On Tue, Apr 12 2016 at 12:42P -0400, Brian Foster <bfoster@xxxxxxxxxx> 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): From: Mike Snitzer <snitzer@xxxxxxxxxx> 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 <snitzer@xxxxxxxxxx> --- 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); +} +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; /* 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) error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, GFP_KERNEL, false); else if (mode & FALLOC_FL_PUNCH_HOLE) diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 6c6ea96..4147af2 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1132,6 +1132,8 @@ extern int blkdev_issue_write_same(struct block_device *bdev, sector_t sector, sector_t nr_sects, gfp_t gfp_mask, struct page *page); extern int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector, sector_t nr_sects, gfp_t gfp_mask, bool discard); +extern int blkdev_ensure_space_exists(struct block_device *bdev, sector_t sector, + sector_t nr_sects, unsigned long flags); static inline int sb_issue_discard(struct super_block *sb, sector_t block, sector_t nr_blocks, gfp_t gfp_mask, unsigned long flags) { -- 2.6.4 (Apple Git-63) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
