From efb9fa9e911b23c7ea5330215bda778a7c69dba8 Mon Sep 17 00:00:00 2001
From: Maxim Patlasov <mpatlasov@parallels.com>
Date: Tue, 18 Dec 2012 14:05:08 +0400
Subject: fuse: truncate file if async dio failed

The patch improves error handling in fuse_direct_IO(): if we successfully
submitted several fuse requests on behalf of synchronous direct write
extending file and some of them failed, let's try to do our best to clean-up.

Changed in v2: reuse fuse_do_setattr(). Thanks to Brian for suggestion.

Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index ff15522..254df56 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1562,10 +1562,9 @@ void fuse_release_nowrite(struct inode *inode)
  * vmtruncate() doesn't allow for this case, so do the rlimit checking
  * and the actual truncation by hand.
  */
-static int fuse_do_setattr(struct dentry *entry, struct iattr *attr,
-			   struct file *file)
+int fuse_do_setattr(struct inode *inode, struct iattr *attr,
+		    struct file *file)
 {
-	struct inode *inode = entry->d_inode;
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	struct fuse_req *req;
 	struct fuse_setattr_in inarg;
@@ -1574,9 +1573,6 @@ static int fuse_do_setattr(struct dentry *entry, struct iattr *attr,
 	loff_t oldsize;
 	int err;
 
-	if (!fuse_allow_current_process(fc))
-		return -EACCES;
-
 	if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS))
 		attr->ia_valid |= ATTR_FORCE;
 
@@ -1671,10 +1667,15 @@ error:
 
 static int fuse_setattr(struct dentry *entry, struct iattr *attr)
 {
+	struct inode *inode = entry->d_inode;
+
+	if (!fuse_allow_current_process(get_fuse_conn(inode)))
+		return -EACCES;
+
 	if (attr->ia_valid & ATTR_FILE)
-		return fuse_do_setattr(entry, attr, attr->ia_file);
+		return fuse_do_setattr(inode, attr, attr->ia_file);
 	else
-		return fuse_do_setattr(entry, attr, NULL);
+		return fuse_do_setattr(inode, attr, NULL);
 }
 
 static int fuse_getattr(struct vfsmount *mnt, struct dentry *entry,
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 8f39f7b..1f8e3d6 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2352,6 +2352,20 @@ int fuse_notify_poll_wakeup(struct fuse_conn *fc,
 	return 0;
 }
 
+static void fuse_do_truncate(struct file *file)
+{
+	struct inode *inode = file->f_mapping->host;
+	struct iattr attr;
+
+	attr.ia_valid = ATTR_SIZE;
+	attr.ia_size = i_size_read(inode);
+
+	attr.ia_file = file;
+	attr.ia_valid |= ATTR_FILE;
+
+	fuse_do_setattr(inode, &attr, file);
+}
+
 static ssize_t
 fuse_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
 			loff_t offset, unsigned long nr_segs)
@@ -2419,8 +2433,12 @@ fuse_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
 		kfree(io);
 	}
 
-	if (rw == WRITE && ret > 0)
-		fuse_write_update_size(inode, pos);
+	if (rw == WRITE) {
+		if (ret > 0)
+			fuse_write_update_size(inode, pos);
+		else if (ret < 0 && offset + count > i_size)
+			fuse_do_truncate(file);
+	}
 
 	return ret;
 }
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 337169a..53b830e 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -863,4 +863,7 @@ int fuse_dev_release(struct inode *inode, struct file *file);
 
 void fuse_write_update_size(struct inode *inode, loff_t pos);
 
+int fuse_do_setattr(struct inode *inode, struct iattr *attr,
+		    struct file *file);
+
 #endif /* _FS_FUSE_I_H */
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