fs/bfs/file.c

   1 /*
   2  *      fs/bfs/file.c
   3  *      BFS file operations.
   4  *      Copyright (C) 1999,2000 Tigran Aivazian <tigran@veritas.com>
   5  */
   6
   7 #include <linux/fs.h>
   8 #include <linux/buffer_head.h>
   9 #include <linux/smp_lock.h>
  10 #include "bfs.h"
  11
  12 #undef DEBUG
  13
  14 #ifdef DEBUG
  15 #define dprintf(x...)   printf(x)
  16 #else
  17 #define dprintf(x...)
  18 #endif
  19
  20 const struct file_operations bfs_file_operations = {
  21         .llseek         = generic_file_llseek,
  22         .read           = do_sync_read,
  23         .aio_read       = generic_file_aio_read,
  24         .write          = do_sync_write,
  25         .aio_write      = generic_file_aio_write,
  26         .mmap           = generic_file_mmap,
  27         .sendfile       = generic_file_sendfile,
  28 };
  29
  30 static int bfs_move_block(unsigned long from, unsigned long to, struct super_block *sb)
  31 {
  32         struct buffer_head *bh, *new;
  33
  34         bh = sb_bread(sb, from);
  35         if (!bh)
  36                 return -EIO;
  37         new = sb_getblk(sb, to);
  38         memcpy(new->b_data, bh->b_data, bh->b_size);
  39         mark_buffer_dirty(new);
  40         bforget(bh);
  41         brelse(new);
  42         return 0;
  43 }
  44
  45 static int bfs_move_blocks(struct super_block *sb, unsigned long start,
  46                            unsigned long end, unsigned long where)
  47 {
  48         unsigned long i;
  49
  50         dprintf("%08lx-%08lx->%08lx\n", start, end, where);
  51         for (i = start; i <= end; i++)
  52                 if(bfs_move_block(i, where + i, sb)) {
  53                         dprintf("failed to move block %08lx -> %08lx\n", i, where + i);
  54                         return -EIO;
  55                 }
  56         return 0;
  57 }
  58
  59 static int bfs_get_block(struct inode * inode, sector_t block,
  60         struct buffer_head * bh_result, int create)
  61 {
  62         unsigned long phys;
  63         int err;
  64         struct super_block *sb = inode->i_sb;
  65         struct bfs_sb_info *info = BFS_SB(sb);
  66         struct bfs_inode_info *bi = BFS_I(inode);
  67         struct buffer_head *sbh = info->si_sbh;
  68
  69         if (block > info->si_blocks)
  70                 return -EIO;
  71
  72         phys = bi->i_sblock + block;
  73         if (!create) {
  74                 if (phys <= bi->i_eblock) {
  75                         dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n",
  76                                 create, (unsigned long)block, phys);
  77                         map_bh(bh_result, sb, phys);
  78                 }
  79                 return 0;
  80         }
  81
  82         /* if the file is not empty and the requested block is within the range
  83            of blocks allocated for this file, we can grant it */
  84         if (inode->i_size && phys <= bi->i_eblock) {
  85                 dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n",
  86                                 create, (unsigned long)block, phys);
  87                 map_bh(bh_result, sb, phys);
  88                 return 0;
  89         }
  90
  91         /* the rest has to be protected against itself */
  92         lock_kernel();
  93
  94         /* if the last data block for this file is the last allocated
  95            block, we can extend the file trivially, without moving it
  96            anywhere */
  97         if (bi->i_eblock == info->si_lf_eblk) {
  98                 dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n",
  99                                 create, (unsigned long)block, phys);
 100                 map_bh(bh_result, sb, phys);
 101                 info->si_freeb -= phys - bi->i_eblock;
 102                 info->si_lf_eblk = bi->i_eblock = phys;
 103                 mark_inode_dirty(inode);
 104                 mark_buffer_dirty(sbh);
 105                 err = 0;
 106                 goto out;
 107         }
 108
 109         /* Ok, we have to move this entire file to the next free block */
 110         phys = info->si_lf_eblk + 1;
 111         if (bi->i_sblock) { /* if data starts on block 0 then there is no data */
 112                 err = bfs_move_blocks(inode->i_sb, bi->i_sblock,
 113                                 bi->i_eblock, phys);
 114                 if (err) {
 115                         dprintf("failed to move ino=%08lx -> fs corruption\n", inode->i_ino);
 116                         goto out;
 117                 }
 118         } else
 119                 err = 0;
 120
 121         dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n",
 122                 create, (unsigned long)block, phys);
 123         bi->i_sblock = phys;
 124         phys += block;
 125         info->si_lf_eblk = bi->i_eblock = phys;
 126
 127         /* this assumes nothing can write the inode back while we are here
 128          * and thus update inode->i_blocks! (XXX)*/
 129         info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks;
 130         mark_inode_dirty(inode);
 131         mark_buffer_dirty(sbh);
 132         map_bh(bh_result, sb, phys);
 133 out:
 134         unlock_kernel();
 135         return err;
 136 }
 137
 138 static int bfs_writepage(struct page *page, struct writeback_control *wbc)
 139 {
 140         return block_write_full_page(page, bfs_get_block, wbc);
 141 }
 142
 143 static int bfs_readpage(struct file *file, struct page *page)
 144 {
 145         return block_read_full_page(page, bfs_get_block);
 146 }
 147
 148 static int bfs_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
 149 {
 150         return block_prepare_write(page, from, to, bfs_get_block);
 151 }
 152
 153 static sector_t bfs_bmap(struct address_space *mapping, sector_t block)
 154 {
 155         return generic_block_bmap(mapping, block, bfs_get_block);
 156 }
 157
 158 const struct address_space_operations bfs_aops = {
 159         .readpage       = bfs_readpage,
 160         .writepage      = bfs_writepage,
 161         .sync_page      = block_sync_page,
 162         .prepare_write  = bfs_prepare_write,
 163         .commit_write   = generic_commit_write,
 164         .bmap           = bfs_bmap,
 165 };
 166
 167 const struct inode_operations bfs_file_inops;