btrfs: allow to set compression level for zlib

Preliminary support for setting compression level for zlib, the
following works:

$ mount -o compess=zlib                 # default
$ mount -o compess=zlib0                # same
$ mount -o compess=zlib9                # level 9, slower sync, less data
$ mount -o compess=zlib1                # level 1, faster sync, more data
$ mount -o remount,compress=zlib3	# level set by remount

The compress-force works the same as compress'.  The level is visible in
the same format in /proc/mounts. Level set via file property does not
work yet.

Required patch: "btrfs: prepare for extensions in compression options"

Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index c248f92..2b52950 100644
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -37,6 +37,7 @@ struct workspace {
 	z_stream strm;
 	char *buf;
 	struct list_head list;
+	int level;
 };
 
 static void zlib_free_workspace(struct list_head *ws)
@@ -96,7 +97,7 @@ static int zlib_compress_pages(struct list_head *ws,
 	*total_out = 0;
 	*total_in = 0;
 
-	if (Z_OK != zlib_deflateInit(&workspace->strm, 3)) {
+	if (Z_OK != zlib_deflateInit(&workspace->strm, workspace->level)) {
 		pr_warn("BTRFS: deflateInit failed\n");
 		ret = -EIO;
 		goto out;
@@ -402,10 +403,22 @@ next:
 	return ret;
 }
 
+static void zlib_set_level(struct list_head *ws, unsigned int type)
+{
+	struct workspace *workspace = list_entry(ws, struct workspace, list);
+	unsigned level = (type & 0xF0) >> 4;
+
+	if (level > 9)
+		level = 9;
+
+	workspace->level = level > 0 ? level : 3;
+}
+
 const struct btrfs_compress_op btrfs_zlib_compress = {
 	.alloc_workspace	= zlib_alloc_workspace,
 	.free_workspace		= zlib_free_workspace,
 	.compress_pages		= zlib_compress_pages,
 	.decompress_bio		= zlib_decompress_bio,
 	.decompress		= zlib_decompress,
+	.set_level              = zlib_set_level,
 };