Commit 76068cae authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: defrag: replace hard coded PAGE_SIZE with sectorsize 



When testing subpage defrag support, I always find some strange inode
nbytes error, after a lot of debugging, it turns out that
defrag_lookup_extent() is using PAGE_SIZE as size for
lookup_extent_mapping().

Since lookup_extent_mapping() is calling __lookup_extent_mapping() with
@strict == 1, this means any extent map smaller than one page will be
ignored, prevent subpage defrag to grab a correct extent map.

There are quite some PAGE_SIZE usage in ioctl.c, but most of them are
correct usages, and can be one of the following cases:

- ioctl structure size check
  We want ioctl structure to be contained inside one page.

- real page operations

The remaining cases in defrag_lookup_extent() and
check_defrag_in_cache() will be addressed in this patch.

Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent cae79686

fs/btrfs/ioctl.c

+6 −5
Original line number Diff line number Diff line
@@ -997,10 +997,11 @@ static int check_defrag_in_cache(struct inode *inode, u64 offset, u32 thresh) 
	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;

	struct extent_map *em = NULL;

	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;

	const u32 sectorsize = btrfs_sb(inode->i_sb)->sectorsize;

	u64 end;



	read_lock(&em_tree->lock);

	em = lookup_extent_mapping(em_tree, offset, PAGE_SIZE);

	em = lookup_extent_mapping(em_tree, offset, sectorsize);

	read_unlock(&em_tree->lock);



	if (em) {
@@ -1090,23 +1091,23 @@ static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start) 
	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;

	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;

	struct extent_map *em;

	u64 len = PAGE_SIZE;

	const u32 sectorsize = BTRFS_I(inode)->root->fs_info->sectorsize;



	/*

	 * hopefully we have this extent in the tree already, try without

	 * the full extent lock

	 */

	read_lock(&em_tree->lock);

	em = lookup_extent_mapping(em_tree, start, len);

	em = lookup_extent_mapping(em_tree, start, sectorsize);

	read_unlock(&em_tree->lock);



	if (!em) {

		struct extent_state *cached = NULL;

		u64 end = start + len - 1;

		u64 end = start + sectorsize - 1;



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

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

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

		em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, sectorsize);

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



		if (IS_ERR(em))