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