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Subject[PATCH 03/12] btrfs: manage heuristic workspace as index 0
Date
While the heuristic workspaces aren't really compression workspaces,
they use the same interface for managing them. So rather than branching,
let's just handle them once again as the index 0 compression type.

Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
---
v2:
- added BTRFS_NR_WORKSPACE_MANAGERS instead of overriding
BTRFS_COMPRESS_TYPES

fs/btrfs/compression.c | 111 +++++++++++------------------------------
fs/btrfs/compression.h | 4 ++
2 files changed, 33 insertions(+), 82 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index d098df768b67..5b508cb3b236 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -769,6 +769,11 @@ static struct list_head *alloc_heuristic_ws(void)
return ERR_PTR(-ENOMEM);
}

+const struct btrfs_compress_op btrfs_heuristic_compress = {
+ .alloc_workspace = alloc_heuristic_ws,
+ .free_workspace = free_heuristic_ws,
+};
+
struct workspace_manager {
struct list_head idle_ws;
spinlock_t ws_lock;
@@ -780,11 +785,10 @@ struct workspace_manager {
wait_queue_head_t ws_wait;
};

-static struct workspace_manager wsm[BTRFS_COMPRESS_TYPES];
-
-static struct workspace_manager btrfs_heuristic_ws;
+static struct workspace_manager wsm[BTRFS_NR_WORKSPACE_MANAGERS];

static const struct btrfs_compress_op * const btrfs_compress_op[] = {
+ &btrfs_heuristic_compress,
&btrfs_zlib_compress,
&btrfs_lzo_compress,
&btrfs_zstd_compress,
@@ -795,22 +799,7 @@ void __init btrfs_init_compress(void)
struct list_head *workspace;
int i;

- INIT_LIST_HEAD(&btrfs_heuristic_ws.idle_ws);
- spin_lock_init(&btrfs_heuristic_ws.ws_lock);
- atomic_set(&btrfs_heuristic_ws.total_ws, 0);
- init_waitqueue_head(&btrfs_heuristic_ws.ws_wait);
-
- workspace = alloc_heuristic_ws();
- if (IS_ERR(workspace)) {
- pr_warn(
- "BTRFS: cannot preallocate heuristic workspace, will try later\n");
- } else {
- atomic_set(&btrfs_heuristic_ws.total_ws, 1);
- btrfs_heuristic_ws.free_ws = 1;
- list_add(workspace, &btrfs_heuristic_ws.idle_ws);
- }
-
- for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
+ for (i = 0; i < BTRFS_NR_WORKSPACE_MANAGERS; i++) {
INIT_LIST_HEAD(&wsm[i].idle_ws);
spin_lock_init(&wsm[i].ws_lock);
atomic_set(&wsm[i].total_ws, 0);
@@ -837,11 +826,10 @@ void __init btrfs_init_compress(void)
* Preallocation makes a forward progress guarantees and we do not return
* errors.
*/
-static struct list_head *__find_workspace(int type, bool heuristic)
+static struct list_head *find_workspace(int type)
{
struct list_head *workspace;
int cpus = num_online_cpus();
- int idx = type - 1;
unsigned nofs_flag;
struct list_head *idle_ws;
spinlock_t *ws_lock;
@@ -849,19 +837,11 @@ static struct list_head *__find_workspace(int type, bool heuristic)
wait_queue_head_t *ws_wait;
int *free_ws;

- if (heuristic) {
- idle_ws = &btrfs_heuristic_ws.idle_ws;
- ws_lock = &btrfs_heuristic_ws.ws_lock;
- total_ws = &btrfs_heuristic_ws.total_ws;
- ws_wait = &btrfs_heuristic_ws.ws_wait;
- free_ws = &btrfs_heuristic_ws.free_ws;
- } else {
- idle_ws = &wsm[idx].idle_ws;
- ws_lock = &wsm[idx].ws_lock;
- total_ws = &wsm[idx].total_ws;
- ws_wait = &wsm[idx].ws_wait;
- free_ws = &wsm[idx].free_ws;
- }
+ idle_ws = &wsm[type].idle_ws;
+ ws_lock = &wsm[type].ws_lock;
+ total_ws = &wsm[type].total_ws;
+ ws_wait = &wsm[type].ws_wait;
+ free_ws = &wsm[type].free_ws;

again:
spin_lock(ws_lock);
@@ -892,10 +872,7 @@ static struct list_head *__find_workspace(int type, bool heuristic)
* context of btrfs_compress_bio/btrfs_compress_pages
*/
nofs_flag = memalloc_nofs_save();
- if (heuristic)
- workspace = alloc_heuristic_ws();
- else
- workspace = btrfs_compress_op[idx]->alloc_workspace();
+ workspace = btrfs_compress_op[type]->alloc_workspace();
memalloc_nofs_restore(nofs_flag);

if (IS_ERR(workspace)) {
@@ -926,38 +903,23 @@ static struct list_head *__find_workspace(int type, bool heuristic)
return workspace;
}

-static struct list_head *find_workspace(int type)
-{
- return __find_workspace(type, false);
-}
-
/*
* put a workspace struct back on the list or free it if we have enough
* idle ones sitting around
*/
-static void __free_workspace(int type, struct list_head *workspace,
- bool heuristic)
+static void free_workspace(int type, struct list_head *workspace)
{
- int idx = type - 1;
struct list_head *idle_ws;
spinlock_t *ws_lock;
atomic_t *total_ws;
wait_queue_head_t *ws_wait;
int *free_ws;

- if (heuristic) {
- idle_ws = &btrfs_heuristic_ws.idle_ws;
- ws_lock = &btrfs_heuristic_ws.ws_lock;
- total_ws = &btrfs_heuristic_ws.total_ws;
- ws_wait = &btrfs_heuristic_ws.ws_wait;
- free_ws = &btrfs_heuristic_ws.free_ws;
- } else {
- idle_ws = &wsm[idx].idle_ws;
- ws_lock = &wsm[idx].ws_lock;
- total_ws = &wsm[idx].total_ws;
- ws_wait = &wsm[idx].ws_wait;
- free_ws = &wsm[idx].free_ws;
- }
+ idle_ws = &wsm[type].idle_ws;
+ ws_lock = &wsm[type].ws_lock;
+ total_ws = &wsm[type].total_ws;
+ ws_wait = &wsm[type].ws_wait;
+ free_ws = &wsm[type].free_ws;

spin_lock(ws_lock);
if (*free_ws <= num_online_cpus()) {
@@ -968,20 +930,12 @@ static void __free_workspace(int type, struct list_head *workspace,
}
spin_unlock(ws_lock);

- if (heuristic)
- free_heuristic_ws(workspace);
- else
- btrfs_compress_op[idx]->free_workspace(workspace);
+ btrfs_compress_op[type]->free_workspace(workspace);
atomic_dec(total_ws);
wake:
cond_wake_up(ws_wait);
}

-static void free_workspace(int type, struct list_head *ws)
-{
- return __free_workspace(type, ws, false);
-}
-
/*
* cleanup function for module exit
*/
@@ -990,14 +944,7 @@ static void free_workspaces(void)
struct list_head *workspace;
int i;

- while (!list_empty(&btrfs_heuristic_ws.idle_ws)) {
- workspace = btrfs_heuristic_ws.idle_ws.next;
- list_del(workspace);
- free_heuristic_ws(workspace);
- atomic_dec(&btrfs_heuristic_ws.total_ws);
- }
-
- for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
+ for (i = 0; i < BTRFS_NR_WORKSPACE_MANAGERS; i++) {
while (!list_empty(&wsm[i].idle_ws)) {
workspace = wsm[i].idle_ws.next;
list_del(workspace);
@@ -1042,8 +989,8 @@ int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,

workspace = find_workspace(type);

- btrfs_compress_op[type - 1]->set_level(workspace, type_level);
- ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
+ btrfs_compress_op[type]->set_level(workspace, type_level);
+ ret = btrfs_compress_op[type]->compress_pages(workspace, mapping,
start, pages,
out_pages,
total_in, total_out);
@@ -1072,7 +1019,7 @@ static int btrfs_decompress_bio(struct compressed_bio *cb)
int type = cb->compress_type;

workspace = find_workspace(type);
- ret = btrfs_compress_op[type - 1]->decompress_bio(workspace, cb);
+ ret = btrfs_compress_op[type]->decompress_bio(workspace, cb);
free_workspace(type, workspace);

return ret;
@@ -1091,7 +1038,7 @@ int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,

workspace = find_workspace(type);

- ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
+ ret = btrfs_compress_op[type]->decompress(workspace, data_in,
dest_page, start_byte,
srclen, destlen);

@@ -1512,7 +1459,7 @@ static void heuristic_collect_sample(struct inode *inode, u64 start, u64 end,
*/
int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end)
{
- struct list_head *ws_list = __find_workspace(0, true);
+ struct list_head *ws_list = find_workspace(0);
struct heuristic_ws *ws;
u32 i;
u8 byte;
@@ -1581,7 +1528,7 @@ int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end)
}

out:
- __free_workspace(0, ws_list, true);
+ free_workspace(0, ws_list);
return ret;
}

diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index 004db0b3111b..7ef62caa60ab 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -132,6 +132,10 @@ struct btrfs_compress_op {
void (*set_level)(struct list_head *ws, unsigned int type);
};

+/* the heuristic workspaces are managed via the 0th workspace manager */
+#define BTRFS_NR_WORKSPACE_MANAGERS (BTRFS_COMPRESS_TYPES + 1)
+
+extern const struct btrfs_compress_op btrfs_heuristic_compress;
extern const struct btrfs_compress_op btrfs_zlib_compress;
extern const struct btrfs_compress_op btrfs_lzo_compress;
extern const struct btrfs_compress_op btrfs_zstd_compress;
--
2.17.1
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