diff options
Diffstat (limited to 'fs/bfs/file.c')
| -rw-r--r-- | fs/bfs/file.c | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/fs/bfs/file.c b/fs/bfs/file.c new file mode 100644 index 000000000..adc223007 --- /dev/null +++ b/fs/bfs/file.c @@ -0,0 +1,199 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/bfs/file.c + * BFS file operations. + * Copyright (C) 1999-2018 Tigran Aivazian <aivazian.tigran@gmail.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_iter = generic_file_read_iter, + .write_iter = generic_file_write_iter, + .mmap = generic_file_mmap, + .splice_read = filemap_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_read_folio(struct file *file, struct folio *folio) +{ + return block_read_full_folio(folio, bfs_get_block); +} + +static void bfs_write_failed(struct address_space *mapping, loff_t to) +{ + struct inode *inode = mapping->host; + + if (to > inode->i_size) + truncate_pagecache(inode, inode->i_size); +} + +static int bfs_write_begin(struct file *file, struct address_space *mapping, + loff_t pos, unsigned len, + struct page **pagep, void **fsdata) +{ + int ret; + + ret = block_write_begin(mapping, pos, len, pagep, bfs_get_block); + if (unlikely(ret)) + bfs_write_failed(mapping, pos + len); + + 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 = { + .dirty_folio = block_dirty_folio, + .invalidate_folio = block_invalidate_folio, + .read_folio = bfs_read_folio, + .writepage = bfs_writepage, + .write_begin = bfs_write_begin, + .write_end = generic_write_end, + .bmap = bfs_bmap, +}; + +const struct inode_operations bfs_file_inops; |