On Thu, Jan 23, 2020 at 04:17:17PM -0800, Darrick J. Wong wrote: > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > The pwrite and pread commands in xfs_io accept an operation length that > can be any quantity that fits in a long long int; and loops to handle > the cases where the operation length is larger than the IO buffer. > > Weirdly, the do_ functions contain code to shorten the operation to the > IO buffer size but the @count parameter is size_t, which means that for > a large argument on a 32-bit system, we rip off the upper bits of the > length, turning your 8GB write into a 0 byte write, which does nothing. > > This was found by running generic/175 and observing that the 8G test > file it creates has zero length after the operation: > > wrote 0/8589934592 bytes at offset 0 > 0.000000 bytes, 0 ops; 0.0001 sec (0.000000 bytes/sec and 0.0000 ops/sec) > > Fix this by pushing long long count all the way through the call stack. > > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> Looks good, Reviewed-by: Christoph Hellwig <hch@xxxxxx>
