Commit 308d9800 authored by Filipe Manana's avatar Filipe Manana Committed by Chris Mason
Browse files

Btrfs: cache extent states in defrag code path 



When locking file ranges in the inode's io_tree, cache the first
extent state that belongs to the target range, so that when unlocking
the range we don't need to search in the io_tree again, reducing cpu
time and making and therefore holding the io_tree's lock for a shorter
period.

Signed-off-by: default avatarFilipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent 3bbb24b2

fs/btrfs/ioctl.c

+9 −4
Original line number Diff line number Diff line
@@ -986,10 +986,13 @@ static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start) 
	read_unlock(&em_tree->lock);



	if (!em) {

		struct extent_state *cached = NULL;

		u64 end = start + len - 1;



		/* get the big lock and read metadata off disk */

		lock_extent(io_tree, start, start + len - 1);

		lock_extent_bits(io_tree, start, end, 0, &cached);

		em = btrfs_get_extent(inode, NULL, 0, start, len, 0);

		unlock_extent(io_tree, start, start + len - 1);

		unlock_extent_cached(io_tree, start, end, &cached, GFP_NOFS);



		if (IS_ERR(em))

			return NULL;
@@ -1128,10 +1131,12 @@ again: 
		page_start = page_offset(page);

		page_end = page_start + PAGE_CACHE_SIZE - 1;

		while (1) {

			lock_extent(tree, page_start, page_end);

			lock_extent_bits(tree, page_start, page_end,

					 0, &cached_state);

			ordered = btrfs_lookup_ordered_extent(inode,

							      page_start);

			unlock_extent(tree, page_start, page_end);

			unlock_extent_cached(tree, page_start, page_end,

					     &cached_state, GFP_NOFS);

			if (!ordered)

				break;

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