From 4f81a4176297db57c7ef3b2893092dd837c1e2a8 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Fri, 12 Oct 2012 21:02:13 +0100 Subject: dm thin: move bio_prison code to separate module The bio prison code will be useful to other future DM targets so move it to a separate module. Signed-off-by: Mike Snitzer Signed-off-by: Joe Thornber Signed-off-by: Alasdair G Kergon --- drivers/md/dm-bio-prison.h | 72 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 drivers/md/dm-bio-prison.h (limited to 'drivers/md/dm-bio-prison.h') diff --git a/drivers/md/dm-bio-prison.h b/drivers/md/dm-bio-prison.h new file mode 100644 index 000000000000..4e0ac376700a --- /dev/null +++ b/drivers/md/dm-bio-prison.h @@ -0,0 +1,72 @@ +/* + * Copyright (C) 2011-2012 Red Hat, Inc. + * + * This file is released under the GPL. + */ + +#ifndef DM_BIO_PRISON_H +#define DM_BIO_PRISON_H + +#include "persistent-data/dm-block-manager.h" /* FIXME: for dm_block_t */ +#include "dm-thin-metadata.h" /* FIXME: for dm_thin_id */ + +#include +#include + +/*----------------------------------------------------------------*/ + +/* + * Sometimes we can't deal with a bio straight away. We put them in prison + * where they can't cause any mischief. Bios are put in a cell identified + * by a key, multiple bios can be in the same cell. When the cell is + * subsequently unlocked the bios become available. + */ +struct dm_bio_prison; +struct dm_bio_prison_cell; + +/* FIXME: this needs to be more abstract */ +struct dm_cell_key { + int virtual; + dm_thin_id dev; + dm_block_t block; +}; + +struct dm_bio_prison *dm_bio_prison_create(unsigned nr_cells); +void dm_bio_prison_destroy(struct dm_bio_prison *prison); + +/* + * This may block if a new cell needs allocating. You must ensure that + * cells will be unlocked even if the calling thread is blocked. + * + * Returns 1 if the cell was already held, 0 if @inmate is the new holder. + */ +int dm_bio_detain(struct dm_bio_prison *prison, struct dm_cell_key *key, + struct bio *inmate, struct dm_bio_prison_cell **ref); + +void dm_cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios); +void dm_cell_release_singleton(struct dm_bio_prison_cell *cell, struct bio *bio); // FIXME: bio arg not needed +void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates); +void dm_cell_error(struct dm_bio_prison_cell *cell); + +/*----------------------------------------------------------------*/ + +/* + * We use the deferred set to keep track of pending reads to shared blocks. + * We do this to ensure the new mapping caused by a write isn't performed + * until these prior reads have completed. Otherwise the insertion of the + * new mapping could free the old block that the read bios are mapped to. + */ + +struct dm_deferred_set; +struct dm_deferred_entry; + +struct dm_deferred_set *dm_deferred_set_create(void); +void dm_deferred_set_destroy(struct dm_deferred_set *ds); + +struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds); +void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head); +int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work); + +/*----------------------------------------------------------------*/ + +#endif -- cgit v1.2.2