Replace indirect calls to alloc_workspace by switch and calls to the
specific callbacks. This is mainly to get rid of the indirection due to
spectre vulnerability mitigations.

Signed-off-by: David Sterba <[email protected]>
---
 fs/btrfs/compression.c | 21 ++++++++++++++++++---
 fs/btrfs/compression.h |  2 --
 fs/btrfs/lzo.c         |  1 -
 fs/btrfs/zlib.c        |  1 -
 fs/btrfs/zstd.c        |  1 -
 5 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index ffc94e15d86e..4a8dab961f88 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -912,7 +912,6 @@ static struct list_head *alloc_heuristic_ws(unsigned int 
level)
 
 const struct btrfs_compress_op btrfs_heuristic_compress = {
        .workspace_manager = &heuristic_wsm,
-       .alloc_workspace = alloc_heuristic_ws,
        .free_workspace = free_heuristic_ws,
 };
 
@@ -924,6 +923,22 @@ static const struct btrfs_compress_op * const 
btrfs_compress_op[] = {
        &btrfs_zstd_compress,
 };
 
+static struct list_head *alloc_workspace(int type, unsigned int level)
+{
+       switch (type) {
+       case BTRFS_COMPRESS_NONE: return alloc_heuristic_ws(level);
+       case BTRFS_COMPRESS_ZLIB: return zlib_alloc_workspace(level);
+       case BTRFS_COMPRESS_LZO:  return lzo_alloc_workspace(level);
+       case BTRFS_COMPRESS_ZSTD: return zstd_alloc_workspace(level);
+       default:
+               /*
+                * This can't happen, the type is validated several times
+                * before we get here.
+                */
+               BUG();
+       }
+}
+
 static void btrfs_init_workspace_manager(int type)
 {
        const struct btrfs_compress_op *ops = btrfs_compress_op[type];
@@ -941,7 +956,7 @@ static void btrfs_init_workspace_manager(int type)
         * Preallocate one workspace for each compression type so we can
         * guarantee forward progress in the worst case
         */
-       workspace = wsm->ops->alloc_workspace(0);
+       workspace = alloc_workspace(type, 0);
        if (IS_ERR(workspace)) {
                pr_warn(
        "BTRFS: cannot preallocate compression workspace, will try later\n");
@@ -1020,7 +1035,7 @@ struct list_head *btrfs_get_workspace(int type, unsigned 
int level)
         * context of btrfs_compress_bio/btrfs_compress_pages
         */
        nofs_flag = memalloc_nofs_save();
-       workspace = wsm->ops->alloc_workspace(level);
+       workspace = alloc_workspace(type, level);
        memalloc_nofs_restore(nofs_flag);
 
        if (IS_ERR(workspace)) {
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index accb1d61df87..8336c2ef6b5a 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -124,8 +124,6 @@ struct list_head *btrfs_get_workspace(int type, unsigned 
int level);
 void btrfs_put_workspace(struct workspace_manager *wsm, struct list_head *ws);
 
 struct btrfs_compress_op {
-       struct list_head *(*alloc_workspace)(unsigned int level);
-
        void (*free_workspace)(struct list_head *workspace);
 
        struct workspace_manager *workspace_manager;
diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c
index bbf917c5ff2d..39b2cf80f77c 100644
--- a/fs/btrfs/lzo.c
+++ b/fs/btrfs/lzo.c
@@ -484,7 +484,6 @@ int lzo_decompress(struct list_head *ws, unsigned char 
*data_in,
 
 const struct btrfs_compress_op btrfs_lzo_compress = {
        .workspace_manager      = &wsm,
-       .alloc_workspace        = lzo_alloc_workspace,
        .free_workspace         = lzo_free_workspace,
        .max_level              = 1,
        .default_level          = 1,
diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index 5679a2e41a52..c5dfab3ab082 100644
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -400,7 +400,6 @@ int zlib_decompress(struct list_head *ws, unsigned char 
*data_in,
 
 const struct btrfs_compress_op btrfs_zlib_compress = {
        .workspace_manager      = &wsm,
-       .alloc_workspace        = zlib_alloc_workspace,
        .free_workspace         = zlib_free_workspace,
        .max_level              = 9,
        .default_level          = BTRFS_ZLIB_DEFAULT_LEVEL,
diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index a346f1187fae..9413f741c2f6 100644
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c
@@ -708,7 +708,6 @@ int zstd_decompress(struct list_head *ws, unsigned char 
*data_in,
 const struct btrfs_compress_op btrfs_zstd_compress = {
        /* ZSTD uses own workspace manager */
        .workspace_manager = NULL,
-       .alloc_workspace = zstd_alloc_workspace,
        .free_workspace = zstd_free_workspace,
        .max_level      = ZSTD_BTRFS_MAX_LEVEL,
        .default_level  = ZSTD_BTRFS_DEFAULT_LEVEL,
-- 
2.23.0

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