diff options
Diffstat (limited to 'fs/bfs/file.c')
| -rw-r--r-- | fs/bfs/file.c | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/fs/bfs/file.c b/fs/bfs/file.c new file mode 100644 index 000000000000..747fd1ea55e0 --- /dev/null +++ b/fs/bfs/file.c @@ -0,0 +1,162 @@ +/* + * fs/bfs/file.c + * BFS file operations. + * Copyright (C) 1999,2000 Tigran Aivazian <tigran@veritas.com> + */ + +#include <linux/fs.h> +#include <linux/buffer_head.h> +#include <linux/smp_lock.h> +#include "bfs.h" + +#undef DEBUG + +#ifdef DEBUG +#define dprintf(x...) printf(x) +#else +#define dprintf(x...) +#endif + +struct file_operations bfs_file_operations = { + .llseek = generic_file_llseek, + .read = generic_file_read, + .write = generic_file_write, + .mmap = generic_file_mmap, + .sendfile = generic_file_sendfile, +}; + +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) +{ + 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); + struct buffer_head *sbh = info->si_sbh; + + if (block < 0 || block > info->si_blocks) + return -EIO; + + phys = bi->i_sblock + block; + if (!create) { + if (phys <= bi->i_eblock) { + dprintf("c=%d, b=%08lx, phys=%08lx (granted)\n", create, 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 (inode->i_size && phys <= bi->i_eblock) { + dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n", + create, block, phys); + map_bh(bh_result, sb, phys); + return 0; + } + + /* the rest has to be protected against itself */ + lock_kernel(); + + /* 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, 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); + mark_buffer_dirty(sbh); + err = 0; + goto out; + } + + /* Ok, we have to move this entire file to the next free block */ + phys = info->si_lf_eblk + 1; + if (bi->i_sblock) { /* if data starts on block 0 then there is no data */ + 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, 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); + mark_buffer_dirty(sbh); + map_bh(bh_result, sb, phys); +out: + unlock_kernel(); + 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_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to) +{ + return block_prepare_write(page, from, to, bfs_get_block); +} + +static sector_t bfs_bmap(struct address_space *mapping, sector_t block) +{ + return generic_block_bmap(mapping, block, bfs_get_block); +} + +struct address_space_operations bfs_aops = { + .readpage = bfs_readpage, + .writepage = bfs_writepage, + .sync_page = block_sync_page, + .prepare_write = bfs_prepare_write, + .commit_write = generic_commit_write, + .bmap = bfs_bmap, +}; + +struct inode_operations bfs_file_inops; |