jim owens
2010-Mar-22 03:32 UTC
[PATCH V3 15/18] Btrfs: change btrfs_get_extent for direct I/O merges.
Direct I/O passes unaligned start and length values that must
be adjusted to block boundaries for lookup and merging when
an add_extent_mapping fails with EEXIST.
Signed-off-by: jim owens <owens6336@gmail.com>
---
fs/btrfs/inode.c | 56 ++++++++++++-----------------------------------------
1 files changed, 13 insertions(+), 43 deletions(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index aad29fe..49dfc1a 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4573,29 +4573,6 @@ out_unlock:
return err;
}
-/* helper for btfs_get_extent. Given an existing extent in the tree,
- * and an extent that you want to insert, deal with overlap and insert
- * the new extent into the tree.
- */
-static int merge_extent_mapping(struct extent_map_tree *em_tree,
- struct extent_map *existing,
- struct extent_map *em,
- u64 map_start, u64 map_len)
-{
- u64 start_diff;
-
- BUG_ON(map_start < em->start || map_start >= extent_map_end(em));
- start_diff = map_start - em->start;
- em->start = map_start;
- em->len = map_len;
- if (em->block_start < EXTENT_MAP_LAST_BYTE &&
- !test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
- em->block_start += start_diff;
- em->block_len -= start_diff;
- }
- return add_extent_mapping(em_tree, em);
-}
-
static noinline int uncompress_inline(struct btrfs_path *path,
struct inode *inode, struct page *page,
size_t pg_offset, u64 extent_offset,
@@ -4873,35 +4850,28 @@ insert:
if (ret == -EEXIST) {
struct extent_map *existing;
- ret = 0;
+ /* start and len might not be block aligned, but extents are */
+ u64 lb_start = start & ~(root->sectorsize - 1);
+ u64 em_tail = em->len - (lb_start - em->start);
- existing = lookup_extent_mapping(em_tree, start, len);
- if (existing && (existing->start > start ||
- existing->start + existing->len <= start)) {
+ existing = lookup_extent_mapping(em_tree, lb_start, em_tail);
+ if (existing && lb_start < existing->start) {
+ em_tail = existing->start - lb_start;
free_extent_map(existing);
existing = NULL;
}
if (!existing) {
- existing = lookup_extent_mapping(em_tree, em->start,
- em->len);
- if (existing) {
- err = merge_extent_mapping(em_tree, existing,
- em, start,
- root->sectorsize);
- free_extent_map(existing);
- if (err) {
- free_extent_map(em);
- em = NULL;
- }
- } else {
- err = -EIO;
- free_extent_map(em);
- em = NULL;
+ if (!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags) &&
+ em->block_start < EXTENT_MAP_LAST_BYTE) {
+ em->block_start += lb_start - em->start;
+ em->block_len -= lb_start - em->start;
}
+ em->start = lb_start;
+ em->len = em_tail;
+ err = add_extent_mapping(em_tree, em);
} else {
free_extent_map(em);
em = existing;
- err = 0;
}
}
write_unlock(&em_tree->lock);
--
1.6.3.3
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