fs/reiserfs/tail_conversion.c

   1 /*
   2  * Copyright 1999 Hans Reiser, see reiserfs/README for licensing and copyright
   3  * details
   4  */
   5
   6 #include <linux/time.h>
   7 #include <linux/pagemap.h>
   8 #include <linux/buffer_head.h>
   9 #include "reiserfs.h"
  10
  11 /*
  12  * access to tail : when one is going to read tail it must make sure, that is
  13  * not running.  direct2indirect and indirect2direct can not run concurrently
  14  */
  15
  16 /*
  17  * Converts direct items to an unformatted node. Panics if file has no
  18  * tail. -ENOSPC if no disk space for conversion
  19  */
  20 /*
  21  * path points to first direct item of the file regardless of how many of
  22  * them are there
  23  */
  24 int direct2indirect(struct reiserfs_transaction_handle *th, struct inode *inode,
  25                     struct treepath *path, struct buffer_head *unbh,
  26                     loff_t tail_offset)
  27 {
  28         struct super_block *sb = inode->i_sb;
  29         struct buffer_head *up_to_date_bh;
  30         struct item_head *p_le_ih = tp_item_head(path);
  31         unsigned long total_tail = 0;
  32
  33         /* Key to search for the last byte of the converted item. */
  34         struct cpu_key end_key;
  35
  36         /*
  37          * new indirect item to be inserted or key
  38          * of unfm pointer to be pasted
  39          */
  40         struct item_head ind_ih;
  41         int blk_size;
  42         /* returned value for reiserfs_insert_item and clones */
  43         int  retval;
  44         /* Handle on an unformatted node that will be inserted in the tree. */
  45         unp_t unfm_ptr;
  46
  47         BUG_ON(!th->t_trans_id);
  48
  49         REISERFS_SB(sb)->s_direct2indirect++;
  50
  51         blk_size = sb->s_blocksize;
  52
  53         /*
  54          * and key to search for append or insert pointer to the new
  55          * unformatted node.
  56          */
  57         copy_item_head(&ind_ih, p_le_ih);
  58         set_le_ih_k_offset(&ind_ih, tail_offset);
  59         set_le_ih_k_type(&ind_ih, TYPE_INDIRECT);
  60
  61         /* Set the key to search for the place for new unfm pointer */
  62         make_cpu_key(&end_key, inode, tail_offset, TYPE_INDIRECT, 4);
  63
  64         /* FIXME: we could avoid this */
  65         if (search_for_position_by_key(sb, &end_key, path) == POSITION_FOUND) {
  66                 reiserfs_error(sb, "PAP-14030",
  67                                "pasted or inserted byte exists in "
  68                                "the tree %K. Use fsck to repair.", &end_key);
  69                 pathrelse(path);
  70                 return -EIO;
  71         }
  72
  73         p_le_ih = tp_item_head(path);
  74
  75         unfm_ptr = cpu_to_le32(unbh->b_blocknr);
  76
  77         if (is_statdata_le_ih(p_le_ih)) {
  78                 /* Insert new indirect item. */
  79                 set_ih_free_space(&ind_ih, 0);  /* delete at nearest future */
  80                 put_ih_item_len(&ind_ih, UNFM_P_SIZE);
  81                 PATH_LAST_POSITION(path)++;
  82                 retval =
  83                     reiserfs_insert_item(th, path, &end_key, &ind_ih, inode,
  84                                          (char *)&unfm_ptr);
  85         } else {
  86                 /* Paste into last indirect item of an object. */
  87                 retval = reiserfs_paste_into_item(th, path, &end_key, inode,
  88                                                     (char *)&unfm_ptr,
  89                                                     UNFM_P_SIZE);
  90         }
  91         if (retval) {
  92                 return retval;
  93         }
  94         /*
  95          * note: from here there are two keys which have matching first
  96          *  three key components. They only differ by the fourth one.
  97          */
  98
  99         /* Set the key to search for the direct items of the file */
 100         make_cpu_key(&end_key, inode, max_reiserfs_offset(inode), TYPE_DIRECT,
 101                      4);
 102
 103         /*
 104          * Move bytes from the direct items to the new unformatted node
 105          * and delete them.
 106          */
 107         while (1) {
 108                 int tail_size;
 109
 110                 /*
 111                  * end_key.k_offset is set so, that we will always have found
 112                  * last item of the file
 113                  */
 114                 if (search_for_position_by_key(sb, &end_key, path) ==
 115                     POSITION_FOUND)
 116                         reiserfs_panic(sb, "PAP-14050",
 117                                        "direct item (%K) not found", &end_key);
 118                 p_le_ih = tp_item_head(path);
 119                 RFALSE(!is_direct_le_ih(p_le_ih),
 120                        "vs-14055: direct item expected(%K), found %h",
 121                        &end_key, p_le_ih);
 122                 tail_size = (le_ih_k_offset(p_le_ih) & (blk_size - 1))
 123                     + ih_item_len(p_le_ih) - 1;
 124
 125                 /*
 126                  * we only send the unbh pointer if the buffer is not
 127                  * up to date.  this avoids overwriting good data from
 128                  * writepage() with old data from the disk or buffer cache
 129                  * Special case: unbh->b_page will be NULL if we are coming
 130                  * through DIRECT_IO handler here.
 131                  */
 132                 if (!unbh->b_page || buffer_uptodate(unbh)
 133                     || PageUptodate(unbh->b_page)) {
 134                         up_to_date_bh = NULL;
 135                 } else {
 136                         up_to_date_bh = unbh;
 137                 }
 138                 retval = reiserfs_delete_item(th, path, &end_key, inode,
 139                                                 up_to_date_bh);
 140
 141                 total_tail += retval;
 142
 143                 /* done: file does not have direct items anymore */
 144                 if (tail_size == retval)
 145                         break;
 146
 147         }
 148         /*
 149          * if we've copied bytes from disk into the page, we need to zero
 150          * out the unused part of the block (it was not up to date before)
 151          */
 152         if (up_to_date_bh) {
 153                 unsigned pgoff =
 154                     (tail_offset + total_tail - 1) & (PAGE_CACHE_SIZE - 1);
 155                 char *kaddr = kmap_atomic(up_to_date_bh->b_page);
 156                 memset(kaddr + pgoff, 0, blk_size - total_tail);
 157                 kunmap_atomic(kaddr);
 158         }
 159
 160         REISERFS_I(inode)->i_first_direct_byte = U32_MAX;
 161
 162         return 0;
 163 }
 164
 165 /* stolen from fs/buffer.c */
 166 void reiserfs_unmap_buffer(struct buffer_head *bh)
 167 {
 168         lock_buffer(bh);
 169         if (buffer_journaled(bh) || buffer_journal_dirty(bh)) {
 170                 BUG();
 171         }
 172         clear_buffer_dirty(bh);
 173         /*
 174          * Remove the buffer from whatever list it belongs to. We are mostly
 175          * interested in removing it from per-sb j_dirty_buffers list, to avoid
 176          * BUG() on attempt to write not mapped buffer
 177          */
 178         if ((!list_empty(&bh->b_assoc_buffers) || bh->b_private) && bh->b_page) {
 179                 struct inode *inode = bh->b_page->mapping->host;
 180                 struct reiserfs_journal *j = SB_JOURNAL(inode->i_sb);
 181                 spin_lock(&j->j_dirty_buffers_lock);
 182                 list_del_init(&bh->b_assoc_buffers);
 183                 reiserfs_free_jh(bh);
 184                 spin_unlock(&j->j_dirty_buffers_lock);
 185         }
 186         clear_buffer_mapped(bh);
 187         clear_buffer_req(bh);
 188         clear_buffer_new(bh);
 189         bh->b_bdev = NULL;
 190         unlock_buffer(bh);
 191 }
 192
 193 /*
 194  * this first locks inode (neither reads nor sync are permitted),
 195  * reads tail through page cache, insert direct item. When direct item
 196  * inserted successfully inode is left locked. Return value is always
 197  * what we expect from it (number of cut bytes). But when tail remains
 198  * in the unformatted node, we set mode to SKIP_BALANCING and unlock
 199  * inode
 200  */
 201 int indirect2direct(struct reiserfs_transaction_handle *th,
 202                     struct inode *inode, struct page *page,
 203                     struct treepath *path,      /* path to the indirect item. */
 204                     const struct cpu_key *item_key,     /* Key to look for
 205                                                          * unformatted node
 206                                                          * pointer to be cut. */
 207                     loff_t n_new_file_size,     /* New file size. */
 208                     char *mode)
 209 {
 210         struct super_block *sb = inode->i_sb;
 211         struct item_head s_ih;
 212         unsigned long block_size = sb->s_blocksize;
 213         char *tail;
 214         int tail_len, round_tail_len;
 215         loff_t pos, pos1;       /* position of first byte of the tail */
 216         struct cpu_key key;
 217
 218         BUG_ON(!th->t_trans_id);
 219
 220         REISERFS_SB(sb)->s_indirect2direct++;
 221
 222         *mode = M_SKIP_BALANCING;
 223
 224         /* store item head path points to. */
 225         copy_item_head(&s_ih, tp_item_head(path));
 226
 227         tail_len = (n_new_file_size & (block_size - 1));
 228         if (get_inode_sd_version(inode) == STAT_DATA_V2)
 229                 round_tail_len = ROUND_UP(tail_len);
 230         else
 231                 round_tail_len = tail_len;
 232
 233         pos =
 234             le_ih_k_offset(&s_ih) - 1 + (ih_item_len(&s_ih) / UNFM_P_SIZE -
 235                                          1) * sb->s_blocksize;
 236         pos1 = pos;
 237
 238         /*
 239          * we are protected by i_mutex. The tail can not disapper, not
 240          * append can be done either
 241          * we are in truncate or packing tail in file_release
 242          */
 243
 244         tail = (char *)kmap(page);      /* this can schedule */
 245
 246         if (path_changed(&s_ih, path)) {
 247                 /* re-search indirect item */
 248                 if (search_for_position_by_key(sb, item_key, path)
 249                     == POSITION_NOT_FOUND)
 250                         reiserfs_panic(sb, "PAP-5520",
 251                                        "item to be converted %K does not exist",
 252                                        item_key);
 253                 copy_item_head(&s_ih, tp_item_head(path));
 254 #ifdef CONFIG_REISERFS_CHECK
 255                 pos = le_ih_k_offset(&s_ih) - 1 +
 256                     (ih_item_len(&s_ih) / UNFM_P_SIZE -
 257                      1) * sb->s_blocksize;
 258                 if (pos != pos1)
 259                         reiserfs_panic(sb, "vs-5530", "tail position "
 260                                        "changed while we were reading it");
 261 #endif
 262         }
 263
 264         /* Set direct item header to insert. */
 265         make_le_item_head(&s_ih, NULL, get_inode_item_key_version(inode),
 266                           pos1 + 1, TYPE_DIRECT, round_tail_len,
 267                           0xffff /*ih_free_space */ );
 268
 269         /*
 270          * we want a pointer to the first byte of the tail in the page.
 271          * the page was locked and this part of the page was up to date when
 272          * indirect2direct was called, so we know the bytes are still valid
 273          */
 274         tail = tail + (pos & (PAGE_CACHE_SIZE - 1));
 275
 276         PATH_LAST_POSITION(path)++;
 277
 278         key = *item_key;
 279         set_cpu_key_k_type(&key, TYPE_DIRECT);
 280         key.key_length = 4;
 281         /* Insert tail as new direct item in the tree */
 282         if (reiserfs_insert_item(th, path, &key, &s_ih, inode,
 283                                  tail ? tail : NULL) < 0) {
 284                 /*
 285                  * No disk memory. So we can not convert last unformatted node
 286                  * to the direct item.  In this case we used to adjust
 287                  * indirect items's ih_free_space. Now ih_free_space is not
 288                  * used, it would be ideal to write zeros to corresponding
 289                  * unformatted node. For now i_size is considered as guard for
 290                  * going out of file size
 291                  */
 292                 kunmap(page);
 293                 return block_size - round_tail_len;
 294         }
 295         kunmap(page);
 296
 297         /* make sure to get the i_blocks changes from reiserfs_insert_item */
 298         reiserfs_update_sd(th, inode);
 299
 300         /*
 301          * note: we have now the same as in above direct2indirect
 302          * conversion: there are two keys which have matching first three
 303          * key components. They only differ by the fourth one.
 304          */
 305
 306         /*
 307          * We have inserted new direct item and must remove last
 308          * unformatted node.
 309          */
 310         *mode = M_CUT;
 311
 312         /* we store position of first direct item in the in-core inode */
 313         /* mark_file_with_tail (inode, pos1 + 1); */
 314         REISERFS_I(inode)->i_first_direct_byte = pos1 + 1;
 315
 316         return block_size - round_tail_len;
 317 }