Btrfs: compression: separate heuristic/compression workspaces

Compression heuristic itself is not a compression type, as current
infrastructure provides workspaces for several compression types, it's
difficult to just add heuristic workspace.

Just refactor the code to support compression/heuristic workspaces with
maximum code sharing and minimum changes in it.

Signed-off-by: Timofey Titovets <nefelim4ag@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ coding style fixes ]
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 083f9c4..b155542 100644 (file)
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -707,7 +707,34 @@ out:
        return ret;
 }
 
-static struct {
+
+struct heuristic_ws {
+       struct list_head list;
+};
+
+static void free_heuristic_ws(struct list_head *ws)
+{
+       struct heuristic_ws *workspace;
+
+       workspace = list_entry(ws, struct heuristic_ws, list);
+
+       kfree(workspace);
+}
+
+static struct list_head *alloc_heuristic_ws(void)
+{
+       struct heuristic_ws *ws;
+
+       ws = kzalloc(sizeof(*ws), GFP_KERNEL);
+       if (!ws)
+               return ERR_PTR(-ENOMEM);
+
+       INIT_LIST_HEAD(&ws->list);
+
+       return &ws->list;
+}
+
+struct workspaces_list {
        struct list_head idle_ws;
        spinlock_t ws_lock;
        /* Number of free workspaces */
@@ -716,7 +743,11 @@ static struct {
        atomic_t total_ws;
        /* Waiters for a free workspace */
        wait_queue_head_t ws_wait;
-} btrfs_comp_ws[BTRFS_COMPRESS_TYPES];
+};
+
+static struct workspaces_list btrfs_comp_ws[BTRFS_COMPRESS_TYPES];
+
+static struct workspaces_list btrfs_heuristic_ws;
 
 static const struct btrfs_compress_op * const btrfs_compress_op[] = {
        &btrfs_zlib_compress,
@@ -726,11 +757,25 @@ static const struct btrfs_compress_op * const btrfs_compress_op[] = {
 
 void __init btrfs_init_compress(void)
 {
+       struct list_head *workspace;
        int i;
 
-       for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
-               struct list_head *workspace;
+       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++) {
                INIT_LIST_HEAD(&btrfs_comp_ws[i].idle_ws);
                spin_lock_init(&btrfs_comp_ws[i].ws_lock);
                atomic_set(&btrfs_comp_ws[i].total_ws, 0);
@@ -757,18 +802,32 @@ 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)
+static struct list_head *__find_workspace(int type, bool heuristic)
 {
        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;
+       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  = &btrfs_comp_ws[idx].idle_ws;
+               ws_lock  = &btrfs_comp_ws[idx].ws_lock;
+               total_ws = &btrfs_comp_ws[idx].total_ws;
+               ws_wait  = &btrfs_comp_ws[idx].ws_wait;
+               free_ws  = &btrfs_comp_ws[idx].free_ws;
+       }
 
-       struct list_head *idle_ws       = &btrfs_comp_ws[idx].idle_ws;
-       spinlock_t *ws_lock             = &btrfs_comp_ws[idx].ws_lock;
-       atomic_t *total_ws              = &btrfs_comp_ws[idx].total_ws;
-       wait_queue_head_t *ws_wait      = &btrfs_comp_ws[idx].ws_wait;
-       int *free_ws                    = &btrfs_comp_ws[idx].free_ws;
 again:
        spin_lock(ws_lock);
        if (!list_empty(idle_ws)) {
@@ -798,7 +857,10 @@ again:
         * context of btrfs_compress_bio/btrfs_compress_pages
         */
        nofs_flag = memalloc_nofs_save();
-       workspace = btrfs_compress_op[idx]->alloc_workspace();
+       if (heuristic)
+               workspace = alloc_heuristic_ws();
+       else
+               workspace = btrfs_compress_op[idx]->alloc_workspace();
        memalloc_nofs_restore(nofs_flag);
 
        if (IS_ERR(workspace)) {
@@ -829,18 +891,38 @@ again:
        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)
+static void __free_workspace(int type, struct list_head *workspace,
+                            bool heuristic)
 {
        int idx = type - 1;
-       struct list_head *idle_ws       = &btrfs_comp_ws[idx].idle_ws;
-       spinlock_t *ws_lock             = &btrfs_comp_ws[idx].ws_lock;
-       atomic_t *total_ws              = &btrfs_comp_ws[idx].total_ws;
-       wait_queue_head_t *ws_wait      = &btrfs_comp_ws[idx].ws_wait;
-       int *free_ws                    = &btrfs_comp_ws[idx].free_ws;
+       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  = &btrfs_comp_ws[idx].idle_ws;
+               ws_lock  = &btrfs_comp_ws[idx].ws_lock;
+               total_ws = &btrfs_comp_ws[idx].total_ws;
+               ws_wait  = &btrfs_comp_ws[idx].ws_wait;
+               free_ws  = &btrfs_comp_ws[idx].free_ws;
+       }
 
        spin_lock(ws_lock);
        if (*free_ws <= num_online_cpus()) {
@@ -851,7 +933,10 @@ static void free_workspace(int type, struct list_head *workspace)
        }
        spin_unlock(ws_lock);
 
-       btrfs_compress_op[idx]->free_workspace(workspace);
+       if (heuristic)
+               free_heuristic_ws(workspace);
+       else
+               btrfs_compress_op[idx]->free_workspace(workspace);
        atomic_dec(total_ws);
 wake:
        /*
@@ -862,6 +947,11 @@ wake:
                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
  */
@@ -870,6 +960,13 @@ 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++) {
                while (!list_empty(&btrfs_comp_ws[i].idle_ws)) {
                        workspace = btrfs_comp_ws[i].idle_ws.next;
@@ -1090,11 +1187,15 @@ int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
  */
 int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end)
 {
+       struct list_head *ws_list = __find_workspace(0, true);
+       struct heuristic_ws *ws;
        u64 index = start >> PAGE_SHIFT;
        u64 end_index = end >> PAGE_SHIFT;
        struct page *page;
        int ret = 1;
 
+       ws = list_entry(ws_list, struct heuristic_ws, list);
+
        while (index <= end_index) {
                page = find_get_page(inode->i_mapping, index);
                kmap(page);
@@ -1103,6 +1204,8 @@ int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end)
                index++;
        }
 
+       __free_workspace(0, ws_list, true);
+
        return ret;
 }