47 lines
1.5 KiB
Diff
47 lines
1.5 KiB
Diff
From d4a276491269b6502c15e0089fba6b616f5c5df8 Mon Sep 17 00:00:00 2001
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From: Goffredo Baroncelli <kreijack@inwind.it>
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Date: Wed, 9 Jan 2013 22:14:43 +0100
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Subject: [PATCH] libblkid: add support for btrfs backup superblock
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Btrfs has three superblock. The first one is placed at 64KB, the second one at
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64MB, the third one at 256GB.
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If the first superblock is valid except that the "magic field" is zeroed, btrfs
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skips the check of the other superblocks. If the first superblock is fully
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invalid, btrfs checks for the other superblock.
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So zeroing the first superblock "magic field" at the beginning seems that the
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filesystem is wiped. But when the first superblock is overwritten (eg by
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another filesystem), then the other two superblock may be considered valid, and
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the filesystem may resurrect.
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This patch allow to find and wipe the other btrfs superblocks signature.
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Signed-off-by: Karel Zak <kzak@redhat.com>
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---
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libblkid/src/superblocks/btrfs.c | 8 ++++++++
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1 file changed, 8 insertions(+)
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diff --git a/libblkid/src/superblocks/btrfs.c b/libblkid/src/superblocks/btrfs.c
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index 039be42..1bd1df9 100644
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--- a/libblkid/src/superblocks/btrfs.c
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+++ b/libblkid/src/superblocks/btrfs.c
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@@ -87,6 +87,14 @@ const struct blkid_idinfo btrfs_idinfo =
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.magics =
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{
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{ .magic = "_BHRfS_M", .len = 8, .kboff = 64, .sboff = 0x40 },
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+ { .magic = "_BHRfS_M",
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+ .len = 8,
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+ .kboff = 64 * 1024,
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+ .sboff = 0x40 },
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+ { .magic = "_BHRfS_M",
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+ .len = 8,
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+ .kboff = 256 * 1024 * 1024,
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+ .sboff = 0x40 },
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{ NULL }
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}
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};
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--
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1.7.11.7
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