fuse: convert to new aops

[mszeredi]
 - don't send zero length write requests
 - it is not legal for the filesystem to return with zero written bytes

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 32 insertions, 14 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index f79de7c8cdfa..11f22a3d728a 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -444,22 +444,25 @@ static size_t fuse_send_write(struct fuse_req *req, struct file *file,
         return outarg.size;
 }
 
-static int fuse_prepare_write(struct file *file, struct page *page,
-                              unsigned offset, unsigned to)
+static int fuse_write_begin(struct file *file, struct address_space *mapping,
+                        loff_t pos, unsigned len, unsigned flags,
+                        struct page **pagep, void **fsdata)
 {
-        /* No op */
+        pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+
+        *pagep = __grab_cache_page(mapping, index);
+        if (!*pagep)
+                return -ENOMEM;
         return 0;
 }
 
-static int fuse_commit_write(struct file *file, struct page *page,
-                             unsigned offset, unsigned to)
+static int fuse_buffered_write(struct file *file, struct inode *inode,
+                               loff_t pos, unsigned count, struct page *page)
 {
         int err;
         size_t nres;
-        unsigned count = to - offset;
-        struct inode *inode = page->mapping->host;
         struct fuse_conn *fc = get_fuse_conn(inode);
-        loff_t pos = page_offset(page) + offset;
+        unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
         struct fuse_req *req;
 
         if (is_bad_inode(inode))
@@ -475,20 +478,35 @@ static int fuse_commit_write(struct file *file, struct page *page,
         nres = fuse_send_write(req, file, inode, pos, count);
         err = req->out.h.error;
         fuse_put_request(fc, req);
-        if (!err && nres != count)
+        if (!err && !nres)
                 err = -EIO;
         if (!err) {
-                pos += count;
+                pos += nres;
                 spin_lock(&fc->lock);
                 if (pos > inode->i_size)
                         i_size_write(inode, pos);
                 spin_unlock(&fc->lock);
 
-                if (offset == 0 && to == PAGE_CACHE_SIZE)
+                if (count == PAGE_CACHE_SIZE)
                         SetPageUptodate(page);
         }
         fuse_invalidate_attr(inode);
-        return err;
+        return err ? err : nres;
+}
+
+static int fuse_write_end(struct file *file, struct address_space *mapping,
+                        loff_t pos, unsigned len, unsigned copied,
+                        struct page *page, void *fsdata)
+{
+        struct inode *inode = mapping->host;
+        int res = 0;
+
+        if (copied)
+                res = fuse_buffered_write(file, inode, pos, copied, page);
+
+        unlock_page(page);
+        page_cache_release(page);
+        return res;
 }
 
 static void fuse_release_user_pages(struct fuse_req *req, int write)
@@ -819,8 +837,8 @@ static const struct file_operations fuse_direct_io_file_operations = {
 
 static const struct address_space_operations fuse_file_aops  = {
         .readpage       = fuse_readpage,
-        .prepare_write  = fuse_prepare_write,
-        .commit_write   = fuse_commit_write,
+        .write_begin    = fuse_write_begin,
+        .write_end      = fuse_write_end,
         .readpages      = fuse_readpages,
         .set_page_dirty = fuse_set_page_dirty,
         .bmap           = fuse_bmap,