/* * fs/bfs/file.c * BFS file operations. * Copyright (C) 1999,2000 Tigran Aivazian <tigran@veritas.com> * * Make the file block allocation algorithm understand the size * of the underlying block device. * Copyright (C) 2007 Dmitri Vorobiev <dmitri.vorobiev@gmail.com> * */ #include <linux/fs.h> #include <linux/buffer_head.h> #include "bfs.h" #undef DEBUG #ifdef DEBUG #define dprintf(x...) printf(x) #else #define dprintf(x...) #endif const struct file_operations bfs_file_operations = { .llseek = generic_file_llseek, .read = do_sync_read, .aio_read = generic_file_aio_read, .write = do_sync_write, .aio_write = generic_file_aio_write, .mmap = generic_file_mmap, .splice_read = generic_file_splice_read, }; static int bfs_move_block(unsigned long from, unsigned long to, struct super_block *sb) { struct buffer_head *bh, *new; bh = sb_bread(sb, from); if (!bh) return -EIO; new = sb_getblk(sb, to); memcpy(new->b_data, bh->b_data, bh->b_size); mark_buffer_dirty(new); bforget(bh); brelse(new); return 0; } static int bfs_move_blocks(struct super_block *sb, unsigned long start, unsigned long end, unsigned long where) { unsigned long i; dprintf("%08lx-%08lx->%08lx\n", start, end, where); for (i = start; i <= end; i++) if(bfs_move_block(i, where + i, sb)) { dprintf("failed to move block %08lx -> %08lx\n", i, where + i); return -EIO; } return 0; } static int bfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh_result, int create) { unsigned long phys; int err; struct super_block *sb = inode->i_sb; struct bfs_sb_info *info = BFS_SB(sb); struct bfs_inode_info *bi = BFS_I(inode); phys = bi->i_sblock + block; if (!create) { if (phys <= bi->i_eblock) { dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n", create, (unsigned long)block, phys); map_bh(bh_result, sb, phys); } return 0; } /* * If the file is not empty and the requested block is within the * range of blocks allocated for this file, we can grant it. */ if (bi->i_sblock && (phys <= bi->i_eblock)) { dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n", create, (unsigned long)block, phys); map_bh(bh_result, sb, phys); return 0; } /* The file will be extended, so let's see if there is enough space. */ if (phys >= info->si_blocks) return -ENOSPC; /* The rest has to be protected against itself. */ mutex_lock(&info->bfs_lock); /* * If the last data block for this file is the last allocated * block, we can extend the file trivially, without moving it * anywhere. */ if (bi->i_eblock == info->si_lf_eblk) { dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n", create, (unsigned long)block, phys); map_bh(bh_result, sb, phys); info->si_freeb -= phys - bi->i_eblock; info->si_lf_eblk = bi->i_eblock = phys; mark_inode_dirty(inode); err = 0; goto out; } /* Ok, we have to move this entire file to the next free block. */ phys = info->si_lf_eblk + 1; if (phys + block >= info->si_blocks) { err = -ENOSPC; goto out; } if (bi->i_sblock) { err = bfs_move_blocks(inode->i_sb, bi->i_sblock, bi->i_eblock, phys); if (err) { dprintf("failed to move ino=%08lx -> fs corruption\n", inode->i_ino); goto out; } } else err = 0; dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n", create, (unsigned long)block, phys); bi->i_sblock = phys; phys += block; info->si_lf_eblk = bi->i_eblock = phys; /* * This assumes nothing can write the inode back while we are here * and thus update inode->i_blocks! (XXX) */ info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks; mark_inode_dirty(inode); map_bh(bh_result, sb, phys); out: mutex_unlock(&info->bfs_lock); return err; } static int bfs_writepage(struct page *page, struct writeback_control *wbc) { return block_write_full_page(page, bfs_get_block, wbc); } static int bfs_readpage(struct file *file, struct page *page) { return block_read_full_page(page, bfs_get_block); } static int bfs_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, void **fsdata) { int ret; ret = block_write_begin(mapping, pos, len, flags, pagep, bfs_get_block); if (unlikely(ret)) { loff_t isize = mapping->host->i_size; if (pos + len > isize) vmtruncate(mapping->host, isize); } return ret; } static sector_t bfs_bmap(struct address_space *mapping, sector_t block) { return generic_block_bmap(mapping, block, bfs_get_block); } const struct address_space_operations bfs_aops = { .readpage = bfs_readpage, .writepage = bfs_writepage, .sync_page = block_sync_page, .write_begin = bfs_write_begin, .write_end = generic_write_end, .bmap = bfs_bmap, }; const struct inode_operations bfs_file_inops;