From d4da6c9ccf648f3f1cb5bf9d981a62c253d30e28 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Mon, 2 Nov 2009 10:15:27 -0800 Subject: Revert "ext4: Remove journal_checksum mount option and enable it by default" MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This reverts commit d0646f7b636d067d715fab52a2ba9c6f0f46b0d7, as requested by Eric Sandeen. It can basically cause an ext4 filesystem to miss recovery (and thus get mounted with errors) if the journal checksum does not match. Quoth Eric: "My hand-wavy hunch about what is happening is that we're finding a bad checksum on the last partially-written transaction, which is not surprising, but if we have a wrapped log and we're doing the initial scan for head/tail, and we abort scanning on that bad checksum, then we are essentially running an unrecovered filesystem. But that's hand-wavy and I need to go look at the code. We lived without journal checksums on by default until now, and at this point they're doing more harm than good, so we should revert the default-changing commit until we can fix it and do some good power-fail testing with the fixes in place." See http://bugzilla.kernel.org/show_bug.cgi?id=14354 for all the gory details. Requested-by: Eric Sandeen Cc: Theodore Tso Cc: Alexey Fisher Cc: Maxim Levitsky Cc: Aneesh Kumar K.V Cc: Mathias Burén Signed-off-by: Linus Torvalds --- Documentation/filesystems/ext4.txt | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt index bf4f4b7e11b3..6d94e0696f8c 100644 --- a/Documentation/filesystems/ext4.txt +++ b/Documentation/filesystems/ext4.txt @@ -134,9 +134,15 @@ ro Mount filesystem read only. Note that ext4 will mount options "ro,noload" can be used to prevent writes to the filesystem. +journal_checksum Enable checksumming of the journal transactions. + This will allow the recovery code in e2fsck and the + kernel to detect corruption in the kernel. It is a + compatible change and will be ignored by older kernels. + journal_async_commit Commit block can be written to disk without waiting for descriptor blocks. If enabled older kernels cannot - mount the device. + mount the device. This will enable 'journal_checksum' + internally. journal=update Update the ext4 file system's journal to the current format. -- cgit v1.2.1