On Tue, Apr 12, 2016 at 05:04:27PM -0400, Mike Snitzer wrote: > On Tue, Apr 12 2016 at 4:39pm -0400, > Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote: > > > On Tue, Apr 12, 2016 at 04:04:59PM -0400, Mike Snitzer wrote: > > > diff --git a/fs/block_dev.c b/fs/block_dev.c > > > index 5a2c3ab..b34c07b 100644 > > > --- a/fs/block_dev.c > > > +++ b/fs/block_dev.c > > > @@ -1801,17 +1801,13 @@ long blkdev_fallocate(struct file *file, int mode, loff_t start, loff_t len) > > > struct request_queue *q = bdev_get_queue(bdev); > > > struct address_space *mapping; > > > loff_t end = start + len - 1; > > > - loff_t bs_mask, isize; > > > + loff_t isize; > > > int error; > > > > > > /* We only support zero range and punch hole. */ > > > if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED) > > > return -EOPNOTSUPP; > > > > > > - /* We haven't a primitive for "ensure space exists" right now. */ > > > - if (!(mode & ~FALLOC_FL_KEEP_SIZE)) > > > - return -EOPNOTSUPP; > > > - > > > /* Only punch if the device can do zeroing discard. */ > > > if ((mode & FALLOC_FL_PUNCH_HOLE) && > > > (!blk_queue_discard(q) || !q->limits.discard_zeroes_data)) > > > @@ -1829,9 +1825,12 @@ long blkdev_fallocate(struct file *file, int mode, loff_t start, loff_t len) > > > return -EINVAL; > > > } > > > > > > - /* Don't allow IO that isn't aligned to logical block size */ > > > - bs_mask = bdev_logical_block_size(bdev) - 1; > > > - if ((start | len) & bs_mask) > > > + /* > > > + * Don't allow IO that isn't aligned to minimum IO size (io_min) > > > + * - for normal device's io_min is usually logical block size > > > + * - but for more exotic devices (e.g. DM thinp) it may be larger > > > + */ > > > + if ((start | len) % bdev_io_min(bdev)) I started by noticing the 64-bit division. However, in researching alignment requirements for fallocate, I noticed that nothing says that we can return -EINVAL for unaligned offset/len for allocate or punch. For file allocations ext4 and xfs simply enlarge the range so that the ends are aligned to the logical block size; for punch they both shrink the range to deallocate until the ends are aligned, and write zeroes to the partial blocks. At least for user-visible fallocate we should do likewise, but for the internal blkdev_ helpers I think it makes more sense to check lbs alignment and let the lower level driver reject the IO if min_io alignment is a hard requirement. Documentation/block/queue-sysfs.txt says that the min_io is the smallest /preferred/ size. But, before that, I'll push out some new fallocate patches for -rc3. > > > return -EINVAL; > > > > Noted. Will update the original patch. > > BTW, I just noticed your "block: require write_same and discard requests > align to logical block size" -- doesn't look right. What happens if we pass a request to thinp that isn't aligned to minimum_io_size? Does it reject the command? > But maybe I'm just too hyper-focused on DM thinp's needs (which would > much prefer these checks be done in terms of minimum_io_size, rather > than logical_block_size, and _not_ assuming power-of-2 math will work). > > But at least for discard: your lbs-based check is fine; since we have > discard_granularity to cover thinp's more specific requirements. --D -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
