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btrfs: don't use slab cache for struct btrfs_delalloc_work

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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: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2015-12-08 14:39:32 +01:00
parent 0de270fa83
commit 100d57025c
1 changed files with 2 additions and 12 deletions
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14
fs/btrfs/inode.c
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@ -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);
}
/*