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: Fan li <fanofcode.li@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
index 2f013e2..c9d1cfd 100644
--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -400,7 +400,7 @@
{
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 @@
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 @@
}
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);