Commit 33336c18 authored by Boris Burkov's avatar Boris Burkov Committed by David Sterba
Browse files

btrfs: preallocate ulist memory for qgroup rsv 



When qgroups are enabled, during data reservation, we allocate the
ulist_nodes that track the exact reserved extents with GFP_ATOMIC
unconditionally. This is unnecessary, and we can follow the model
already employed by the struct extent_state we preallocate in the non
qgroups case, which should reduce the risk of allocation failures with
GFP_ATOMIC.

Add a prealloc node to struct ulist which ulist_add will grab when it is
present, and try to allocate it before taking the tree lock while we can
still take advantage of a less strict gfp mask. The lifetime of that
node belongs to the new prealloc field, until it is used, at which point
it belongs to the ulist linked list.

Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarBoris Burkov <boris@bur.io>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 28cb13f2

fs/btrfs/extent-io-tree.c

+4 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include <trace/events/btrfs.h>

#include "messages.h"

#include "ctree.h"

#include "extent_io.h"

#include "extent-io-tree.h"

#include "btrfs_inode.h"
@@ -1084,6 +1085,9 @@ static int __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, 
		 */

		prealloc = alloc_extent_state(mask);

	}

	/* Optimistically preallocate the extent changeset ulist node. */

	if (changeset)

		extent_changeset_prealloc(changeset, mask);



	spin_lock(&tree->lock);

	if (cached_state && *cached_state) {

fs/btrfs/extent_io.h

+5 −0
Original line number Diff line number Diff line
@@ -215,6 +215,11 @@ static inline struct extent_changeset *extent_changeset_alloc(void) 
	return ret;

}



static inline void extent_changeset_prealloc(struct extent_changeset *changeset, gfp_t gfp_mask)

{

	ulist_prealloc(&changeset->range_changed, gfp_mask);

}



static inline void extent_changeset_release(struct extent_changeset *changeset)

{

	if (!changeset)

fs/btrfs/ulist.c

+18 −3
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ void ulist_init(struct ulist *ulist) 
	INIT_LIST_HEAD(&ulist->nodes);

	ulist->root = RB_ROOT;

	ulist->nnodes = 0;

	ulist->prealloc = NULL;

}



/*
@@ -68,6 +69,8 @@ void ulist_release(struct ulist *ulist) 
	list_for_each_entry_safe(node, next, &ulist->nodes, list) {

		kfree(node);

	}

	kfree(ulist->prealloc);

	ulist->prealloc = NULL;

	ulist->root = RB_ROOT;

	INIT_LIST_HEAD(&ulist->nodes);

}
@@ -105,6 +108,12 @@ struct ulist *ulist_alloc(gfp_t gfp_mask) 
	return ulist;

}



void ulist_prealloc(struct ulist *ulist, gfp_t gfp_mask)

{

	if (!ulist->prealloc)

		ulist->prealloc = kzalloc(sizeof(*ulist->prealloc), gfp_mask);

}



/*

 * Free dynamically allocated ulist.

 *
@@ -206,9 +215,15 @@ int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux, 
			*old_aux = node->aux;

		return 0;

	}



	if (ulist->prealloc) {

		node = ulist->prealloc;

		ulist->prealloc = NULL;

	} else {

		node = kmalloc(sizeof(*node), gfp_mask);

		if (!node)

			return -ENOMEM;

	}



	node->val = val;

	node->aux = aux;

fs/btrfs/ulist.h

+2 −0
Original line number Diff line number Diff line
@@ -41,12 +41,14 @@ struct ulist { 


	struct list_head nodes;

	struct rb_root root;

	struct ulist_node *prealloc;

};



void ulist_init(struct ulist *ulist);

void ulist_release(struct ulist *ulist);

void ulist_reinit(struct ulist *ulist);

struct ulist *ulist_alloc(gfp_t gfp_mask);

void ulist_prealloc(struct ulist *ulist, gfp_t mask);

void ulist_free(struct ulist *ulist);

int ulist_add(struct ulist *ulist, u64 val, u64 aux, gfp_t gfp_mask);

int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux,