Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / md / dm-bio-prison.h

diff --git a/kernel/drivers/md/dm-bio-prison.h b/kernel/drivers/md/dm-bio-prison.h
new file mode 100644 (file)
index 0000000..74cf011
--- /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