/* * fs/logfs/file.c - prepare_write, commit_write and friends * * As should be obvious for Linux kernel code, license is GPLv2 * * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org> */ #include "logfs.h" #include <linux/sched.h> #include <linux/writeback.h> static int logfs_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, void **fsdata) { struct inode *inode = mapping->host; struct page *page; pgoff_t index = pos >> PAGE_CACHE_SHIFT; page = grab_cache_page_write_begin(mapping, index, flags); if (!page) return -ENOMEM; *pagep = page; if ((len == PAGE_CACHE_SIZE) || PageUptodate(page)) return 0; if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) { unsigned start = pos & (PAGE_CACHE_SIZE - 1); unsigned end = start + len; /* Reading beyond i_size is simple: memset to zero */ zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE); return 0; } return logfs_readpage_nolock(page); } static int logfs_write_end(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned copied, struct page *page, void *fsdata) { struct inode *inode = mapping->host; pgoff_t index = page->index; unsigned start = pos & (PAGE_CACHE_SIZE - 1); unsigned end = start + copied; int ret = 0; BUG_ON(PAGE_CACHE_SIZE != inode->i_sb->s_blocksize); BUG_ON(page->index > I3_BLOCKS); if (copied < len) { /* * Short write of a non-initialized paged. Just tell userspace * to retry the entire page. */ if (!PageUptodate(page)) { copied = 0; goto out; } } if (copied == 0) goto out; /* FIXME: do we need to update inode? */ if (i_size_read(inode) < (index << PAGE_CACHE_SHIFT) + end) { i_size_write(inode, (index << PAGE_CACHE_SHIFT) + end); mark_inode_dirty_sync(inode); } SetPageUptodate(page); if (!PageDirty(page)) { if (!get_page_reserve(inode, page)) __set_page_dirty_nobuffers(page); else ret = logfs_write_buf(inode, page, WF_LOCK); } out: unlock_page(page); page_cache_release(page); return ret ? ret : copied; } int logfs_readpage(struct file *file, struct page *page) { int ret; ret = logfs_readpage_nolock(page); unlock_page(page); return ret; } /* Clear the page's dirty flag in the radix tree. */ /* TODO: mucking with PageWriteback is silly. Add a generic function to clear * the dirty bit from the radix tree for filesystems that don't have to wait * for page writeback to finish (i.e. any compressing filesystem). */ static void clear_radix_tree_dirty(struct page *page) { BUG_ON(PagePrivate(page) || page->private); set_page_writeback(page); end_page_writeback(page); } static int __logfs_writepage(struct page *page) { struct inode *inode = page->mapping->host; int err; err = logfs_write_buf(inode, page, WF_LOCK); if (err) set_page_dirty(page); else clear_radix_tree_dirty(page); unlock_page(page); return err; } static int logfs_writepage(struct page *page, struct writeback_control *wbc) { struct inode *inode = page->mapping->host; loff_t i_size = i_size_read(inode); pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; unsigned offset; u64 bix; level_t level; log_file("logfs_writepage(%lx, %lx, %p)\n", inode->i_ino, page->index, page); logfs_unpack_index(page->index, &bix, &level); /* Indirect blocks are never truncated */ if (level != 0) return __logfs_writepage(page); /* * TODO: everything below is a near-verbatim copy of nobh_writepage(). * The relevant bits should be factored out after logfs is merged. */ /* Is the page fully inside i_size? */ if (bix < end_index) return __logfs_writepage(page); /* Is the page fully outside i_size? (truncate in progress) */ offset = i_size & (PAGE_CACHE_SIZE-1); if (bix > end_index || offset == 0) { unlock_page(page); return 0; /* don't care */ } /* * The page straddles i_size. It must be zeroed out on each and every * writepage invokation because it may be mmapped. "A file is mapped * in multiples of the page size. For a file that is not a multiple of * the page size, the remaining memory is zeroed when mapped, and * writes to that region are not written out to the file." */ zero_user_segment(page, offset, PAGE_CACHE_SIZE); return __logfs_writepage(page); } static void logfs_invalidatepage(struct page *page, unsigned long offset) { struct logfs_block *block = logfs_block(page); if (block->reserved_bytes) { struct super_block *sb = page->mapping->host->i_sb; struct logfs_super *super = logfs_super(sb); super->s_dirty_pages -= block->reserved_bytes; block->ops->free_block(sb, block); BUG_ON(bitmap_weight(block->alias_map, LOGFS_BLOCK_FACTOR)); } else move_page_to_btree(page); BUG_ON(PagePrivate(page) || page->private); } static int logfs_releasepage(struct page *page, gfp_t only_xfs_uses_this) { return 0; /* None of these are easy to release */ } long logfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct inode *inode = file->f_path.dentry->d_inode; struct logfs_inode *li = logfs_inode(inode); unsigned int oldflags, flags; int err; switch (cmd) { case FS_IOC_GETFLAGS: flags = li->li_flags & LOGFS_FL_USER_VISIBLE; return put_user(flags, (int __user *)arg); case FS_IOC_SETFLAGS: if (IS_RDONLY(inode)) return -EROFS; if (!is_owner_or_cap(inode)) return -EACCES; err = get_user(flags, (int __user *)arg); if (err) return err; mutex_lock(&inode->i_mutex); oldflags = li->li_flags; flags &= LOGFS_FL_USER_MODIFIABLE; flags |= oldflags & ~LOGFS_FL_USER_MODIFIABLE; li->li_flags = flags; mutex_unlock(&inode->i_mutex); inode->i_ctime = CURRENT_TIME; mark_inode_dirty_sync(inode); return 0; default: return -ENOTTY; } } int logfs_fsync(struct file *file, int datasync) { struct super_block *sb = file->f_mapping->host->i_sb; logfs_write_anchor(sb); return 0; } static int logfs_setattr(struct dentry *dentry, struct iattr *attr) { struct inode *inode = dentry->d_inode; int err = 0; err = inode_change_ok(inode, attr); if (err) return err; if (attr->ia_valid & ATTR_SIZE) { err = logfs_truncate(inode, attr->ia_size); if (err) return err; } setattr_copy(inode, attr); mark_inode_dirty(inode); return 0; } const struct inode_operations logfs_reg_iops = { .setattr = logfs_setattr, }; const struct file_operations logfs_reg_fops = { .aio_read = generic_file_aio_read, .aio_write = generic_file_aio_write, .fsync = logfs_fsync, .unlocked_ioctl = logfs_ioctl, .llseek = generic_file_llseek, .mmap = generic_file_readonly_mmap, .open = generic_file_open, .read = do_sync_read, .write = do_sync_write, }; const struct address_space_operations logfs_reg_aops = { .invalidatepage = logfs_invalidatepage, .readpage = logfs_readpage, .releasepage = logfs_releasepage, .set_page_dirty = __set_page_dirty_nobuffers, .writepage = logfs_writepage, .writepages = generic_writepages, .write_begin = logfs_write_begin, .write_end = logfs_write_end, };