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Commit 100d5702 authored by David Sterba's avatar David Sterba
Browse files

btrfs: don't use slab cache for struct btrfs_delalloc_work 



Although we prefer to use separate caches for various structs, it seems
better not to do that for struct btrfs_delalloc_work. Objects of this
type are allocated rarely, when transaction commit calls
btrfs_start_delalloc_roots, requesting delayed iputs.

The objects are temporary (with some IO involved) but still allocated
and freed within __start_delalloc_inodes. Memory allocation failure is
handled.

The slab cache is empty most of the time (observed on several systems),
so if we need to allocate a new slab object, the first one has to
allocate a full page. In a potential case of low memory conditions this
might fail with higher probability compared to using the generic slab
caches.

Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 0de270fa

fs/btrfs/inode.c

+2 −12
Original line number Diff line number Diff line
@@ -77,7 +77,6 @@ static const struct file_operations btrfs_dir_file_operations; 
static struct extent_io_ops btrfs_extent_io_ops;



static struct kmem_cache *btrfs_inode_cachep;

static struct kmem_cache *btrfs_delalloc_work_cachep;

struct kmem_cache *btrfs_trans_handle_cachep;

struct kmem_cache *btrfs_transaction_cachep;

struct kmem_cache *btrfs_path_cachep;
@@ -9159,8 +9158,6 @@ void btrfs_destroy_cachep(void) 
		kmem_cache_destroy(btrfs_path_cachep);

	if (btrfs_free_space_cachep)

		kmem_cache_destroy(btrfs_free_space_cachep);

	if (btrfs_delalloc_work_cachep)

		kmem_cache_destroy(btrfs_delalloc_work_cachep);

}



int btrfs_init_cachep(void)
@@ -9195,13 +9192,6 @@ int btrfs_init_cachep(void) 
	if (!btrfs_free_space_cachep)

		goto fail;



	btrfs_delalloc_work_cachep = kmem_cache_create("btrfs_delalloc_work",

			sizeof(struct btrfs_delalloc_work), 0,

			SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,

			NULL);

	if (!btrfs_delalloc_work_cachep)

		goto fail;



	return 0;

fail:

	btrfs_destroy_cachep();
@@ -9446,7 +9436,7 @@ struct btrfs_delalloc_work *btrfs_alloc_delalloc_work(struct inode *inode, 
{

	struct btrfs_delalloc_work *work;



	work = kmem_cache_zalloc(btrfs_delalloc_work_cachep, GFP_NOFS);

	work = kmalloc(sizeof(*work), GFP_NOFS);

	if (!work)

		return NULL;
@@ -9465,7 +9455,7 @@ struct btrfs_delalloc_work *btrfs_alloc_delalloc_work(struct inode *inode, 
void btrfs_wait_and_free_delalloc_work(struct btrfs_delalloc_work *work)

{

	wait_for_completion(&work->completion);

	kmem_cache_free(btrfs_delalloc_work_cachep, work);

	kfree(work);

}



/*