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Commit 46773be4 authored by Adrian Hunter's avatar Adrian Hunter Committed by Artem Bityutskiy
Browse files

UBIFS: improve garbage collection 



Make garbage collection try to keep data nodes from the same
inode together and in ascending order.  This improves
performance when reading those nodes especially when bulk-read
is used.

Signed-off-by: default avatarAdrian Hunter <ext-adrian.hunter@nokia.com>
parent bed79935

fs/ubifs/gc.c

+72 −10
Original line number Diff line number Diff line
@@ -95,6 +95,48 @@ static int switch_gc_head(struct ubifs_info *c) 
	return err;

}



/**

 * joinup - bring data nodes for an inode together.

 * @c: UBIFS file-system description object

 * @sleb: describes scanned LEB

 * @inum: inode number

 * @blk: block number

 * @data: list to which to add data nodes

 *

 * This function looks at the first few nodes in the scanned LEB @sleb and adds

 * them to @data if they are data nodes from @inum and have a larger block

 * number than @blk. This function returns %0 on success and a negative error

 * code on failure.

 */

static int joinup(struct ubifs_info *c, struct ubifs_scan_leb *sleb, ino_t inum,

		  unsigned int blk, struct list_head *data)

{

	int err, cnt = 6, lnum = sleb->lnum, offs;

	struct ubifs_scan_node *snod, *tmp;

	union ubifs_key *key;



	list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) {

		key = &snod->key;

		if (key_inum(c, key) == inum &&

		    key_type(c, key) == UBIFS_DATA_KEY &&

		    key_block(c, key) > blk) {

			offs = snod->offs;

			err = ubifs_tnc_has_node(c, key, 0, lnum, offs, 0);

			if (err < 0)

				return err;

			list_del(&snod->list);

			if (err) {

				list_add_tail(&snod->list, data);

				blk = key_block(c, key);

			} else

				kfree(snod);

			cnt = 6;

		} else if (--cnt == 0)

			break;

	}

	return 0;

}



/**

 * move_nodes - move nodes.

 * @c: UBIFS file-system description object
@@ -116,16 +158,21 @@ static int switch_gc_head(struct ubifs_info *c) 
static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb)

{

	struct ubifs_scan_node *snod, *tmp;

	struct list_head large, medium, small;

	struct list_head data, large, medium, small;

	struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;

	int avail, err, min = INT_MAX;

	unsigned int blk = 0;

	ino_t inum = 0;



	INIT_LIST_HEAD(&data);

	INIT_LIST_HEAD(&large);

	INIT_LIST_HEAD(&medium);

	INIT_LIST_HEAD(&small);



	list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) {

		struct list_head *lst;

	while (!list_empty(&sleb->nodes)) {

		struct list_head *lst = sleb->nodes.next;



		snod = list_entry(lst, struct ubifs_scan_node, list);



		ubifs_assert(snod->type != UBIFS_IDX_NODE);

		ubifs_assert(snod->type != UBIFS_REF_NODE);
@@ -136,7 +183,6 @@ static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb) 
		if (err < 0)

			goto out;



		lst = &snod->list;

		list_del(lst);

		if (!err) {

			/* The node is obsolete, remove it from the list */
@@ -145,15 +191,30 @@ static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb) 
		}



		/*

		 * Sort the list of nodes so that large nodes go first, and

		 * small nodes go last.

		 * Sort the list of nodes so that data nodes go first, large

		 * nodes go second, and small nodes go last.

		 */

		if (snod->len > MEDIUM_NODE_WM)

			list_add(lst, &large);

		if (key_type(c, &snod->key) == UBIFS_DATA_KEY) {

			if (inum != key_inum(c, &snod->key)) {

				if (inum) {

					/*

					 * Try to move data nodes from the same

					 * inode together.

					 */

					err = joinup(c, sleb, inum, blk, &data);

					if (err)

						goto out;

				}

				inum = key_inum(c, &snod->key);

				blk = key_block(c, &snod->key);

			}

			list_add_tail(lst, &data);

		} else if (snod->len > MEDIUM_NODE_WM)

			list_add_tail(lst, &large);

		else if (snod->len > SMALL_NODE_WM)

			list_add(lst, &medium);

			list_add_tail(lst, &medium);

		else

			list_add(lst, &small);

			list_add_tail(lst, &small);



		/* And find the smallest node */

		if (snod->len < min)
@@ -164,6 +225,7 @@ static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb) 
	 * Join the tree lists so that we'd have one roughly sorted list

	 * ('large' will be the head of the joined list).

	 */

	list_splice(&data, &large);

	list_splice(&medium, large.prev);

	list_splice(&small, large.prev);