From: Mikulas Patocka <[email protected]> Allocate additional space after the 'struct dm_clone' for the target requested per_io_data_size and place DM_NOCLONE_MAGIC at the end.
Update both dm_per_bio_data() and dm_bio_from_per_bio_data() to branch accordingly based on whether bio/data is from clone or noclone. Signed-off-by: Mikulas Patocka <[email protected]> Signed-off-by: Mike Snitzer <[email protected]> --- drivers/md/dm.c | 32 ++++++++++++++++++++++++++++---- 1 file changed, 28 insertions(+), 4 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index d84735be6927..7e022f840419 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -26,6 +26,8 @@ #include <linux/pr.h> #include <linux/refcount.h> +#include <asm/unaligned.h> + #define DM_MSG_PREFIX "core" /* @@ -105,16 +107,29 @@ struct dm_io { /* * One of these is allocated per noclone bio. */ +#define DM_NOCLONE_MAGIC 9693664 struct dm_noclone { struct mapped_device *md; + struct bio *bio; bio_end_io_t *orig_bi_end_io; void *orig_bi_private; unsigned long start_time; + /* ... per-bio-data ... */ + /* DM_NOCLONE_MAGIC */ }; +static void noclone_endio(struct bio *bio); + void *dm_per_bio_data(struct bio *bio, size_t data_size) { - struct dm_target_io *tio = container_of(bio, struct dm_target_io, clone); + struct dm_target_io *tio; + + if (bio->bi_end_io == noclone_endio) { + struct dm_noclone *noclone = bio->bi_private; + return noclone + 1; + } + + tio = container_of(bio, struct dm_target_io, clone); if (!tio->inside_dm_io) return (char *)bio - offsetof(struct dm_target_io, clone) - data_size; return (char *)bio - offsetof(struct dm_target_io, clone) - offsetof(struct dm_io, tio) - data_size; @@ -124,9 +139,14 @@ EXPORT_SYMBOL_GPL(dm_per_bio_data); struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size) { struct dm_io *io = (struct dm_io *)((char *)data + data_size); - if (io->magic == DM_IO_MAGIC) + unsigned magic = get_unaligned(&io->magic); + if (magic == DM_NOCLONE_MAGIC) { + struct dm_noclone *noclone = (struct dm_noclone *)data - 1; + return noclone->bio; + } + if (magic == DM_IO_MAGIC) return (struct bio *)((char *)io + offsetof(struct dm_io, tio) + offsetof(struct dm_target_io, clone)); - BUG_ON(io->magic != DM_TIO_MAGIC); + BUG_ON(magic != DM_TIO_MAGIC); return (struct bio *)((char *)io + offsetof(struct dm_target_io, clone)); } EXPORT_SYMBOL_GPL(dm_bio_from_per_bio_data); @@ -1793,14 +1813,18 @@ static blk_qc_t dm_process_bio(struct mapped_device *md, /* Already been here if bio->bi_end_io is noclone_endio, reentered via dm_wq_work() */ if (bio->bi_end_io != noclone_endio) { - noclone = kmalloc_node(sizeof(*noclone), GFP_NOWAIT, md->numa_node_id); + noclone = kmalloc_node(sizeof(*noclone) + ti->per_io_data_size + sizeof(unsigned), + GFP_NOWAIT, md->numa_node_id); if (unlikely(!noclone)) goto no_fast_path; noclone->md = md; noclone->start_time = jiffies; + noclone->bio = bio; noclone->orig_bi_end_io = bio->bi_end_io; noclone->orig_bi_private = bio->bi_private; + put_unaligned(DM_NOCLONE_MAGIC, + (unsigned *)((char *)noclone + sizeof(*noclone) + ti->per_io_data_size)); bio->bi_end_io = noclone_endio; bio->bi_private = noclone; } else -- 2.15.0 -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
