5 files changed, 481 insertions, 29 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index af639807524..bba83762c48 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -47,6 +47,14 @@ struct fuse_req *fuse_request_alloc(void)
 	return req;
 }
 
+struct fuse_req *fuse_request_alloc_nofs(void)
+{
+	struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, GFP_NOFS);
+	if (req)
+		fuse_request_init(req);
+	return req;
+}
+
 void fuse_request_free(struct fuse_req *req)
 {
 	kmem_cache_free(fuse_req_cachep, req);
@@ -430,6 +438,17 @@ void request_send_background(struct fuse_conn *fc, struct fuse_req *req)
 }
 
 /*
+ * Called under fc->lock
+ *
+ * fc->connected must have been checked previously
+ */
+void request_send_background_locked(struct fuse_conn *fc, struct fuse_req *req)
+{
+	req->isreply = 1;
+	request_send_nowait_locked(fc, req);
+}
+
+/*
  * Lock the request.  Up to the next unlock_request() there mustn't be
  * anything that could cause a page-fault.  If the request was already
  * aborted bail out.
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index c4807b3fc8a..48b9971ecd9 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1107,6 +1107,50 @@ static void iattr_to_fattr(struct iattr *iattr, struct fuse_setattr_in *arg)
 }
 
 /*
+ * Prevent concurrent writepages on inode
+ *
+ * This is done by adding a negative bias to the inode write counter
+ * and waiting for all pending writes to finish.
+ */
+void fuse_set_nowrite(struct inode *inode)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	BUG_ON(!mutex_is_locked(&inode->i_mutex));
+
+	spin_lock(&fc->lock);
+	BUG_ON(fi->writectr < 0);
+	fi->writectr += FUSE_NOWRITE;
+	spin_unlock(&fc->lock);
+	wait_event(fi->page_waitq, fi->writectr == FUSE_NOWRITE);
+}
+
+/*
+ * Allow writepages on inode
+ *
+ * Remove the bias from the writecounter and send any queued
+ * writepages.
+ */
+static void __fuse_release_nowrite(struct inode *inode)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	BUG_ON(fi->writectr != FUSE_NOWRITE);
+	fi->writectr = 0;
+	fuse_flush_writepages(inode);
+}
+
+void fuse_release_nowrite(struct inode *inode)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+
+	spin_lock(&fc->lock);
+	__fuse_release_nowrite(inode);
+	spin_unlock(&fc->lock);
+}
+
+/*
  * Set attributes, and at the same time refresh them.
  *
  * Truncation is slightly complicated, because the 'truncate' request
@@ -1122,6 +1166,8 @@ static int fuse_do_setattr(struct dentry *entry, struct iattr *attr,
 	struct fuse_req *req;
 	struct fuse_setattr_in inarg;
 	struct fuse_attr_out outarg;
+	bool is_truncate = false;
+	loff_t oldsize;
 	int err;
 
 	if (!fuse_allow_task(fc, current))
@@ -1145,12 +1191,16 @@ static int fuse_do_setattr(struct dentry *entry, struct iattr *attr,
 			send_sig(SIGXFSZ, current, 0);
 			return -EFBIG;
 		}
+		is_truncate = true;
 	}
 
 	req = fuse_get_req(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
+	if (is_truncate)
+		fuse_set_nowrite(inode);
+
 	memset(&inarg, 0, sizeof(inarg));
 	memset(&outarg, 0, sizeof(outarg));
 	iattr_to_fattr(attr, &inarg);
@@ -1181,16 +1231,44 @@ static int fuse_do_setattr(struct dentry *entry, struct iattr *attr,
 	if (err) {
 		if (err == -EINTR)
 			fuse_invalidate_attr(inode);
-		return err;
+		goto error;
 	}
 
 	if ((inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
 		make_bad_inode(inode);
-		return -EIO;
+		err = -EIO;
+		goto error;
+	}
+
+	spin_lock(&fc->lock);
+	fuse_change_attributes_common(inode, &outarg.attr,
+				      attr_timeout(&outarg));
+	oldsize = inode->i_size;
+	i_size_write(inode, outarg.attr.size);
+
+	if (is_truncate) {
+		/* NOTE: this may release/reacquire fc->lock */
+		__fuse_release_nowrite(inode);
+	}
+	spin_unlock(&fc->lock);
+
+	/*
+	 * Only call invalidate_inode_pages2() after removing
+	 * FUSE_NOWRITE, otherwise fuse_launder_page() would deadlock.
+	 */
+	if (S_ISREG(inode->i_mode) && oldsize != outarg.attr.size) {
+		if (outarg.attr.size < oldsize)
+			fuse_truncate(inode->i_mapping, outarg.attr.size);
+		invalidate_inode_pages2(inode->i_mapping);
 	}
 
-	fuse_change_attributes(inode, &outarg.attr, attr_timeout(&outarg), 0);
 	return 0;
+
+error:
+	if (is_truncate)
+		fuse_release_nowrite(inode);
+
+	return err;
 }
 
 static int fuse_setattr(struct dentry *entry, struct iattr *attr)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 676b0bc8a86..68051f3bdf9 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -210,6 +210,49 @@ u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id)
 	return (u64) v0 + ((u64) v1 << 32);
 }
 
+/*
+ * Check if page is under writeback
+ *
+ * This is currently done by walking the list of writepage requests
+ * for the inode, which can be pretty inefficient.
+ */
+static bool fuse_page_is_writeback(struct inode *inode, pgoff_t index)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct fuse_req *req;
+	bool found = false;
+
+	spin_lock(&fc->lock);
+	list_for_each_entry(req, &fi->writepages, writepages_entry) {
+		pgoff_t curr_index;
+
+		BUG_ON(req->inode != inode);
+		curr_index = req->misc.write.in.offset >> PAGE_CACHE_SHIFT;
+		if (curr_index == index) {
+			found = true;
+			break;
+		}
+	}
+	spin_unlock(&fc->lock);
+
+	return found;
+}
+
+/*
+ * Wait for page writeback to be completed.
+ *
+ * Since fuse doesn't rely on the VM writeback tracking, this has to
+ * use some other means.
+ */
+static int fuse_wait_on_page_writeback(struct inode *inode, pgoff_t index)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	wait_event(fi->page_waitq, !fuse_page_is_writeback(inode, index));
+	return 0;
+}
+
 static int fuse_flush(struct file *file, fl_owner_t id)
 {
 	struct inode *inode = file->f_path.dentry->d_inode;
@@ -245,6 +288,21 @@ static int fuse_flush(struct file *file, fl_owner_t id)
 	return err;
 }
 
+/*
+ * Wait for all pending writepages on the inode to finish.
+ *
+ * This is currently done by blocking further writes with FUSE_NOWRITE
+ * and waiting for all sent writes to complete.
+ *
+ * This must be called under i_mutex, otherwise the FUSE_NOWRITE usage
+ * could conflict with truncation.
+ */
+static void fuse_sync_writes(struct inode *inode)
+{
+	fuse_set_nowrite(inode);
+	fuse_release_nowrite(inode);
+}
+
 int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
 		      int isdir)
 {
@@ -261,6 +319,17 @@ int fuse_fsync_common(struct file *file, struct dentry *de, int datasync,
 	if ((!isdir && fc->no_fsync) || (isdir && fc->no_fsyncdir))
 		return 0;
 
+	/*
+	 * Start writeback against all dirty pages of the inode, then
+	 * wait for all outstanding writes, before sending the FSYNC
+	 * request.
+	 */
+	err = write_inode_now(inode, 0);
+	if (err)
+		return err;
+
+	fuse_sync_writes(inode);
+
 	req = fuse_get_req(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
@@ -340,6 +409,13 @@ static int fuse_readpage(struct file *file, struct page *page)
 	if (is_bad_inode(inode))
 		goto out;
 
+	/*
+	 * Page writeback can extend beyond the liftime of the
+	 * page-cache page, so make sure we read a properly synced
+	 * page.
+	 */
+	fuse_wait_on_page_writeback(inode, page->index);
+
 	req = fuse_get_req(fc);
 	err = PTR_ERR(req);
 	if (IS_ERR(req))
@@ -411,6 +487,8 @@ static int fuse_readpages_fill(void *_data, struct page *page)
 	struct inode *inode = data->inode;
 	struct fuse_conn *fc = get_fuse_conn(inode);
 
+	fuse_wait_on_page_writeback(inode, page->index);
+
 	if (req->num_pages &&
 	    (req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
 	     (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
@@ -477,11 +555,10 @@ static ssize_t fuse_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 }
 
 static void fuse_write_fill(struct fuse_req *req, struct file *file,
-			    struct inode *inode, loff_t pos, size_t count,
-			    int writepage)
+			    struct fuse_file *ff, struct inode *inode,
+			    loff_t pos, size_t count, int writepage)
 {
 	struct fuse_conn *fc = get_fuse_conn(inode);
-	struct fuse_file *ff = file->private_data;
 	struct fuse_write_in *inarg = &req->misc.write.in;
 	struct fuse_write_out *outarg = &req->misc.write.out;
 
@@ -490,7 +567,7 @@ static void fuse_write_fill(struct fuse_req *req, struct file *file,
 	inarg->offset = pos;
 	inarg->size = count;
 	inarg->write_flags = writepage ? FUSE_WRITE_CACHE : 0;
-	inarg->flags = file->f_flags;
+	inarg->flags = file ? file->f_flags : 0;
 	req->in.h.opcode = FUSE_WRITE;
 	req->in.h.nodeid = get_node_id(inode);
 	req->in.argpages = 1;
@@ -511,7 +588,7 @@ static size_t fuse_send_write(struct fuse_req *req, struct file *file,
 			      fl_owner_t owner)
 {
 	struct fuse_conn *fc = get_fuse_conn(inode);
-	fuse_write_fill(req, file, inode, pos, count, 0);
+	fuse_write_fill(req, file, file->private_data, inode, pos, count, 0);
 	if (owner != NULL) {
 		struct fuse_write_in *inarg = &req->misc.write.in;
 		inarg->write_flags |= FUSE_WRITE_LOCKOWNER;
@@ -546,6 +623,12 @@ static int fuse_buffered_write(struct file *file, struct inode *inode,
 	if (is_bad_inode(inode))
 		return -EIO;
 
+	/*
+	 * Make sure writepages on the same page are not mixed up with
+	 * plain writes.
+	 */
+	fuse_wait_on_page_writeback(inode, page->index);
+
 	req = fuse_get_req(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
@@ -716,21 +799,225 @@ static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
 	return res;
 }
 
-static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
+static void fuse_writepage_free(struct fuse_conn *fc, struct fuse_req *req)
 {
-	if ((vma->vm_flags & VM_SHARED)) {
-		if ((vma->vm_flags & VM_WRITE))
-			return -ENODEV;
-		else
-			vma->vm_flags &= ~VM_MAYWRITE;
+	__free_page(req->pages[0]);
+	fuse_file_put(req->ff);
+	fuse_put_request(fc, req);
+}
+
+static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req)
+{
+	struct inode *inode = req->inode;
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
+
+	list_del(&req->writepages_entry);
+	dec_bdi_stat(bdi, BDI_WRITEBACK);
+	dec_zone_page_state(req->pages[0], NR_WRITEBACK_TEMP);
+	bdi_writeout_inc(bdi);
+	wake_up(&fi->page_waitq);
+}
+
+/* Called under fc->lock, may release and reacquire it */
+static void fuse_send_writepage(struct fuse_conn *fc, struct fuse_req *req)
+{
+	struct fuse_inode *fi = get_fuse_inode(req->inode);
+	loff_t size = i_size_read(req->inode);
+	struct fuse_write_in *inarg = &req->misc.write.in;
+
+	if (!fc->connected)
+		goto out_free;
+
+	if (inarg->offset + PAGE_CACHE_SIZE <= size) {
+		inarg->size = PAGE_CACHE_SIZE;
+	} else if (inarg->offset < size) {
+		inarg->size = size & (PAGE_CACHE_SIZE - 1);
+	} else {
+		/* Got truncated off completely */
+		goto out_free;
 	}
-	return generic_file_mmap(file, vma);
+
+	req->in.args[1].size = inarg->size;
+	fi->writectr++;
+	request_send_background_locked(fc, req);
+	return;
+
+ out_free:
+	fuse_writepage_finish(fc, req);
+	spin_unlock(&fc->lock);
+	fuse_writepage_free(fc, req);
+	spin_lock(&fc->lock);
 }
 
-static int fuse_set_page_dirty(struct page *page)
+/*
+ * If fi->writectr is positive (no truncate or fsync going on) send
+ * all queued writepage requests.
+ *
+ * Called with fc->lock
+ */
+void fuse_flush_writepages(struct inode *inode)
 {
-	printk("fuse_set_page_dirty: should not happen\n");
-	dump_stack();
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct fuse_req *req;
+
+	while (fi->writectr >= 0 && !list_empty(&fi->queued_writes)) {
+		req = list_entry(fi->queued_writes.next, struct fuse_req, list);
+		list_del_init(&req->list);
+		fuse_send_writepage(fc, req);
+	}
+}
+
+static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_req *req)
+{
+	struct inode *inode = req->inode;
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	mapping_set_error(inode->i_mapping, req->out.h.error);
+	spin_lock(&fc->lock);
+	fi->writectr--;
+	fuse_writepage_finish(fc, req);
+	spin_unlock(&fc->lock);
+	fuse_writepage_free(fc, req);
+}
+
+static int fuse_writepage_locked(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	struct inode *inode = mapping->host;
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	struct fuse_req *req;
+	struct fuse_file *ff;
+	struct page *tmp_page;
+
+	set_page_writeback(page);
+
+	req = fuse_request_alloc_nofs();
+	if (!req)
+		goto err;
+
+	tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+	if (!tmp_page)
+		goto err_free;
+
+	spin_lock(&fc->lock);
+	BUG_ON(list_empty(&fi->write_files));
+	ff = list_entry(fi->write_files.next, struct fuse_file, write_entry);
+	req->ff = fuse_file_get(ff);
+	spin_unlock(&fc->lock);
+
+	fuse_write_fill(req, NULL, ff, inode, page_offset(page), 0, 1);
+
+	copy_highpage(tmp_page, page);
+	req->num_pages = 1;
+	req->pages[0] = tmp_page;
+	req->page_offset = 0;
+	req->end = fuse_writepage_end;
+	req->inode = inode;
+
+	inc_bdi_stat(mapping->backing_dev_info, BDI_WRITEBACK);
+	inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
+	end_page_writeback(page);
+
+	spin_lock(&fc->lock);
+	list_add(&req->writepages_entry, &fi->writepages);
+	list_add_tail(&req->list, &fi->queued_writes);
+	fuse_flush_writepages(inode);
+	spin_unlock(&fc->lock);
+
+	return 0;
+
+err_free:
+	fuse_request_free(req);
+err:
+	end_page_writeback(page);
+	return -ENOMEM;
+}
+
+static int fuse_writepage(struct page *page, struct writeback_control *wbc)
+{
+	int err;
+
+	err = fuse_writepage_locked(page);
+	unlock_page(page);
+
+	return err;
+}
+
+static int fuse_launder_page(struct page *page)
+{
+	int err = 0;
+	if (clear_page_dirty_for_io(page)) {
+		struct inode *inode = page->mapping->host;
+		err = fuse_writepage_locked(page);
+		if (!err)
+			fuse_wait_on_page_writeback(inode, page->index);
+	}
+	return err;
+}
+
+/*
+ * Write back dirty pages now, because there may not be any suitable
+ * open files later
+ */
+static void fuse_vma_close(struct vm_area_struct *vma)
+{
+	filemap_write_and_wait(vma->vm_file->f_mapping);
+}
+
+/*
+ * Wait for writeback against this page to complete before allowing it
+ * to be marked dirty again, and hence written back again, possibly
+ * before the previous writepage completed.
+ *
+ * Block here, instead of in ->writepage(), so that the userspace fs
+ * can only block processes actually operating on the filesystem.
+ *
+ * Otherwise unprivileged userspace fs would be able to block
+ * unrelated:
+ *
+ * - page migration
+ * - sync(2)
+ * - try_to_free_pages() with order > PAGE_ALLOC_COSTLY_ORDER
+ */
+static int fuse_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+{
+	/*
+	 * Don't use page->mapping as it may become NULL from a
+	 * concurrent truncate.
+	 */
+	struct inode *inode = vma->vm_file->f_mapping->host;
+
+	fuse_wait_on_page_writeback(inode, page->index);
+	return 0;
+}
+
+static struct vm_operations_struct fuse_file_vm_ops = {
+	.close		= fuse_vma_close,
+	.fault		= filemap_fault,
+	.page_mkwrite	= fuse_page_mkwrite,
+};
+
+static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) {
+		struct inode *inode = file->f_dentry->d_inode;
+		struct fuse_conn *fc = get_fuse_conn(inode);
+		struct fuse_inode *fi = get_fuse_inode(inode);
+		struct fuse_file *ff = file->private_data;
+		/*
+		 * file may be written through mmap, so chain it onto the
+		 * inodes's write_file list
+		 */
+		spin_lock(&fc->lock);
+		if (list_empty(&ff->write_entry))
+			list_add(&ff->write_entry, &fi->write_files);
+		spin_unlock(&fc->lock);
+	}
+	file_accessed(file);
+	vma->vm_ops = &fuse_file_vm_ops;
 	return 0;
 }
 
@@ -940,10 +1227,12 @@ static const struct file_operations fuse_direct_io_file_operations = {
 
 static const struct address_space_operations fuse_file_aops  = {
 	.readpage	= fuse_readpage,
+	.writepage	= fuse_writepage,
+	.launder_page	= fuse_launder_page,
 	.write_begin	= fuse_write_begin,
 	.write_end	= fuse_write_end,
 	.readpages	= fuse_readpages,
-	.set_page_dirty	= fuse_set_page_dirty,
+	.set_page_dirty	= __set_page_dirty_nobuffers,
 	.bmap		= fuse_bmap,
 };
 
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index c0481e48d16..4b094fbc9c7 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -15,6 +15,7 @@
 #include <linux/mm.h>
 #include <linux/backing-dev.h>
 #include <linux/mutex.h>
+#include <linux/rwsem.h>
 
 /** Max number of pages that can be used in a single read request */
 #define FUSE_MAX_PAGES_PER_REQ 32
@@ -25,6 +26,9 @@
 /** Congestion starts at 75% of maximum */
 #define FUSE_CONGESTION_THRESHOLD (FUSE_MAX_BACKGROUND * 75 / 100)
 
+/** Bias for fi->writectr, meaning new writepages must not be sent */
+#define FUSE_NOWRITE INT_MIN
+
 /** It could be as large as PATH_MAX, but would that have any uses? */
 #define FUSE_NAME_MAX 1024
 
@@ -73,6 +77,19 @@ struct fuse_inode {
 
 	/** Files usable in writepage.  Protected by fc->lock */
 	struct list_head write_files;
+
+	/** Writepages pending on truncate or fsync */
+	struct list_head queued_writes;
+
+	/** Number of sent writes, a negative bias (FUSE_NOWRITE)
+	 * means more writes are blocked */
+	int writectr;
+
+	/** Waitq for writepage completion */
+	wait_queue_head_t page_waitq;
+
+	/** List of writepage requestst (pending or sent) */
+	struct list_head writepages;
 };
 
 /** FUSE specific file data */
@@ -242,6 +259,12 @@ struct fuse_req {
 	/** File used in the request (or NULL) */
 	struct fuse_file *ff;
 
+	/** Inode used in the request or NULL */
+	struct inode *inode;
+
+	/** Link on fi->writepages */
+	struct list_head writepages_entry;
+
 	/** Request completion callback */
 	void (*end)(struct fuse_conn *, struct fuse_req *);
 
@@ -504,6 +527,11 @@ void fuse_init_symlink(struct inode *inode);
 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
 			    u64 attr_valid, u64 attr_version);
 
+void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
+				   u64 attr_valid);
+
+void fuse_truncate(struct address_space *mapping, loff_t offset);
+
 /**
  * Initialize the client device
  */
@@ -522,6 +550,8 @@ void fuse_ctl_cleanup(void);
  */
 struct fuse_req *fuse_request_alloc(void);
 
+struct fuse_req *fuse_request_alloc_nofs(void);
+
 /**
  * Free a request
  */
@@ -558,6 +588,8 @@ void request_send_noreply(struct fuse_conn *fc, struct fuse_req *req);
  */
 void request_send_background(struct fuse_conn *fc, struct fuse_req *req);
 
+void request_send_background_locked(struct fuse_conn *fc, struct fuse_req *req);
+
 /* Abort all requests */
 void fuse_abort_conn(struct fuse_conn *fc);
 
@@ -600,3 +632,8 @@ u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id);
 
 int fuse_update_attributes(struct inode *inode, struct kstat *stat,
 			   struct file *file, bool *refreshed);
+
+void fuse_flush_writepages(struct inode *inode);
+
+void fuse_set_nowrite(struct inode *inode);
+void fuse_release_nowrite(struct inode *inode);
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index c4fcfd59cd8..7d01c68852a 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -59,7 +59,11 @@ static struct inode *fuse_alloc_inode(struct super_block *sb)
 	fi->nodeid = 0;
 	fi->nlookup = 0;
 	fi->attr_version = 0;
+	fi->writectr = 0;
 	INIT_LIST_HEAD(&fi->write_files);
+	INIT_LIST_HEAD(&fi->queued_writes);
+	INIT_LIST_HEAD(&fi->writepages);
+	init_waitqueue_head(&fi->page_waitq);
 	fi->forget_req = fuse_request_alloc();
 	if (!fi->forget_req) {
 		kmem_cache_free(fuse_inode_cachep, inode);
@@ -73,6 +77,7 @@ static void fuse_destroy_inode(struct inode *inode)
 {
 	struct fuse_inode *fi = get_fuse_inode(inode);
 	BUG_ON(!list_empty(&fi->write_files));
+	BUG_ON(!list_empty(&fi->queued_writes));
 	if (fi->forget_req)
 		fuse_request_free(fi->forget_req);
 	kmem_cache_free(fuse_inode_cachep, inode);
@@ -109,7 +114,7 @@ static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)
 	return 0;
 }
 
-static void fuse_truncate(struct address_space *mapping, loff_t offset)
+void fuse_truncate(struct address_space *mapping, loff_t offset)
 {
 	/* See vmtruncate() */
 	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
@@ -117,19 +122,12 @@ static void fuse_truncate(struct address_space *mapping, loff_t offset)
 	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
 }
 
-
-void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
-			    u64 attr_valid, u64 attr_version)
+void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
+				   u64 attr_valid)
 {
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	struct fuse_inode *fi = get_fuse_inode(inode);
-	loff_t oldsize;
 
-	spin_lock(&fc->lock);
-	if (attr_version != 0 && fi->attr_version > attr_version) {
-		spin_unlock(&fc->lock);
-		return;
-	}
 	fi->attr_version = ++fc->attr_version;
 	fi->i_time = attr_valid;
 
@@ -159,6 +157,22 @@ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
 	fi->orig_i_mode = inode->i_mode;
 	if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS))
 		inode->i_mode &= ~S_ISVTX;
+}
+
+void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
+			    u64 attr_valid, u64 attr_version)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	loff_t oldsize;
+
+	spin_lock(&fc->lock);
+	if (attr_version != 0 && fi->attr_version > attr_version) {
+		spin_unlock(&fc->lock);
+		return;
+	}
+
+	fuse_change_attributes_common(inode, attr, attr_valid);
 
 	oldsize = inode->i_size;
 	i_size_write(inode, attr->size);
@@ -468,6 +482,8 @@ static struct fuse_conn *new_conn(struct super_block *sb)
 		atomic_set(&fc->num_waiting, 0);
 		fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
 		fc->bdi.unplug_io_fn = default_unplug_io_fn;
+		/* fuse does it's own writeback accounting */
+		fc->bdi.capabilities = BDI_CAP_NO_ACCT_WB;
 		fc->dev = sb->s_dev;
 		err = bdi_init(&fc->bdi);
 		if (err)
@@ -475,6 +491,19 @@ static struct fuse_conn *new_conn(struct super_block *sb)
 		err = bdi_register_dev(&fc->bdi, fc->dev);
 		if (err)
 			goto error_bdi_destroy;
+		/*
+		 * For a single fuse filesystem use max 1% of dirty +
+		 * writeback threshold.
+		 *
+		 * This gives about 1M of write buffer for memory maps on a
+		 * machine with 1G and 10% dirty_ratio, which should be more
+		 * than enough.
+		 *
+		 * Privileged users can raise it by writing to
+		 *
+		 *    /sys/class/bdi/<bdi>/max_ratio
+		 */
+		bdi_set_max_ratio(&fc->bdi, 1);
 		fc->reqctr = 0;
 		fc->blocked = 1;
 		fc->attr_version = 1;