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btrfs: make zstd memory requirements monotonic

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It is possible based on the level configurations that a higher level
workspace uses less memory than a lower level workspace. In order to
reuse workspaces, this must be made a monotonic relationship. This
precomputes the required memory for each level and enforces the
monotonicity between level and memory required. This is also done
in upstream zstd in [1].

[1] a68b76afef

Cc: Nick Terrell <terrelln@fb.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Dennis Zhou 2019-02-04 15:20:07 -05:00 committed by David Sterba
parent e0dc87afcd
commit d3c6ab752c
1 changed files with 33 additions and 5 deletions
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38
fs/btrfs/zstd.c
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@ -20,6 +20,7 @@
#define ZSTD_BTRFS_MAX_WINDOWLOG 17
#define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG)
#define ZSTD_BTRFS_DEFAULT_LEVEL 3
#define ZSTD_BTRFS_MAX_LEVEL 15
static ZSTD_parameters zstd_get_btrfs_parameters(unsigned int level,
size_t src_len)
@ -44,8 +45,39 @@ struct workspace {
static struct workspace_manager wsm;
static size_t zstd_ws_mem_sizes[ZSTD_BTRFS_MAX_LEVEL];
/*
* zstd_calc_ws_mem_sizes - calculate monotonic memory bounds
*
* It is possible based on the level configurations that a higher level
* workspace uses less memory than a lower level workspace. In order to reuse
* workspaces, this must be made a monotonic relationship. This precomputes
* the required memory for each level and enforces the monotonicity between
* level and memory required.
*/
static void zstd_calc_ws_mem_sizes(void)
{
size_t max_size = 0;
unsigned int level;
for (level = 1; level <= ZSTD_BTRFS_MAX_LEVEL; level++) {
ZSTD_parameters params =
zstd_get_btrfs_parameters(level, ZSTD_BTRFS_MAX_INPUT);
size_t level_size =
max_t(size_t,
ZSTD_CStreamWorkspaceBound(params.cParams),
ZSTD_DStreamWorkspaceBound(ZSTD_BTRFS_MAX_INPUT));
max_size = max_t(size_t, max_size, level_size);
zstd_ws_mem_sizes[level - 1] = max_size;
}
}
static void zstd_init_workspace_manager(void)
{
zstd_calc_ws_mem_sizes();
btrfs_init_workspace_manager(&wsm, &btrfs_zstd_compress);
}
@ -80,17 +112,13 @@ static void zstd_free_workspace(struct list_head *ws)
static struct list_head *zstd_alloc_workspace(unsigned int level)
{
ZSTD_parameters params =
zstd_get_btrfs_parameters(level, ZSTD_BTRFS_MAX_INPUT);
struct workspace *workspace;
workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
if (!workspace)
return ERR_PTR(-ENOMEM);
workspace->size = max_t(size_t,
ZSTD_CStreamWorkspaceBound(params.cParams),
ZSTD_DStreamWorkspaceBound(ZSTD_BTRFS_MAX_INPUT));
workspace->size = zstd_ws_mem_sizes[level - 1];
workspace->mem = kvmalloc(workspace->size, GFP_KERNEL);
workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!workspace->mem || !workspace->buf)