If the file already has more than one block, then the current
block size cannot change. But if the file block size is less
than the maximum block size supported by the file system, and
there are multiple blocks in the file, the current code will
almost always extend the rangelock to its maximum size.
This means that all writes become serialized and even reads
are slowed as they will more often contend with writes. This
commit adjusts the test so that we will not lock the entire
range if there is more than one block in the file already.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com>
Signed-off-by: Mark Maybee <mark.maybee@perforce.com>
Closes#18046Closes#18064