diff options
Diffstat (limited to 'kernel/drivers/md/dm-bio-prison.h')
-rw-r--r-- | kernel/drivers/md/dm-bio-prison.h | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/kernel/drivers/md/dm-bio-prison.h b/kernel/drivers/md/dm-bio-prison.h new file mode 100644 index 000000000..74cf01144 --- /dev/null +++ b/kernel/drivers/md/dm-bio-prison.h @@ -0,0 +1,125 @@ +/* + * 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 <linux/bio.h> +#include <linux/rbtree.h> + +/*----------------------------------------------------------------*/ + +/* + * 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; + +/* + * Keys define a range of blocks within either a virtual or physical + * device. + */ +struct dm_cell_key { + int virtual; + dm_thin_id dev; + dm_block_t block_begin, block_end; +}; + +/* + * Treat this as opaque, only in header so callers can manage allocation + * themselves. + */ +struct dm_bio_prison_cell { + struct list_head user_list; /* for client use */ + struct rb_node node; + + struct dm_cell_key key; + struct bio *holder; + struct bio_list bios; +}; + +struct dm_bio_prison *dm_bio_prison_create(void); +void dm_bio_prison_destroy(struct dm_bio_prison *prison); + +/* + * These two functions just wrap a mempool. This is a transitory step: + * Eventually all bio prison clients should manage their own cell memory. + * + * Like mempool_alloc(), dm_bio_prison_alloc_cell() can only fail if called + * in interrupt context or passed GFP_NOWAIT. + */ +struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, + gfp_t gfp); +void dm_bio_prison_free_cell(struct dm_bio_prison *prison, + struct dm_bio_prison_cell *cell); + +/* + * Creates, or retrieves a cell that overlaps the given key. + * + * Returns 1 if pre-existing cell returned, zero if new cell created using + * @cell_prealloc. + */ +int dm_get_cell(struct dm_bio_prison *prison, + struct dm_cell_key *key, + struct dm_bio_prison_cell *cell_prealloc, + struct dm_bio_prison_cell **cell_result); + +/* + * An atomic op that combines retrieving or creating a cell, and adding a + * bio to it. + * + * 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 *cell_prealloc, + struct dm_bio_prison_cell **cell_result); + +void dm_cell_release(struct dm_bio_prison *prison, + struct dm_bio_prison_cell *cell, + struct bio_list *bios); +void dm_cell_release_no_holder(struct dm_bio_prison *prison, + struct dm_bio_prison_cell *cell, + struct bio_list *inmates); +void dm_cell_error(struct dm_bio_prison *prison, + struct dm_bio_prison_cell *cell, int error); + +/* + * Visits the cell and then releases. Guarantees no new inmates are + * inserted between the visit and release. + */ +void dm_cell_visit_release(struct dm_bio_prison *prison, + void (*visit_fn)(void *, struct dm_bio_prison_cell *), + void *context, 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 |