bbdaa7a48f
commit 33fab972497ae66822c0b6846d4f9382938575b6 upstream.
When creating a subvolume, at create_subvol(), we allocate an anonymous
device and later call btrfs_get_new_fs_root(), which in turn just calls
btrfs_get_root_ref(). There we call btrfs_init_fs_root() which assigns
the anonymous device to the root, but if after that call there's an error,
when we jump to 'fail' label, we call btrfs_put_root(), which frees the
anonymous device and then returns an error that is propagated back to
create_subvol(). Than create_subvol() frees the anonymous device again.
When this happens, if the anonymous device was not reallocated after
the first time it was freed with btrfs_put_root(), we get a kernel
message like the following:
(...)
[13950.282466] BTRFS: error (device dm-0) in create_subvol:663: errno=-5 IO failure
[13950.283027] ida_free called for id=65 which is not allocated.
[13950.285974] BTRFS info (device dm-0): forced readonly
(...)
If the anonymous device gets reallocated by another btrfs filesystem
or any other kernel subsystem, then bad things can happen.
So fix this by setting the root's anonymous device to 0 at
btrfs_get_root_ref(), before we call btrfs_put_root(), if an error
happened.
Fixes: 2dfb1e43f57dd3 ("btrfs: preallocate anon block device at first phase of snapshot creation")
CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.