C++ PageUptodate函数代码示例

/*
 * Try to write data in the inode.
 * If the inode has inline data, check whether the new write can be
 * in the inode also. If not, create the page the handle, move the data
 * to the page make it update and let the later codes create extent for it.
 */
int ext4_try_to_write_inline_data(struct address_space *mapping,
				  struct inode *inode,
				  loff_t pos, unsigned len,
				  unsigned flags,
				  struct page **pagep)
{
	int ret;
	handle_t *handle;
	struct page *page;
	struct ext4_iloc iloc;

	if (pos + len > ext4_get_max_inline_size(inode))
		goto convert;

	ret = ext4_get_inode_loc(inode, &iloc);
	if (ret)
		return ret;

	/*
	 * The possible write could happen in the inode,
	 * so try to reserve the space in inode first.
	 */
	handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
	if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
		handle = NULL;
		goto out;
	}

	ret = ext4_prepare_inline_data(handle, inode, pos + len);
	if (ret && ret != -ENOSPC)
		goto out;

	/* We don't have space in inline inode, so convert it to extent. */
	if (ret == -ENOSPC) {
		ext4_journal_stop(handle);
		brelse(iloc.bh);
		goto convert;
	}

	flags |= AOP_FLAG_NOFS;

	page = grab_cache_page_write_begin(mapping, 0, flags);
	if (!page) {
		ret = -ENOMEM;
		goto out;
	}

	*pagep = page;
	down_read(&EXT4_I(inode)->xattr_sem);
	if (!ext4_has_inline_data(inode)) {
		ret = 0;
		unlock_page(page);
		page_cache_release(page);
		goto out_up_read;
	}

	if (!PageUptodate(page)) {
		ret = ext4_read_inline_page(inode, page);
		if (ret < 0)
			goto out_up_read;
	}

	ret = 1;
	handle = NULL;
out_up_read:
	up_read(&EXT4_I(inode)->xattr_sem);
out:
	if (handle)
		ext4_journal_stop(handle);
	brelse(iloc.bh);
	return ret;
convert:
	return ext4_convert_inline_data_to_extent(mapping,
						  inode, flags);
}

static int f2fs_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 f2fs_sb_info *sbi = F2FS_I_SB(inode);
    struct page *page = NULL;
    struct page *ipage;
    pgoff_t index = ((unsigned long long) pos) >> PAGE_CACHE_SHIFT;
    struct dnode_of_data dn;
    int err = 0;

    trace_f2fs_write_begin(inode, pos, len, flags);

    f2fs_balance_fs(sbi);

    /*
     * We should check this at this moment to avoid deadlock on inode page
     * and #0 page. The locking rule for inline_data conversion should be:
     * lock_page(page #0) -> lock_page(inode_page)
     */
    if (index != 0) {
        err = f2fs_convert_inline_inode(inode);
        if (err)
            goto fail;
    }
repeat:
    page = grab_cache_page_write_begin(mapping, index, flags);
    if (!page) {
        err = -ENOMEM;
        goto fail;
    }

    *pagep = page;

    f2fs_lock_op(sbi);

    /* check inline_data */
    ipage = get_node_page(sbi, inode->i_ino);
    if (IS_ERR(ipage)) {
        err = PTR_ERR(ipage);
        goto unlock_fail;
    }

    set_new_dnode(&dn, inode, ipage, ipage, 0);

    if (f2fs_has_inline_data(inode)) {
        if (pos + len <= MAX_INLINE_DATA) {
            read_inline_data(page, ipage);
            set_inode_flag(F2FS_I(inode), FI_DATA_EXIST);
            sync_inode_page(&dn);
            goto put_next;
        }
        err = f2fs_convert_inline_page(&dn, page);
        if (err)
            goto put_fail;
    }

    err = f2fs_get_block(&dn, index);
    if (err)
        goto put_fail;
put_next:
    f2fs_put_dnode(&dn);
    f2fs_unlock_op(sbi);

    f2fs_wait_on_page_writeback(page, DATA);

    if (len == PAGE_CACHE_SIZE)
        goto out_update;
    if (PageUptodate(page))
        goto out_clear;

    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);
        goto out_update;
    }

    if (dn.data_blkaddr == NEW_ADDR) {
        zero_user_segment(page, 0, PAGE_CACHE_SIZE);
    } else {
        struct f2fs_io_info fio = {
            .sbi = sbi,
            .type = DATA,
            .rw = READ_SYNC,
            .blk_addr = dn.data_blkaddr,
            .page = page,
            .encrypted_page = NULL,
        };
        err = f2fs_submit_page_bio(&fio);
        if (err)
            goto fail;

        lock_page(page);
        if (unlikely(!PageUptodate(page))) {
            err = -EIO;
            goto fail;
//.........这里部分代码省略.........

static int gfs2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
	struct page *page = vmf->page;
	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	unsigned long last_index;
	u64 pos = page->index << PAGE_CACHE_SHIFT;
	unsigned int data_blocks, ind_blocks, rblocks;
	int alloc_required = 0;
	struct gfs2_holder gh;
	struct gfs2_alloc *al;
	int ret;

	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
	ret = gfs2_glock_nq(&gh);
	if (ret)
		goto out;

	set_bit(GLF_DIRTY, &ip->i_gl->gl_flags);
	set_bit(GIF_SW_PAGED, &ip->i_flags);

	ret = gfs2_write_alloc_required(ip, pos, PAGE_CACHE_SIZE, &alloc_required);
	if (ret || !alloc_required)
		goto out_unlock;
	ret = -ENOMEM;
	al = gfs2_alloc_get(ip);
	if (al == NULL)
		goto out_unlock;

	ret = gfs2_quota_lock_check(ip);
	if (ret)
		goto out_alloc_put;
	gfs2_write_calc_reserv(ip, PAGE_CACHE_SIZE, &data_blocks, &ind_blocks);
	al->al_requested = data_blocks + ind_blocks;
	ret = gfs2_inplace_reserve(ip);
	if (ret)
		goto out_quota_unlock;

	rblocks = RES_DINODE + ind_blocks;
	if (gfs2_is_jdata(ip))
		rblocks += data_blocks ? data_blocks : 1;
	if (ind_blocks || data_blocks)
		rblocks += RES_STATFS + RES_QUOTA;
	ret = gfs2_trans_begin(sdp, rblocks, 0);
	if (ret)
		goto out_trans_fail;

	lock_page(page);
	ret = -EINVAL;
	last_index = ip->i_inode.i_size >> PAGE_CACHE_SHIFT;
	if (page->index > last_index)
		goto out_unlock_page;
	ret = 0;
	if (!PageUptodate(page) || page->mapping != ip->i_inode.i_mapping)
		goto out_unlock_page;
	if (gfs2_is_stuffed(ip)) {
		ret = gfs2_unstuff_dinode(ip, page);
		if (ret)
			goto out_unlock_page;
	}
	ret = gfs2_allocate_page_backing(page);

out_unlock_page:
	unlock_page(page);
	gfs2_trans_end(sdp);
out_trans_fail:
	gfs2_inplace_release(ip);
out_quota_unlock:
	gfs2_quota_unlock(ip);
out_alloc_put:
	gfs2_alloc_put(ip);
out_unlock:
	gfs2_glock_dq(&gh);
out:
	gfs2_holder_uninit(&gh);
	if (ret == -ENOMEM)
		ret = VM_FAULT_OOM;
	else if (ret)
		ret = VM_FAULT_SIGBUS;
	return ret;
}

int __microfs_readpage(struct file* file, struct page* page)
{
	struct inode* inode = page->mapping->host;
	struct super_block* sb = inode->i_sb;
	struct microfs_sb_info* sbi = MICROFS_SB(sb);
	
	int err = 0;
	int small_blks = sbi->si_blksz <= PAGE_SIZE;
	
	__u32 i;
	__u32 j;
	
	__u32 data_offset = 0;
	__u32 data_length = 0;
	__u32 blk_data_offset = 0;
	__u32 blk_data_length = 0;
	
	__u32 pgholes = 0;
	
	__u32 blk_ptrs = i_blks(i_size_read(inode), sbi->si_blksz);
	__u32 blk_nr = small_blks
		? page->index * (PAGE_SIZE >> sbi->si_blkshift)
		: page->index / (sbi->si_blksz / PAGE_SIZE);
	
	int index_mask = small_blks
		? 0
		: (1 << (sbi->si_blkshift - PAGE_SHIFT)) - 1;
	
	__u32 max_index = i_blks(i_size_read(inode), PAGE_SIZE);
	__u32 start_index = (small_blks ? page->index : page->index & ~index_mask);
	__u32 end_index = (small_blks ? page->index : start_index | index_mask) + 1;
	
	struct microfs_readpage_request rdreq;
	
	if (end_index > max_index)
		end_index = max_index;
	
	pr_spam("__microfs_readpage: sbi->si_blksz=%u, blk_ptrs=%u, blk_nr=%u\n",
		sbi->si_blksz, blk_ptrs, blk_nr);
	pr_spam("__microfs_readpage: start_index=%u, end_index=%u, max_index=%u\n",
		start_index, end_index, max_index);
	
	mutex_lock(&sbi->si_metadata_blkptrbuf.d_mutex);
	for (i = 0; (data_length < PAGE_SIZE && blk_nr + i < blk_ptrs) &&
			(i == 0 || sbi->si_blksz < PAGE_SIZE); ++i) {
		err = __microfs_find_block(sb, inode, blk_ptrs, blk_nr + i,
			&blk_data_offset, &blk_data_length);
		if (unlikely(err)) {
			mutex_unlock(&sbi->si_metadata_blkptrbuf.d_mutex);
			goto err_find_block;
		}
		if (!data_offset)
			data_offset = blk_data_offset;
		data_length += blk_data_length;
	}
	mutex_unlock(&sbi->si_metadata_blkptrbuf.d_mutex);
	
	pr_spam("__microfs_readpage: data_offset=0x%x, data_length=%u\n",
		data_offset, data_length);
	
	rdreq.rr_bhoffset = data_offset - (data_offset & PAGE_MASK);
	rdreq.rr_npages = end_index - start_index;
	rdreq.rr_pages = kmalloc(rdreq.rr_npages * sizeof(void*), GFP_KERNEL);
	if (!rdreq.rr_pages) {
		pr_err("__microfs_readpage: failed to allocate rdreq.rr_pages (%u slots)\n",
			rdreq.rr_npages);
		err = -ENOMEM;
		goto err_mem;
	}
	
	pr_spam("__microfs_readpage: rdreq.rr_pages=0x%p, rdreq.rr_npages=%u\n",
		rdreq.rr_pages, rdreq.rr_npages);
	
	for (i = 0, j = start_index; j < end_index; ++i, ++j) {
		rdreq.rr_pages[i] = (j == page->index)
			? page
			: grab_cache_page_nowait(page->mapping, j);
		if (rdreq.rr_pages[i] == page) {
			pr_spam("__microfs_readpage: target page 0x%p at index %u\n",
				page, j);
		} else if (rdreq.rr_pages[i] == NULL) {
			pgholes++;
			pr_spam("__microfs_readpage: busy page at index %u\n", j);
		} else if (PageUptodate(rdreq.rr_pages[i])) {
			unlock_page(rdreq.rr_pages[i]);
			put_page(rdreq.rr_pages[i]);
			rdreq.rr_pages[i] = NULL;
			pgholes++;
			pr_spam("__microfs_readpage: page up to date at index %u\n", j);
		} else {
			pr_spam("__microfs_readpage: new page 0x%p added for index %u\n",
				rdreq.rr_pages[i], j);
		}
	}
	
	pr_spam("__microfs_readpage: pgholes=%u\n", pgholes);
	
	if (pgholes) {
		/* It seems that one or more pages have been reclaimed, but
		 * it is also possible that another thread is trying to read
//.........这里部分代码省略.........

static int jffs2_write_begin(struct file *filp, struct address_space *mapping,
                             loff_t pos, unsigned len, unsigned flags,
                             struct page **pagep, void **fsdata)
{
    struct page *pg;
    struct inode *inode = mapping->host;
    struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
    pgoff_t index = pos >> PAGE_CACHE_SHIFT;
    uint32_t pageofs = index << PAGE_CACHE_SHIFT;
    int ret = 0;

    pg = grab_cache_page_write_begin(mapping, index, flags);
    if (!pg)
        return -ENOMEM;
    *pagep = pg;

    D1(printk(KERN_DEBUG "jffs2_write_begin()\n"));

    if (pageofs > inode->i_size) {
        /* Make new hole frag from old EOF to new page */
        struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
        struct jffs2_raw_inode ri;
        struct jffs2_full_dnode *fn;
        uint32_t alloc_len;

        D1(printk(KERN_DEBUG "Writing new hole frag 0x%x-0x%x between current EOF and new page\n",
                  (unsigned int)inode->i_size, pageofs));

        ret = jffs2_reserve_space(c, sizeof(ri), &alloc_len,
                                  ALLOC_NORMAL, JFFS2_SUMMARY_INODE_SIZE);
        if (ret)
            goto out_page;

        mutex_lock(&f->sem);
        memset(&ri, 0, sizeof(ri));

        ri.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
        ri.nodetype = cpu_to_je16(JFFS2_NODETYPE_INODE);
        ri.totlen = cpu_to_je32(sizeof(ri));
        ri.hdr_crc = cpu_to_je32(crc32(0, &ri, sizeof(struct jffs2_unknown_node)-4));

        ri.ino = cpu_to_je32(f->inocache->ino);
        ri.version = cpu_to_je32(++f->highest_version);
        ri.mode = cpu_to_jemode(inode->i_mode);
        ri.uid = cpu_to_je16(inode->i_uid);
        ri.gid = cpu_to_je16(inode->i_gid);
        ri.isize = cpu_to_je32(max((uint32_t)inode->i_size, pageofs));
        ri.atime = ri.ctime = ri.mtime = cpu_to_je32(get_seconds());
        ri.offset = cpu_to_je32(inode->i_size);
        ri.dsize = cpu_to_je32(pageofs - inode->i_size);
        ri.csize = cpu_to_je32(0);
        ri.compr = JFFS2_COMPR_ZERO;
        ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
        ri.data_crc = cpu_to_je32(0);

        fn = jffs2_write_dnode(c, f, &ri, NULL, 0, ALLOC_NORMAL);

        if (IS_ERR(fn)) {
            ret = PTR_ERR(fn);
            jffs2_complete_reservation(c);
            mutex_unlock(&f->sem);
            goto out_page;
        }
        ret = jffs2_add_full_dnode_to_inode(c, f, fn);
        if (f->metadata) {
            jffs2_mark_node_obsolete(c, f->metadata->raw);
            jffs2_free_full_dnode(f->metadata);
            f->metadata = NULL;
        }
        if (ret) {
            D1(printk(KERN_DEBUG "Eep. add_full_dnode_to_inode() failed in write_begin, returned %d\n", ret));
            jffs2_mark_node_obsolete(c, fn->raw);
            jffs2_free_full_dnode(fn);
            jffs2_complete_reservation(c);
            mutex_unlock(&f->sem);
            goto out_page;
        }
        jffs2_complete_reservation(c);
        inode->i_size = pageofs;
        mutex_unlock(&f->sem);
    }

    /*
     * Read in the page if it wasn't already present. Cannot optimize away
     * the whole page write case until jffs2_write_end can handle the
     * case of a short-copy.
     */
    if (!PageUptodate(pg)) {
        mutex_lock(&f->sem);
        ret = jffs2_do_readpage_nolock(inode, pg);
        mutex_unlock(&f->sem);
        if (ret)
            goto out_page;
    }
    D1(printk(KERN_DEBUG "end write_begin(). pg->flags %lx\n", pg->flags));
    return ret;

out_page:
    unlock_page(pg);
    page_cache_release(pg);
//.........这里部分代码省略.........

/*
 * This is a little more tricky than the file -> pipe splicing. There are
 * basically three cases:
 *
 *	- Destination page already exists in the address space and there
 *	  are users of it. For that case we have no other option that
 *	  copying the data. Tough luck.
 *	- Destination page already exists in the address space, but there
 *	  are no users of it. Make sure it's uptodate, then drop it. Fall
 *	  through to last case.
 *	- Destination page does not exist, we can add the pipe page to
 *	  the page cache and avoid the copy.
 *
 * If asked to move pages to the output file (SPLICE_F_MOVE is set in
 * sd->flags), we attempt to migrate pages from the pipe to the output
 * file address space page cache. This is possible if no one else has
 * the pipe page referenced outside of the pipe and page cache. If
 * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
 * a new page in the output file page cache and fill/dirty that.
 */
static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
			struct splice_desc *sd)
{
	struct file *file = sd->file;
	struct address_space *mapping = file->f_mapping;
	unsigned int offset, this_len;
	struct page *page;
	pgoff_t index;
	int ret;

	/*
	 * make sure the data in this buffer is uptodate
	 */
	ret = buf->ops->pin(pipe, buf);
	if (unlikely(ret))
		return ret;

	index = sd->pos >> PAGE_CACHE_SHIFT;
	offset = sd->pos & ~PAGE_CACHE_MASK;

	this_len = sd->len;
	if (this_len + offset > PAGE_CACHE_SIZE)
		this_len = PAGE_CACHE_SIZE - offset;

	/*
	 * Reuse buf page, if SPLICE_F_MOVE is set and we are doing a full
	 * page.
	 */
	if ((sd->flags & SPLICE_F_MOVE) && this_len == PAGE_CACHE_SIZE) {
		/*
		 * If steal succeeds, buf->page is now pruned from the
		 * pagecache and we can reuse it. The page will also be
		 * locked on successful return.
		 */
		if (buf->ops->steal(pipe, buf))
			goto find_page;

		page = buf->page;
		if (add_to_page_cache(page, mapping, index, GFP_KERNEL)) {
			unlock_page(page);
			goto find_page;
		}

		page_cache_get(page);

		if (!(buf->flags & PIPE_BUF_FLAG_LRU))
			lru_cache_add(page);
	} else {
find_page:
		page = find_lock_page(mapping, index);
		if (!page) {
			ret = -ENOMEM;
			page = page_cache_alloc_cold(mapping);
			if (unlikely(!page))
				goto out_ret;

			/*
			 * This will also lock the page
			 */
			ret = add_to_page_cache_lru(page, mapping, index,
						    GFP_KERNEL);
			if (unlikely(ret))
				goto out;
		}

		/*
		 * We get here with the page locked. If the page is also
		 * uptodate, we don't need to do more. If it isn't, we
		 * may need to bring it in if we are not going to overwrite
		 * the full page.
		 */
		if (!PageUptodate(page)) {
			if (this_len < PAGE_CACHE_SIZE) {
				ret = mapping->a_ops->readpage(file, page);
				if (unlikely(ret))
					goto out;

				lock_page(page);

				if (!PageUptodate(page)) {
//.........这里部分代码省略.........

//.........这里部分代码省略.........
			/*
			 * add_to_page_cache() locks the page, unlock it
			 * to avoid convoluting the logic below even more.
			 */
			unlock_page(page);
		}

		pages[spd.nr_pages++] = page;
		index++;
	}

	/*
	 * Now loop over the map and see if we need to start IO on any
	 * pages, fill in the partial map, etc.
	 */
	index = *ppos >> PAGE_CACHE_SHIFT;
	nr_pages = spd.nr_pages;
	spd.nr_pages = 0;
	for (page_nr = 0; page_nr < nr_pages; page_nr++) {
		unsigned int this_len;

		if (!len)
			break;

		/*
		 * this_len is the max we'll use from this page
		 */
		this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
		page = pages[page_nr];

		/*
		 * If the page isn't uptodate, we may need to start io on it
		 */
		if (!PageUptodate(page)) {
			/*
			 * If in nonblock mode then dont block on waiting
			 * for an in-flight io page
			 */
			if (flags & SPLICE_F_NONBLOCK)
				break;

			lock_page(page);

			/*
			 * page was truncated, stop here. if this isn't the
			 * first page, we'll just complete what we already
			 * added
			 */
			if (!page->mapping) {
				unlock_page(page);
				break;
			}
			/*
			 * page was already under io and is now done, great
			 */
			if (PageUptodate(page)) {
				unlock_page(page);
				goto fill_it;
			}

			/*
			 * need to read in the page
			 */
			error = mapping->a_ops->readpage(in, page);
			if (unlikely(error)) {
				/*

int jffs2_prepare_write (struct file *filp, struct page *pg, unsigned start, unsigned end)
{
	struct inode *inode = pg->mapping->host;
	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
	uint32_t pageofs = pg->index << PAGE_CACHE_SHIFT;
	int ret = 0;

	D1(printk(KERN_DEBUG "jffs2_prepare_write()\n"));

	if (pageofs > inode->i_size) {
		/* Make new hole frag from old EOF to new page */
		struct jffs2_sb_info *c = JFFS2_SB_INFO(inode->i_sb);
		struct jffs2_raw_inode ri;
		struct jffs2_full_dnode *fn;
		uint32_t phys_ofs, alloc_len;
		
		D1(printk(KERN_DEBUG "Writing new hole frag 0x%x-0x%x between current EOF and new page\n",
			  (unsigned int)inode->i_size, pageofs));

		ret = jffs2_reserve_space(c, sizeof(ri), &phys_ofs, &alloc_len, ALLOC_NORMAL);
		if (ret)
			return ret;

		down(&f->sem);
		memset(&ri, 0, sizeof(ri));

		ri.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
		ri.nodetype = cpu_to_je16(JFFS2_NODETYPE_INODE);
		ri.totlen = cpu_to_je32(sizeof(ri));
		ri.hdr_crc = cpu_to_je32(crc32(0, &ri, sizeof(struct jffs2_unknown_node)-4));

		ri.ino = cpu_to_je32(f->inocache->ino);
		ri.version = cpu_to_je32(++f->highest_version);
		ri.mode = cpu_to_jemode(inode->i_mode);
		ri.uid = cpu_to_je16(inode->i_uid);
		ri.gid = cpu_to_je16(inode->i_gid);
		ri.isize = cpu_to_je32(max((uint32_t)inode->i_size, pageofs));
		ri.atime = ri.ctime = ri.mtime = cpu_to_je32(get_seconds());
		ri.offset = cpu_to_je32(inode->i_size);
		ri.dsize = cpu_to_je32(pageofs - inode->i_size);
		ri.csize = cpu_to_je32(0);
		ri.compr = JFFS2_COMPR_ZERO;
		ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
		ri.data_crc = cpu_to_je32(0);
		
		fn = jffs2_write_dnode(c, f, &ri, NULL, 0, phys_ofs, ALLOC_NORMAL);

		if (IS_ERR(fn)) {
			ret = PTR_ERR(fn);
			jffs2_complete_reservation(c);
			up(&f->sem);
			return ret;
		}
		ret = jffs2_add_full_dnode_to_inode(c, f, fn);
		if (f->metadata) {
			jffs2_mark_node_obsolete(c, f->metadata->raw);
			jffs2_free_full_dnode(f->metadata);
			f->metadata = NULL;
		}
		if (ret) {
			D1(printk(KERN_DEBUG "Eep. add_full_dnode_to_inode() failed in prepare_write, returned %d\n", ret));
			jffs2_mark_node_obsolete(c, fn->raw);
			jffs2_free_full_dnode(fn);
			jffs2_complete_reservation(c);
			up(&f->sem);
			return ret;
		}
		jffs2_complete_reservation(c);
		inode->i_size = pageofs;
		up(&f->sem);
	}
	
	/* Read in the page if it wasn't already present, unless it's a whole page */
	if (!PageUptodate(pg) && (start || end < PAGE_CACHE_SIZE)) {
		down(&f->sem);
		ret = jffs2_do_readpage_nolock(inode, pg);
		up(&f->sem);
	}
	D1(printk(KERN_DEBUG "end prepare_write(). pg->flags %lx\n", pg->flags));
	return ret;
}

static int gfs2_write_begin(struct file *file, struct address_space *mapping,
			    loff_t pos, unsigned len, unsigned flags,
			    struct page **pagep, void **fsdata)
{
	struct gfs2_inode *ip = GFS2_I(mapping->host);
	struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
	struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
	unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
	unsigned requested = 0;
	int alloc_required;
	int error = 0;
	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
	unsigned from = pos & (PAGE_CACHE_SIZE - 1);
	struct page *page;

	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
	error = gfs2_glock_nq(&ip->i_gh);
	if (unlikely(error))
		goto out_uninit;
	if (&ip->i_inode == sdp->sd_rindex) {
		error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE,
					   GL_NOCACHE, &m_ip->i_gh);
		if (unlikely(error)) {
			gfs2_glock_dq(&ip->i_gh);
			goto out_uninit;
		}
	}

	alloc_required = gfs2_write_alloc_required(ip, pos, len);

	if (alloc_required || gfs2_is_jdata(ip))
		gfs2_write_calc_reserv(ip, len, &data_blocks, &ind_blocks);

	if (alloc_required) {
		struct gfs2_alloc_parms ap = { .aflags = 0, };
		requested = data_blocks + ind_blocks;
		ap.target = requested;
		error = gfs2_quota_lock_check(ip, &ap);
		if (error)
			goto out_unlock;

		error = gfs2_inplace_reserve(ip, &ap);
		if (error)
			goto out_qunlock;
	}

	rblocks = RES_DINODE + ind_blocks;
	if (gfs2_is_jdata(ip))
		rblocks += data_blocks ? data_blocks : 1;
	if (ind_blocks || data_blocks)
		rblocks += RES_STATFS + RES_QUOTA;
	if (&ip->i_inode == sdp->sd_rindex)
		rblocks += 2 * RES_STATFS;
	if (alloc_required)
		rblocks += gfs2_rg_blocks(ip, requested);

	error = gfs2_trans_begin(sdp, rblocks,
				 PAGE_CACHE_SIZE/sdp->sd_sb.sb_bsize);
	if (error)
		goto out_trans_fail;

	error = -ENOMEM;
	flags |= AOP_FLAG_NOFS;
	page = grab_cache_page_write_begin(mapping, index, flags);
	*pagep = page;
	if (unlikely(!page))
		goto out_endtrans;

	if (gfs2_is_stuffed(ip)) {
		error = 0;
		if (pos + len > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
			error = gfs2_unstuff_dinode(ip, page);
			if (error == 0)
				goto prepare_write;
		} else if (!PageUptodate(page)) {
			error = stuffed_readpage(ip, page);
		}
		goto out;
	}

prepare_write:
	error = __block_write_begin(page, from, len, gfs2_block_map);
out:
	if (error == 0)
		return 0;

	unlock_page(page);
	page_cache_release(page);

	gfs2_trans_end(sdp);
	if (pos + len > ip->i_inode.i_size)
		gfs2_trim_blocks(&ip->i_inode);
	goto out_trans_fail;

out_endtrans:
	gfs2_trans_end(sdp);
out_trans_fail:
	if (alloc_required) {
		gfs2_inplace_release(ip);
out_qunlock:
//.........这里部分代码省略.........

static int nilfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
	struct page *page = vmf->page;
	struct inode *inode = vma->vm_file->f_dentry->d_inode;
	struct nilfs_transaction_info ti;
	int ret;

	if (unlikely(nilfs_near_disk_full(inode->i_sb->s_fs_info)))
		return VM_FAULT_SIGBUS; /* -ENOSPC */

	lock_page(page);
	if (page->mapping != inode->i_mapping ||
	    page_offset(page) >= i_size_read(inode) || !PageUptodate(page)) {
		unlock_page(page);
		return VM_FAULT_NOPAGE; /* make the VM retry the fault */
	}

	/*
	 * check to see if the page is mapped already (no holes)
	 */
	if (PageMappedToDisk(page))
		goto mapped;

	if (page_has_buffers(page)) {
		struct buffer_head *bh, *head;
		int fully_mapped = 1;

		bh = head = page_buffers(page);
		do {
			if (!buffer_mapped(bh)) {
				fully_mapped = 0;
				break;
			}
		} while (bh = bh->b_this_page, bh != head);

		if (fully_mapped) {
			SetPageMappedToDisk(page);
			goto mapped;
		}
	}
	unlock_page(page);

	/*
	 * fill hole blocks
	 */
	ret = nilfs_transaction_begin(inode->i_sb, &ti, 1);
	/* never returns -ENOMEM, but may return -ENOSPC */
	if (unlikely(ret))
		return VM_FAULT_SIGBUS;

	file_update_time(vma->vm_file);
	ret = block_page_mkwrite(vma, vmf, nilfs_get_block);
	if (ret != VM_FAULT_LOCKED) {
		nilfs_transaction_abort(inode->i_sb);
		return ret;
	}
	nilfs_set_file_dirty(inode, 1 << (PAGE_SHIFT - inode->i_blkbits));
	nilfs_transaction_commit(inode->i_sb);

 mapped:
	wait_for_stable_page(page);
 out:
	sb_end_pagefault(inode->i_sb);
	return block_page_mkwrite_return(ret);
}

int direct2indirect(struct reiserfs_transaction_handle *th, struct inode *inode,
		    struct treepath *path, struct buffer_head *unbh,
		    loff_t tail_offset)
{
	struct super_block *sb = inode->i_sb;
	struct buffer_head *up_to_date_bh;
	struct item_head *p_le_ih = PATH_PITEM_HEAD(path);
	unsigned long total_tail = 0;
	struct cpu_key end_key;	
	struct item_head ind_ih;	
	int blk_size, retval;	
	unp_t unfm_ptr;		

	BUG_ON(!th->t_trans_id);

	REISERFS_SB(sb)->s_direct2indirect++;

	blk_size = sb->s_blocksize;

	copy_item_head(&ind_ih, p_le_ih);
	set_le_ih_k_offset(&ind_ih, tail_offset);
	set_le_ih_k_type(&ind_ih, TYPE_INDIRECT);

	
	make_cpu_key(&end_key, inode, tail_offset, TYPE_INDIRECT, 4);

	
	if (search_for_position_by_key(sb, &end_key, path) == POSITION_FOUND) {
		reiserfs_error(sb, "PAP-14030",
			       "pasted or inserted byte exists in "
			       "the tree %K. Use fsck to repair.", &end_key);
		pathrelse(path);
		return -EIO;
	}

	p_le_ih = PATH_PITEM_HEAD(path);

	unfm_ptr = cpu_to_le32(unbh->b_blocknr);

	if (is_statdata_le_ih(p_le_ih)) {
		
		set_ih_free_space(&ind_ih, 0);	
		put_ih_item_len(&ind_ih, UNFM_P_SIZE);
		PATH_LAST_POSITION(path)++;
		retval =
		    reiserfs_insert_item(th, path, &end_key, &ind_ih, inode,
					 (char *)&unfm_ptr);
	} else {
		
		retval = reiserfs_paste_into_item(th, path, &end_key, inode,
						    (char *)&unfm_ptr,
						    UNFM_P_SIZE);
	}
	if (retval) {
		return retval;
	}
	
	

	
	make_cpu_key(&end_key, inode, max_reiserfs_offset(inode), TYPE_DIRECT,
		     4);

	while (1) {
		int tail_size;

		if (search_for_position_by_key(sb, &end_key, path) ==
		    POSITION_FOUND)
			reiserfs_panic(sb, "PAP-14050",
				       "direct item (%K) not found", &end_key);
		p_le_ih = PATH_PITEM_HEAD(path);
		RFALSE(!is_direct_le_ih(p_le_ih),
		       "vs-14055: direct item expected(%K), found %h",
		       &end_key, p_le_ih);
		tail_size = (le_ih_k_offset(p_le_ih) & (blk_size - 1))
		    + ih_item_len(p_le_ih) - 1;

		if (!unbh->b_page || buffer_uptodate(unbh)
		    || PageUptodate(unbh->b_page)) {
			up_to_date_bh = NULL;
		} else {
			up_to_date_bh = unbh;
		}
		retval = reiserfs_delete_item(th, path, &end_key, inode,
						up_to_date_bh);

		total_tail += retval;
		if (tail_size == retval)
			
			break;

	}
	if (up_to_date_bh) {
		unsigned pgoff =
		    (tail_offset + total_tail - 1) & (PAGE_CACHE_SIZE - 1);
		char *kaddr = kmap_atomic(up_to_date_bh->b_page);
		memset(kaddr + pgoff, 0, blk_size - total_tail);
		kunmap_atomic(kaddr);
	}

//.........这里部分代码省略.........

/*
 * Prepare the write for the inline data.
 * If the the data can be written into the inode, we just read
 * the page and make it uptodate, and start the journal.
 * Otherwise read the page, makes it dirty so that it can be
 * handle in writepages(the i_disksize update is left to the
 * normal ext4_da_write_end).
 */
int ext4_da_write_inline_data_begin(struct address_space *mapping,
				    struct inode *inode,
				    loff_t pos, unsigned len,
				    unsigned flags,
				    struct page **pagep,
				    void **fsdata)
{
	int ret, inline_size;
	handle_t *handle;
	struct page *page;
	struct ext4_iloc iloc;

	ret = ext4_get_inode_loc(inode, &iloc);
	if (ret)
		return ret;

	handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
	if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
		handle = NULL;
		goto out;
	}

	inline_size = ext4_get_max_inline_size(inode);

	ret = -ENOSPC;
	if (inline_size >= pos + len) {
		ret = ext4_prepare_inline_data(handle, inode, pos + len);
		if (ret && ret != -ENOSPC)
			goto out;
	}

	if (ret == -ENOSPC) {
		ret = ext4_da_convert_inline_data_to_extent(mapping,
							    inode,
							    flags,
							    fsdata);
		goto out;
	}

	/*
	 * We cannot recurse into the filesystem as the transaction
	 * is already started.
	 */
	flags |= AOP_FLAG_NOFS;

	page = grab_cache_page_write_begin(mapping, 0, flags);
	if (!page) {
		ret = -ENOMEM;
		goto out;
	}

	down_read(&EXT4_I(inode)->xattr_sem);
	if (!ext4_has_inline_data(inode)) {
		ret = 0;
		goto out_release_page;
	}

	if (!PageUptodate(page)) {
		ret = ext4_read_inline_page(inode, page);
		if (ret < 0)
			goto out_release_page;
	}

	up_read(&EXT4_I(inode)->xattr_sem);
	*pagep = page;
	handle = NULL;
	brelse(iloc.bh);
	return 1;
out_release_page:
	up_read(&EXT4_I(inode)->xattr_sem);
	unlock_page(page);
	page_cache_release(page);
out:
	if (handle)
		ext4_journal_stop(handle);
	brelse(iloc.bh);
	return ret;
}

/*
 * Returns a pointer to a buffer containing at least LEN bytes of
 * filesystem starting at byte offset OFFSET into the filesystem.
 */
static void *cramfs_read_comm(struct super_block *sb, unsigned int offset, unsigned int len)
{
	struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
	struct page *pages[BLKS_PER_BUF];
	unsigned i, blocknr, buffer;
	unsigned long devsize;
	char *data;

	if (!len)
		return NULL;
	blocknr = offset >> PAGE_CACHE_SHIFT;
	offset &= PAGE_CACHE_SIZE - 1;

	/* Check if an existing buffer already has the data.. */
	for (i = 0; i < READ_BUFFERS; i++) {
		unsigned int blk_offset;

		if (buffer_dev[i] != sb)
			continue;
		if (blocknr < buffer_blocknr[i])
			continue;
		blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_SHIFT;
		blk_offset += offset;
		if (blk_offset + len > BUFFER_SIZE)
			continue;
		return read_buffers[i] + blk_offset;
	}

	devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;

	/* Ok, read in BLKS_PER_BUF pages completely first. */
	for (i = 0; i < BLKS_PER_BUF; i++) {
		struct page *page = NULL;

		if (blocknr + i < devsize) {
			page = read_mapping_page_async(mapping, blocknr + i,
									NULL);
			/* synchronous error? */
			if (IS_ERR(page))
				page = NULL;
		}
		pages[i] = page;
	}

	for (i = 0; i < BLKS_PER_BUF; i++) {
		struct page *page = pages[i];
		if (page) {
			wait_on_page_locked(page);
			if (!PageUptodate(page)) {
				/* asynchronous error */
				page_cache_release(page);
				pages[i] = NULL;
			}
		}
	}

	buffer = next_buffer;
	next_buffer = NEXT_BUFFER(buffer);
	buffer_blocknr[buffer] = blocknr;
	buffer_dev[buffer] = sb;

	data = read_buffers[buffer];
	for (i = 0; i < BLKS_PER_BUF; i++) {
		struct page *page = pages[i];
		if (page) {
			memcpy(data, kmap(page), PAGE_CACHE_SIZE);
			kunmap(page);
			page_cache_release(page);
		} else
			memset(data, 0, PAGE_CACHE_SIZE);
		data += PAGE_CACHE_SIZE;
	}
	return read_buffers[buffer] + offset;
}

static int gfs2_write_begin(struct file *file, struct address_space *mapping,
			    loff_t pos, unsigned len, unsigned flags,
			    struct page **pagep, void **fsdata)
{
	struct gfs2_inode *ip = GFS2_I(mapping->host);
	struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
	unsigned int data_blocks, ind_blocks, rblocks;
	int alloc_required;
	int error = 0;
	struct gfs2_alloc *al;
	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
	unsigned from = pos & (PAGE_CACHE_SIZE - 1);
	unsigned to = from + len;
	struct page *page;

	gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_ATIME, &ip->i_gh);
	error = gfs2_glock_nq_atime(&ip->i_gh);
	if (unlikely(error))
		goto out_uninit;

	error = -ENOMEM;
	page = grab_cache_page_write_begin(mapping, index, flags);
	*pagep = page;
	if (!page)
		goto out_unlock;

	gfs2_write_calc_reserv(ip, len, &data_blocks, &ind_blocks);

	error = gfs2_write_alloc_required(ip, pos, len, &alloc_required);
	if (error)
		goto out_putpage;


	ip->i_alloc.al_requested = 0;
	if (alloc_required) {
		al = gfs2_alloc_get(ip);

		error = gfs2_quota_lock(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
		if (error)
			goto out_alloc_put;

		error = gfs2_quota_check(ip, ip->i_inode.i_uid, ip->i_inode.i_gid);
		if (error)
			goto out_qunlock;

		al->al_requested = data_blocks + ind_blocks;
		error = gfs2_inplace_reserve(ip);
		if (error)
			goto out_qunlock;
	}

	rblocks = RES_DINODE + ind_blocks;
	if (gfs2_is_jdata(ip))
		rblocks += data_blocks ? data_blocks : 1;
	if (ind_blocks || data_blocks)
		rblocks += RES_STATFS + RES_QUOTA;

	error = gfs2_trans_begin(sdp, rblocks, 0);
	if (error)
		goto out;

	if (gfs2_is_stuffed(ip)) {
		if (pos + len > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
			error = gfs2_unstuff_dinode(ip, page);
			if (error == 0)
				goto prepare_write;
		} else if (!PageUptodate(page))
			error = stuffed_readpage(ip, page);
		goto out;
	}

prepare_write:
	error = block_prepare_write(page, from, to, gfs2_get_block);

out:
	if (error) {
		gfs2_trans_end(sdp);
		if (alloc_required) {
			gfs2_inplace_release(ip);
out_qunlock:
			gfs2_quota_unlock(ip);
out_alloc_put:
			gfs2_alloc_put(ip);
		}
out_putpage:
		page_cache_release(page);
		if (pos + len > ip->i_inode.i_size)
			vmtruncate(&ip->i_inode, ip->i_inode.i_size);
out_unlock:
		gfs2_glock_dq_m(1, &ip->i_gh);
out_uninit:
		gfs2_holder_uninit(&ip->i_gh);
	}

	return error;
}

/* Read separately compressed datablock directly into page cache */
int squashfs_readpage_block(struct page *target_page, u64 block, int bsize)

{
	struct inode *inode = target_page->mapping->host;
	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;

	int file_end = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
	int mask = (1 << (msblk->block_log - PAGE_CACHE_SHIFT)) - 1;
	int start_index = target_page->index & ~mask;
	int end_index = start_index | mask;
	int i, n, pages, missing_pages, bytes, res = -ENOMEM;
	struct page **page;
	struct squashfs_page_actor *actor;
	void *pageaddr;

	if (end_index > file_end)
		end_index = file_end;

	pages = end_index - start_index + 1;

	page = kmalloc(sizeof(void *) * pages, GFP_KERNEL);
	if (page == NULL)
		return res;

	/*
	 * Create a "page actor" which will kmap and kunmap the
	 * page cache pages appropriately within the decompressor
	 */
	actor = squashfs_page_actor_init_special(page, pages, 0);
	if (actor == NULL)
		goto out;

	/* Try to grab all the pages covered by the Squashfs block */
	for (missing_pages = 0, i = 0, n = start_index; i < pages; i++, n++) {
		page[i] = (n == target_page->index) ? target_page :
			grab_cache_page_nowait(target_page->mapping, n);

		if (page[i] == NULL) {
			missing_pages++;
			continue;
		}

		if (PageUptodate(page[i])) {
			unlock_page(page[i]);
			page_cache_release(page[i]);
			page[i] = NULL;
			missing_pages++;
		}
	}

	if (missing_pages) {
		/*
		 * Couldn't get one or more pages, this page has either
		 * been VM reclaimed, but others are still in the page cache
		 * and uptodate, or we're racing with another thread in
		 * squashfs_readpage also trying to grab them.  Fall back to
		 * using an intermediate buffer.
		 */
		res = squashfs_read_cache(target_page, block, bsize, pages,
								page);
		if (res < 0)
			goto mark_errored;

		goto out;
	}

	/* Decompress directly into the page cache buffers */
	res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
	if (res < 0)
		goto mark_errored;

	/* Last page may have trailing bytes not filled */
	bytes = res % PAGE_CACHE_SIZE;
	if (bytes) {
		pageaddr = kmap_atomic(page[pages - 1]);
		memset(pageaddr + bytes, 0, PAGE_CACHE_SIZE - bytes);
		kunmap_atomic(pageaddr);
	}

	/* Mark pages as uptodate, unlock and release */
	for (i = 0; i < pages; i++) {
		flush_dcache_page(page[i]);
		SetPageUptodate(page[i]);
		unlock_page(page[i]);
		if (page[i] != target_page)
			page_cache_release(page[i]);
	}

	kfree(actor);
	kfree(page);

	return 0;

mark_errored:
	/* Decompression failed, mark pages as errored.  Target_page is
	 * dealt with by the caller
	 */
	for (i = 0; i < pages; i++) {
		if (page[i] == NULL || page[i] == target_page)
//.........这里部分代码省略.........