git.oblomov.eu Git - linux-2.6/blob - fs/reiserfs/tail_conversion.c

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