Don't bother zeroing the page if it's already a hole under there.
We can save one allocation from this.
Signed-off-by: Li Dongyang <jerry87...@gmail.com>
---
fs/btrfs/inode.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 85a1e50..017052e 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3481,6 +3481,7 @@ int btrfs_truncate_page(struct inode *inode, loff_t from,
loff_t len,
struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
struct btrfs_ordered_extent *ordered;
struct extent_state *cached_state = NULL;
+ struct extent_map *em = NULL;
char *kaddr;
u32 blocksize = root->sectorsize;
pgoff_t index = from >> PAGE_CACHE_SHIFT;
@@ -3538,6 +3539,20 @@ again:
goto again;
}
+ em = btrfs_get_extent_fiemap(inode, NULL, 0, page_start,
+ PAGE_CACHE_SIZE, 0);
+ if (!IS_ERR_OR_NULL(em) && em->block_start == EXTENT_MAP_HOLE) {
+ u64 em_end = extent_map_end(em);
+ if (em->start <= page_start &&
+ em_end >= page_start + PAGE_CACHE_SIZE) {
+ btrfs_delalloc_release_space(inode, PAGE_CACHE_SIZE);
+ unlock_extent_cached(io_tree, page_start, page_end,
+ &cached_state, GFP_NOFS);
+ ret = 0;
+ goto out_unlock;
+ }
+ }
+
clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, page_end,
EXTENT_DIRTY | EXTENT_DELALLOC |
EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
@@ -3574,6 +3589,8 @@ out_unlock:
unlock_page(page);
page_cache_release(page);
out:
+ if (em)
+ free_extent_map(em);
return ret;
}
--
1.7.12.3
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