linux/fs/reiserfs/tail_conversion.c
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   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 */
  24int 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 */
 166void 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 */
 201int 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}
 318