http://bugzilla.kernel.org/show_bug.cgi?id=14601
Summary: Wrong handling of META_BG when getting number of
blocks for group descriptors
Product: File System
Version: 2.5
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: ext4
AssignedTo: [email protected]
ReportedBy: [email protected]
Regression: No
Created an attachment (id=23778)
--> (http://bugzilla.kernel.org/attachment.cgi?id=23778)
ext3/balloc.c and ext4/balloc.c change to count number of descriptors blocks
When computing number of blocks for group descriptors for a given group, the
total number of blocks for group descriptors is returned in case META_BG is
enabled and group is inside the first groups (such as block of its descriptor
is below s_first_meta_bg). I think it should be limited to s_first_meta_bg.
This behaviour is incoherent with e2fsprogs behaviour (see
http://marc.info/?l=linux-ext4&m=125794126219545&w=2) and can lead to
corruption in case performing e2fsck on a filesystem where an uninitialized
block bitmap was initialized by kernel.
I attach a proposed change, but:
- I did not compiled, nor tried it.
- it is for ext3 and ext4.
- I am not sure it is enough: there is some other location where s_gdb_count is
used and where perhaps ext4_bg_num_gdb should be used instead as in
ext4_setup_system_zone (I do not understand the behaviour here, it seems to not
take META_BG flag into account at all) or ex4_iget.
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Jan Kara <[email protected]> changed:
What |Removed |Added
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CC| |[email protected]
--- Comment #1 from Jan Kara <[email protected]> 2009-11-17 21:47:49 ---
Thanks for the patch. It looks good but please look at
Documentation/SubmittingPatches how a patch for kernel should look like (most
notably it misses a Signed-off-by, it should be in a unified format and with a
changelog). Also please create one patch for ext3 and one patch for ext4 since
I will merge the ext3 part and Ted Tso takes care of ext4. Thanks.
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Theodore Tso <[email protected]> changed:
What |Removed |Added
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--- Comment #2 from Theodore Tso <[email protected]> 2009-11-17 22:57:23 ---
Jan, I have a IMHO better set of patches which I plan to merge for ext4; it
ends up simplifying the code, and makes it easier to read. I'll backport my
ext4 fixes to ext3 and send them to you. It's on my todo list.
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--- Comment #3 from Jan Kara <[email protected]> 2009-11-18 09:52:46 ---
OK, I'll wait for your backport then. Thanks.
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