Commit 2d55a637 authored by Brian Foster's avatar Brian Foster Committed by Kent Overstreet
Browse files

bcachefs: refactor fiemap processing into extent helper and struct 



The bulk of the loop in bch2_fiemap() involves processing the
current extent key from the iter, including following indirections
and trimming the extent size and such. This patch makes a few
changes to reduce the size of the loop and facilitate future changes
to support delalloc extents.

Define a new bch_fiemap_extent structure to wrap the bkey buffer
that holds the extent key to report to userspace along with
associated fiemap flags. Update bch2_fill_extent() to take the
bch_fiemap_extent as a param instead of the individual fields.
Finally, lift the bulk of the extent processing into a
bch2_fiemap_extent() helper that takes the current key and formats
the bch_fiemap_extent appropriately for the fill function.

No functional changes intended by this patch.

Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
parent d020a9fb

fs/bcachefs/fs.c

+53 −34
Original line number Diff line number Diff line
@@ -1262,10 +1262,18 @@ static int bch2_tmpfile(struct mnt_idmap *idmap, 
	return finish_open_simple(file, 0);

}



struct bch_fiemap_extent {

	struct bkey_buf	kbuf;

	unsigned	flags;

};



static int bch2_fill_extent(struct bch_fs *c,

			    struct fiemap_extent_info *info,

			    struct bkey_s_c k, unsigned flags)

			    struct bch_fiemap_extent *fe)

{

	struct bkey_s_c k = bkey_i_to_s_c(fe->kbuf.k);

	unsigned flags = fe->flags;



	if (bkey_extent_is_direct_data(k.k)) {

		struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);

		const union bch_extent_entry *entry;
@@ -1318,6 +1326,36 @@ static int bch2_fill_extent(struct bch_fs *c, 
	}

}



static int bch2_fiemap_extent(struct btree_trans *trans,

			      struct btree_iter *iter, struct bkey_s_c k,

			      struct bch_fiemap_extent *cur)

{

	s64 offset_into_extent	= iter->pos.offset - bkey_start_offset(k.k);

	unsigned sectors	= k.k->size - offset_into_extent;



	bch2_bkey_buf_reassemble(&cur->kbuf, trans->c, k);



	enum btree_id data_btree = BTREE_ID_extents;

	int ret = bch2_read_indirect_extent(trans, &data_btree, &offset_into_extent,

					    &cur->kbuf);

	if (ret)

		return ret;



	k = bkey_i_to_s_c(cur->kbuf.k);

	sectors = min_t(unsigned, sectors, k.k->size - offset_into_extent);



	bch2_cut_front(POS(k.k->p.inode,

			   bkey_start_offset(k.k) + offset_into_extent),

		       cur->kbuf.k);

	bch2_key_resize(&cur->kbuf.k->k, sectors);

	cur->kbuf.k->k.p = iter->pos;

	cur->kbuf.k->k.p.offset += cur->kbuf.k->k.size;



	cur->flags = 0;



	return 0;

}



static int bch2_fiemap(struct inode *vinode, struct fiemap_extent_info *info,

		       u64 start, u64 len)

{
@@ -1326,7 +1364,7 @@ static int bch2_fiemap(struct inode *vinode, struct fiemap_extent_info *info, 
	struct btree_trans *trans;

	struct btree_iter iter;

	struct bkey_s_c k;

	struct bkey_buf cur, prev;

	struct bch_fiemap_extent cur, prev;

	bool have_extent = false;

	int ret = 0;
@@ -1340,15 +1378,14 @@ static int bch2_fiemap(struct inode *vinode, struct fiemap_extent_info *info, 


	start >>= 9;



	bch2_bkey_buf_init(&cur);

	bch2_bkey_buf_init(&prev);

	bch2_bkey_buf_init(&cur.kbuf);

	bch2_bkey_buf_init(&prev.kbuf);

	trans = bch2_trans_get(c);



	bch2_trans_iter_init(trans, &iter, BTREE_ID_extents,

			     POS(ei->v.i_ino, start), 0);



	while (!ret || bch2_err_matches(ret, BCH_ERR_transaction_restart)) {

		enum btree_id data_btree = BTREE_ID_extents;



		bch2_trans_begin(trans);
@@ -1373,39 +1410,21 @@ static int bch2_fiemap(struct inode *vinode, struct fiemap_extent_info *info, 
			continue;

		}



		s64 offset_into_extent	= iter.pos.offset - bkey_start_offset(k.k);

		unsigned sectors	= k.k->size - offset_into_extent;



		bch2_bkey_buf_reassemble(&cur, c, k);



		ret = bch2_read_indirect_extent(trans, &data_btree,

					&offset_into_extent, &cur);

		ret = bch2_fiemap_extent(trans, &iter, k, &cur);

		if (ret)

			continue;



		k = bkey_i_to_s_c(cur.k);

		bch2_bkey_buf_realloc(&prev, c, k.k->u64s);



		sectors = min_t(unsigned, sectors, k.k->size - offset_into_extent);

		start = iter.pos.offset + sectors;



		bch2_cut_front(POS(k.k->p.inode,

				   bkey_start_offset(k.k) +

				   offset_into_extent),

			       cur.k);

		bch2_key_resize(&cur.k->k, sectors);

		cur.k->k.p = iter.pos;

		cur.k->k.p.offset += cur.k->k.size;

			break;

		bch2_bkey_buf_realloc(&prev.kbuf, c, cur.kbuf.k->k.u64s);

		start = cur.kbuf.k->k.p.offset;



		if (have_extent) {

			bch2_trans_unlock(trans);

			ret = bch2_fill_extent(c, info,

					bkey_i_to_s_c(prev.k), 0);

			ret = bch2_fill_extent(c, info, &prev);

			if (ret)

				break;

		}



		bkey_copy(prev.k, cur.k);

		bkey_copy(prev.kbuf.k, cur.kbuf.k);

		prev.flags = cur.flags;

		have_extent = true;



		bch2_btree_iter_set_pos(trans, &iter, POS(iter.pos.inode, start));
@@ -1414,13 +1433,13 @@ static int bch2_fiemap(struct inode *vinode, struct fiemap_extent_info *info, 


	if (!ret && have_extent) {

		bch2_trans_unlock(trans);

		ret = bch2_fill_extent(c, info, bkey_i_to_s_c(prev.k),

				       FIEMAP_EXTENT_LAST);

		prev.flags |= FIEMAP_EXTENT_LAST;

		ret = bch2_fill_extent(c, info, &prev);

	}



	bch2_trans_put(trans);

	bch2_bkey_buf_exit(&cur, c);

	bch2_bkey_buf_exit(&prev, c);

	bch2_bkey_buf_exit(&cur.kbuf, c);

	bch2_bkey_buf_exit(&prev.kbuf, c);

	return ret < 0 ? ret : 0;

}