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f2fs: optimize code of f2fs_update_extent_tree_range

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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: Fan li <fanofcode.li@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Fan Li 2015-09-17 18:42:06 +08:00 committed by Jaegeuk Kim
parent 41a099de3a
commit 4d1fa815f2
1 changed files with 68 additions and 115 deletions
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183
fs/f2fs/extent_cache.c
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@ -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) {
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;
}
}
if (!en)
en = next_en;
/* 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;
org_end = dei.fofs + dei.len;
f2fs_bug_on(sbi, pos >= org_end);
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;
}
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) {
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;
}
if (__is_extent_same(&dei, &et->largest))
et->largest = en->ei;
goto next;
}
__detach_extent_node(sbi, et, en);
/*
* if we remove node in rb-tree, our parent node pointer may
* point the wrong place, discard them.
*/
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) {
if (end < org_end && org_end - end >= F2FS_MIN_EXTENT_LEN) {
if (parts) {
set_extent_info(&ei, end,
end - dei.fofs + dei.blk,
endofs - end);
en2 = __insert_extent_tree(sbi, et, &ei,
NULL, NULL);
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;
next_en = en;
}
parts++;
}
update:
/* 2.2 update in global extent list */
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 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;
}
/* 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);