erasure-code: enforce chunk size alignment (giant) #3083
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Do not assume the alignment is a power of two in the is_n_align_sized() predicate. When used in the context of erasure code it is common for chunks to not be powers of two. Signed-off-by: Loic Dachary <loic@dachary.org> (cherry picked from commit 73ad2d6)
Let say the ErasureCode::encode function is given a 4096 bytes bufferlist made of a 1249 bytes bufferptr followed by a 2847 bytes bufferptr, both properly starting on SIMD_ALIGN address. As a result the second 2048 had to be reallocated when bufferlist::substr_of gets the second 2048 buffer, the address starts at 799 bytes after the beginning of the 2847 buffer ptr and is not SIMD_ALIGN'ed. The ErasureCode::encode must enforce a size alignment based on the chunk size in addition to the memory alignment required by SIMD operations, using the bufferlist::rebuild_aligned_size_and_memory function instead of bufferlist::rebuild_aligned. http://tracker.ceph.com/issues/10211 Fixes: #10211 Signed-off-by: Loic Dachary <loic@dachary.org> (cherry picked from commit 4e955f4)
The function bufferlist::rebuild_aligned checks memory and size alignment with the same variable. It is however useful to separate memory alignment constraints from size alignment constraints. For instance rebuild_aligned could be called to allocate an erasure coded buffer where each 2048 bytes chunk needs to start on a memory address aligned on 32 bytes. Signed-off-by: Loic Dachary <loic@dachary.org> (cherry picked from commit 9ade88e)
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SUCCESS: make check on 99b6486 output is http://paste.ubuntu.com/9528744/ |
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Feb 10, 2015
…lignement-giant erasure-code: enforce chunk size alignment (giant)
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