type(&key, TYPE_DIRECT);
 249         key.key_length = 4;
 250         /* Insert tail as new direct item in the tree */
 251         if (reiserfs_insert_item(th, path, &key, &s_ih, inode,
 252                                  tail ? tail : NULL) < 0) {
 253                 /* No disk memory. So we can not convert last unformatted node
 254                    to the direct item.  In this case we used to adjust
 255                    indirect items's ih_free_space. Now ih_free_space is not
 256                    used, it would be ideal to write zeros to corresponding
 257                    unformatted node. For now i_size is considered as guard for
 258                    going out of file size */
 259                 kunmap(page);
 260                 return block_size - round_tail_len;
 261         }
 262         kunmap(page);
 263
 264         /* make sure to get the i_blocks changes from reiserfs_insert_item */
 265         reiserfs_update_sd(th, inode);
 266
 267         // note: we have now the same as in above direct2indirect
 268         // conversion: there are two keys which have matching first three
 269         // key components. They only differ by the fouhth one.
 270
 271         /* We have inserted new direct item and must remove last
 272            unformatted node. */
 273         *mode = M_CUT;
 274
 275         /* we store position of first direct item in the in-core inode */
 276         /* mark_file_with_tail (inode, pos1 + 1); */
 277         REISERFS_I(inode)->i_first_direct_byte = pos1 + 1;
 278
 279         return block_size - round_tail_len;
 280 }