Commit 4d1fa815 authored by Fan Li's avatar Fan Li Committed by Jaegeuk Kim
Browse files

f2fs: optimize code of f2fs_update_extent_tree_range 



Fix 2 potential problems:
1. when largest extent needs to be invalidated, it will be reset in
   __drop_largest_extent, which makes __is_extent_same after always
   return false, and largest extent unchanged. Now we update it properly.

2. when extent is split and the latter part remains in tree, next_en
   should be the latter part instead of next extent of original extent.
   It will cause merge failure if there is in-place update, although
   there is not, I think this fix will still makes codes less ambiguous.

This patch also simplifies codes of invalidating extents, and optimizes the
procedues that split extent into two.
There are a few modifications after last patch:
1. prev_en now is updated properly.
2. more codes and branches are simplified.

Signed-off-by: default avatarFan li <fanofcode.li@samsung.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 41a099de

fs/f2fs/extent_cache.c

+62 −109
Original line number Diff line number Diff line
@@ -400,7 +400,7 @@ static unsigned int f2fs_update_extent_tree_range(struct inode *inode, 
{

	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);

	struct extent_tree *et = F2FS_I(inode)->extent_tree;

	struct extent_node *en = NULL, *en1 = NULL, *en2 = NULL, *en3 = NULL;

	struct extent_node *en = NULL, *en1 = NULL;

	struct extent_node *prev_en = NULL, *next_en = NULL;

	struct extent_info ei, dei, prev;

	struct rb_node **insert_p = NULL, *insert_parent = NULL;
@@ -422,148 +422,101 @@ static unsigned int f2fs_update_extent_tree_range(struct inode *inode, 
	prev = et->largest;

	dei.len = 0;



	/* we do not guarantee that the largest extent is cached all the time */

	/*

	 * drop largest extent before lookup, in case it's already

	 * been shrunk from extent tree

	 */

	__drop_largest_extent(inode, fofs, len);



	/* 1. lookup first extent node in range [fofs, fofs + len - 1] */

	en = __lookup_extent_tree_ret(et, fofs, &prev_en, &next_en,

					&insert_p, &insert_parent);

	if (!en) {

		if (next_en) {

	if (!en)

		en = next_en;

			f2fs_bug_on(sbi, en->ei.fofs <= pos);

			pos = en->ei.fofs;

		} else {

			/*

			 * skip searching in the tree since there is no

			 * larger extent node in the cache.

			 */

			goto update_extent;

		}

	}



	/* 2. invlidate all extent nodes in range [fofs, fofs + len - 1] */

	while (en) {

		struct rb_node *node;

	while (en && en->ei.fofs < end) {

		unsigned int org_end;

		int parts = 0;	/* # of parts current extent split into */



		if (pos >= end)

			break;

		next_en = en1 = NULL;



		dei = en->ei;

		en1 = en2 = NULL;



		node = rb_next(&en->rb_node);



		/*

		 * 2.1 there are four cases when we invalidate blkaddr in extent

		 * node, |V: valid address, X: will be invalidated|

		 */

		/* case#1, invalidate right part of extent node |VVVVVXXXXX| */

		if (pos > dei.fofs && end >= dei.fofs + dei.len) {

			en->ei.len = pos - dei.fofs;



			if (en->ei.len < F2FS_MIN_EXTENT_LEN) {

				__detach_extent_node(sbi, et, en);

				insert_p = NULL;

				insert_parent = NULL;

				goto update;

			}

		org_end = dei.fofs + dei.len;

		f2fs_bug_on(sbi, pos >= org_end);



			if (__is_extent_same(&dei, &et->largest))

				et->largest = en->ei;

			goto next;

		if (pos > dei.fofs &&	pos - dei.fofs >= F2FS_MIN_EXTENT_LEN) {

			en->ei.len = pos - en->ei.fofs;

			prev_en = en;

			parts = 1;

		}



		/* case#2, invalidate left part of extent node |XXXXXVVVVV| */

		if (pos <= dei.fofs && end < dei.fofs + dei.len) {

		if (end < org_end && org_end - end >= F2FS_MIN_EXTENT_LEN) {

			if (parts) {

				set_extent_info(&ei, end,

						end - dei.fofs + dei.blk,

						org_end - end);

				en1 = __insert_extent_tree(sbi, et, &ei,

							NULL, NULL);

				next_en = en1;

			} else {

				en->ei.fofs = end;

				en->ei.blk += end - dei.fofs;

				en->ei.len -= end - dei.fofs;



			if (en->ei.len < F2FS_MIN_EXTENT_LEN) {

				__detach_extent_node(sbi, et, en);

				insert_p = NULL;

				insert_parent = NULL;

				goto update;

				next_en = en;

			}

			parts++;

		}



			if (__is_extent_same(&dei, &et->largest))

				et->largest = en->ei;

			goto next;

		if (!next_en) {

			struct rb_node *node = rb_next(&en->rb_node);



			next_en = node ?

				rb_entry(node, struct extent_node, rb_node)

				: NULL;

		}



		if (parts) {

			if (en->ei.len > et->largest.len)

				et->largest = en->ei;

		} else {

			__detach_extent_node(sbi, et, en);

		}



		/*

		 * if we remove node in rb-tree, our parent node pointer may

		 * point the wrong place, discard them.

		 * if original extent is split into zero or two parts, extent

		 * tree has been altered by deletion or insertion, therefore

		 * invalidate pointers regard to tree.

		 */

		if (parts != 1) {

			insert_p = NULL;

			insert_parent = NULL;



		/* case#3, invalidate entire extent node |XXXXXXXXXX| */

		if (pos <= dei.fofs && end >= dei.fofs + dei.len) {

			if (__is_extent_same(&dei, &et->largest))

				et->largest.len = 0;

			goto update;

		}



		/*

		 * case#4, invalidate data in the middle of extent node

		 * |VVVXXXXVVV|

		 */

		if (dei.len > F2FS_MIN_EXTENT_LEN) {

			unsigned int endofs;



			/*  insert left part of split extent into cache */

			if (pos - dei.fofs >= F2FS_MIN_EXTENT_LEN) {

				set_extent_info(&ei, dei.fofs, dei.blk,

							pos - dei.fofs);

				en1 = __insert_extent_tree(sbi, et, &ei,

								NULL, NULL);

			}



			/* insert right part of split extent into cache */

			endofs = dei.fofs + dei.len;

			if (endofs - end >= F2FS_MIN_EXTENT_LEN) {

				set_extent_info(&ei, end,

						end - dei.fofs + dei.blk,

						endofs - end);

				en2 = __insert_extent_tree(sbi, et, &ei,

								NULL, NULL);

			}

		}

update:

		/* 2.2 update in global extent list */

		/* update in global extent list */

		spin_lock(&sbi->extent_lock);

		if (en && !list_empty(&en->list))

		if (!parts && !list_empty(&en->list))

			list_del(&en->list);

		if (en1)

			list_add_tail(&en1->list, &sbi->extent_list);

		if (en2)

			list_add_tail(&en2->list, &sbi->extent_list);

		spin_unlock(&sbi->extent_lock);



		/* 2.3 release extent node */

		if (en)

		/* release extent node */

		if (!parts)

			kmem_cache_free(extent_node_slab, en);

next:

		en = node ? rb_entry(node, struct extent_node, rb_node) : NULL;

		next_en = en;

		if (en)

			pos = en->ei.fofs;



		en = next_en;

	}



update_extent:

	/* 3. update extent in extent cache */

	if (blkaddr) {

		struct extent_node *den = NULL;



		set_extent_info(&ei, fofs, blkaddr, len);

		en3 = __try_merge_extent_node(sbi, et, &ei, &den,

		en1 = __try_merge_extent_node(sbi, et, &ei, &den,

							prev_en, next_en);

		if (!en3)

			en3 = __insert_extent_tree(sbi, et, &ei,

		if (!en1)

			en1 = __insert_extent_tree(sbi, et, &ei,

						insert_p, insert_parent);



		/* give up extent_cache, if split and small updates happen */
@@ -575,11 +528,11 @@ update_extent: 
		}



		spin_lock(&sbi->extent_lock);

		if (en3) {

			if (list_empty(&en3->list))

				list_add_tail(&en3->list, &sbi->extent_list);

		if (en1) {

			if (list_empty(&en1->list))

				list_add_tail(&en1->list, &sbi->extent_list);

			else

				list_move_tail(&en3->list, &sbi->extent_list);

				list_move_tail(&en1->list, &sbi->extent_list);

		}

		if (den && !list_empty(&den->list))

			list_del(&den->list);

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