fs/ubifs/commit.c

12  * This file implements functions that manage the running of the commit process.
14  * commit and those functions are called here.
16  * The commit is the process whereby all updates to the index and LEB properties
21  * The commit is split into two parts named "commit start" and "commit end".
22  * During commit start, the commit process has exclusive access to the journal
23  * by holding the commit semaphore down for writing. As few I/O operations as
24  * possible are performed during commit start, instead the nodes that are to be
25  * written are merely identified. During commit end, the commit semaphore is no
27  * to use the file system while the bulk of the commit I/O is performed. The
28  * purpose of this two-step approach is to prevent the commit from causing any
29  * latency blips. Note that in any case, the commit does not prevent lookups
40  * nothing_to_commit - check if there is nothing to commit.
43  * This is a helper function which checks if there is anything to commit. It is
44  * used as an optimization to avoid starting the commit if it is not really
45  * necessary. Indeed, the commit operation always assumes flash I/O (e.g.,
46  * writing the commit start node to the log), and it is better to avoid doing
47  * this unnecessarily. E.g., 'ubifs_sync_fs()' runs the commit, but if there is
48  * nothing to commit, it is more optimal to avoid any flash I/O.
54  * This function returns %1 if there is nothing to commit and %0 otherwise.
60 	 * commit for various recovery-related reasons.  in nothing_to_commit()
67 	 * commit.  in nothing_to_commit()
90  * do_commit - commit the journal.
93  * This function implements UBIFS commit. It has to be called with commit lock
209 	dbg_cmt("commit end");  in do_commit()
216 	ubifs_err(c, "commit failed, error %d", err);  in do_commit()
226  * run_bg_commit - run background commit if it is needed.
229  * This function runs background commit if it is needed. Returns zero in case
236 	 * Run background commit only if background commit was requested or if  in run_bg_commit()
237 	 * commit is required.  in run_bg_commit()
270  * o when the journal is about to be full, it starts in-advance commit.
320  * ubifs_commit_required - set commit state to "required".
323  * This function is called if a commit is required but cannot be done from the
350  * ubifs_request_bg_commit - notify the background thread to do a commit.
353  * This function is called if the journal is full enough to make a commit
370  * wait_for_commit - wait for commit.
373  * This function sleeps until the commit operation is no longer running.
381 	 * when the commit ends. It is possible, although very unlikely, that we  in wait_for_commit()
382 	 * will wake up and see the subsequent commit running, rather than the  in wait_for_commit()
388 	dbg_cmt("commit finished, pid %d woke up", current->pid);  in wait_for_commit()
393  * ubifs_run_commit - run or wait for commit.
396  * This function runs commit and returns zero in case of success and a negative
411 		 * We set the commit state to 'running required' to indicate  in ubifs_run_commit()
422 	/* Ok, the commit is indeed needed */  in ubifs_run_commit()
457  * ubifs_gc_should_commit - determine if it is time for GC to run commit.
460  * This function is called by garbage collection to determine if commit should
461  * be run. If commit state is @COMMIT_BACKGROUND, which means that the journal
462  * is full enough to start commit, this function returns true. It is not
463  * absolutely necessary to commit yet, but it feels like this should be better
464  * then to keep doing GC. This function returns %1 if GC has to initiate commit
473 		dbg_cmt("commit required now");  in ubifs_gc_should_commit()
476 		dbg_cmt("commit not requested");  in ubifs_gc_should_commit()
546  * the index must exist on flash. This is the "old" index. The commit process
548  * part of the old index. This function is run at commit end in order to check