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Commit fb1cd01a authored by Artem Bityutskiy's avatar Artem Bityutskiy
Browse files

UBIFS: introduce a helpful variable 



This patch introduces a helpful @c->idx_leb_size variable.
The patch also fixes some spelling issues and makes comments
use "LEB" instead of "eraseblock", which is more correct.

Signed-off-by: default avatarArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
parent c9927c3e

fs/ubifs/budget.c

+15 −18
Original line number Diff line number Diff line
@@ -194,29 +194,26 @@ static int make_free_space(struct ubifs_info *c) 
}



/**

 * ubifs_calc_min_idx_lebs - calculate amount of eraseblocks for the index.

 * ubifs_calc_min_idx_lebs - calculate amount of LEBs for the index.

 * @c: UBIFS file-system description object

 *

 * This function calculates and returns the number of eraseblocks which should

 * be kept for index usage.

 * This function calculates and returns the number of LEBs which should be kept

 * for index usage.

 */

int ubifs_calc_min_idx_lebs(struct ubifs_info *c)

{

	int idx_lebs, eff_leb_size = c->leb_size - c->max_idx_node_sz;

	int idx_lebs;

	long long idx_size;



	idx_size = c->old_idx_sz + c->budg_idx_growth + c->budg_uncommitted_idx;



	/* And make sure we have thrice the index size of space reserved */

	idx_size = idx_size + (idx_size << 1);



	idx_size += idx_size << 1;

	/*

	 * We do not maintain 'old_idx_size' as 'old_idx_lebs'/'old_idx_bytes'

	 * pair, nor similarly the two variables for the new index size, so we

	 * have to do this costly 64-bit division on fast-path.

	 */

	idx_size += eff_leb_size - 1;

	idx_lebs = div_u64(idx_size, eff_leb_size);

	idx_lebs = div_u64(idx_size + c->idx_leb_size - 1, c->idx_leb_size);

	/*

	 * The index head is not available for the in-the-gaps method, so add an

	 * extra LEB to compensate.
@@ -310,15 +307,15 @@ static int can_use_rp(struct ubifs_info *c) 
 * do_budget_space - reserve flash space for index and data growth.

 * @c: UBIFS file-system description object

 *

 * This function makes sure UBIFS has enough free eraseblocks for index growth

 * and data.

 * This function makes sure UBIFS has enough free LEBs for index growth and

 * data.

 *

 * When budgeting index space, UBIFS reserves thrice as many LEBs as the index

 * would take if it was consolidated and written to the flash. This guarantees

 * that the "in-the-gaps" commit method always succeeds and UBIFS will always

 * be able to commit dirty index. So this function basically adds amount of

 * budgeted index space to the size of the current index, multiplies this by 3,

 * and makes sure this does not exceed the amount of free eraseblocks.

 * and makes sure this does not exceed the amount of free LEBs.

 *

 * Notes about @c->min_idx_lebs and @c->lst.idx_lebs variables:

 * o @c->lst.idx_lebs is the number of LEBs the index currently uses. It might
@@ -695,12 +692,12 @@ long long ubifs_reported_space(const struct ubifs_info *c, long long free) 
 * This function calculates amount of free space to report to user-space.

 *

 * Because UBIFS may introduce substantial overhead (the index, node headers,

 * alignment, wastage at the end of eraseblocks, etc), it cannot report real

 * amount of free flash space it has (well, because not all dirty space is

 * reclaimable, UBIFS does not actually know the real amount). If UBIFS did so,

 * it would bread user expectations about what free space is. Users seem to

 * accustomed to assume that if the file-system reports N bytes of free space,

 * they would be able to fit a file of N bytes to the FS. This almost works for

 * alignment, wastage at the end of LEBs, etc), it cannot report real amount of

 * free flash space it has (well, because not all dirty space is reclaimable,

 * UBIFS does not actually know the real amount). If UBIFS did so, it would

 * bread user expectations about what free space is. Users seem to accustomed

 * to assume that if the file-system reports N bytes of free space, they would

 * be able to fit a file of N bytes to the FS. This almost works for

 * traditional file-systems, because they have way less overhead than UBIFS.

 * So, to keep users happy, UBIFS tries to take the overhead into account.

 */

fs/ubifs/sb.c

+0 −1
Original line number Diff line number Diff line
@@ -623,7 +623,6 @@ int ubifs_read_superblock(struct ubifs_info *c) 
	c->main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS;

	c->main_lebs -= c->log_lebs + c->lpt_lebs + c->orph_lebs;

	c->main_first = c->leb_cnt - c->main_lebs;

	c->report_rp_size = ubifs_reported_space(c, c->rp_size);



	err = validate_sb(c, sup);

out:

fs/ubifs/super.c

+3 −0
Original line number Diff line number Diff line
@@ -700,6 +700,8 @@ static int init_constants_sb(struct ubifs_info *c) 
	if (err)

		return err;



	/* Initialize effective LEB size used in budgeting calculations */

	c->idx_leb_size = c->leb_size - c->max_idx_node_sz;

	return 0;

}
@@ -716,6 +718,7 @@ static void init_constants_master(struct ubifs_info *c) 
	long long tmp64;



	c->min_idx_lebs = ubifs_calc_min_idx_lebs(c);

	c->report_rp_size = ubifs_reported_space(c, c->rp_size);



	/*

	 * Calculate total amount of FS blocks. This number is not used

fs/ubifs/ubifs.h

+5 −2
Original line number Diff line number Diff line
@@ -1015,6 +1015,8 @@ struct ubifs_debug_info; 
 * @min_io_shift: number of bits in @min_io_size minus one

 * @leb_size: logical eraseblock size in bytes

 * @half_leb_size: half LEB size

 * @idx_leb_size: how many bytes of an LEB are effectively available when it is

 *                used to store indexing nodes (@leb_size - @max_idx_node_sz)

 * @leb_cnt: count of logical eraseblocks

 * @max_leb_cnt: maximum count of logical eraseblocks

 * @old_leb_cnt: count of logical eraseblocks before re-size
@@ -1132,8 +1134,8 @@ struct ubifs_debug_info; 
 *             previous commit start

 * @uncat_list: list of un-categorized LEBs

 * @empty_list: list of empty LEBs

 * @freeable_list: list of freeable non-index LEBs (free + dirty == leb_size)

 * @frdi_idx_list: list of freeable index LEBs (free + dirty == leb_size)

 * @freeable_list: list of freeable non-index LEBs (free + dirty == @leb_size)

 * @frdi_idx_list: list of freeable index LEBs (free + dirty == @leb_size)

 * @freeable_cnt: number of freeable LEBs in @freeable_list

 *

 * @ltab_lnum: LEB number of LPT's own lprops table
@@ -1253,6 +1255,7 @@ struct ubifs_info { 
	int min_io_shift;

	int leb_size;

	int half_leb_size;

	int idx_leb_size;

	int leb_cnt;

	int max_leb_cnt;

	int old_leb_cnt;