OSCL-LXR linux-6.0.1/​drivers/​md/​persistent-data/​dm-transaction-manager.h	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * Copyright (C) 2011 Red Hat, Inc.
  *
  * This file is released under the GPL.
  */
 
 #ifndef _LINUX_DM_TRANSACTION_MANAGER_H
 #define _LINUX_DM_TRANSACTION_MANAGER_H
 
 #include "dm-block-manager.h"
 
 struct dm_transaction_manager;
 struct dm_space_map;
 
 /*----------------------------------------------------------------*/
 
 /*
  * This manages the scope of a transaction.  It also enforces immutability
  * of the on-disk data structures by limiting access to writeable blocks.
  *
  * Clients should not fiddle with the block manager directly.
  */
 
 void dm_tm_destroy(struct dm_transaction_manager *tm);
 
 /*
  * The non-blocking version of a transaction manager is intended for use in
  * fast path code that needs to do lookups e.g. a dm mapping function.
  * You create the non-blocking variant from a normal tm.  The interface is
  * the same, except that most functions will just return -EWOULDBLOCK.
  * Methods that return void yet may block should not be called on a clone
  * viz. dm_tm_inc, dm_tm_dec.  Call dm_tm_destroy() as you would with a normal
  * tm when you've finished with it.  You may not destroy the original prior
  * to clones.
  */
 struct dm_transaction_manager *dm_tm_create_non_blocking_clone(struct dm_transaction_manager *real);
 
 /*
  * We use a 2-phase commit here.
  *
  * i) Make all changes for the transaction *except* for the superblock.
  * Then call dm_tm_pre_commit() to flush them to disk.
  *
  * ii) Lock your superblock.  Update.  Then call dm_tm_commit() which will
  * unlock the superblock and flush it.  No other blocks should be updated
  * during this period.  Care should be taken to never unlock a partially
  * updated superblock; perform any operations that could fail *before* you
  * take the superblock lock.
  */
 int dm_tm_pre_commit(struct dm_transaction_manager *tm);
 int dm_tm_commit(struct dm_transaction_manager *tm, struct dm_block *superblock);
 
 /*
  * These methods are the only way to get hold of a writeable block.
  */
 
 /*
  * dm_tm_new_block() is pretty self-explanatory.  Make sure you do actually
  * write to the whole of @data before you unlock, otherwise you could get
  * a data leak.  (The other option is for tm_new_block() to zero new blocks
  * before handing them out, which will be redundant in most, if not all,
  * cases).
  * Zeroes the new block and returns with write lock held.
  */
 int dm_tm_new_block(struct dm_transaction_manager *tm,
             struct dm_block_validator *v,
             struct dm_block **result);
 
 /*
  * dm_tm_shadow_block() allocates a new block and copies the data from @orig
  * to it.  It then decrements the reference count on original block.  Use
  * this to update the contents of a block in a data structure, don't
  * confuse this with a clone - you shouldn't access the orig block after
  * this operation.  Because the tm knows the scope of the transaction it
  * can optimise requests for a shadow of a shadow to a no-op.  Don't forget
  * to unlock when you've finished with the shadow.
  *
  * The @inc_children flag is used to tell the caller whether it needs to
  * adjust reference counts for children.  (Data in the block may refer to
  * other blocks.)
  *
  * Shadowing implicitly drops a reference on @orig so you must not have
  * it locked when you call this.
  */
 int dm_tm_shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
                struct dm_block_validator *v,
                struct dm_block **result, int *inc_children);
 
 /*
  * Read access.  You can lock any block you want.  If there's a write lock
  * on it outstanding then it'll block.
  */
 int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b,
             struct dm_block_validator *v,
             struct dm_block **result);
 
 void dm_tm_unlock(struct dm_transaction_manager *tm, struct dm_block *b);
 
 /*
  * Functions for altering the reference count of a block directly.
  */
 void dm_tm_inc(struct dm_transaction_manager *tm, dm_block_t b);
 void dm_tm_inc_range(struct dm_transaction_manager *tm, dm_block_t b, dm_block_t e);
 void dm_tm_dec(struct dm_transaction_manager *tm, dm_block_t b);
 void dm_tm_dec_range(struct dm_transaction_manager *tm, dm_block_t b, dm_block_t e);
 
 /*
  * Builds up runs of adjacent blocks, and then calls the given fn
  * (typically dm_tm_inc/dec).  Very useful when you have to perform
  * the same tm operation on all values in a btree leaf.
  */
 typedef void (*dm_tm_run_fn)(struct dm_transaction_manager *, dm_block_t, dm_block_t);
 void dm_tm_with_runs(struct dm_transaction_manager *tm,
              const __le64 *value_le, unsigned count, dm_tm_run_fn fn);
 
 int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b, uint32_t *result);
 
 /*
  * Finds out if a given block is shared (ie. has a reference count higher
  * than one).
  */
 int dm_tm_block_is_shared(struct dm_transaction_manager *tm, dm_block_t b,
               int *result);
 
 struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm);
 
 /*
  * If you're using a non-blocking clone the tm will build up a list of
  * requested blocks that weren't in core.  This call will request those
  * blocks to be prefetched.
  */
 void dm_tm_issue_prefetches(struct dm_transaction_manager *tm);
 
 /*
  * A little utility that ties the knot by producing a transaction manager
  * that has a space map managed by the transaction manager...
  *
  * Returns a tm that has an open transaction to write the new disk sm.
  * Caller should store the new sm root and commit.
  *
  * The superblock location is passed so the metadata space map knows it
  * shouldn't be used.
  */
 int dm_tm_create_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
              struct dm_transaction_manager **tm,
              struct dm_space_map **sm);
 
 int dm_tm_open_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
                void *sm_root, size_t root_len,
                struct dm_transaction_manager **tm,
                struct dm_space_map **sm);
 
 #endif  /* _LINUX_DM_TRANSACTION_MANAGER_H */

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