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path: root/fs/ext4/mmp.c
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2011-10-18ext4: Fix comparison endianness problem in MMP initializationDarrick J. Wong
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>
2011-10-18ext4: MMP: fix error message rate-limiting logic in kmmpdNikitas Angelinas
Current logic would print an error message only once, and then 'failed_writes' would stay at 1. Rework the loop to increment 'failed_writes' and print the error message every s_mmp_update_interval * 60 seconds, as intended according to the comment. Signed-off-by: Nikitas Angelinas <nikitas_angelinas@xyratex.com> Signed-off-by: Andrew Perepechko <andrew_perepechko@xyratex.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Acked-by: Andreas Dilger <adilger@dilger.ca>
2011-10-18ext4: MMP: kmmpd should use nodename from init_uts_ns.name, not sysnameNikitas Angelinas
sysname holds "Linux" by default, i.e. what appears when doing a "uname -s"; nodename should be used to print the machine's hostname, i.e. what is returned when doing a "uname -n" or "hostname", and what gethostname(2)/sethostname(2) manipulate, in order to notify the administrator of the node which is contending to mount the filesystem. Acked-by: Andreas Dilger <adilger@dilger.ca> Signed-off-by: Nikitas Angelinas <nikitas_angelinas@xyratex.com> Signed-off-by: Andrew Perepechko <andrew_perepechko@xyratex.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-05-24ext4: add support for multiple mount protectionJohann Lombardi
Prevent an ext4 filesystem from being mounted multiple times. A sequence number is stored on disk and is periodically updated (every 5 seconds by default) by a mounted filesystem. At mount time, we now wait for s_mmp_update_interval seconds to make sure that the MMP sequence does not change. In case of failure, the nodename, bdevname and the time at which the MMP block was last updated is displayed. Signed-off-by: Andreas Dilger <adilger@whamcloud.com> Signed-off-by: Johann Lombardi <johann@whamcloud.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>