On 7/6/17 02:26, Christoph Hellwig wrote: > On Tue, Jul 04, 2017 at 05:27:02PM +0900, Damien Le Moal wrote: >> The BIO issuing loop in __blkdev_issue_zeroout() is allocating BIOs >> with a maximum number of bvec (pages) equal to >> >> min(nr_sects, (sector_t)BIO_MAX_PAGES) >> >> This works since the BIO will always be limited to the absolute maximum >> number of pages but this is ineficient as too many bvec entries may be >> requested since different units (number of sectors vs number of pages) >> are used in the min() operation. Fix this by correctly using the same >> unit (number of pages), making sure that this number is at least 1 for >> cases where the number of sectors is less that the number of sectors in >> a page. >> >> Also remove a trailing space after the bit shift in the internal loop >> min() call. > > Can you move the nr sectors calculation into a helper and add some > comments? Sure, no problem. I will send a v3 today. -- Damien Le Moal, Western Digital
