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7 commits

Author SHA1 Message Date
Uwe Kleine-König
bf48aabb89 tree-wide: fix typos "offest" -> "offset"
This patch was generated by

	git grep -E -i -l 'offest' | xargs -r perl -p -i -e 's/offest/offset/'

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-12-04 15:39:50 +01:00
Joel Becker
73be192b17 ocfs2: Add statistics for the checksum and ecc operations.
It would be nice to know how often we get checksum failures.  Even
better, how many of them we can fix with the single bit ecc.  So, we add
a statistics structure.  The structure can be installed into debugfs
wherever the user wants.

For ocfs2, we'll put it in the superblock-specific debugfs directory and
pass it down from our higher-level functions.  The stats are only
registered with debugfs when the filesystem supports metadata ecc.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
2009-06-03 19:15:36 -07:00
Joel Becker
58896c4d0e ocfs2: One more hamming code optimization.
The previous optimization used a fast find-highest-bit-set operation to
give us a good starting point in calc_code_bit().  This version lets the
caller cache the previous code buffer bit offset.  Thus, the next call
always starts where the last one left off.

This reduces the calculation another 39%, for a total 80% reduction from
the original, naive implementation.  At least, on my machine.  This also
brings the parity calculation to within an order of magnitude of the
crc32 calculation.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
2009-01-05 08:40:35 -08:00
Joel Becker
7bb458a585 ocfs2: Another hamming code optimization.
In the calc_code_bit() function, we must find all powers of two beneath
the code bit number, *after* it's shifted by those powers of two.  This
requires a loop to see where it ends up.

We can optimize it by starting at its most significant bit.  This shaves
32% off the time, for a total of 67.6% shaved off of the original, naive
implementation.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
2009-01-05 08:40:35 -08:00
Joel Becker
e798b3f8a9 ocfs2: Don't hand-code xor in ocfs2_hamming_encode().
When I wrote ocfs2_hamming_encode(), I was following documentation of
the algorithm and didn't have quite the (possibly still imperfect) grasp
of it I do now.  As part of this, I literally hand-coded xor.  I would
test a bit, and then add that bit via xor to the parity word.

I can, of course, just do a single xor of the parity word and the source
word (the code buffer bit offset).  This cuts CPU usage by 53% on a
mostly populated buffer (an inode containing utmp.h inline).

Joel

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
2009-01-05 08:40:34 -08:00
Joel Becker
d6b32bbb3e ocfs2: block read meta ecc.
Add block check calls to the read_block validate functions.  This is the
almost all of the read-side checking of metaecc.  xattr buckets are not checked
yet.   Writes are also unchecked, and so a read-write mount will quickly fail.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
2009-01-05 08:40:31 -08:00
Joel Becker
70ad1ba7b4 ocfs2: Add the underlying blockcheck code.
This is the code that computes crc32 and ecc for ocfs2 metadata blocks.
There are high-level functions that check whether the filesystem has the
ecc feature, mid-level functions that work on a single block or array of
buffer_heads, and the low-level ecc hamming code that can handle
multiple buffers like crc32_le().

It's not hooked up to the filesystem yet.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
2009-01-05 08:40:31 -08:00