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