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Subject[PATCH 06/11] btrfs: add compression interface in (get/put)_workspace()
Date
There are two levels of workspace management. First, alloc()/free()
which are responsible for actually creating and destroy workspaces.
Second, at a higher level, get()/put() which is the compression code
asking for a workspace from a workspace_manager.

The compression code shouldn't really care how it gets a workspace, but
that it got a workspace. This adds get_workspace() and put_workspace()
to be the higher level interface which is responsible for indexing into
the appropriate compression type. It also introduces
btrfs_put_workspace() and btrfs_get_workspace() to be the generic
implementations of the higher interface.

Signed-off-by: Dennis Zhou <dennis@kernel.org>
---
fs/btrfs/compression.c | 57 +++++++++++++++++++++++++-----------------
1 file changed, 34 insertions(+), 23 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 63fa3eaeeacc..2e748d8785f0 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -841,7 +841,7 @@ static void btrfs_cleanup_workspace_manager(struct workspace_manager *wsman)
* Preallocation makes a forward progress guarantees and we do not return
* errors.
*/
-static struct list_head *find_workspace(int type)
+static struct list_head *btrfs_get_workspace(struct workspace_manager *wsman)
{
struct list_head *workspace;
int cpus = num_online_cpus();
@@ -852,11 +852,11 @@ static struct list_head *find_workspace(int type)
wait_queue_head_t *ws_wait;
int *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;
+ idle_ws = &wsman->idle_ws;
+ ws_lock = &wsman->ws_lock;
+ total_ws = &wsman->total_ws;
+ ws_wait = &wsman->ws_wait;
+ free_ws = &wsman->free_ws;

again:
spin_lock(ws_lock);
@@ -887,7 +887,7 @@ static struct list_head *find_workspace(int type)
* context of btrfs_compress_bio/btrfs_compress_pages
*/
nofs_flag = memalloc_nofs_save();
- workspace = wsm[type].ops->alloc_workspace();
+ workspace = wsman->ops->alloc_workspace();
memalloc_nofs_restore(nofs_flag);

if (IS_ERR(workspace)) {
@@ -918,11 +918,17 @@ static struct list_head *find_workspace(int type)
return workspace;
}

+static struct list_head *get_workspace(int type)
+{
+ return btrfs_get_workspace(&wsm[type]);
+}
+
/*
* 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)
+static void btrfs_put_workspace(struct workspace_manager *wsman,
+ struct list_head *ws)
{
struct list_head *idle_ws;
spinlock_t *ws_lock;
@@ -930,27 +936,32 @@ static void free_workspace(int type, struct list_head *workspace)
wait_queue_head_t *ws_wait;
int *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;
+ idle_ws = &wsman->idle_ws;
+ ws_lock = &wsman->ws_lock;
+ total_ws = &wsman->total_ws;
+ ws_wait = &wsman->ws_wait;
+ free_ws = &wsman->free_ws;

spin_lock(ws_lock);
if (*free_ws <= num_online_cpus()) {
- list_add(workspace, idle_ws);
+ list_add(ws, idle_ws);
(*free_ws)++;
spin_unlock(ws_lock);
goto wake;
}
spin_unlock(ws_lock);

- wsm[type].ops->free_workspace(workspace);
+ wsman->ops->free_workspace(ws);
atomic_dec(total_ws);
wake:
cond_wake_up(ws_wait);
}

+static void put_workspace(int type, struct list_head *ws)
+{
+ return btrfs_put_workspace(&wsm[type], ws);
+}
+
/*
* Given an address space and start and length, compress the bytes into @pages
* that are allocated on demand.
@@ -984,14 +995,14 @@ int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
struct list_head *workspace;
int ret;

- workspace = find_workspace(type);
+ workspace = get_workspace(type);

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);
- free_workspace(type, workspace);
+ put_workspace(type, workspace);
return ret;
}

@@ -1015,9 +1026,9 @@ static int btrfs_decompress_bio(struct compressed_bio *cb)
int ret;
int type = cb->compress_type;

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

return ret;
}
@@ -1033,13 +1044,13 @@ int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
struct list_head *workspace;
int ret;

- workspace = find_workspace(type);
+ workspace = get_workspace(type);

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

- free_workspace(type, workspace);
+ put_workspace(type, workspace);
return ret;
}

@@ -1467,7 +1478,7 @@ 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);
+ struct list_head *ws_list = get_workspace(0);
struct heuristic_ws *ws;
u32 i;
u8 byte;
@@ -1536,7 +1547,7 @@ int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end)
}

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

--
2.17.1
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