Hi Fan,
On Thu, Sep 10, 2015 at 04:48:22PM +0800, Fan Li wrote:
> Fix 3 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.
>
> 3. now we update extent in range, fofs may not be on the largest
> extent if the new extent overlaps with it. so add a new function
> to drop largest extent properly.
>
> This patch also simpfies codes of invalidating extents, and optimizes
> the procedues that split extent into two.
>
>
> Signed-off-by: Fan li <fanofcode...@samsung.com>
> ---
> fs/f2fs/extent_cache.c | 161
> +++++++++++++++++++++---------------------------
> 1 file changed, 70 insertions(+), 91 deletions(-)
>
> diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
> index 997ac86..cbd1108 100644
> --- a/fs/f2fs/extent_cache.c
> +++ b/fs/f2fs/extent_cache.c
> @@ -163,6 +163,15 @@ static void __drop_largest_extent(struct inode *inode,
> pgoff_t fofs)
> largest->len = 0;
> }
>
> +static void __drop_largest_extent_range(struct inode *inode,
> + pgoff_t fofs, unsigned int len)
> +{
> + struct extent_info *largest = &F2FS_I(inode)->extent_tree->largest;
> +
> + if (fofs < largest->fofs + largest->len && fofs + len > largest->fofs)
> + largest->len = 0;
> +}
> +
> void f2fs_drop_largest_extent(struct inode *inode, pgoff_t fofs)
> {
> if (!f2fs_may_extent_tree(inode))
> @@ -399,7 +408,7 @@ 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;
> @@ -419,8 +428,11 @@ 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(inode, fofs);
> + /*
> + * drop largest extent before lookup, in case it's already
> + * been shrunk from extent tree
> + */
> + __drop_largest_extent_range(inode, fofs, len);
Could you write for the above fix as a sepearte patch?
>
> /* 1. lookup first extent node in range [fofs, fofs + len - 1] */
> en = __lookup_extent_tree_ret(et, fofs, &prev_en, &next_en,
> @@ -441,114 +453,81 @@ unsigned int f2fs_update_extent_tree_range(struct
> inode *inode,
>
> /* 2. invlidate all extent nodes in range [fofs, fofs + len - 1] */
> while (en) {
> - struct rb_node *node;
> + struct rb_node *node = NULL;
> + int parts = 0; /* # of parts current extent split into */
> + unsigned int org_end;
>
> if (pos >= end)
> break;
>
> dei = en->ei;
> - en1 = en2 = NULL;
> + next_en = en1 = NULL;
>
> - node = rb_next(&en->rb_node);
> + f2fs_bug_on(sbi, pos < dei.fofs || pos >= dei.fofs + dei.len);
>
> - /*
> - * 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) {
> + if (pos > dei.fofs && pos - dei.fofs >= F2FS_MIN_EXTENT_LEN) {
> en->ei.len = pos - dei.fofs;
> + parts = 1;
> + }
>
> - 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;
> + 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;
Here, don't we need to set prev_en like:
prev_en = en;
Thanks,
> + } else {
> + en->ei.fofs = end;
> + en->ei.blk += end - dei.fofs;
> + en->ei.len -= end - dei.fofs;
> + next_en = en;
> }
> -
> - if (__is_extent_same(&dei, &et->largest))
> - et->largest = en->ei;
> - goto next;
> + parts++;
> }
>
> - /* 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 (!next_en) {
> + node = rb_next(&en->rb_node);
> + next_en = node ?
> + rb_entry(node, struct extent_node, rb_node)
> + : NULL;
> + }
>
> - if (__is_extent_same(&dei, &et->largest))
> + if (parts) {
> + if (en->ei.len > et->largest.len)
> et->largest = en->ei;
> - goto next;
> + } else {
> + __detach_extent_node(sbi, et, en);
> }
>
> - __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.
> */
> - 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;
> + if (parts != 1) {
> + insert_p = NULL;
> + insert_parent = NULL;
> }
>
> - /*
> - * 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;
> + if (next_en)
> + pos = next_en->ei.fofs;
> }
>
> update_extent:
> @@ -557,10 +536,10 @@ update_extent:
> 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 */
> @@ -572,11 +551,11 @@ 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);
> --
> 1.7.9.5
------------------------------------------------------------------------------
_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
