b7ca9c9273
Change existing users of the function dm_cell_release_singleton to share cell_defer_except instead, and then remove the now-unused function. Everywhere that calls dm_cell_release_singleton, the bio in question is the holder of the cell. If there are no non-holder entries in the cell then cell_defer_except behaves exactly like dm_cell_release_singleton. Conversely, if there *are* non-holder entries then dm_cell_release_singleton must not be used because those entries would need to be deferred. Consequently, it is safe to replace use of dm_cell_release_singleton with cell_defer_except. This patch is a pre-requisite for "dm thin: fix race between simultaneous io and discards to same block". Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Alasdair G Kergon <agk@redhat.com>
72 lines
2.3 KiB
C
72 lines
2.3 KiB
C
/*
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* Copyright (C) 2011-2012 Red Hat, Inc.
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*
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* This file is released under the GPL.
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*/
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#ifndef DM_BIO_PRISON_H
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#define DM_BIO_PRISON_H
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#include "persistent-data/dm-block-manager.h" /* FIXME: for dm_block_t */
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#include "dm-thin-metadata.h" /* FIXME: for dm_thin_id */
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#include <linux/list.h>
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#include <linux/bio.h>
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/*----------------------------------------------------------------*/
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/*
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* Sometimes we can't deal with a bio straight away. We put them in prison
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* where they can't cause any mischief. Bios are put in a cell identified
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* by a key, multiple bios can be in the same cell. When the cell is
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* subsequently unlocked the bios become available.
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*/
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struct dm_bio_prison;
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struct dm_bio_prison_cell;
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/* FIXME: this needs to be more abstract */
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struct dm_cell_key {
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int virtual;
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dm_thin_id dev;
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dm_block_t block;
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};
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struct dm_bio_prison *dm_bio_prison_create(unsigned nr_cells);
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void dm_bio_prison_destroy(struct dm_bio_prison *prison);
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/*
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* This may block if a new cell needs allocating. You must ensure that
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* cells will be unlocked even if the calling thread is blocked.
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*
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* Returns 1 if the cell was already held, 0 if @inmate is the new holder.
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*/
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int dm_bio_detain(struct dm_bio_prison *prison, struct dm_cell_key *key,
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struct bio *inmate, struct dm_bio_prison_cell **ref);
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void dm_cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios);
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void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates);
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void dm_cell_error(struct dm_bio_prison_cell *cell);
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/*----------------------------------------------------------------*/
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/*
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* We use the deferred set to keep track of pending reads to shared blocks.
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* We do this to ensure the new mapping caused by a write isn't performed
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* until these prior reads have completed. Otherwise the insertion of the
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* new mapping could free the old block that the read bios are mapped to.
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*/
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struct dm_deferred_set;
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struct dm_deferred_entry;
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struct dm_deferred_set *dm_deferred_set_create(void);
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void dm_deferred_set_destroy(struct dm_deferred_set *ds);
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struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds);
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void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head);
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int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work);
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/*----------------------------------------------------------------*/
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#endif
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