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authorLinus Torvalds <torvalds@linux-foundation.org>2009-11-02 13:15:27 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-11-02 13:15:27 -0500
commitd4da6c9ccf648f3f1cb5bf9d981a62c253d30e28 (patch)
tree709f8bdc50a3a1d47632047eb3670b4a4a6ff045 /Documentation/filesystems
parentc35102c3e15f90fe604523a2fbffd9dc158b455a (diff)
Revert "ext4: Remove journal_checksum mount option and enable it by default"
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 <sandeen@redhat.com> Cc: Theodore Tso <tytso@mit.edu> Cc: Alexey Fisher <bug-track@fisher-privat.net> Cc: Maxim Levitsky <maximlevitsky@gmail.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Mathias Burén <mathias.buren@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/ext4.txt8
1 files changed, 7 insertions, 1 deletions
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
134 mount options "ro,noload" can be used to prevent 134 mount options "ro,noload" can be used to prevent
135 writes to the filesystem. 135 writes to the filesystem.
136 136
137journal_checksum Enable checksumming of the journal transactions.
138 This will allow the recovery code in e2fsck and the
139 kernel to detect corruption in the kernel. It is a
140 compatible change and will be ignored by older kernels.
141
137journal_async_commit Commit block can be written to disk without waiting 142journal_async_commit Commit block can be written to disk without waiting
138 for descriptor blocks. If enabled older kernels cannot 143 for descriptor blocks. If enabled older kernels cannot
139 mount the device. 144 mount the device. This will enable 'journal_checksum'
145 internally.
140 146
141journal=update Update the ext4 file system's journal to the current 147journal=update Update the ext4 file system's journal to the current
142 format. 148 format.