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40 lines
1.5 KiB
Plaintext
40 lines
1.5 KiB
Plaintext
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dnl #
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dnl # 2.6.30 API change
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dnl #
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dnl # The bdev_physical_block_size() interface was added to provide a way
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dnl # to determine the smallest write which can be performed without a
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dnl # read-modify-write operation. From the kernel documentation:
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dnl #
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dnl # What: /sys/block/<disk>/queue/physical_block_size
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dnl # Date: May 2009
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dnl # Contact: Martin K. Petersen <martin.petersen@oracle.com>
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dnl # Description:
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dnl # This is the smallest unit the storage device can write
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dnl # without resorting to read-modify-write operation. It is
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dnl # usually the same as the logical block size but may be
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dnl # bigger. One example is SATA drives with 4KB sectors
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dnl # that expose a 512-byte logical block size to the
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dnl # operating system.
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dnl #
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dnl # Unfortunately, this interface isn't entirely reliable because
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dnl # drives are sometimes known to misreport this value.
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dnl #
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AC_DEFUN([ZFS_AC_KERNEL_BDEV_PHYSICAL_BLOCK_SIZE], [
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AC_MSG_CHECKING([whether bdev_physical_block_size() is available])
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tmp_flags="$EXTRA_KCFLAGS"
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EXTRA_KCFLAGS="-Wno-unused-but-set-variable"
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ZFS_LINUX_TRY_COMPILE([
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#include <linux/blkdev.h>
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],[
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struct block_device *bdev = NULL;
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bdev_physical_block_size(bdev);
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],[
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AC_MSG_RESULT(yes)
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AC_DEFINE(HAVE_BDEV_PHYSICAL_BLOCK_SIZE, 1,
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[bdev_physical_block_size() is available])
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],[
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AC_MSG_RESULT(no)
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])
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EXTRA_KCFLAGS="$tmp_flags"
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])
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