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bogus min size estimates by 'btrfs inspect min' #271

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cmurf opened this issue Jul 12, 2020 · 2 comments
Open

bogus min size estimates by 'btrfs inspect min' #271

cmurf opened this issue Jul 12, 2020 · 2 comments
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@cmurf
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@cmurf cmurf commented Jul 12, 2020 •
edited 

5.8.0-0.rc4.1.fc33.x86_64+debug
btrfs-progs v5.7

Example 1

$ sudo btrfs insp min /
1048576 bytes (1.00MiB)
$ sudo btrfs fi us /
Overall:
    Device size:		 105.00GiB
    Device allocated:		  55.03GiB
    Device unallocated:		  49.97GiB
    Device missing:		     0.00B
    Used:			  24.80GiB
    Free (estimated):		  78.75GiB	(min: 78.75GiB)
    Data ratio:			      1.00
    Metadata ratio:		      1.00
    Global reserve:		  62.25MiB	(used: 0.00B)
    Multiple profiles:		        no

Data,single: Size:53.00GiB, Used:24.22GiB (45.69%)
   /dev/sda4	  53.00GiB

Metadata,single: Size:2.00GiB, Used:596.48MiB (29.13%)
   /dev/sda4	   2.00GiB

System,single: Size:32.00MiB, Used:16.00KiB (0.05%)
   /dev/sda4	  32.00MiB

Unallocated:
   /dev/sda4	  49.97GiB

I'm expecting minimum size around 25-26G. 1MiB is plainly not possible.

Example 2:

$ sudo btrfs inspect min /
50542411776 bytes (47.07GiB)
$ sudo btrfs fi us /
Overall:
    Device size:		 178.00GiB
    Device allocated:		  46.04GiB
    Device unallocated:		 131.96GiB
    Device missing:		     0.00B
    Used:			  19.42GiB
    Free (estimated):		 156.41GiB	(min: 156.41GiB)
    Data ratio:			      1.00
    Metadata ratio:		      1.00
    Global reserve:		  64.09MiB	(used: 0.00B)
    Multiple profiles:		        no

Data,single: Size:43.01GiB, Used:18.56GiB (43.15%)
   /dev/nvme0n1p7	  43.01GiB

Metadata,single: Size:3.00GiB, Used:879.53MiB (28.63%)
   /dev/nvme0n1p7	   3.00GiB

System,single: Size:32.00MiB, Used:32.00KiB (0.10%)
   /dev/nvme0n1p7	  32.00MiB

Unallocated:
   /dev/nvme0n1p7	 131.96GiB

I'm expecting a minimum shrink value of ~20-21G. The estimate seems based on 'device allocated' amount.

strace-example1.txt
strace-example2.txt
@cmurf
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@cmurf cmurf commented Jul 12, 2020

Contrived reproduce steps pretty much shows btrfs insp min isn't working correctly. The resize below its min size succeeds.

truncate -s 100g test.raw
losetup /dev/loop0 test.raw
mkfs.btrfs -msingle -dsingle /dev/loop0
mount /dev/loop0 /media
cd /media

Terrible script to try to get a bunch of partially filled bgs.

#!/bin/bash
for i in $(seq 90);do
    fallocate -l 1g "File${i}"
done
sync ./
for i in $(seq 90);do
    if (( $i % 2 )); then
    rm "File${i}"
    fi
done

Check out the bg usage map.

# /home/chris/Applications/btrfs-debugfs -b /media
block group offset       22020096 len 1073741824 used   24379392 chunk_objectid 256 flags 1 usage 0.02
block group offset     1095761920 len 1073741824 used          0 chunk_objectid 256 flags 1 usage 0.00
block group offset     2169503744 len 1073741824 used          0 chunk_objectid 256 flags 1 usage 0.00
block group offset     3243245568 len 1073741824 used          0 chunk_objectid 256 flags 1 usage 0.00
block group offset     4316987392 len 1073741824 used          0 chunk_objectid 256 flags 1 usage 0.00
block group offset     5390729216 len 1073741824 used          0 chunk_objectid 256 flags 1 usage 0.00
block group offset     6464471040 len 1073741824 used          0 chunk_objectid 256 flags 1 usage 0.00
block group offset     7538212864 len 1073741824 used          0 chunk_objectid 256 flags 1 usage 0.00
block group offset     8611954688 len 1073741824 used          0 chunk_objectid 256 flags 1 usage 0.00
block group offset     9685696512 len 1073741824 used          0 chunk_objectid 256 flags 1 usage 0.00
block group offset    10759438336 len 1073741824 used          0 chunk_objectid 256 flags 1 usage 0.00
block group offset    11833180160 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    12906921984 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    13980663808 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    15054405632 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    16128147456 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    17201889280 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    18275631104 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    19349372928 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    20423114752 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    21496856576 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    22570598400 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    23644340224 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    24718082048 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    25791823872 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    26865565696 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    27939307520 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    29013049344 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    30086791168 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    31160532992 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    32234274816 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    33308016640 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    34381758464 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    35455500288 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    36529242112 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    37602983936 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    38676725760 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    39750467584 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    40824209408 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    41897951232 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    42971693056 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    44045434880 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    45119176704 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    46192918528 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    47266660352 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    48340402176 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    49414144000 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    50487885824 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    51561627648 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    52635369472 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    53709111296 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    54782853120 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    55856594944 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    56930336768 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    58004078592 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    59077820416 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    60151562240 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    61225304064 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    62299045888 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    63372787712 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    64446529536 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    65520271360 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    66594013184 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    67667755008 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    68741496832 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    69815238656 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    70888980480 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    71962722304 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    73036464128 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    74110205952 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    75183947776 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    76257689600 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    77331431424 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    78405173248 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    79478915072 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    80552656896 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    81626398720 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    82700140544 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    83773882368 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    84847624192 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    85921366016 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    86995107840 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    88068849664 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    89142591488 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    90216333312 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    91290075136 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    92363816960 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    93437558784 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    94511300608 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    95585042432 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    96658784256 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
block group offset    97732526080 len 1073741824 used  805306368 chunk_objectid 256 flags 1 usage 0.75
block group offset    98806267904 len 1073741824 used  268435456 chunk_objectid 256 flags 1 usage 0.25
total_free 55810195456 min_used 0 free_of_min_used 1073741824 block_group_of_min_used 10759438336
balance block group (10759438336) can reduce the number of data block group

# btrfs fi us /media
Overall:
    Device size:		 100.00GiB
    Device allocated:		  71.01GiB
    Device unallocated:		  28.99GiB
    Device missing:		     0.00B
    Used:			  45.02GiB
    Free (estimated):		  54.97GiB	(min: 54.97GiB)
    Data ratio:			      1.00
    Metadata ratio:		      1.00
    Global reserve:		   3.25MiB	(used: 0.00B)
    Multiple profiles:		        no

Data,single: Size:71.00GiB, Used:45.02GiB (63.40%)
   /dev/loop0	  71.00GiB

Metadata,single: Size:8.00MiB, Used:240.00KiB (2.93%)
   /dev/loop0	   8.00MiB

System,single: Size:4.00MiB, Used:16.00KiB (0.39%)
   /dev/loop0	   4.00MiB

Unallocated:
   /dev/loop0	  28.99GiB

Get a minimum shrink estimate.

# btrfs insp min /media
77356597248 bytes (72.04GiB)

# btrfs fi show
Label: none  uuid: d2c502c8-0a13-4319-a2f5-1e9b8cde6e21
	Total devices 1 FS bytes used 45.02GiB
	devid    1 size 100.00GiB used 71.01GiB path /dev/loop0

Shrink below the minimum suggested.

# btrfs fi resize 1:60g /media
Resize '/media' of '1:60g'

Shrink succeeds.

# btrfs fi show
Label: none  uuid: d2c502c8-0a13-4319-a2f5-1e9b8cde6e21
	Total devices 1 FS bytes used 45.01GiB
	devid    1 size 60.00GiB used 47.01GiB path /dev/loop0

# dmesg
...
[  809.184095] loop: module loaded
[  819.331244] BTRFS: device fsid d2c502c8-0a13-4319-a2f5-1e9b8cde6e21 devid 1 transid 5 /dev/loop0 scanned by mkfs.btrfs (1631)
[  825.551808] BTRFS info (device loop0): disk space caching is enabled
[  825.551820] BTRFS info (device loop0): has skinny extents
[  825.551826] BTRFS info (device loop0): flagging fs with big metadata feature
[  825.557609] BTRFS info (device loop0): enabling ssd optimizations
[  825.557832] BTRFS info (device loop0): checking UUID tree
[ 1940.201619] BTRFS info (device loop0): resizing devid 1
[ 1940.230687] BTRFS info (device loop0): relocating block group 96658784256 flags data
[ 1941.319242] BTRFS info (device loop0): found 1 extents, stage: move data extents
[ 1941.916171] BTRFS info (device loop0): found 1 extents, stage: update data pointers
[ 1941.981280] BTRFS info (device loop0): relocating block group 95585042432 flags data
[ 1945.458993] BTRFS info (device loop0): found 3 extents, stage: move data extents
[ 1946.568904] BTRFS info (device loop0): found 3 extents, stage: update data pointers
[ 1946.618748] BTRFS info (device loop0): relocating block group 93437558784 flags data
[ 1947.674701] BTRFS info (device loop0): found 1 extents, stage: move data extents
[ 1948.338065] BTRFS info (device loop0): found 1 extents, stage: update data pointers
[ 1948.392810] BTRFS info (device loop0): relocating block group 92363816960 flags data
[ 1952.989938] BTRFS info (device loop0): found 4 extents, stage: move data extents
[ 1953.745552] BTRFS info (device loop0): found 4 extents, stage: update data pointers
[ 1953.799482] BTRFS info (device loop0): relocating block group 91290075136 flags data
[ 1958.807490] BTRFS info (device loop0): found 3 extents, stage: move data extents
[ 1958.967339] BTRFS info (device loop0): found 3 extents, stage: update data pointers
[ 1959.053767] BTRFS info (device loop0): relocating block group 89142591488 flags data
[ 1960.148365] BTRFS info (device loop0): found 1 extents, stage: move data extents
[ 1961.220043] BTRFS info (device loop0): found 1 extents, stage: update data pointers
[ 1961.296691] BTRFS info (device loop0): relocating block group 88068849664 flags data
[ 1967.239693] BTRFS info (device loop0): found 4 extents, stage: move data extents
[ 1968.318766] BTRFS info (device loop0): found 4 extents, stage: update data pointers
[ 1968.398055] BTRFS info (device loop0): relocating block group 86995107840 flags data
[ 1973.328082] BTRFS info (device loop0): found 3 extents, stage: move data extents
[ 1974.514197] BTRFS info (device loop0): found 3 extents, stage: update data pointers
[ 1974.606972] BTRFS info (device loop0): relocating block group 84847624192 flags data
[ 1975.682479] BTRFS info (device loop0): found 1 extents, stage: move data extents
[ 1976.860417] BTRFS info (device loop0): found 1 extents, stage: update data pointers
[ 1976.936851] BTRFS info (device loop0): relocating block group 83773882368 flags data
[ 1979.257083] register-python (2425) used greatest stack depth: 11320 bytes left
[ 1984.156603] BTRFS info (device loop0): found 4 extents, stage: move data extents
[ 1984.234248] BTRFS info (device loop0): found 4 extents, stage: update data pointers
[ 1984.320864] BTRFS info (device loop0): relocating block group 82700140544 flags data
[ 1990.487070] BTRFS info (device loop0): found 3 extents, stage: move data extents
[ 1990.823143] BTRFS info (device loop0): found 3 extents, stage: update data pointers
[ 1990.905550] BTRFS info (device loop0): relocating block group 80552656896 flags data
[ 1992.006413] BTRFS info (device loop0): found 1 extents, stage: move data extents
[ 1993.385682] BTRFS info (device loop0): found 1 extents, stage: update data pointers
[ 1993.476219] BTRFS info (device loop0): relocating block group 79478915072 flags data
[ 2002.053800] BTRFS info (device loop0): found 4 extents, stage: move data extents
[ 2002.135986] BTRFS info (device loop0): found 4 extents, stage: update data pointers
[ 2002.224580] BTRFS info (device loop0): relocating block group 78405173248 flags data
[ 2007.903679] BTRFS info (device loop0): found 3 extents, stage: move data extents
[ 2009.986309] BTRFS info (device loop0): found 3 extents, stage: update data pointers
[ 2010.073363] BTRFS info (device loop0): relocating block group 76257689600 flags data
[ 2011.173721] BTRFS info (device loop0): found 1 extents, stage: move data extents
[ 2013.002750] BTRFS info (device loop0): found 1 extents, stage: update data pointers
[ 2013.080625] BTRFS info (device loop0): relocating block group 75183947776 flags data
[ 2023.202883] BTRFS info (device loop0): found 4 extents, stage: move data extents
[ 2023.273449] BTRFS info (device loop0): found 4 extents, stage: update data pointers
[ 2023.361832] BTRFS info (device loop0): relocating block group 74110205952 flags data
[ 2032.853760] BTRFS info (device loop0): found 3 extents, stage: move data extents
[ 2032.936725] BTRFS info (device loop0): found 3 extents, stage: update data pointers
[ 2033.032209] BTRFS info (device loop0): relocating block group 71962722304 flags data
[ 2034.140232] BTRFS info (device loop0): found 1 extents, stage: move data extents
[ 2036.639227] BTRFS info (device loop0): found 1 extents, stage: update data pointers
[ 2036.755283] BTRFS info (device loop0): relocating block group 70888980480 flags data
[ 2049.507142] BTRFS info (device loop0): found 4 extents, stage: move data extents
[ 2049.608053] BTRFS info (device loop0): found 4 extents, stage: update data pointers
[ 2049.712009] BTRFS info (device loop0): relocating block group 69815238656 flags data
[ 2060.183711] BTRFS info (device loop0): found 3 extents, stage: move data extents
[ 2060.268794] BTRFS info (device loop0): found 3 extents, stage: update data pointers
[ 2060.367497] BTRFS info (device loop0): relocating block group 67667755008 flags data
[ 2061.476323] BTRFS info (device loop0): found 1 extents, stage: move data extents
[ 2063.679664] BTRFS info (device loop0): found 1 extents, stage: update data pointers
[ 2063.770147] BTRFS info (device loop0): relocating block group 66594013184 flags data
[ 2078.041004] BTRFS info (device loop0): found 4 extents, stage: move data extents
[ 2078.126446] BTRFS info (device loop0): found 4 extents, stage: update data pointers
[ 2078.196914] BTRFS info (device loop0): relocating block group 65520271360 flags data
[ 2089.814043] BTRFS info (device loop0): found 3 extents, stage: move data extents
[ 2089.914795] BTRFS info (device loop0): found 3 extents, stage: update data pointers
[ 2089.994960] BTRFS info (device loop0): relocating block group 63372787712 flags data
[ 2091.081320] BTRFS info (device loop0): found 1 extents, stage: move data extents
[ 2094.636617] BTRFS info (device loop0): found 1 extents, stage: update data pointers
[ 2094.727825] BTRFS info (device loop0): resize device /dev/loop0 (devid 1) from 107374182400 to 64424509440
$
@cmurf cmurf mentioned this issue Jul 12, 2020
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@cmurf cmurf commented Jul 12, 2020

Related
storaged-project/libblockdev#548
@kdave kdave added the bug label Jul 14, 2020
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