On Tue, Apr 12 2016 at 4:39pm -0400, Darrick J. Wong <[email protected]> wrote:
> On Tue, Apr 12, 2016 at 04:04:59PM -0400, Mike Snitzer wrote: > > On Tue, Apr 12 2016 at 12:42P -0400, > > Brian Foster <[email protected]> wrote: > > > > > Hi all, > > > > > > This is v2 of the XFS and block device reservation experiment. The > > > significant changes in v2 are that the bdev interface has been condensed > > > to a single callback function, the XFS transaction reservation > > > management has been reworked to make transactions responsible for > > > tracking and releasing excess reservation (for non-delalloc cases) and a > > > workaround for the fallocate over-reservation issue is included. Beyond > > > that, this version adds a bunch of miscellaneous cleanups and fixes some > > > of the nastier locking/leak issues present in the first rfc. > > > > > > Patches 1-2 refactor some XFS reserve pool and block accounting code in > > > preparation for subsequent patches. Patches 3-5 add block/device-mapper > > > reservation support. Patches 6-10 add the core reservation > > > infrastructure and management bits to XFS. See the link to the original > > > rfc below for instructions and further details around the purpose of > > > this series. > > > > > > Finally, note that this is still highly experimental/theoretical and > > > should not be used on production systems. Thoughts, reviews, flames > > > appreciated. > > > > Thanks for carrying on with this work Brian. > > > > I've started to review your patchset and Darrick's fallocate patchset. > > I've pushed a branch to linux-dm.git that combines the 2, see: > > https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/log/?h=dm-fallocate > > > > and then added this RFC patch, at the end, which relies on both of your > > patchsets -- you'll see blkdev_ensure_space_exists() has a FIXME which > > implies it isn't much more than simply stubbed out at this point > > (completely untested): > > Hmm, ok, but -rc3 broke a bunch of stuff. Guess I should repost with all > the PAGE_CACHE_ -> PAGE_ stuff fixed. :) Yeah, the kernel.org kbuild robots just spammed us about that same exact breakage. > > From: Mike Snitzer <[email protected]> > > Date: Tue, 12 Apr 2016 15:54:31 -0400 > > Subject: [RFC PATCH] block: wire blkdev_fallocate() to > > block_device_operations' reserve_space > > > > This effectively exposes the primitive for "ensure space exists". It > > relies on block_device_operations' reserve_space method. > > > > Signed-off-by: Mike Snitzer <[email protected]> > > --- > > block/blk-lib.c | 26 ++++++++++++++++++++++++++ > > fs/block_dev.c | 20 +++++++++++--------- > > include/linux/blkdev.h | 2 ++ > > 3 files changed, 39 insertions(+), 9 deletions(-) > > > > diff --git a/block/blk-lib.c b/block/blk-lib.c > > index 9dca6bb..5042a84 100644 > > --- a/block/blk-lib.c > > +++ b/block/blk-lib.c > > @@ -314,3 +314,29 @@ int blkdev_issue_zeroout(struct block_device *bdev, > > sector_t sector, > > return __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask); > > } > > EXPORT_SYMBOL(blkdev_issue_zeroout); > > + > > +/** > > + * blkdev_ensure_space_exists - preallocate a block range > > + * @bdev: blockdev to preallocate space for > > + * @sector: start sector > > + * @nr_sects: number of sectors to preallocate > > + * @gfp_mask: memory allocation flags (for bio_alloc) > > + * @flags: FALLOC_FL_* to control behaviour > > + * > > + * Description: > > + * Ensure space exists, or is preallocated, for the sectors in question. > > + */ > > +int blkdev_ensure_space_exists(struct block_device *bdev, sector_t sector, > > + sector_t nr_sects, unsigned long flags) > > +{ > > + sector_t res; > > + const struct block_device_operations *ops = bdev->bd_disk->fops; > > + > > + if (!ops->reserve_space) > > + return -EOPNOTSUPP; > > + > > + // FIXME: check with Brian Foster on whether it makes sense to > > + // use BDEV_RES_GET/BDEV_RES_MOD instead of BDEV_RES_PROVISION? > > + return ops->reserve_space(bdev, BDEV_RES_PROVISION, sector, nr_sects, > > &res); > > /me thinks BDEV_RES_PROVISION is correct here, because regular-mode file > fallocate (for ext4/xfs anyway) allocates blocks and maps them to specific > file > offsets as unwritten extents. afaict RES_PROVISION -> thin_provision_space() > and thin_provision_space() seems to allocate blocks and map them to the > device's LBAs. > > If I'm reading the patches correctly, RES_GET/RES_MOD seem to reserve N blocks > but doesn't map them to any specific LBA. Right that is how I read it too. I just put that FIXME in to cover my ass incase I was being an idiot ;) > > +} > > +EXPORT_SYMBOL(blkdev_ensure_space_exists); > > 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)) > > return -EINVAL; > > Noted. Will update the original patch. OK, thanks. Once your new patchset is available I'll rebase my 'dm-fallocate' test branch accordingly. > > /* Invalidate the page cache, including dirty pages. */ > > @@ -1839,7 +1838,10 @@ long blkdev_fallocate(struct file *file, int mode, > > loff_t start, loff_t len) > > truncate_inode_pages_range(mapping, start, end); > > > > error = -EINVAL; > > - if (mode & FALLOC_FL_ZERO_RANGE) > > + if (!(mode & ~FALLOC_FL_KEEP_SIZE)) > > + error = blkdev_ensure_space_exists(bdev, start >> 9, len >> 9, > > + mode); > > + else if (mode & FALLOC_FL_ZERO_RANGE) > > This whole thing got converted to a switch statement due to some feedback > from hch. > > Anyway, will try to have a new blockdev fallocate patchset done by the end > of the day. > > (Is there a test case for this?) No, but once my patch is in place to join your patchset with Brian's then any basic fallocate tests against a DM thinp volume _should_ work. /me assumes xfstests has such tests? Only missing bit would be to layer the filesystem ontop of DM thinp? Or extend the tests your added to test DM thinp devices directly. I think Eric Sandeen (now cc'd) made xfstests capable or creating DM thinp volumes for certain tests. -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
