From: Amir Goldstein amir73il@gmail.com
commit 3428030da004a1128cbdcf93dc03e16f184d845b upstream.
Generalize the helper ovl_open_maybe_copy_up() and use it to copy up file with data before FS_IOC_SETFLAGS ioctl.
The FS_IOC_SETFLAGS ioctl is a bit of an odd ball in vfs, which probably caused the confusion. File may be open O_RDONLY, but ioctl modifies the file. VFS does not call mnt_want_write_file() nor lock inode mutex, but fs-specific code for FS_IOC_SETFLAGS does. So ovl_ioctl() calls mnt_want_write_file() for the overlay file, and fs-specific code calls mnt_want_write_file() for upper fs file, but there was no call for ovl_want_write() for copy up duration which prevents overlayfs from copying up on a frozen upper fs.
Fixes: dab5ca8fd9dd ("ovl: add lsattr/chattr support") Cc: stable@vger.kernel.org # v4.19 Signed-off-by: Amir Goldstein amir73il@gmail.com Acked-by: Vivek Goyal vgoyal@redhat.com Signed-off-by: Miklos Szeredi mszeredi@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/overlayfs/copy_up.c | 6 +++--- fs/overlayfs/file.c | 5 ++--- fs/overlayfs/overlayfs.h | 2 +- 3 files changed, 6 insertions(+), 7 deletions(-)
--- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -878,14 +878,14 @@ static bool ovl_open_need_copy_up(struct return true; }
-int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags) +int ovl_maybe_copy_up(struct dentry *dentry, int flags) { int err = 0;
- if (ovl_open_need_copy_up(dentry, file_flags)) { + if (ovl_open_need_copy_up(dentry, flags)) { err = ovl_want_write(dentry); if (!err) { - err = ovl_copy_up_flags(dentry, file_flags); + err = ovl_copy_up_flags(dentry, flags); ovl_drop_write(dentry); } } --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -116,11 +116,10 @@ static int ovl_real_fdget(const struct f
static int ovl_open(struct inode *inode, struct file *file) { - struct dentry *dentry = file_dentry(file); struct file *realfile; int err;
- err = ovl_open_maybe_copy_up(dentry, file->f_flags); + err = ovl_maybe_copy_up(file_dentry(file), file->f_flags); if (err) return err;
@@ -390,7 +389,7 @@ static long ovl_ioctl(struct file *file, if (ret) return ret;
- ret = ovl_copy_up_with_data(file_dentry(file)); + ret = ovl_maybe_copy_up(file_dentry(file), O_WRONLY); if (!ret) { ret = ovl_real_ioctl(file, cmd, arg);
--- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -411,7 +411,7 @@ extern const struct file_operations ovl_ int ovl_copy_up(struct dentry *dentry); int ovl_copy_up_with_data(struct dentry *dentry); int ovl_copy_up_flags(struct dentry *dentry, int flags); -int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags); +int ovl_maybe_copy_up(struct dentry *dentry, int flags); int ovl_copy_xattr(struct dentry *old, struct dentry *new); int ovl_set_attr(struct dentry *upper, struct kstat *stat); struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper);