On Mon, May 22, 2023 at 9:37 AM Darrick J. Wong <djwong@xxxxxxxxxx> wrote: > > If someone calls fallocate(UNSHARE_RANGE) on a loop bdev, shouldn't > there be a way to pass that through to the fallocate call to the backing > file? > > --D > Yeah, I think we could add a REQ_UNSHARE bit (similar to REQ_NOUNMAP) to pass down the intent to the backing file (and possibly beyond...). I took a stab at implementing it as a follow up patch so that there's less review churn on the current series. If it looks good, I can add it to the end of the series (or incorporate this into the existing block and loop patches): From: Sarthak Kukreti <sarthakkukreti@xxxxxxxxxxxx> Date: Mon, 22 May 2023 14:18:15 -0700 Subject: [PATCH] block: Pass unshare intent via REQ_OP_PROVISION Allow REQ_OP_PROVISION to pass in an extra REQ_UNSHARE bit to annotate unshare requests to underlying layers. Layers that support FALLOC_FL_UNSHARE will be able to use this as an indicator of which fallocate() mode to use. Signed-off-by: Sarthak Kukreti <sarthakkukreti@xxxxxxxxxxxx> --- block/blk-lib.c | 6 +++++- block/fops.c | 6 +++++- drivers/block/loop.c | 35 +++++++++++++++++++++++++++++------ include/linux/blk_types.h | 3 +++ include/linux/blkdev.h | 3 ++- 5 files changed, 44 insertions(+), 9 deletions(-) diff --git a/block/blk-lib.c b/block/blk-lib.c index 3cff5fb654f5..bea6f5a700b3 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -350,6 +350,7 @@ EXPORT_SYMBOL(blkdev_issue_secure_erase); * @sector: start sector * @nr_sects: number of sectors to provision * @gfp_mask: memory allocation flags (for bio_alloc) + * @flags: controls detailed behavior * * Description: * Issues a provision request to the block device for the range of sectors. @@ -357,7 +358,7 @@ EXPORT_SYMBOL(blkdev_issue_secure_erase); * underlying storage pool to allocate space for this block range. */ int blkdev_issue_provision(struct block_device *bdev, sector_t sector, - sector_t nr_sects, gfp_t gfp) + sector_t nr_sects, gfp_t gfp, unsigned flags) { sector_t bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1; unsigned int max_sectors = bdev_max_provision_sectors(bdev); @@ -380,6 +381,9 @@ int blkdev_issue_provision(struct block_device *bdev, sector_t sector, bio->bi_iter.bi_sector = sector; bio->bi_iter.bi_size = req_sects << SECTOR_SHIFT; + if (flags & BLKDEV_UNSHARE_RANGE) + bio->bi_opf |= REQ_UNSHARE; + sector += req_sects; nr_sects -= req_sects; if (!nr_sects) { diff --git a/block/fops.c b/block/fops.c index be2e41f160bf..6848756f0557 100644 --- a/block/fops.c +++ b/block/fops.c @@ -659,7 +659,11 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start, case FALLOC_FL_KEEP_SIZE: case FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE: error = blkdev_issue_provision(bdev, start >> SECTOR_SHIFT, - len >> SECTOR_SHIFT, GFP_KERNEL); + len >> SECTOR_SHIFT, GFP_KERNEL, + (mode & + FALLOC_FL_UNSHARE_RANGE) ? + BLKDEV_UNSHARE_RANGE : + 0); break; case FALLOC_FL_ZERO_RANGE: case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE: diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 7fe1a6629754..c844b145d666 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -306,6 +306,30 @@ static int lo_read_simple(struct loop_device *lo, struct request *rq, return 0; } +static bool validate_fallocate_mode(struct loop_device *lo, int mode) +{ + bool ret = true; + + switch (mode) { + case FALLOC_FL_PUNCH_HOLE: + case FALLOC_FL_ZERO_RANGE: + if (!bdev_max_discard_sectors(lo->lo_device)) + ret = false; + break; + case 0: + case FALLOC_FL_UNSHARE_RANGE: + if (!bdev_max_provision_sectors(lo->lo_device)) + ret = false; + break; + + default: + ret = false; + } + + return ret; +} + + static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos, int mode) { @@ -316,11 +340,7 @@ static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos, struct file *file = lo->lo_backing_file; int ret; - if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE) && - !bdev_max_discard_sectors(lo->lo_device)) - return -EOPNOTSUPP; - - if (mode == 0 && !bdev_max_provision_sectors(lo->lo_device)) + if (!validate_fallocate_mode(lo, mode)) return -EOPNOTSUPP; mode |= FALLOC_FL_KEEP_SIZE; @@ -493,7 +513,10 @@ static int do_req_filebacked(struct loop_device *lo, struct request *rq) case REQ_OP_DISCARD: return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE); case REQ_OP_PROVISION: - return lo_fallocate(lo, rq, pos, 0); + return lo_fallocate(lo, rq, pos, + (rq->cmd_flags & REQ_UNSHARE) ? + FALLOC_FL_UNSHARE_RANGE : + 0); case REQ_OP_WRITE: if (cmd->use_aio) return lo_rw_aio(lo, cmd, pos, ITER_SOURCE); diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index b7bb0226fdee..1a536fd897cb 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -423,6 +423,8 @@ enum req_flag_bits { */ /* for REQ_OP_WRITE_ZEROES: */ __REQ_NOUNMAP, /* do not free blocks when zeroing */ + /* for REQ_OP_PROVISION: */ + __REQ_UNSHARE, /* unshare blocks */ __REQ_NR_BITS, /* stops here */ }; @@ -451,6 +453,7 @@ enum req_flag_bits { #define REQ_FS_PRIVATE (__force blk_opf_t)(1ULL << __REQ_FS_PRIVATE) #define REQ_NOUNMAP (__force blk_opf_t)(1ULL << __REQ_NOUNMAP) +#define REQ_UNSHARE (__force blk_opf_t)(1ULL << __REQ_UNSHARE) #define REQ_FAILFAST_MASK \ (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER) diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 462ce586d46f..60c09b0d3fc9 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1049,10 +1049,11 @@ int blkdev_issue_secure_erase(struct block_device *bdev, sector_t sector, sector_t nr_sects, gfp_t gfp); extern int blkdev_issue_provision(struct block_device *bdev, sector_t sector, - sector_t nr_sects, gfp_t gfp_mask); + sector_t nr_sects, gfp_t gfp_mask, unsigned int flags); #define BLKDEV_ZERO_NOUNMAP (1 << 0) /* do not free blocks */ #define BLKDEV_ZERO_NOFALLBACK (1 << 1) /* don't write explicit zeroes */ +#define BLKDEV_UNSHARE_RANGE (1 << 2) /* unshare range on provision */ extern int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector, sector_t nr_sects, gfp_t gfp_mask, struct bio **biop, -- 2.39.2