![]() The first one is placed at 64KB, the second > one at 64MB, the third one at 256GB. > On Sun, at 07:28:55PM +0100, Goffredo Baroncelli wrote: > Currently wipefs doesn't clear all the superblock of btrfs. The body of a message to majordomo info at To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in by another filesystem), then the other two superblocks may be considered > valid, and the filesystem may resurrect.Īnd for that purpose all the superblock copies should be taken intoĪccount, regardless of the tricks that btrfs_mount applies. But when the first superblock is overwritten > (e.g. > So zeroing the first superblock "magic field" at the beginning seems > that the filesystem is wiped. ![]() > If the first superblock is fully invalid, btrfs checks for the other > superblock. > If the first superblock is valid except that the "magic field" is zeroed, > btrfs skips the check of the other superblocks. It can have as much as 4 superblock backup copies: > Currently wipefs doesn't clear all the superblock of btrfs. On Sun, at 07:28:55PM +0100, Goffredo Baroncelli wrote: Libblkid/src/superblocks/superblocks.h | 2 ++ĭavid Sterba Jan. Libblkid/src/superblocks/superblocks.c | 2 ++ This patch allow to find and wipe the other btrfs superblocks signature. by another filesystem), then the other two superblock may be considered Second one at 64MB, the third one at 256GB. Subject: Add support for wiping the other btrfs superblock.ītrfs has three superblock. # Now even if we zero the 1st superblock the filesystem doesn't resurrect dev/loop0: 8 bytes were erased at offset 0x4000000040 (btrfs ): dev/loop0: 8 bytes were erased at offset 0x04000040 (btrfs ): dev/loop0: 8 bytes were erased at offset 0x00010040 (btrfs): UUID: sudo ~/btrfs/util-linux/wipefs -a /dev/loop0 $ sudo ~/btrfs/util-linux/wipefs /dev/loop0 # With this patch, wipefs is able to find all the superblock: ![]() # it seems that the filesystem is disappeared $ sudo mkfs.btrfs -L "Btrfs-test" /dev/loop0 # make a filesystem, wipe it and check if it disappears by another filesystem), then the other two superblocks may be considered But when the first superblock is overwritten So zeroing the first superblock "magic field" at the beginning seems If the first superblock is fully invalid, btrfs checks for the other If the first superblock is valid except that the "magic field" is zeroed,ītrfs skips the check of the other superblocks. The first one is placed at 64KB, the second Only the firstītrfs has three superblocks. UTCĬurrently wipefs doesn't clear all the superblock of btrfs. Subject: Btrfs: wipe all the superblock Ĭontent-Type: text/plain charset=ISO-8859-1 X-Original-To: from ( )īy (Postfix) with ESMTP id 1FCE04020F
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