| Message ID | 20180503072052.22002-1-wqu@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, May 03, 2018 at 03:20:52PM +0800, Qu Wenruo wrote: > When doing qgroup rescan using the following script (modified from > btrfs/017 test case), we can sometimes hit qgroup corruption. > > ------ > umount $dev &> /dev/null > umount $mnt &> /dev/null > > mkfs.btrfs -f -n 64k $dev > mount $dev $mnt > > extent_size=8192 > > xfs_io -f -d -c "pwrite 0 $extent_size" $mnt/foo > /dev/null > btrfs subvolume snapshot $mnt $mnt/snap > > xfs_io -f -c "reflink $mnt/foo" $mnt/foo-reflink > /dev/null > xfs_io -f -c "reflink $mnt/foo" $mnt/snap/foo-reflink > /dev/null > xfs_io -f -c "reflink $mnt/foo" $mnt/snap/foo-reflink2 > /dev/unll > btrfs quota enable $mnt > > # -W is the new option to only wait rescan while not starting new one > btrfs quota rescan -W $mnt > btrfs qgroup show -prce $mnt > > # Need to patch btrfs-progs to report qgroup mismatch as error > btrfs check $dev || _fail > ------ > > For fast machine, we can hit some corruption which missed accounting > tree blocks: > ------ > qgroupid rfer excl max_rfer max_excl parent child > -------- ---- ---- -------- -------- ------ ----- > 0/5 8.00KiB 0.00B none none --- --- > 0/257 8.00KiB 0.00B none none --- --- > ------ > > This is due to the fact that we're always searching commit root for > btrfs_find_all_roots() at qgroup_rescan_leaf(), but the leaf we get is > from current transaction, not commit root. > > And if our tree blocks get modified in current transaction, we won't > find any owner in commit root, thus causing the corruption. > > Fix it by searching commit root for extent tree for > qgroup_rescan_leaf(). > > Reported-by: Nikolay Borisov <nborisov@suse.com> > Signed-off-by: Qu Wenruo <wqu@suse.com> Added to misc-next, thanks. > --- > > Please keep in mind that it is possible to hit another type of race > which double accounting tree blocks: > ------ > qgroupid rfer excl max_rfer max_excl parent child > -------- ---- ---- -------- -------- ------ ----- > 0/5 136.00KiB 128.00KiB none none --- --- > 0/257 136.00KiB 128.00KiB none none --- --- > ------ > For this type of corruption, this patch could reduce the possibility, > but the root cause is race between transaction commit and qgroup rescan, > which needs to be addressed in another patch. Both patches are now in misc-next, I saw the btrfs/017 failures occasionally so will watch if it's all ok now. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 5/3/18 3:20 AM, Qu Wenruo wrote: > When doing qgroup rescan using the following script (modified from > btrfs/017 test case), we can sometimes hit qgroup corruption. > > ------ > umount $dev &> /dev/null > umount $mnt &> /dev/null > > mkfs.btrfs -f -n 64k $dev > mount $dev $mnt > > extent_size=8192 > > xfs_io -f -d -c "pwrite 0 $extent_size" $mnt/foo > /dev/null > btrfs subvolume snapshot $mnt $mnt/snap > > xfs_io -f -c "reflink $mnt/foo" $mnt/foo-reflink > /dev/null > xfs_io -f -c "reflink $mnt/foo" $mnt/snap/foo-reflink > /dev/null > xfs_io -f -c "reflink $mnt/foo" $mnt/snap/foo-reflink2 > /dev/unll > btrfs quota enable $mnt > > # -W is the new option to only wait rescan while not starting new one > btrfs quota rescan -W $mnt > btrfs qgroup show -prce $mnt > > # Need to patch btrfs-progs to report qgroup mismatch as error > btrfs check $dev || _fail > ------ > > For fast machine, we can hit some corruption which missed accounting > tree blocks: > ------ > qgroupid rfer excl max_rfer max_excl parent child > -------- ---- ---- -------- -------- ------ ----- > 0/5 8.00KiB 0.00B none none --- --- > 0/257 8.00KiB 0.00B none none --- --- > ------ > > This is due to the fact that we're always searching commit root for > btrfs_find_all_roots() at qgroup_rescan_leaf(), but the leaf we get is > from current transaction, not commit root. > > And if our tree blocks get modified in current transaction, we won't > find any owner in commit root, thus causing the corruption. > > Fix it by searching commit root for extent tree for > qgroup_rescan_leaf(). > > Reported-by: Nikolay Borisov <nborisov@suse.com> > Signed-off-by: Qu Wenruo <wqu@suse.com> > --- > > Please keep in mind that it is possible to hit another type of race > which double accounting tree blocks: > ------ > qgroupid rfer excl max_rfer max_excl parent child > -------- ---- ---- -------- -------- ------ ----- > 0/5 136.00KiB 128.00KiB none none --- --- > 0/257 136.00KiB 128.00KiB none none --- --- > ------ > For this type of corruption, this patch could reduce the possibility, > but the root cause is race between transaction commit and qgroup rescan, > which needs to be addressed in another patch. > --- > fs/btrfs/qgroup.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c > index 4baa4ba2d630..829e8fe5c97e 100644 > --- a/fs/btrfs/qgroup.c > +++ b/fs/btrfs/qgroup.c > @@ -2681,6 +2681,11 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work) > path = btrfs_alloc_path(); > if (!path) > goto out; > + /* > + * Rescan should only search for commit root, and any later difference > + * should be recorded by qgroup > + */ > + path->search_commit_root = 1; > > err = 0; > while (!err && !btrfs_fs_closing(fs_info)) { > If we're searching the commit root here, do we need the tree mod sequence number dance in qgroup_rescan_leaf anymore? -Jeff
On 2018年05月12日 01:08, Jeff Mahoney wrote: > On 5/3/18 3:20 AM, Qu Wenruo wrote: >> When doing qgroup rescan using the following script (modified from >> btrfs/017 test case), we can sometimes hit qgroup corruption. >> >> ------ >> umount $dev &> /dev/null >> umount $mnt &> /dev/null >> >> mkfs.btrfs -f -n 64k $dev >> mount $dev $mnt >> >> extent_size=8192 >> >> xfs_io -f -d -c "pwrite 0 $extent_size" $mnt/foo > /dev/null >> btrfs subvolume snapshot $mnt $mnt/snap >> >> xfs_io -f -c "reflink $mnt/foo" $mnt/foo-reflink > /dev/null >> xfs_io -f -c "reflink $mnt/foo" $mnt/snap/foo-reflink > /dev/null >> xfs_io -f -c "reflink $mnt/foo" $mnt/snap/foo-reflink2 > /dev/unll >> btrfs quota enable $mnt >> >> # -W is the new option to only wait rescan while not starting new one >> btrfs quota rescan -W $mnt >> btrfs qgroup show -prce $mnt >> >> # Need to patch btrfs-progs to report qgroup mismatch as error >> btrfs check $dev || _fail >> ------ >> >> For fast machine, we can hit some corruption which missed accounting >> tree blocks: >> ------ >> qgroupid rfer excl max_rfer max_excl parent child >> -------- ---- ---- -------- -------- ------ ----- >> 0/5 8.00KiB 0.00B none none --- --- >> 0/257 8.00KiB 0.00B none none --- --- >> ------ >> >> This is due to the fact that we're always searching commit root for >> btrfs_find_all_roots() at qgroup_rescan_leaf(), but the leaf we get is >> from current transaction, not commit root. >> >> And if our tree blocks get modified in current transaction, we won't >> find any owner in commit root, thus causing the corruption. >> >> Fix it by searching commit root for extent tree for >> qgroup_rescan_leaf(). >> >> Reported-by: Nikolay Borisov <nborisov@suse.com> >> Signed-off-by: Qu Wenruo <wqu@suse.com> >> --- >> >> Please keep in mind that it is possible to hit another type of race >> which double accounting tree blocks: >> ------ >> qgroupid rfer excl max_rfer max_excl parent child >> -------- ---- ---- -------- -------- ------ ----- >> 0/5 136.00KiB 128.00KiB none none --- --- >> 0/257 136.00KiB 128.00KiB none none --- --- >> ------ >> For this type of corruption, this patch could reduce the possibility, >> but the root cause is race between transaction commit and qgroup rescan, >> which needs to be addressed in another patch. >> --- >> fs/btrfs/qgroup.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c >> index 4baa4ba2d630..829e8fe5c97e 100644 >> --- a/fs/btrfs/qgroup.c >> +++ b/fs/btrfs/qgroup.c >> @@ -2681,6 +2681,11 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work) >> path = btrfs_alloc_path(); >> if (!path) >> goto out; >> + /* >> + * Rescan should only search for commit root, and any later difference >> + * should be recorded by qgroup >> + */ >> + path->search_commit_root = 1; >> >> err = 0; >> while (!err && !btrfs_fs_closing(fs_info)) { >> > > If we're searching the commit root here, do we need the tree mod > sequence number dance in qgroup_rescan_leaf anymore? No, so I'll remove it in next version. Thanks for pointing this out, Qu > > -Jeff >
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 4baa4ba2d630..829e8fe5c97e 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -2681,6 +2681,11 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work) path = btrfs_alloc_path(); if (!path) goto out; + /* + * Rescan should only search for commit root, and any later difference + * should be recorded by qgroup + */ + path->search_commit_root = 1; err = 0; while (!err && !btrfs_fs_closing(fs_info)) {
When doing qgroup rescan using the following script (modified from btrfs/017 test case), we can sometimes hit qgroup corruption. ------ umount $dev &> /dev/null umount $mnt &> /dev/null mkfs.btrfs -f -n 64k $dev mount $dev $mnt extent_size=8192 xfs_io -f -d -c "pwrite 0 $extent_size" $mnt/foo > /dev/null btrfs subvolume snapshot $mnt $mnt/snap xfs_io -f -c "reflink $mnt/foo" $mnt/foo-reflink > /dev/null xfs_io -f -c "reflink $mnt/foo" $mnt/snap/foo-reflink > /dev/null xfs_io -f -c "reflink $mnt/foo" $mnt/snap/foo-reflink2 > /dev/unll btrfs quota enable $mnt # -W is the new option to only wait rescan while not starting new one btrfs quota rescan -W $mnt btrfs qgroup show -prce $mnt # Need to patch btrfs-progs to report qgroup mismatch as error btrfs check $dev || _fail ------ For fast machine, we can hit some corruption which missed accounting tree blocks: ------ qgroupid rfer excl max_rfer max_excl parent child -------- ---- ---- -------- -------- ------ ----- 0/5 8.00KiB 0.00B none none --- --- 0/257 8.00KiB 0.00B none none --- --- ------ This is due to the fact that we're always searching commit root for btrfs_find_all_roots() at qgroup_rescan_leaf(), but the leaf we get is from current transaction, not commit root. And if our tree blocks get modified in current transaction, we won't find any owner in commit root, thus causing the corruption. Fix it by searching commit root for extent tree for qgroup_rescan_leaf(). Reported-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> --- Please keep in mind that it is possible to hit another type of race which double accounting tree blocks: ------ qgroupid rfer excl max_rfer max_excl parent child -------- ---- ---- -------- -------- ------ ----- 0/5 136.00KiB 128.00KiB none none --- --- 0/257 136.00KiB 128.00KiB none none --- --- ------ For this type of corruption, this patch could reduce the possibility, but the root cause is race between transaction commit and qgroup rescan, which needs to be addressed in another patch. --- fs/btrfs/qgroup.c | 5 +++++ 1 file changed, 5 insertions(+)