14  * space management.
16  * Factors such as compression, wasted space at the ends of LEBs, space in other
18  * impossible to accurately predict the amount of space needed. Consequently
31  * When pessimistic budget calculations say that there is no enough space,
68  * This function runs garbage collector to make some more free space. Returns
76 	/* Make some free space by garbage-collecting dirty space */  in run_gc()
109  * make_free_space - make more free space on the file-system.
113  * is supposedly no free space. But in most cases there is some free space:
115  *     needed, so shrinking the liability is one way to make free space - the
116  *     cached data will take less space then it was budgeted for;
117  *   o GC may turn some dark space into free space (budgeting treats dark space
121  * So this function tries to do the above. Returns %-EAGAIN if some free space
123  * Returns %-ENOSPC if it couldn't do more free space, and other negative error
179 	/* And make sure we have thrice the index size of space reserved */  in ubifs_calc_min_idx_lebs()
199  * ubifs_calc_available - calculate available FS space.
203  * This function calculates and returns amount of FS space available for use.
213 	 * Now 'available' contains theoretically available flash space  in ubifs_calc_available()
214 	 * assuming there is no index, so we have to subtract the space which  in ubifs_calc_available()
225 	 * one head's space.  in ubifs_calc_available()
234 	/* Subtract the dead space which is not available for use */  in ubifs_calc_available()
238 	 * Subtract dark space, which might or might not be usable - it depends  in ubifs_calc_available()
241 	 * space cannot be used.  in ubifs_calc_available()
246 	 * However, there is more dark space. The index may be bigger than  in ubifs_calc_available()
248 	 * their dark space is not included in total_dark, so it is subtracted  in ubifs_calc_available()
264  * UBIFS has so-called "reserved pool" which is flash space reserved
278  * do_budget_space - reserve flash space for index and data growth.
284  * When budgeting index space, UBIFS reserves thrice as many LEBs as the index
288  * budgeted index space to the size of the current index, multiplies this by 3,
294  *    there is free space. IOW, the index may take a lot of LEBs, but the LEBs
307 	/* First budget index space */  in do_budget_space()
324 	 * dirty space, @c->idx_gc_cnt are available because they are index  in do_budget_space()
341 		dbg_budg("out of indexing space: min_idx_lebs %d (old %d), rsvd_idx_lebs %d",  in do_budget_space()
350 		dbg_budg("out of data space: available %lld, outstanding %lld",  in do_budget_space()
422  * ubifs_budget_space - ensure there is enough space to complete an operation.
427  * approximation of how much flash space the operation needs. The goal of this
428  * function is to make sure UBIFS always has flash space to flush all dirty
431  * %-ENOSPC if there is no free space and other negative error codes in case of
462 		dbg_budg("no space");  in ubifs_budget_space()
487 		dbg_budg("no space for fast budgeting");  in ubifs_budget_space()
508 		ubifs_err(c, "cannot budget space, error %d", err);  in ubifs_budget_space()
513  * ubifs_release_budget - release budgeted free space.
517  * This function releases the space budgeted by 'ubifs_budget_space()'. Note,
588 	/* And re-calculate the indexing space reservation */  in ubifs_convert_page_budget()
600  * clean. It also causes the "no space" flags to be cleared.
608 	/* The "no space" flags will be cleared because dd_growth is > 0 */  in ubifs_release_dirty_inode_budget()
615  * ubifs_reported_space - calculate reported free space.
617  * @free: amount of free space
619  * This function calculates amount of free space which will be reported to
620  * user-space. User-space application tend to expect that if the file-system
624  * overhead, and UBIFS has to report slightly less free space to meet the above
627  * This function assumes free space is made up of uncompressed data nodes and
629  * space to write the index thrice).
632  * UBIFS reports less space than it actually has.
639 	 * Reported space size is @free * X, where X is UBIFS block size  in ubifs_reported_space()
648 	 * Note, the multiplier 3 is because UBIFS reserves thrice as more space  in ubifs_reported_space()
661  * ubifs_get_free_space_nolock - return amount of free space.
664  * This function calculates amount of free space to report to user-space.
668  * free flash space it has (well, because not all dirty space is reclaimable,
670  * bread user expectations about what free space is. Users seem to accustomed
671  * to assume that if the file-system reports N bytes of free space, they would
686 	 * When reporting free space to user-space, UBIFS guarantees that it is  in ubifs_get_free_space_nolock()
687 	 * possible to write a file of free space size. This means that for  in ubifs_get_free_space_nolock()
691 	 * Thus, amend the available space.  in ubifs_get_free_space_nolock()
713  * ubifs_get_free_space - return amount of free space.
716  * This function calculates and returns amount of free space to report to
717  * user-space.