On Tue, May 12, 2020 at 09:43:06AM -0400, Zygo Blaxell wrote:
> On Mon, May 11, 2020 at 04:31:32PM +0800, Qu Wenruo wrote:
> > Hi Zygo,
> >
> > Would you like to test this diff?
> >
> > Although I haven't find a solid reason yet, there is another report and
> > with the help from the reporter, it turns out that balance hangs at
> > relocating DATA_RELOC tree block.
> >
> > After some more digging, DATA_RELOC tree doesn't need REF_COW bit at all
> > since we can't create snapshot for data reloc tree.
> >
> > By removing the REF_COW bit, we could ensure that data reloc tree always
> > get cowed for relocation (just like extent tree), this would hugely
> > reduce the complexity for data reloc tree.
> >
> > Not sure if this would help, but it passes my local balance run.
>
> I ran it last night. It did 30804 loops during a metadata block group
> balance, and is now looping on a data block group as I write this.
Here's the block group that is failing, and some poking around with it:
root@tester:~# ~/share/python-btrfs/examples/show_block_group_contents.py 4368594108416 /media/testfs/
block group vaddr 4368594108416 length 1073741824 flags DATA used 530509824 used_pct 49
extent vaddr 4368594108416 length 121053184 refs 1 gen 1318394 flags DATA
inline shared data backref parent 4374646833152 count 1
extent vaddr 4368715161600 length 120168448 refs 1 gen 1318394 flags DATA
inline shared data backref parent 4374801383424 count 1
extent vaddr 4368835330048 length 127623168 refs 1 gen 1318394 flags DATA
inline shared data backref parent 4374801383424 count 1
extent vaddr 4368962953216 length 124964864 refs 1 gen 1318394 flags DATA
inline shared data backref parent 4374801383424 count 1
extent vaddr 4369182420992 length 36700160 refs 1 gen 1321064 flags DATA
inline extent data backref root 257 objectid 257 offset 822607872 count 1
The extent data backref is unusual--during loops, I don't usually see those.
And...as I write this, it disappeared (it was part of the bees hash table, and
was overwritten). Now there are 4 extents reported in the balance loop (note:
I added a loop counter to the log message):
[Tue May 12 09:44:22 2020] BTRFS info (device dm-0): found 5 extents, loops 378, stage: update data pointers
[Tue May 12 09:44:23 2020] BTRFS info (device dm-0): found 5 extents, loops 379, stage: update data pointers
[Tue May 12 09:44:24 2020] BTRFS info (device dm-0): found 5 extents, loops 380, stage: update data pointers
[Tue May 12 09:44:26 2020] BTRFS info (device dm-0): found 5 extents, loops 381, stage: update data pointers
[Tue May 12 09:44:27 2020] BTRFS info (device dm-0): found 5 extents, loops 382, stage: update data pointers
[Tue May 12 10:04:49 2020] BTRFS info (device dm-0): found 5 extents, loops 383, stage: update data pointers
[Tue May 12 10:04:53 2020] BTRFS info (device dm-0): found 4 extents, loops 384, stage: update data pointers
[Tue May 12 10:04:58 2020] BTRFS info (device dm-0): found 4 extents, loops 385, stage: update data pointers
[Tue May 12 10:05:00 2020] BTRFS info (device dm-0): found 4 extents, loops 386, stage: update data pointers
[Tue May 12 10:05:00 2020] BTRFS info (device dm-0): found 4 extents, loops 387, stage: update data pointers
[Tue May 12 10:05:01 2020] BTRFS info (device dm-0): found 4 extents, loops 388, stage: update data pointers
Some of the extents that remain are confusing python-btrfs a little:
root@tester:~# ~/share/python-btrfs/examples/show_block_group_data_extent_filenames.py 4368594108416 /media/testfs/
block group vaddr 4368594108416 length 1073741824 flags DATA used 530509824 used_pct 49
extent vaddr 4368594108416 length 121053184 refs 1 gen 1318394 flags DATA
Traceback (most recent call last):
File "/root/share/python-btrfs/examples/show_block_group_data_extent_filenames.py", line 52, in <module>
inodes, bytes_missed = logical_to_ino_fn(fs.fd, extent.vaddr)
File "/root/share/python-btrfs/examples/show_block_group_data_extent_filenames.py", line 28, in find_out_about_v1_or_v2
inodes, bytes_missed = using_v2(fd, vaddr)
File "/root/share/python-btrfs/examples/show_block_group_data_extent_filenames.py", line 17, in using_v2
inodes, bytes_missed = btrfs.ioctl.logical_to_ino_v2(fd, vaddr, ignore_offset=True)
File "/media/share/python-btrfs/examples/btrfs/ioctl.py", line 565, in logical_to_ino_v2
return _logical_to_ino(fd, vaddr, bufsize, ignore_offset, _v2=True)
File "/media/share/python-btrfs/examples/btrfs/ioctl.py", line 581, in _logical_to_ino
fcntl.ioctl(fd, IOC_LOGICAL_INO_V2, args)
OSError: [Errno 22] Invalid argument
root@tester:~# btrfs ins log 4368594108416 /media/testfs/
/media/testfs//snap-1589258042/testhost/var/log/messages.6.lzma
/media/testfs//current/testhost/var/log/messages.6.lzma
/media/testfs//snap-1589249822/testhost/var/log/messages.6.lzma
ERROR: ino paths ioctl: No such file or directory
/media/testfs//snap-1589249547/testhost/var/log/messages.6.lzma
ERROR: ino paths ioctl: No such file or directory
/media/testfs//snap-1589248407/testhost/var/log/messages.6.lzma
/media/testfs//snap-1589256422/testhost/var/log/messages.6.lzma
ERROR: ino paths ioctl: No such file or directory
/media/testfs//snap-1589251322/testhost/var/log/messages.6.lzma
/media/testfs//snap-1589251682/testhost/var/log/messages.6.lzma
/media/testfs//snap-1589253842/testhost/var/log/messages.6.lzma
/media/testfs//snap-1589246727/testhost/var/log/messages.6.lzma
/media/testfs//snap-1589258582/testhost/var/log/messages.6.lzma
/media/testfs//snap-1589244027/testhost/var/log/messages.6.lzma
/media/testfs//snap-1589245227/testhost/var/log/messages.6.lzma
ERROR: ino paths ioctl: No such file or directory
ERROR: ino paths ioctl: No such file or directory
/media/testfs//snap-1589246127/testhost/var/log/messages.6.lzma
/media/testfs//snap-1589247327/testhost/var/log/messages.6.lzma
ERROR: ino paths ioctl: No such file or directory
Hmmm, I wonder if there's a problem with deleted snapshots? I have those
nearly continuously in my test environment, which is creating and deleting
snapshots all the time.
root@tester:~# btrfs ins log 4368594108416 -P /media/testfs/
inode 20838190 offset 0 root 10347
inode 20838190 offset 0 root 8013
inode 20838190 offset 0 root 10332
inode 20838190 offset 0 root 10330
inode 20838190 offset 0 root 10331
inode 20838190 offset 0 root 10328
inode 20838190 offset 0 root 10329
inode 20838190 offset 0 root 10343
inode 20838190 offset 0 root 10333
inode 20838190 offset 0 root 10334
inode 20838190 offset 0 root 10336
inode 20838190 offset 0 root 10338
inode 20838190 offset 0 root 10325
inode 20838190 offset 0 root 10349
inode 20838190 offset 0 root 10320
inode 20838190 offset 0 root 10321
inode 20838190 offset 0 root 10322
inode 20838190 offset 0 root 10323
inode 20838190 offset 0 root 10324
inode 20838190 offset 0 root 10326
inode 20838190 offset 0 root 10327
root@tester:~# btrfs sub list -d /media/testfs/
ID 10201 gen 1321166 top level 0 path DELETED
ID 10210 gen 1321166 top level 0 path DELETED
ID 10230 gen 1321166 top level 0 path DELETED
ID 10254 gen 1321166 top level 0 path DELETED
ID 10257 gen 1321166 top level 0 path DELETED
ID 10274 gen 1321166 top level 0 path DELETED
ID 10281 gen 1321166 top level 0 path DELETED
ID 10287 gen 1321166 top level 0 path DELETED
ID 10296 gen 1321166 top level 0 path DELETED
ID 10298 gen 1321166 top level 0 path DELETED
ID 10299 gen 1321166 top level 0 path DELETED
ID 10308 gen 1321166 top level 0 path DELETED
ID 10311 gen 1321166 top level 0 path DELETED
ID 10313 gen 1321166 top level 0 path DELETED
ID 10315 gen 1321166 top level 0 path DELETED
ID 10317 gen 1321166 top level 0 path DELETED
ID 10322 gen 1321166 top level 0 path DELETED
ID 10323 gen 1321166 top level 0 path DELETED
ID 10327 gen 1321166 top level 0 path DELETED
ID 10328 gen 1321166 top level 0 path DELETED
ID 10330 gen 1321166 top level 0 path DELETED
ID 10333 gen 1321166 top level 0 path DELETED
> > Thanks,
> > Qu
>
> > From 82f3b96a68561b2de9712262cb652192b8ea9b1b Mon Sep 17 00:00:00 2001
> > From: Qu Wenruo <wqu@xxxxxxxx>
> > Date: Mon, 11 May 2020 16:27:43 +0800
> > Subject: [PATCH] btrfs: Remove the REF_COW bit for data reloc tree
> >
> > Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
> > ---
> > fs/btrfs/disk-io.c | 9 ++++++++-
> > fs/btrfs/inode.c | 6 ++++--
> > fs/btrfs/relocation.c | 3 ++-
> > 3 files changed, 14 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> > index 56675d3cd23a..cb90966a8aab 100644
> > --- a/fs/btrfs/disk-io.c
> > +++ b/fs/btrfs/disk-io.c
> > @@ -1418,9 +1418,16 @@ static int btrfs_init_fs_root(struct btrfs_root *root)
> > if (ret)
> > goto fail;
> >
> > - if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
> > + if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID &&
> > + root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID) {
> > set_bit(BTRFS_ROOT_REF_COWS, &root->state);
> > btrfs_check_and_init_root_item(&root->root_item);
> > + } else if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID) {
> > + /*
> > + * Data reloc tree won't be snapshotted, thus it's COW only
> > + * tree, it's needed to set TRACK_DIRTY bit for it.
> > + */
> > + set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
> > }
> >
> > btrfs_init_free_ino_ctl(root);
> > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> > index 5d567082f95a..71841535c7ca 100644
> > --- a/fs/btrfs/inode.c
> > +++ b/fs/btrfs/inode.c
> > @@ -4129,7 +4129,8 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
> > * extent just the way it is.
> > */
> > if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
> > - root == fs_info->tree_root)
> > + root == fs_info->tree_root ||
> > + root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID)
> > btrfs_drop_extent_cache(BTRFS_I(inode), ALIGN(new_size,
> > fs_info->sectorsize),
> > (u64)-1, 0);
> > @@ -4334,7 +4335,8 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
> >
> > if (found_extent &&
> > (test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
> > - root == fs_info->tree_root)) {
> > + root == fs_info->tree_root ||
> > + root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID)) {
> > struct btrfs_ref ref = { 0 };
> >
> > bytes_deleted += extent_num_bytes;
> > diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> > index f25deca18a5d..a85dd5d465f6 100644
> > --- a/fs/btrfs/relocation.c
> > +++ b/fs/btrfs/relocation.c
> > @@ -1087,7 +1087,8 @@ int replace_file_extents(struct btrfs_trans_handle *trans,
> > * if we are modifying block in fs tree, wait for readpage
> > * to complete and drop the extent cache
> > */
> > - if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
> > + if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
> > + root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID) {
> > if (first) {
> > inode = find_next_inode(root, key.objectid);
> > first = 0;
> > --
> > 2.26.2
> >
>
>
>
>
