On Thu, Jun 2, 2022 at 8:15 AM Dave Chinner <david@xxxxxxxxxxxxx> wrote: > > On Thu, Jun 02, 2022 at 07:24:26AM +0300, Amir Goldstein wrote: > > On Thu, Jun 2, 2022 at 3:38 AM Dave Chinner <david@xxxxxxxxxxxxx> wrote: > > > > > > On Wed, Jun 01, 2022 at 01:45:46PM +0300, Amir Goldstein wrote: > > > > From: Brian Foster <bfoster@xxxxxxxxxx> > > > > > > > > commit 1cd738b13ae9b29e03d6149f0246c61f76e81fcf upstream. > > > > > > > > The assert in xfs_btree_del_cursor() checks that the bmapbt block > > > > allocation field has been handled correctly before the cursor is > > > > freed. This field is used for accurate calculation of indirect block > > > > reservation requirements (for delayed allocations), for example. > > > > generic/019 reproduces a scenario where this assert fails because > > > > the filesystem has shutdown while in the middle of a bmbt record > > > > insertion. This occurs after a bmbt block has been allocated via the > > > > cursor but before the higher level bmap function (i.e. > > > > xfs_bmap_add_extent_hole_real()) completes and resets the field. > > > > > > > > Update the assert to accommodate the transient state if the > > > > filesystem has shutdown. While here, clean up the indentation and > > > > comments in the function. > > > > > > > > Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx> > > > > Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx> > > > > Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> > > > > Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx> > > > > --- > > > > fs/xfs/libxfs/xfs_btree.c | 33 ++++++++++++--------------------- > > > > 1 file changed, 12 insertions(+), 21 deletions(-) > > > > > > https://git.kernel.org/pub/scm/fs/xfs/xfs-linux.git/commit/?h=for-next&id=56486f307100e8fc66efa2ebd8a71941fa10bf6f > > > > > > > Warm from the over :) > > > > I will need more time to verify that this new fix is not breaking LTS > > but I don't think that it should be blocking taking the old 5.12 fix now. > > Right? > > Rule #1: don't introduce new bugs into stable kernels. > > This commit has a known (and fixed) bug in it. If you are going to > back port it to a stable kernel, then you need to also pull in the > fix for that commit, too. Oh. I misunderstood. I thought this wasn't a Fixes: situation. I thought you pointed me to another related bug fix. > > But the bigger question is this: why propose backports of commits > that only change debug code? > > ASSERT()s are not compiled into production kernels - they are only > compiled into developer builds when CONFIG_XFS_DEBUG=y is set. It is > test code, not production code, hence nobody will be using this in > production kernels. > > I don't see the value in backporting debug fixes unless there > is some other dependency that requires them. The value is in testing of LTS kernel. For my backport work to be serious, I need to do serious testing. Serious means running as many tests as I can and running the tests on many configs and many times over. When I first joined Luis in testing LTS baseline, CONFIG_XFS_DEBUG was not enabled on the tested kernels. I enabled it so I could get better test coverage for fstests that use error injection and tests that check for asserts. This helped me find a regression with one of the backported patches [1]. IOW, for LTS code to be in good quality, it needs to also have the correct assertions. For the same reason, I am also going to queue the following as stable candidate: 756b1c343333 xfs: use current->journal_info for detecting transaction recursion Because it has already proved to be helpful in detecting bugs on our internal product tests. > But if you are going to back port them, Rule #1 applies. > Of course. I will defer sending this patch to stable and test it along with the new fix. Thanks! Amir. [1] https://lore.kernel.org/linux-xfs/YpY6hUknor2S1iMd@bfoster/T/#mf1add66b8309a75a8984f28ea08718f22033bce7
