1 files changed, 535 insertions, 0 deletions

diff --git a/fs/btrfs/block-rsv.c b/fs/btrfs/block-rsv.c
new file mode 100644
index 000000000..eb41dc2f6
--- /dev/null
+++ b/fs/btrfs/block-rsv.c
@@ -0,0 +1,535 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "misc.h"
+#include "ctree.h"
+#include "block-rsv.h"
+#include "space-info.h"
+#include "transaction.h"
+#include "block-group.h"
+
+/*
+ * HOW DO BLOCK RESERVES WORK
+ *
+ *   Think of block_rsv's as buckets for logically grouped metadata
+ *   reservations.  Each block_rsv has a ->size and a ->reserved.  ->size is
+ *   how large we want our block rsv to be, ->reserved is how much space is
+ *   currently reserved for this block reserve.
+ *
+ *   ->failfast exists for the truncate case, and is described below.
+ *
+ * NORMAL OPERATION
+ *
+ *   -> Reserve
+ *     Entrance: btrfs_block_rsv_add, btrfs_block_rsv_refill
+ *
+ *     We call into btrfs_reserve_metadata_bytes() with our bytes, which is
+ *     accounted for in space_info->bytes_may_use, and then add the bytes to
+ *     ->reserved, and ->size in the case of btrfs_block_rsv_add.
+ *
+ *     ->size is an over-estimation of how much we may use for a particular
+ *     operation.
+ *
+ *   -> Use
+ *     Entrance: btrfs_use_block_rsv
+ *
+ *     When we do a btrfs_alloc_tree_block() we call into btrfs_use_block_rsv()
+ *     to determine the appropriate block_rsv to use, and then verify that
+ *     ->reserved has enough space for our tree block allocation.  Once
+ *     successful we subtract fs_info->nodesize from ->reserved.
+ *
+ *   -> Finish
+ *     Entrance: btrfs_block_rsv_release
+ *
+ *     We are finished with our operation, subtract our individual reservation
+ *     from ->size, and then subtract ->size from ->reserved and free up the
+ *     excess if there is any.
+ *
+ *     There is some logic here to refill the delayed refs rsv or the global rsv
+ *     as needed, otherwise the excess is subtracted from
+ *     space_info->bytes_may_use.
+ *
+ * TYPES OF BLOCK RESERVES
+ *
+ * BLOCK_RSV_TRANS, BLOCK_RSV_DELOPS, BLOCK_RSV_CHUNK
+ *   These behave normally, as described above, just within the confines of the
+ *   lifetime of their particular operation (transaction for the whole trans
+ *   handle lifetime, for example).
+ *
+ * BLOCK_RSV_GLOBAL
+ *   It is impossible to properly account for all the space that may be required
+ *   to make our extent tree updates.  This block reserve acts as an overflow
+ *   buffer in case our delayed refs reserve does not reserve enough space to
+ *   update the extent tree.
+ *
+ *   We can steal from this in some cases as well, notably on evict() or
+ *   truncate() in order to help users recover from ENOSPC conditions.
+ *
+ * BLOCK_RSV_DELALLOC
+ *   The individual item sizes are determined by the per-inode size
+ *   calculations, which are described with the delalloc code.  This is pretty
+ *   straightforward, it's just the calculation of ->size encodes a lot of
+ *   different items, and thus it gets used when updating inodes, inserting file
+ *   extents, and inserting checksums.
+ *
+ * BLOCK_RSV_DELREFS
+ *   We keep a running tally of how many delayed refs we have on the system.
+ *   We assume each one of these delayed refs are going to use a full
+ *   reservation.  We use the transaction items and pre-reserve space for every
+ *   operation, and use this reservation to refill any gap between ->size and
+ *   ->reserved that may exist.
+ *
+ *   From there it's straightforward, removing a delayed ref means we remove its
+ *   count from ->size and free up reservations as necessary.  Since this is
+ *   the most dynamic block reserve in the system, we will try to refill this
+ *   block reserve first with any excess returned by any other block reserve.
+ *
+ * BLOCK_RSV_EMPTY
+ *   This is the fallback block reserve to make us try to reserve space if we
+ *   don't have a specific bucket for this allocation.  It is mostly used for
+ *   updating the device tree and such, since that is a separate pool we're
+ *   content to just reserve space from the space_info on demand.
+ *
+ * BLOCK_RSV_TEMP
+ *   This is used by things like truncate and iput.  We will temporarily
+ *   allocate a block reserve, set it to some size, and then truncate bytes
+ *   until we have no space left.  With ->failfast set we'll simply return
+ *   ENOSPC from btrfs_use_block_rsv() to signal that we need to unwind and try
+ *   to make a new reservation.  This is because these operations are
+ *   unbounded, so we want to do as much work as we can, and then back off and
+ *   re-reserve.
+ */
+
+static u64 block_rsv_release_bytes(struct btrfs_fs_info *fs_info,
+				    struct btrfs_block_rsv *block_rsv,
+				    struct btrfs_block_rsv *dest, u64 num_bytes,
+				    u64 *qgroup_to_release_ret)
+{
+	struct btrfs_space_info *space_info = block_rsv->space_info;
+	u64 qgroup_to_release = 0;
+	u64 ret;
+
+	spin_lock(&block_rsv->lock);
+	if (num_bytes == (u64)-1) {
+		num_bytes = block_rsv->size;
+		qgroup_to_release = block_rsv->qgroup_rsv_size;
+	}
+	block_rsv->size -= num_bytes;
+	if (block_rsv->reserved >= block_rsv->size) {
+		num_bytes = block_rsv->reserved - block_rsv->size;
+		block_rsv->reserved = block_rsv->size;
+		block_rsv->full = 1;
+	} else {
+		num_bytes = 0;
+	}
+	if (qgroup_to_release_ret &&
+	    block_rsv->qgroup_rsv_reserved >= block_rsv->qgroup_rsv_size) {
+		qgroup_to_release = block_rsv->qgroup_rsv_reserved -
+				    block_rsv->qgroup_rsv_size;
+		block_rsv->qgroup_rsv_reserved = block_rsv->qgroup_rsv_size;
+	} else {
+		qgroup_to_release = 0;
+	}
+	spin_unlock(&block_rsv->lock);
+
+	ret = num_bytes;
+	if (num_bytes > 0) {
+		if (dest) {
+			spin_lock(&dest->lock);
+			if (!dest->full) {
+				u64 bytes_to_add;
+
+				bytes_to_add = dest->size - dest->reserved;
+				bytes_to_add = min(num_bytes, bytes_to_add);
+				dest->reserved += bytes_to_add;
+				if (dest->reserved >= dest->size)
+					dest->full = 1;
+				num_bytes -= bytes_to_add;
+			}
+			spin_unlock(&dest->lock);
+		}
+		if (num_bytes)
+			btrfs_space_info_free_bytes_may_use(fs_info,
+							    space_info,
+							    num_bytes);
+	}
+	if (qgroup_to_release_ret)
+		*qgroup_to_release_ret = qgroup_to_release;
+	return ret;
+}
+
+int btrfs_block_rsv_migrate(struct btrfs_block_rsv *src,
+			    struct btrfs_block_rsv *dst, u64 num_bytes,
+			    bool update_size)
+{
+	int ret;
+
+	ret = btrfs_block_rsv_use_bytes(src, num_bytes);
+	if (ret)
+		return ret;
+
+	btrfs_block_rsv_add_bytes(dst, num_bytes, update_size);
+	return 0;
+}
+
+void btrfs_init_block_rsv(struct btrfs_block_rsv *rsv, unsigned short type)
+{
+	memset(rsv, 0, sizeof(*rsv));
+	spin_lock_init(&rsv->lock);
+	rsv->type = type;
+}
+
+void btrfs_init_metadata_block_rsv(struct btrfs_fs_info *fs_info,
+				   struct btrfs_block_rsv *rsv,
+				   unsigned short type)
+{
+	btrfs_init_block_rsv(rsv, type);
+	rsv->space_info = btrfs_find_space_info(fs_info,
+					    BTRFS_BLOCK_GROUP_METADATA);
+}
+
+struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_fs_info *fs_info,
+					      unsigned short type)
+{
+	struct btrfs_block_rsv *block_rsv;
+
+	block_rsv = kmalloc(sizeof(*block_rsv), GFP_NOFS);
+	if (!block_rsv)
+		return NULL;
+
+	btrfs_init_metadata_block_rsv(fs_info, block_rsv, type);
+	return block_rsv;
+}
+
+void btrfs_free_block_rsv(struct btrfs_fs_info *fs_info,
+			  struct btrfs_block_rsv *rsv)
+{
+	if (!rsv)
+		return;
+	btrfs_block_rsv_release(fs_info, rsv, (u64)-1, NULL);
+	kfree(rsv);
+}
+
+int btrfs_block_rsv_add(struct btrfs_root *root,
+			struct btrfs_block_rsv *block_rsv, u64 num_bytes,
+			enum btrfs_reserve_flush_enum flush)
+{
+	int ret;
+
+	if (num_bytes == 0)
+		return 0;
+
+	ret = btrfs_reserve_metadata_bytes(root, block_rsv, num_bytes, flush);
+	if (!ret)
+		btrfs_block_rsv_add_bytes(block_rsv, num_bytes, true);
+
+	return ret;
+}
+
+int btrfs_block_rsv_check(struct btrfs_block_rsv *block_rsv, int min_factor)
+{
+	u64 num_bytes = 0;
+	int ret = -ENOSPC;
+
+	if (!block_rsv)
+		return 0;
+
+	spin_lock(&block_rsv->lock);
+	num_bytes = div_factor(block_rsv->size, min_factor);
+	if (block_rsv->reserved >= num_bytes)
+		ret = 0;
+	spin_unlock(&block_rsv->lock);
+
+	return ret;
+}
+
+int btrfs_block_rsv_refill(struct btrfs_root *root,
+			   struct btrfs_block_rsv *block_rsv, u64 min_reserved,
+			   enum btrfs_reserve_flush_enum flush)
+{
+	u64 num_bytes = 0;
+	int ret = -ENOSPC;
+
+	if (!block_rsv)
+		return 0;
+
+	spin_lock(&block_rsv->lock);
+	num_bytes = min_reserved;
+	if (block_rsv->reserved >= num_bytes)
+		ret = 0;
+	else
+		num_bytes -= block_rsv->reserved;
+	spin_unlock(&block_rsv->lock);
+
+	if (!ret)
+		return 0;
+
+	ret = btrfs_reserve_metadata_bytes(root, block_rsv, num_bytes, flush);
+	if (!ret) {
+		btrfs_block_rsv_add_bytes(block_rsv, num_bytes, false);
+		return 0;
+	}
+
+	return ret;
+}
+
+u64 btrfs_block_rsv_release(struct btrfs_fs_info *fs_info,
+			    struct btrfs_block_rsv *block_rsv, u64 num_bytes,
+			    u64 *qgroup_to_release)
+{
+	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
+	struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_refs_rsv;
+	struct btrfs_block_rsv *target = NULL;
+
+	/*
+	 * If we are the delayed_rsv then push to the global rsv, otherwise dump
+	 * into the delayed rsv if it is not full.
+	 */
+	if (block_rsv == delayed_rsv)
+		target = global_rsv;
+	else if (block_rsv != global_rsv && !delayed_rsv->full)
+		target = delayed_rsv;
+
+	if (target && block_rsv->space_info != target->space_info)
+		target = NULL;
+
+	return block_rsv_release_bytes(fs_info, block_rsv, target, num_bytes,
+				       qgroup_to_release);
+}
+
+int btrfs_block_rsv_use_bytes(struct btrfs_block_rsv *block_rsv, u64 num_bytes)
+{
+	int ret = -ENOSPC;
+
+	spin_lock(&block_rsv->lock);
+	if (block_rsv->reserved >= num_bytes) {
+		block_rsv->reserved -= num_bytes;
+		if (block_rsv->reserved < block_rsv->size)
+			block_rsv->full = 0;
+		ret = 0;
+	}
+	spin_unlock(&block_rsv->lock);
+	return ret;
+}
+
+void btrfs_block_rsv_add_bytes(struct btrfs_block_rsv *block_rsv,
+			       u64 num_bytes, bool update_size)
+{
+	spin_lock(&block_rsv->lock);
+	block_rsv->reserved += num_bytes;
+	if (update_size)
+		block_rsv->size += num_bytes;
+	else if (block_rsv->reserved >= block_rsv->size)
+		block_rsv->full = 1;
+	spin_unlock(&block_rsv->lock);
+}
+
+int btrfs_cond_migrate_bytes(struct btrfs_fs_info *fs_info,
+			     struct btrfs_block_rsv *dest, u64 num_bytes,
+			     int min_factor)
+{
+	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
+	u64 min_bytes;
+
+	if (global_rsv->space_info != dest->space_info)
+		return -ENOSPC;
+
+	spin_lock(&global_rsv->lock);
+	min_bytes = div_factor(global_rsv->size, min_factor);
+	if (global_rsv->reserved < min_bytes + num_bytes) {
+		spin_unlock(&global_rsv->lock);
+		return -ENOSPC;
+	}
+	global_rsv->reserved -= num_bytes;
+	if (global_rsv->reserved < global_rsv->size)
+		global_rsv->full = 0;
+	spin_unlock(&global_rsv->lock);
+
+	btrfs_block_rsv_add_bytes(dest, num_bytes, true);
+	return 0;
+}
+
+void btrfs_update_global_block_rsv(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
+	struct btrfs_space_info *sinfo = block_rsv->space_info;
+	u64 num_bytes;
+	unsigned min_items;
+
+	/*
+	 * The global block rsv is based on the size of the extent tree, the
+	 * checksum tree and the root tree.  If the fs is empty we want to set
+	 * it to a minimal amount for safety.
+	 */
+	num_bytes = btrfs_root_used(&fs_info->extent_root->root_item) +
+		btrfs_root_used(&fs_info->csum_root->root_item) +
+		btrfs_root_used(&fs_info->tree_root->root_item);
+
+	/*
+	 * We at a minimum are going to modify the csum root, the tree root, and
+	 * the extent root.
+	 */
+	min_items = 3;
+
+	/*
+	 * But we also want to reserve enough space so we can do the fallback
+	 * global reserve for an unlink, which is an additional 5 items (see the
+	 * comment in __unlink_start_trans for what we're modifying.)
+	 *
+	 * But we also need space for the delayed ref updates from the unlink,
+	 * so its 10, 5 for the actual operation, and 5 for the delayed ref
+	 * updates.
+	 */
+	min_items += 10;
+
+	num_bytes = max_t(u64, num_bytes,
+			  btrfs_calc_insert_metadata_size(fs_info, min_items));
+
+	spin_lock(&sinfo->lock);
+	spin_lock(&block_rsv->lock);
+
+	block_rsv->size = min_t(u64, num_bytes, SZ_512M);
+
+	if (block_rsv->reserved < block_rsv->size) {
+		num_bytes = block_rsv->size - block_rsv->reserved;
+		btrfs_space_info_update_bytes_may_use(fs_info, sinfo,
+						      num_bytes);
+		block_rsv->reserved = block_rsv->size;
+	} else if (block_rsv->reserved > block_rsv->size) {
+		num_bytes = block_rsv->reserved - block_rsv->size;
+		btrfs_space_info_update_bytes_may_use(fs_info, sinfo,
+						      -num_bytes);
+		block_rsv->reserved = block_rsv->size;
+		btrfs_try_granting_tickets(fs_info, sinfo);
+	}
+
+	if (block_rsv->reserved == block_rsv->size)
+		block_rsv->full = 1;
+	else
+		block_rsv->full = 0;
+
+	if (block_rsv->size >= sinfo->total_bytes)
+		sinfo->force_alloc = CHUNK_ALLOC_FORCE;
+	spin_unlock(&block_rsv->lock);
+	spin_unlock(&sinfo->lock);
+}
+
+void btrfs_init_global_block_rsv(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_space_info *space_info;
+
+	space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
+	fs_info->chunk_block_rsv.space_info = space_info;
+
+	space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
+	fs_info->global_block_rsv.space_info = space_info;
+	fs_info->trans_block_rsv.space_info = space_info;
+	fs_info->empty_block_rsv.space_info = space_info;
+	fs_info->delayed_block_rsv.space_info = space_info;
+	fs_info->delayed_refs_rsv.space_info = space_info;
+
+	fs_info->extent_root->block_rsv = &fs_info->delayed_refs_rsv;
+	fs_info->csum_root->block_rsv = &fs_info->delayed_refs_rsv;
+	fs_info->dev_root->block_rsv = &fs_info->global_block_rsv;
+	fs_info->tree_root->block_rsv = &fs_info->global_block_rsv;
+	if (fs_info->quota_root)
+		fs_info->quota_root->block_rsv = &fs_info->global_block_rsv;
+	fs_info->chunk_root->block_rsv = &fs_info->chunk_block_rsv;
+
+	btrfs_update_global_block_rsv(fs_info);
+}
+
+void btrfs_release_global_block_rsv(struct btrfs_fs_info *fs_info)
+{
+	btrfs_block_rsv_release(fs_info, &fs_info->global_block_rsv, (u64)-1,
+				NULL);
+	WARN_ON(fs_info->trans_block_rsv.size > 0);
+	WARN_ON(fs_info->trans_block_rsv.reserved > 0);
+	WARN_ON(fs_info->chunk_block_rsv.size > 0);
+	WARN_ON(fs_info->chunk_block_rsv.reserved > 0);
+	WARN_ON(fs_info->delayed_block_rsv.size > 0);
+	WARN_ON(fs_info->delayed_block_rsv.reserved > 0);
+	WARN_ON(fs_info->delayed_refs_rsv.reserved > 0);
+	WARN_ON(fs_info->delayed_refs_rsv.size > 0);
+}
+
+static struct btrfs_block_rsv *get_block_rsv(
+					const struct btrfs_trans_handle *trans,
+					const struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_block_rsv *block_rsv = NULL;
+
+	if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
+	    (root == fs_info->csum_root && trans->adding_csums) ||
+	    (root == fs_info->uuid_root))
+		block_rsv = trans->block_rsv;
+
+	if (!block_rsv)
+		block_rsv = root->block_rsv;
+
+	if (!block_rsv)
+		block_rsv = &fs_info->empty_block_rsv;
+
+	return block_rsv;
+}
+
+struct btrfs_block_rsv *btrfs_use_block_rsv(struct btrfs_trans_handle *trans,
+					    struct btrfs_root *root,
+					    u32 blocksize)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_block_rsv *block_rsv;
+	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
+	int ret;
+	bool global_updated = false;
+
+	block_rsv = get_block_rsv(trans, root);
+
+	if (unlikely(block_rsv->size == 0))
+		goto try_reserve;
+again:
+	ret = btrfs_block_rsv_use_bytes(block_rsv, blocksize);
+	if (!ret)
+		return block_rsv;
+
+	if (block_rsv->failfast)
+		return ERR_PTR(ret);
+
+	if (block_rsv->type == BTRFS_BLOCK_RSV_GLOBAL && !global_updated) {
+		global_updated = true;
+		btrfs_update_global_block_rsv(fs_info);
+		goto again;
+	}
+
+	/*
+	 * The global reserve still exists to save us from ourselves, so don't
+	 * warn_on if we are short on our delayed refs reserve.
+	 */
+	if (block_rsv->type != BTRFS_BLOCK_RSV_DELREFS &&
+	    btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
+		static DEFINE_RATELIMIT_STATE(_rs,
+				DEFAULT_RATELIMIT_INTERVAL * 10,
+				/*DEFAULT_RATELIMIT_BURST*/ 1);
+		if (__ratelimit(&_rs))
+			WARN(1, KERN_DEBUG
+				"BTRFS: block rsv %d returned %d\n",
+				block_rsv->type, ret);
+	}
+try_reserve:
+	ret = btrfs_reserve_metadata_bytes(root, block_rsv, blocksize,
+					   BTRFS_RESERVE_NO_FLUSH);
+	if (!ret)
+		return block_rsv;
+	/*
+	 * If we couldn't reserve metadata bytes try and use some from
+	 * the global reserve if its space type is the same as the global
+	 * reservation.
+	 */
+	if (block_rsv->type != BTRFS_BLOCK_RSV_GLOBAL &&
+	    block_rsv->space_info == global_rsv->space_info) {
+		ret = btrfs_block_rsv_use_bytes(global_rsv, blocksize);
+		if (!ret)
+			return global_rsv;
+	}
+	return ERR_PTR(ret);
+}