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-rw-r--r--fs/overlayfs/file.c60
1 files changed, 60 insertions, 0 deletions
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index ce7d002173a6..061a22511b5b 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -31,6 +31,66 @@ static struct file *ovl_open_realfile(const struct file *file)
return realfile;
}
+#define OVL_SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT)
+
+static int ovl_change_flags(struct file *file, unsigned int flags)
+{
+ struct inode *inode = file_inode(file);
+ int err;
+
+ /* No atime modificaton on underlying */
+ flags |= O_NOATIME;
+
+ /* If some flag changed that cannot be changed then something's amiss */
+ if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK))
+ return -EIO;
+
+ flags &= OVL_SETFL_MASK;
+
+ if (((flags ^ file->f_flags) & O_APPEND) && IS_APPEND(inode))
+ return -EPERM;
+
+ if (flags & O_DIRECT) {
+ if (!file->f_mapping->a_ops ||
+ !file->f_mapping->a_ops->direct_IO)
+ return -EINVAL;
+ }
+
+ if (file->f_op->check_flags) {
+ err = file->f_op->check_flags(flags);
+ if (err)
+ return err;
+ }
+
+ spin_lock(&file->f_lock);
+ file->f_flags = (file->f_flags & ~OVL_SETFL_MASK) | flags;
+ spin_unlock(&file->f_lock);
+
+ return 0;
+}
+
+static int ovl_real_fdget(const struct file *file, struct fd *real)
+{
+ struct inode *inode = file_inode(file);
+
+ real->flags = 0;
+ real->file = file->private_data;
+
+ /* Has it been copied up since we'd opened it? */
+ if (unlikely(file_inode(real->file) != ovl_inode_real(inode))) {
+ real->flags = FDPUT_FPUT;
+ real->file = ovl_open_realfile(file);
+
+ return PTR_ERR_OR_ZERO(real->file);
+ }
+
+ /* Did the flags change since open? */
+ if (unlikely((file->f_flags ^ real->file->f_flags) & ~O_NOATIME))
+ return ovl_change_flags(real->file, file->f_flags);
+
+ return 0;
+}
+
static int ovl_open(struct inode *inode, struct file *file)
{
struct dentry *dentry = file_dentry(file);