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Richard Yao
f091db9248
In 2016, the authors of PVS Studio ran it on the FreeBSD kernel, which identified a number of bugs / cleanup opportunities in the FreeBSD ZFS kernel code. A few of them persist to the present day: https://reviews.freebsd.org/D5245 Note that the scan was done against freebsd/freebsd-src@46763fd4ca. In particular, we have the following in free_blocks(): \sys\cddl\contrib\opensolaris\uts\common\fs\zfs\dnode_sync.c (174): error V547: Expression '__left >= __right' is always true. Unsigned type value is always >= 0. \sys\cddl\contrib\opensolaris\uts\common\fs\zfs\dnode_sync.c (171): error V634: The priority of the '*' operation is higher than that of the '<<' operation. It's possible that parentheses should be used in the expression. \sys\cddl\contrib\opensolaris\uts\common\fs\zfs\dnode_sync.c (175): error V547: Expression '__left >= __right' is always true. Unsigned type value is always >= 0. A couple of assertions accidentally typecast the arguments they check to unsigned in such a way that the result is always true. Also, parentheses are missing around `1<<epbs` in `(db->db_blkid * 1<<epbs)`. This works out to be okay due to multiplication not caring what order of operations we use, but it is better to fix it to be `(db->db_blkid << epbs)`. A few of the function local variables probably never should have been 32-bit in the first place, so we make them 64-bit. We also replace the existing assertions with additional assertions to ensure that 64-bit unsigned arithmetic is safe. Reviewed-by: Alexander Motin <mav@FreeBSD.org> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu> Closes #14407