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;