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author | Pete Zaitcev <zaitcev@kotori.zaitcev.us> | 2017-05-23 17:45:43 -0600 |
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committer | Thiago da Silva <thiago@redhat.com> | 2017-06-06 14:53:45 -0400 |
commit | 960cdd09dcabe5e125d8ee1c54fcc1f908e8ef11 (patch) | |
tree | 51e7d4237bedd2129b38fa3eb2b4733e59252fb0 /src | |
parent | de984f59e7a6cca8c1f3cf1d93b87ff144a2b974 (diff) | |
download | liberasurecode-960cdd09dcabe5e125d8ee1c54fcc1f908e8ef11.tar.gz |
Stop using ceill() to compute padded data size
The well-known idiom to compute a required number of data blocks
of size B to contain data of length d is:
(d + (B-1))/B
The code we use, with ceill(), computes the same value, but does
it in an unorthodox way. This makes a reviewer to doubt himself
and even run tests to make sure we're really computing the
obvious thing.
Apropos the reviewer confusion, the code in Phazr.IO looks weird.
It uses (word_size - hamming_distance) to compute the necessary
number of blocks... but then returns the amount of memory needed
to store blocks of a different size (word_size). We left all of it
alone and return exactly the same values that the old computation
returned.
All these computations were the only thing in the code that used
-lm, so drop that too.
Coincidentially, this patch solves the crash of distro-built
packages of liberasurecode (see Red Hat bug #1454543). But it's
a side effect. Expect a proper patch soon.
Change-Id: Ib297f6df304abf5ca8c27d3392b1107a525e0be0
Diffstat (limited to 'src')
-rw-r--r-- | src/backends/phazrio/libphazr.c | 2 | ||||
-rw-r--r-- | src/erasurecode.c | 8 | ||||
-rw-r--r-- | src/erasurecode_helpers.c | 4 |
3 files changed, 7 insertions, 7 deletions
diff --git a/src/backends/phazrio/libphazr.c b/src/backends/phazrio/libphazr.c index 74ad8ad..41ed74e 100644 --- a/src/backends/phazrio/libphazr.c +++ b/src/backends/phazrio/libphazr.c @@ -88,7 +88,7 @@ struct libphazr_descriptor { static int get_padded_blocksize(int w, int hd, int blocksize) { int word_size = w / 8; - return (int) ceill((double) blocksize / (word_size - hd)) * word_size; + return ((blocksize + ((word_size - hd) - 1)) / (word_size - hd)) * word_size; } static int pio_matrix_encode(void *desc, char **data, char **parity, int blocksize) diff --git a/src/erasurecode.c b/src/erasurecode.c index fb6d5de..d4a06c2 100644 --- a/src/erasurecode.c +++ b/src/erasurecode.c @@ -1194,8 +1194,8 @@ int liberasurecode_verify_stripe_metadata(int desc, /** * This computes the aligned size of a buffer passed into * the encode function. The encode function must pad fragments - * to be algined with the word size (w) and the last fragment also - * needs to be aligned. This computes the sum of the algined fragment + * to be aligned with the word size (w) and the last fragment also + * needs to be aligned. This computes the sum of the aligned fragment * sizes for a given buffer to encode. */ int liberasurecode_get_aligned_data_size(int desc, uint64_t data_len) @@ -1218,8 +1218,8 @@ int liberasurecode_get_aligned_data_size(int desc, uint64_t data_len) alignment_multiple = k * word_size; - ret = (int) ceill( (double) - data_len / alignment_multiple) * alignment_multiple; + ret = ((data_len + alignment_multiple - 1) / alignment_multiple) + * alignment_multiple; out: return ret; diff --git a/src/erasurecode_helpers.c b/src/erasurecode_helpers.c index 40db93c..fd14298 100644 --- a/src/erasurecode_helpers.c +++ b/src/erasurecode_helpers.c @@ -199,8 +199,8 @@ int get_aligned_data_size(ec_backend_t instance, int data_len) alignment_multiple = k * word_size; } - aligned_size = (int) - ceill((double) data_len / alignment_multiple) * alignment_multiple; + aligned_size = ((data_len + alignment_multiple - 1) / alignment_multiple) + * alignment_multiple; return aligned_size; } |