Bug 15768

Summary: Incorrectly calculated free blocks result in ENOSPC from writepage
Product: File System Reporter: Dmitry Monakhov (dmonakhov)
Component: ext4Assignee: fs_ext4 (fs_ext4)
Severity: high CC: dmonakhov, maciej.rutecki, rjw, tytso
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: from 2.6.11 to 2.6.33-rc4 Subsystem:
Regression: No Bisected commit-id:
Bug Depends on:    
Bug Blocks: 15310    
Attachments: testcase

Description Dmitry Monakhov 2010-04-12 11:24:47 UTC
Created attachment 25965 [details]

No mount per-sb counters (freeblocks/freeinodes/dir and etc) are initialized 
before journal was replayed.
But in fact if journal wasn't empty statistics will be probably changed after
journal replay. This result in per-sb counter  inconsistency which result in
incorrect delalloc reservation. See testcase.
This is long standing bug at least from 2.6.12 where the linus's tree starts i (was too lazy to dig in to old-git tree).
But it case of ext3 this result only in incorrect numbers from statfs()
The fix is simple, we just have to move counter initialisation after journal_reply.
I've open this bug only as testcase storage.
Comment 1 Dmitry Monakhov 2010-04-12 11:32:41 UTC
dmesg after testcase check 

kjournald2 starting: pid 1310, dev sdb1:8, commit interval 5 seconds
EXT4-fs (sdb1): internal journal on sdb1:8
EXT4-fs (sdb1): delayed allocation enabled
EXT4-fs: file extents enabled
EXT4-fs: mballoc enabled
EXT4-fs (sdb1): recovery complete
EXT4-fs (sdb1): mounted filesystem with ordered data mode
mpage_da_map_blocks block allocation failed for inode 14 at logical offset 4667 with max blocks 5192 with error -28
This should not happen.!! Data will be lost
Total free blocks count 0
Free/Dirty block details
Block reservation details
Comment 2 Dmitry Monakhov 2010-04-12 11:49:51 UTC
proposed patch http://patchwork.ozlabs.org/patch/49963/
Comment 3 Dmitry Monakhov 2010-04-12 18:30:35 UTC
(In reply to comment #2)
> proposed patch http://patchwork.ozlabs.org/patch/49963/
Opps, the patch attached is wrong in case of no_journal mode.
Will send new version soon.
Comment 4 Dmitry Monakhov 2010-04-12 19:14:30 UTC
Updated version of the fix posted here.
Comment 5 Rafael J. Wysocki 2010-05-04 21:15:42 UTC
Patch : http://patchwork.ozlabs.org/patch/49989/
Handled-By : Dmitry Monakhov <dmonakhov@openvz.org>
Comment 6 Rafael J. Wysocki 2010-06-13 11:44:30 UTC
Fixed by commit 84061e07c5fbbbf9dc8aef8fb750fc3a2dfc31f3 .