Re: [PATCH] Fix bug in FUSE where the attribute cache for a file wasnot cleared when a file is opened with O_TRUNC.

[Miklos Szeredi]

Ken,

Thanks for the patch.

Here's a slightly updated one.  Does this also look OK?

Miklos


----
Subject: fuse: fix attributes after open(O_TRUNC)
From: Ken Sumrall <ksumrall@xxxxxxxxxxx>

The attribute cache for a file was not being cleared when a file is
opened with O_TRUNC.

If the filesystem's open operation truncates the file
("atomic_o_trunc" feature flag is set) then the kernel should
invalidate the cached st_mtime and st_ctime attributes.

Also i_size should be explicitly be set to zero as it is used
sometimes without refreshing the cache.

Signed-off-by: Ken Sumrall <ksumrall@xxxxxxxxxxx>
Cc: Anfei <anfei.zhou@xxxxxxxxx>
Cc: "Anand V. Avati" <avati@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Miklos Szeredi <miklos@xxxxxxxxxx>
Cc: stable@xxxxxxxxxx
---

 fs/fuse/file.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

Index: linux-2.6/fs/fuse/file.c
===================================================================
--- linux-2.6.orig/fs/fuse/file.c	2010-10-27 14:04:02.000000000 +0200
+++ linux-2.6/fs/fuse/file.c	2010-10-30 13:14:07.000000000 +0200
@@ -134,6 +134,7 @@ EXPORT_SYMBOL_GPL(fuse_do_open);
 void fuse_finish_open(struct inode *inode, struct file *file)
 {
 	struct fuse_file *ff = file->private_data;
+	struct fuse_conn *fc = get_fuse_conn(inode);
 
 	if (ff->open_flags & FOPEN_DIRECT_IO)
 		file->f_op = &fuse_direct_io_file_operations;
@@ -141,6 +142,15 @@ void fuse_finish_open(struct inode *inod
 		invalidate_inode_pages2(inode->i_mapping);
 	if (ff->open_flags & FOPEN_NONSEEKABLE)
 		nonseekable_open(inode, file);
+	if (fc->atomic_o_trunc && (file->f_flags & O_TRUNC)) {
+		struct fuse_inode *fi = get_fuse_inode(inode);
+
+		spin_lock(&fc->lock);
+		fi->attr_version = ++fc->attr_version;
+		i_size_write(inode, 0);
+		spin_unlock(&fc->lock);
+		fuse_invalidate_attr(inode);
+	}
 }
 
 int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
--
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