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ddf7e8984c
commit b19c98f237 upstream.
Syzbot reported a panic that looks like this:
assertion failed: fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE_PAUSED, in fs/btrfs/ioctl.c:465
------------[ cut here ]------------
kernel BUG at fs/btrfs/messages.c:259!
RIP: 0010:btrfs_assertfail+0x2c/0x30 fs/btrfs/messages.c:259
Call Trace:
<TASK>
btrfs_exclop_balance fs/btrfs/ioctl.c:465 [inline]
btrfs_ioctl_balance fs/btrfs/ioctl.c:3564 [inline]
btrfs_ioctl+0x531e/0x5b30 fs/btrfs/ioctl.c:4632
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
The reproducer is running a balance and a cancel or pause in parallel.
The way balance finishes is a bit wonky, if we were paused we need to
save the balance_ctl in the fs_info, but clear it otherwise and cleanup.
However we rely on the return values being specific errors, or having a
cancel request or no pause request. If balance completes and returns 0,
but we have a pause or cancel request we won't do the appropriate
cleanup, and then the next time we try to start a balance we'll trip
this ASSERT.
The error handling is just wrong here, we always want to clean up,
unless we got -ECANCELLED and we set the appropriate pause flag in the
exclusive op. With this patch the reproducer ran for an hour without
tripping, previously it would trip in less than a few minutes.
Reported-by: syzbot+c0f3acf145cb465426d5@syzkaller.appspotmail.com
CC: stable@vger.kernel.org # 6.1+
Signed-off-by: Josef Bacik <josef@toxicpanda.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
============
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In order to build the documentation, use ``make htmldocs`` or
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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.