Bug 208405

Summary: 【ubifs】A potential space leak problem while linking tmpfile
Product: File System Reporter: Zhihao Cheng (chengzhihao1)
Component: OtherAssignee: fs_other
Status: NEW ---    
Severity: normal CC: info
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 5.8 Subsystem:
Regression: No Bisected commit-id:
Attachments: reproduce.patch
a.c
diff
a.c
test.sh

Description Zhihao Cheng 2020-07-01 08:42:07 UTC 
There is a potential space leak problem while linking tmpfile, in which case, inode node(with nlink=0) is valid in tnc (on flash), which leads to space leak. Meanwhile, the corresponding data nodes won't be released from tnc.

The reproducer:
Step 1. Apply reproduce.patch
Step 2. mount **fresh** ubifs on '/root/temp'
Step 3. gcc -o aa a.c
Step 4. ./aa && dmesg
[ 3810.325408] NOT FOUND
[ 3811.215275] COMMIT START
[ 3811.216363] orphan commit orpahns 1
[ 3811.217532] commmit noorphan 0
[ 3811.218545] COMMIT END
[ 3811.222095] total orphans 0
[ 3811.223224] COMMIT START
[ 3811.224177] orphan commit orpahns 0
[ 3811.225450] commmit noorphan 1
[ 3811.226586] COMMIT END
[ 3811.227350] delete 65 from orphan
Step 5. Manually powercut when see 'delete 65 from orphan' in dmesg
Step 6. mount ubifs
[ 3863.152517] COMMIT START
[ 3863.152901] orphan commit orpahns 0
[ 3863.153491] commmit noorphan 1
[ 3863.153920] COMMIT END
[ 3863.154256] UBIFS (ubi0:0): recovery completed
[ 3863.154455] Found 65 0              # Find inode 65, nlink=0
Comment 1 Zhihao Cheng 2020-07-01 08:42:28 UTC 
Created attachment 290021 [details]
reproduce.patch
Comment 2 Zhihao Cheng 2020-07-01 08:42:38 UTC 
Created attachment 290023 [details]
a.c
Comment 3 Zhihao Cheng 2024-04-01 07:40:25 UTC 
New reproducer:
1. Apply diff
2. ./test.sh 1
3. powercut when you see "Do powercut"
4. ./test.sh

df stat (Used 54M)
Filesystem     Type   Size  Used Avail Use% Mounted on
/dev/ubi0_0    ubifs  110M   54M   52M  51% /root/temp

du stat (Used 0 bytes)
0	/root/temp/dir
0	/root/temp/f2
Comment 4 Zhihao Cheng 2024-04-01 07:40:38 UTC 
Created attachment 306072 [details]
diff
Comment 5 Zhihao Cheng 2024-04-01 07:40:58 UTC 
Created attachment 306073 [details]
a.c
Comment 6 Zhihao Cheng 2024-04-01 07:41:11 UTC 
Created attachment 306074 [details]
test.sh