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Commit d45f00ae authored by Al Viro's avatar Al Viro
Browse files

overlayfs: barriers for opening upper-layer directory 



make sure that
	a) all stores done by opening struct file don't leak past storing
the reference in od->upperfile
	b) the lockless side has read dependency barrier

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 54ef6df3

fs/overlayfs/readdir.c

+2 −1
Original line number Diff line number Diff line
@@ -454,12 +454,13 @@ static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end, 
	if (!od->is_upper && ovl_path_type(dentry) == OVL_PATH_MERGE) {

		struct inode *inode = file_inode(file);



		realfile = od->upperfile;

		realfile =lockless_dereference(od->upperfile);

		if (!realfile) {

			struct path upperpath;



			ovl_path_upper(dentry, &upperpath);

			realfile = ovl_path_open(&upperpath, O_RDONLY);

			smp_mb__before_spinlock();

			mutex_lock(&inode->i_mutex);

			if (!od->upperfile) {

				if (IS_ERR(realfile)) {