kernel/include/trace/events/btrfs.h, branch linux-5.1.y

btrfs: qgroup: Move reserved data accounting from btrfs_delayed_ref_head to btrfs_qgroup_extent_record

2019-02-25T13:13:39Z

[BUG] Btrfs/139 will fail with a high probability if the testing machine (VM) has only 2G RAM. Resulting the final write success while it should fail due to EDQUOT, and the fs will have quota exceeding the limit by 16K. The simplified reproducer will be: (needs a 2G ram VM) $ mkfs.btrfs -f $dev $ mount $dev $mnt $ btrfs subv create $mnt/subv $ btrfs quota enable $mnt $ btrfs quota rescan -w $mnt $ btrfs qgroup limit -e 1G $mnt/subv $ for i in $(seq -w 1 8); do xfs_io -f -c "pwrite 0 128M" $mnt/subv/file_$i > /dev/null echo "file $i written" > /dev/kmsg done $ sync $ btrfs qgroup show -pcre --raw $mnt The last pwrite will not trigger EDQUOT and final 'qgroup show' will show something like: qgroupid rfer excl max_rfer max_excl parent child -------- ---- ---- -------- -------- ------ ----- 0/5 16384 16384 none none --- --- 0/256 1073758208 1073758208 none 1073741824 --- --- And 1073758208 is larger than > 1073741824. [CAUSE] It's a bug in btrfs qgroup data reserved space management. For quota limit, we must ensure that: reserved (data + metadata) + rfer/excl <= limit Since rfer/excl is only updated at transaction commmit time, reserved space needs to be taken special care. One important part of reserved space is data, and for a new data extent written to disk, we still need to take the reserved space until rfer/excl numbers get updated. Originally when an ordered extent finishes, we migrate the reserved qgroup data space from extent_io tree to delayed ref head of the data extent, expecting delayed ref will only be cleaned up at commit transaction time. However for small RAM machine, due to memory pressure dirty pages can be flushed back to disk without committing a transaction. The related events will be something like: file 1 written btrfs_finish_ordered_io: ino=258 ordered offset=0 len=54947840 btrfs_finish_ordered_io: ino=258 ordered offset=54947840 len=5636096 btrfs_finish_ordered_io: ino=258 ordered offset=61153280 len=57344 btrfs_finish_ordered_io: ino=258 ordered offset=61210624 len=8192 btrfs_finish_ordered_io: ino=258 ordered offset=60583936 len=569344 cleanup_ref_head: num_bytes=54947840 cleanup_ref_head: num_bytes=5636096 cleanup_ref_head: num_bytes=569344 cleanup_ref_head: num_bytes=57344 cleanup_ref_head: num_bytes=8192 ^^^^^^^^^^^^^^^^ This will free qgroup data reserved space file 2 written ... file 8 written cleanup_ref_head: num_bytes=8192 ... btrfs_commit_transaction <<< the only transaction committed during the test When file 2 is written, we have already freed 128M reserved qgroup data space for ino 258. Thus later write won't trigger EDQUOT. This allows us to write more data beyond qgroup limit. In my 2G ram VM, it could reach about 1.2G before hitting EDQUOT. [FIX] By moving reserved qgroup data space from btrfs_delayed_ref_head to btrfs_qgroup_extent_record, we can ensure that reserved qgroup data space won't be freed half way before commit transaction, thus fix the problem. Fixes: f64d5ca86821 ("btrfs: delayed_ref: Add new function to record reserved space into delayed ref") Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: don't use global reserve for chunk allocation

2019-02-25T13:13:34Z

We've done this forever because of the voodoo around knowing how much space we have. However, we have better ways of doing this now, and on normal file systems we'll easily have a global reserve of 512MiB, and since metadata chunks are usually 1GiB that means we'll allocate metadata chunks more readily. Instead use the actual used amount when determining if we need to allocate a chunk or not. This has a side effect for mixed block group fs'es where we are no longer allocating enough chunks for the data/metadata requirements. To deal with this add a ALLOC_CHUNK_FORCE step to the flushing state machine. This will only get used if we've already made a full loop through the flushing machinery and tried committing the transaction. If we have then we can try and force a chunk allocation since we likely need it to make progress. This resolves issues I was seeing with the mixed bg tests in xfstests without the new flushing state. Reviewed-by: Nikolay Borisov Signed-off-by: Josef Bacik [ merged with patch "add ALLOC_CHUNK_FORCE to the flushing code" ] Signed-off-by: David Sterba

btrfs: add new flushing states for the delayed refs rsv

2018-12-17T13:51:47Z

A nice thing we gain with the delayed refs rsv is the ability to flush the delayed refs on demand to deal with enospc pressure. Add states to flush delayed refs on demand, and this will allow us to remove a lot of ad-hoc work around checking to see if we should commit the transaction to run our delayed refs. Signed-off-by: Josef Bacik Signed-off-by: David Sterba

btrfs: Remove fsid/metadata_fsid fields from btrfs_info

2018-12-17T13:51:37Z

Currently btrfs_fs_info structure contains a copy of the fsid/metadata_uuid fields. Same values are also contained in the btrfs_fs_devices structure which fs_info has a reference to. Let's reduce duplication by removing the fields from fs_info and always refer to the ones in fs_devices. No functional changes. Signed-off-by: Nikolay Borisov Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: qgroup: Introduce trace event to analyse the number of dirty extents accounted

2018-10-15T15:23:36Z

Number of qgroup dirty extents is directly linked to the performance overhead, so add a new trace event, trace_qgroup_num_dirty_extents(), to record how many dirty extents is processed in btrfs_qgroup_account_extents(). This will be pretty handy to analyze later balance performance improvement. Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: Remove 'objectid' member from struct btrfs_root

2018-10-15T15:23:25Z

There are two members in struct btrfs_root which indicate root's objectid: objectid and root_key.objectid. They are both set to the same value in __setup_root(): static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info, u64 objectid) { ... root->objectid = objectid; ... root->root_key.objectid = objecitd; ... } and not changed to other value after initialization. grep in btrfs directory shows both are used in many places: $ grep -rI "root->root_key.objectid" | wc -l 133 $ grep -rI "root->objectid" | wc -l 55 (4.17, inc. some noise) It is confusing to have two similar variable names and it seems that there is no rule about which should be used in a certain case. Since ->root_key itself is needed for tree reloc tree, let's remove 'objecitd' member and unify code to use ->root_key.objectid in all places. Signed-off-by: Misono Tomohiro Reviewed-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: Get rid of the confusing btrfs_file_extent_inline_len

2018-08-06T11:12:38Z

We used to call btrfs_file_extent_inline_len() to get the uncompressed data size of an inlined extent. However this function is hiding evil, for compressed extent, it has no choice but to directly read out ram_bytes from btrfs_file_extent_item. While for uncompressed extent, it uses item size to calculate the real data size, and ignoring ram_bytes completely. In fact, for corrupted ram_bytes, due to above behavior kernel btrfs_print_leaf() can't even print correct ram_bytes to expose the bug. Since we have the tree-checker to verify all EXTENT_DATA, such mismatch can be detected pretty easily, thus we can trust ram_bytes without the evil btrfs_file_extent_inline_len(). Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: remove the logged extents infrastructure

2018-08-06T11:12:30Z

This is no longer used anywhere, remove all of it. Signed-off-by: Josef Bacik Reviewed-by: Filipe Manana Signed-off-by: David Sterba

btrfs: qgroup: Allow trace_btrfs_qgroup_account_extent() to record its transid

2018-05-28T16:07:30Z

When debugging quota rescan race, some times btrfs rescan could account some old (committed) leaf and then re-account newly committed leaf in next generation. This race needs extra transid to locate, so add @transid for trace_btrfs_qgroup_account_extent() for such debug. Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: trace: Allow trace_qgroup_update_counters() to record old rfer/excl value

2018-05-28T16:07:29Z

Origin trace_qgroup_update_counters() only records qgroup id and its reference count change. It's good enough to debug qgroup accounting change, but when rescan race is involved, it's pretty hard to distinguish which modification belongs to which rescan. So add old_rfer and old_excl trace output to help distinguishing different rescan instance. (Different rescan instance should reset its qgroup->rfer to 0) For trace event parameter, it just changes from u64 qgroup_id to struct btrfs_qgroup *qgroup, so number of parameters is not changed at all. Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba