bcachefs: bch2_extent_fallocate()

This factors out part of __bchfs_fallocate() in fs-io.c into an new,
lower level io.c helper, which creates a single extent reservation.

This is prep work for nocow support - the new helper will shortly gain
the ability to create unwritten extents.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

3 files changed, 40 insertions, 28 deletions

diff --git a/fs/bcachefs/fs-io.c b/fs/bcachefs/fs-io.c
index e59d5e29951f..96b06b0a06b0 100644
--- a/fs/bcachefs/fs-io.c
+++ b/fs/bcachefs/fs-io.c
@@ -3044,7 +3044,7 @@ static int __bchfs_fallocate(struct bch_inode_info *inode, int mode,
 	struct btree_trans trans;
 	struct btree_iter iter;
 	struct bpos end_pos = POS(inode->v.i_ino, end_sector);
-	unsigned replicas = io_opts(c, &inode->ei_inode).data_replicas;
+	struct bch_io_opts opts = io_opts(c, &inode->ei_inode);
 	int ret = 0;
 
 	bch2_trans_init(&trans, c, BTREE_ITER_MAX, 512);
@@ -3055,9 +3055,7 @@ static int __bchfs_fallocate(struct bch_inode_info *inode, int mode,
 
 	while (!ret && bkey_cmp(iter.pos, end_pos) < 0) {
 		s64 i_sectors_delta = 0;
-		struct disk_reservation disk_res = { 0 };
 		struct quota_res quota_res = { 0 };
-		struct bkey_i_reservation reservation;
 		struct bkey_s_c k;
 		unsigned sectors;
 		u32 snapshot;
@@ -3077,7 +3075,7 @@ static int __bchfs_fallocate(struct bch_inode_info *inode, int mode,
 
 		/* already reserved */
 		if (k.k->type == KEY_TYPE_reservation &&
-		    bkey_s_c_to_reservation(k).v->nr_replicas >= replicas) {
+		    bkey_s_c_to_reservation(k).v->nr_replicas >= opts.data_replicas) {
 			bch2_btree_iter_advance(&iter);
 			continue;
 		}
@@ -3088,16 +3086,7 @@ static int __bchfs_fallocate(struct bch_inode_info *inode, int mode,
 			continue;
 		}
 
-		bkey_reservation_init(&reservation.k_i);
-		reservation.k.type	= KEY_TYPE_reservation;
-		reservation.k.p		= k.k->p;
-		reservation.k.size	= k.k->size;
-
-		bch2_cut_front(iter.pos,	&reservation.k_i);
-		bch2_cut_back(end_pos,		&reservation.k_i);
-
-		sectors = reservation.k.size;
-		reservation.v.nr_replicas = bch2_bkey_nr_ptrs_allocated(k);
+		sectors = bpos_min(k.k->p, end_pos).offset - iter.pos.offset;
 
 		if (!bkey_extent_is_allocation(k.k)) {
 			ret = bch2_quota_reservation_add(c, inode,
@@ -3107,25 +3096,15 @@ static int __bchfs_fallocate(struct bch_inode_info *inode, int mode,
 				goto bkey_err;
 		}
 
-		if (reservation.v.nr_replicas < replicas ||
-		    bch2_bkey_sectors_compressed(k)) {
-			ret = bch2_disk_reservation_get(c, &disk_res, sectors,
-							replicas, 0);
-			if (unlikely(ret))
-				goto bkey_err;
-
-			reservation.v.nr_replicas = disk_res.nr_replicas;
-		}
-
-		ret = bch2_extent_update(&trans, inode_inum(inode), &iter,
-				&reservation.k_i, &disk_res,
-				0, &i_sectors_delta, true);
+		ret = bch2_extent_fallocate(&trans, inode_inum(inode), &iter,
+					    sectors, opts, &i_sectors_delta,
+					    writepoint_hashed((unsigned long) current));
 		if (ret)
 			goto bkey_err;
+
 		i_sectors_acct(c, inode, &quota_res, i_sectors_delta);
 bkey_err:
 		bch2_quota_reservation_put(c, inode, &quota_res);
-		bch2_disk_reservation_put(c, &disk_res);
 		if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 			ret = 0;
 	}
diff --git a/fs/bcachefs/io.c b/fs/bcachefs/io.c
index 72a922a164e2..94906e6da555 100644
--- a/fs/bcachefs/io.c
+++ b/fs/bcachefs/io.c
@@ -361,6 +361,36 @@ err:
 	return ret;
 }
 
+/* Overwrites whatever was present with zeroes: */
+int bch2_extent_fallocate(struct btree_trans *trans,
+			  subvol_inum inum,
+			  struct btree_iter *iter,
+			  unsigned sectors,
+			  struct bch_io_opts opts,
+			  s64 *i_sectors_delta,
+			  struct write_point_specifier write_point)
+{
+	int ret;
+	struct bch_fs *c = trans->c;
+	struct disk_reservation disk_res = { 0 };
+	struct bkey_i_reservation *reservation =
+		bch2_trans_kmalloc(trans, sizeof(*reservation));
+
+	ret = PTR_ERR_OR_ZERO(reservation);
+	if (ret)
+		return ret;
+
+	bkey_reservation_init(&reservation->k_i);
+	reservation->k.p = iter->pos;
+	bch2_key_resize(&reservation->k, sectors);
+	reservation->v.nr_replicas = opts.data_replicas;
+
+	ret = bch2_extent_update(trans, inum, iter, &reservation->k_i, &disk_res,
+				 0, i_sectors_delta, true);
+	bch2_disk_reservation_put(c, &disk_res);
+	return ret;
+}
+
 /*
  * Returns -BCH_ERR_transacton_restart if we had to drop locks:
  */
diff --git a/fs/bcachefs/io.h b/fs/bcachefs/io.h
index 43e78a368e84..da59d1196a47 100644
--- a/fs/bcachefs/io.h
+++ b/fs/bcachefs/io.h
@@ -74,6 +74,9 @@ int bch2_sum_sector_overwrites(struct btree_trans *, struct btree_iter *,
 int bch2_extent_update(struct btree_trans *, subvol_inum,
 		       struct btree_iter *, struct bkey_i *,
 		       struct disk_reservation *, u64, s64 *, bool);
+int bch2_extent_fallocate(struct btree_trans *, subvol_inum, struct btree_iter *,
+			  unsigned, struct bch_io_opts, s64 *,
+			  struct write_point_specifier);
 
 int bch2_fpunch_at(struct btree_trans *, struct btree_iter *,
 		   subvol_inum, u64, s64 *);