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Date: Mon, 18 May 2009 16:30:29 -0500
From: Eric Sandeen <sandeen@...hat.com>
To: ext4 development <linux-ext4@...r.kernel.org>
Subject: [PATCH] resize2fs: fix ENOSPC corruption case
http://people.redhat.com/esandeen/livecd-creator-imagefile.bz2
contains an image (for now) which, when resized to 578639, corrupts
the filesystem.
This is a bit crazy, I guess, because the fs currently has only
1 free block, but still, we should be graceful about the failure.
Perhaps it would make sense to check the requested valuea against
the minimum value resize2fs would compute for "-P" and fail (at
least without a force).
But in any case, this exposed 2 bugs when moving that one block
required an extent split, which is what hit the ENOSPC.
For starters, ext2fs_extent_set_bmap() in the "(re/un)mapping last
block in extent" case was replacing the old extent before the
new one was created; when the new extent creation failed, it
left us in an inconsistent state. Simply changing the order of
the two should fix this problem.
Next, ext2fs_extent_insert was calling ext2fs_extent_delete()
on *any* error, including one caused by failure to allocate a new
block to split the node to hold that extent ... the handle was left
unchanged, and we deleted the -original- extent.
As a quick fix for this, just don't do the delete if we fail the split,
though this may need to be smarter. I don't think we have terribly
consistent behavior about where a handle is left on various errors.
Signed-off-by: Eric Sandeen <sandeen@...hat.com>
---
Index: e2fsprogs/lib/ext2fs/extent.c
===================================================================
--- e2fsprogs.orig/lib/ext2fs/extent.c
+++ e2fsprogs/lib/ext2fs/extent.c
@@ -1068,16 +1068,17 @@ errcode_t ext2fs_extent_insert(ext2_exte
retval = ext2fs_extent_replace(handle, 0, extent);
if (retval)
- goto errout;
+ goto errout_delete;
retval = update_path(handle);
if (retval)
- goto errout;
+ goto errout_delete;
return 0;
-errout:
+errout_delete:
ext2fs_extent_delete(handle, 0);
+errout:
return retval;
}
@@ -1239,16 +1240,17 @@ again:
#ifdef DEBUG
printf("(re/un)mapping last block in extent\n");
#endif
- extent.e_len--;
- retval = ext2fs_extent_replace(handle, 0, &extent);
- if (retval)
- goto done;
+ /* Make sure insert works before replacing old extent */
if (physical) {
retval = ext2fs_extent_insert(handle,
EXT2_EXTENT_INSERT_AFTER, &newextent);
if (retval)
goto done;
}
+ extent.e_len--;
+ retval = ext2fs_extent_replace(handle, 0, &extent);
+ if (retval)
+ goto done;
} else if (logical == extent.e_lblk) {
#ifdef DEBUG
printf("(re/un)mapping first block in extent\n");
--
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