New: ext4_get_blocks may be called while ext4_truncate() is in progress
https://bugzilla.kernel.org/show_bug.cgi?id=15827
Summary: ext4_get_blocks may be called while ext4_truncate()
is in progress
Product: File System
Version: 2.5
Kernel Version: v2.6.29-rc5
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: high
Priority: P1
Component: ext4
AssignedTo: [email protected]
ReportedBy: [email protected]
Regression: No
Created an attachment (id=26081)
--> (https://bugzilla.kernel.org/attachment.cgi?id=26081)
dmesg output
During truncate we may need to restart new transaction, to avoid deadlock on i_data_sem it was dropped
commit 487caeef9fc08c0565e082c40a8aaf58dad92bbb
Author: Jan Kara <[email protected]> Date: Mon Aug 17 22:17:20 2009 -0400
Jan given a good explanation why this approach would work, I have better explanation why this can't work work.
Yes we have blocked all writers beyond i_size, but writers(flush, page_mkwrite) before i_size still may change node blocks, so 'path' which was lookup by truncate is not longer valid. So we are in big big troubles.
I've add created inode's history tracer patch which spotted the issue. See attachments.
--- Comment #1 from Dmitry Monakhov <[email protected]> 2010-04-21 15:41:13 --- Created an attachment (id=26082)
--> (https://bugzilla.kernel.org/attachment.cgi?id=26082)
debug patch against ext4.git/next + patches from bug #15792
The debug patch is rather ugly, but still useful.
Signature · 3 lines
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[Bug 15827] ext4_get_blocks may be called while ext4_truncate() is in progress
https://bugzilla.kernel.org/show_bug.cgi?id=15827
Dmitry Monakhov <[email protected]> changed:
What |Removed |Added
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Status|NEW |RESOLVED
Resolution| |CODE_FIXSignature · 3 lines
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