* space_cache=v1 and v2 at the time time?
@ 2020-05-27 2:12 Chris Murphy
2020-05-28 21:04 ` Hans van Kranenburg
0 siblings, 1 reply; 4+ messages in thread
From: Chris Murphy @ 2020-05-27 2:12 UTC (permalink / raw)
To: Btrfs BTRFS
What are the implications of not clearing v1 before enabling v2?
From btrfs insp dump-t, I still see the v1 bitmaps present:
root tree
leaf 6468501504 items 42 free space 9246 generation 22 owner ROOT_TREE
leaf 6468501504 flags 0x1(WRITTEN) backref revision 1
...
item 30 key (FREE_SPACE UNTYPED 22020096) itemoff 11145 itemsize 41
location key (256 INODE_ITEM 0)
cache generation 17 entries 0 bitmaps 0
item 31 key (FREE_SPACE UNTYPED 1095761920) itemoff 11104 itemsize 41
location key (257 INODE_ITEM 0)
cache generation 17 entries 0 bitmaps 0
...
And later the free space tree:
free space tree key (FREE_SPACE_TREE ROOT_ITEM 0)
leaf 6471073792 items 39 free space 15196 generation 22 owner FREE_SPACE_TREE
leaf 6471073792 flags 0x1(WRITTEN) backref revision 1
fs uuid 3c464210-08c7-4cf0-b175-e4b781ebea19
chunk uuid f1d18732-7c3d-401c-8637-e7d4d9c7a0b8
item 0 key (1048576 FREE_SPACE_INFO 4194304) itemoff 16275 itemsize 8
free space info extent count 2 flags 0
item 1 key (1048576 FREE_SPACE_EXTENT 16384) itemoff 16275 itemsize 0
free space extent
item 2 key (1081344 FREE_SPACE_EXTENT 4161536) itemoff 16275 itemsize 0
free space extent
...
I was surprised there's no warning when I use space_cache=v2 without
first clearing v1.
--
Chris Murphy
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: space_cache=v1 and v2 at the time time? 2020-05-27 2:12 space_cache=v1 and v2 at the time time? Chris Murphy @ 2020-05-28 21:04 ` Hans van Kranenburg 2020-06-01 17:52 ` David Sterba 0 siblings, 1 reply; 4+ messages in thread From: Hans van Kranenburg @ 2020-05-28 21:04 UTC (permalink / raw) To: Chris Murphy, Btrfs BTRFS Hi, On 5/27/20 4:12 AM, Chris Murphy wrote: > What are the implications of not clearing v1 before enabling v2? > > From btrfs insp dump-t, I still see the v1 bitmaps present: > > root tree > leaf 6468501504 items 42 free space 9246 generation 22 owner ROOT_TREE > leaf 6468501504 flags 0x1(WRITTEN) backref revision 1 > ... > item 30 key (FREE_SPACE UNTYPED 22020096) itemoff 11145 itemsize 41 > location key (256 INODE_ITEM 0) > cache generation 17 entries 0 bitmaps 0 > item 31 key (FREE_SPACE UNTYPED 1095761920) itemoff 11104 itemsize 41 > location key (257 INODE_ITEM 0) > cache generation 17 entries 0 bitmaps 0 > ... > > > And later the free space tree: > > free space tree key (FREE_SPACE_TREE ROOT_ITEM 0) > leaf 6471073792 items 39 free space 15196 generation 22 owner FREE_SPACE_TREE > leaf 6471073792 flags 0x1(WRITTEN) backref revision 1 > fs uuid 3c464210-08c7-4cf0-b175-e4b781ebea19 > chunk uuid f1d18732-7c3d-401c-8637-e7d4d9c7a0b8 > item 0 key (1048576 FREE_SPACE_INFO 4194304) itemoff 16275 itemsize 8 > free space info extent count 2 flags 0 > item 1 key (1048576 FREE_SPACE_EXTENT 16384) itemoff 16275 itemsize 0 > free space extent > item 2 key (1081344 FREE_SPACE_EXTENT 4161536) itemoff 16275 itemsize 0 > free space extent > ... > > I was surprised there's no warning when I use space_cache=v2 without > first clearing v1. It's just sitting there, occupying some space, doing nothing. Hans ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: space_cache=v1 and v2 at the time time? 2020-05-28 21:04 ` Hans van Kranenburg @ 2020-06-01 17:52 ` David Sterba 2020-06-01 20:35 ` Hans van Kranenburg 0 siblings, 1 reply; 4+ messages in thread From: David Sterba @ 2020-06-01 17:52 UTC (permalink / raw) To: Hans van Kranenburg; +Cc: Chris Murphy, Btrfs BTRFS On Thu, May 28, 2020 at 11:04:07PM +0200, Hans van Kranenburg wrote: > Hi, > > On 5/27/20 4:12 AM, Chris Murphy wrote: > > What are the implications of not clearing v1 before enabling v2? > > > > From btrfs insp dump-t, I still see the v1 bitmaps present: > > > > root tree > > leaf 6468501504 items 42 free space 9246 generation 22 owner ROOT_TREE > > leaf 6468501504 flags 0x1(WRITTEN) backref revision 1 > > ... > > item 30 key (FREE_SPACE UNTYPED 22020096) itemoff 11145 itemsize 41 > > location key (256 INODE_ITEM 0) > > cache generation 17 entries 0 bitmaps 0 > > item 31 key (FREE_SPACE UNTYPED 1095761920) itemoff 11104 itemsize 41 > > location key (257 INODE_ITEM 0) > > cache generation 17 entries 0 bitmaps 0 > > ... > > > > > > And later the free space tree: > > > > free space tree key (FREE_SPACE_TREE ROOT_ITEM 0) > > leaf 6471073792 items 39 free space 15196 generation 22 owner FREE_SPACE_TREE > > leaf 6471073792 flags 0x1(WRITTEN) backref revision 1 > > fs uuid 3c464210-08c7-4cf0-b175-e4b781ebea19 > > chunk uuid f1d18732-7c3d-401c-8637-e7d4d9c7a0b8 > > item 0 key (1048576 FREE_SPACE_INFO 4194304) itemoff 16275 itemsize 8 > > free space info extent count 2 flags 0 > > item 1 key (1048576 FREE_SPACE_EXTENT 16384) itemoff 16275 itemsize 0 > > free space extent > > item 2 key (1081344 FREE_SPACE_EXTENT 4161536) itemoff 16275 itemsize 0 > > free space extent > > ... > > > > I was surprised there's no warning when I use space_cache=v2 without > > first clearing v1. > > It's just sitting there, occupying some space, doing nothing. Hm that's not ideal, right? There's support in btrfs check, "btrfs check --clear-space-cache v1", but it needs unmounted filesystem. I don't remember if that was discussed when v2 was introduced, but it seems strange. As we want to make v2 default soon, the conversion should work without such surprises. ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: space_cache=v1 and v2 at the time time? 2020-06-01 17:52 ` David Sterba @ 2020-06-01 20:35 ` Hans van Kranenburg 0 siblings, 0 replies; 4+ messages in thread From: Hans van Kranenburg @ 2020-06-01 20:35 UTC (permalink / raw) To: dsterba, Chris Murphy, Btrfs BTRFS Hi, On 6/1/20 7:52 PM, David Sterba wrote: > On Thu, May 28, 2020 at 11:04:07PM +0200, Hans van Kranenburg wrote: >> Hi, >> >> On 5/27/20 4:12 AM, Chris Murphy wrote: >>> What are the implications of not clearing v1 before enabling v2? >>> >>> From btrfs insp dump-t, I still see the v1 bitmaps present: >>> >>> root tree >>> leaf 6468501504 items 42 free space 9246 generation 22 owner ROOT_TREE >>> leaf 6468501504 flags 0x1(WRITTEN) backref revision 1 >>> ... >>> item 30 key (FREE_SPACE UNTYPED 22020096) itemoff 11145 itemsize 41 >>> location key (256 INODE_ITEM 0) >>> cache generation 17 entries 0 bitmaps 0 >>> item 31 key (FREE_SPACE UNTYPED 1095761920) itemoff 11104 itemsize 41 >>> location key (257 INODE_ITEM 0) >>> cache generation 17 entries 0 bitmaps 0 >>> ... >>> >>> >>> And later the free space tree: >>> >>> free space tree key (FREE_SPACE_TREE ROOT_ITEM 0) >>> leaf 6471073792 items 39 free space 15196 generation 22 owner FREE_SPACE_TREE >>> leaf 6471073792 flags 0x1(WRITTEN) backref revision 1 >>> fs uuid 3c464210-08c7-4cf0-b175-e4b781ebea19 >>> chunk uuid f1d18732-7c3d-401c-8637-e7d4d9c7a0b8 >>> item 0 key (1048576 FREE_SPACE_INFO 4194304) itemoff 16275 itemsize 8 >>> free space info extent count 2 flags 0 >>> item 1 key (1048576 FREE_SPACE_EXTENT 16384) itemoff 16275 itemsize 0 >>> free space extent >>> item 2 key (1081344 FREE_SPACE_EXTENT 4161536) itemoff 16275 itemsize 0 >>> free space extent >>> ... >>> >>> I was surprised there's no warning when I use space_cache=v2 without >>> first clearing v1. >> >> It's just sitting there, occupying some space, doing nothing. > > Hm that's not ideal, right? There's support in btrfs check, > "btrfs check --clear-space-cache v1", but it needs unmounted filesystem. > I don't remember if that was discussed when v2 was introduced, but it > seems strange. As we want to make v2 default soon, the conversion should > work without such surprises. I guess the most straightforward thing to do would be to execute a copy of this remove space cache v1 code before creating the v2 tree when mounting first time with v2 enabled. K ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-06-01 20:35 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-05-27 2:12 space_cache=v1 and v2 at the time time? Chris Murphy 2020-05-28 21:04 ` Hans van Kranenburg 2020-06-01 17:52 ` David Sterba 2020-06-01 20:35 ` Hans van Kranenburg
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