forked from luck/tmp_suning_uos_patched
ext4: Fix comparison endianness problem in MMP initialization
As part of startup, the MMP initialization code does this: mmp->mmp_seq = seq = cpu_to_le32(mmp_new_seq()); Next, mmp->mmp_seq is written out to disk, a delay happens, and then the MMP block is read back in and the sequence value is tested: if (seq != le32_to_cpu(mmp->mmp_seq)) { /* fail the mount */ On a LE system such as x86, the *le32* functions do nothing and this works. Unfortunately, on a BE system such as ppc64, this comparison becomes: if (cpu_to_le32(new_seq) != le32_to_cpu(cpu_to_le32(new_seq)) { /* fail the mount */ Except for a few palindromic sequence numbers, this test always causes the mount to fail, which makes MMP filesystems generally unmountable on ppc64. The attached patch fixes this situation. Signed-off-by: Darrick J. Wong <djwong@us.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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@ -296,7 +296,8 @@ int ext4_multi_mount_protect(struct super_block *sb,
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/*
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* write a new random sequence number.
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*/
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mmp->mmp_seq = seq = cpu_to_le32(mmp_new_seq());
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seq = mmp_new_seq();
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mmp->mmp_seq = cpu_to_le32(seq);
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retval = write_mmp_block(bh);
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if (retval)
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