[RFC PATCH 3/3] btrfs: allow setting zstd level
From: Adam Borowski <hidden>
Date: 2017-09-15 15:37:14
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
Capped at 15 because of currently used encoding, which is also a reasonable limit because highest levels shine only on blocks much bigger than btrfs' 128KB. Memory is allocated for the biggest supported level rather than for what is actually used. Signed-off-by: Adam Borowski <redacted> --- fs/btrfs/compression.c | 21 +++++++++++++++------ fs/btrfs/props.c | 2 +- fs/btrfs/super.c | 3 ++- fs/btrfs/zstd.c | 24 +++++++++++++++++++----- 4 files changed, 37 insertions(+), 13 deletions(-)
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 71782ec976c7..2d4337756fef 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c@@ -1091,13 +1091,22 @@ int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end) unsigned int btrfs_compress_str2level(const char *str) { - if (strncmp(str, "zlib", 4) != 0) + long level; + int max; + + if (strncmp(str, "zlib", 4) == 0) + max = 9; + else if (strncmp(str, "zstd", 4) == 0) + max = 15; // encoded on 4 bits, real max is 22 + else return 0; - if ('1' <= str[4] && str[4] <= '9' ) - return str[4] - '0'; - if (str[4] == ':' && '1' <= str[5] && str[5] <= '9') - return str[5] - '0'; + str += 4; + if (*str == ':') + str++; - return 0; + if (kstrtoul(str, 10, &level)) + return 0; + + return (level > max) ? 0 : level; }
diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
index f6a05f836629..2e35aa2b2d79 100644
--- a/fs/btrfs/props.c
+++ b/fs/btrfs/props.c@@ -414,7 +414,7 @@ static int prop_compression_apply(struct inode *inode, type = BTRFS_COMPRESS_LZO; else if (!strncmp("zlib", value, 4)) type = BTRFS_COMPRESS_ZLIB; - else if (!strncmp("zstd", value, len)) + else if (!strncmp("zstd", value, 4)) type = BTRFS_COMPRESS_ZSTD; else return -EINVAL;
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 537e04120457..f9d4522336db 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c@@ -515,9 +515,10 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options, btrfs_clear_opt(info->mount_opt, NODATASUM); btrfs_set_fs_incompat(info, COMPRESS_LZO); no_compress = 0; - } else if (strcmp(args[0].from, "zstd") == 0) { + } else if (strncmp(args[0].from, "zstd", 4) == 0) { compress_type = "zstd"; info->compress_type = BTRFS_COMPRESS_ZSTD; + info->compress_level = btrfs_compress_str2level(args[0].from); btrfs_set_opt(info->mount_opt, COMPRESS); btrfs_clear_opt(info->mount_opt, NODATACOW); btrfs_clear_opt(info->mount_opt, NODATASUM);
diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index 607ce47b483a..99e11cb2d60e 100644
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c@@ -26,11 +26,14 @@ #define ZSTD_BTRFS_MAX_WINDOWLOG 17 #define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG) #define ZSTD_BTRFS_DEFAULT_LEVEL 3 +// Max supported by the algorithm is 22, but gains for small blocks (128KB) +// are limited, thus we cap at 15. +#define ZSTD_BTRFS_MAX_LEVEL 15 -static ZSTD_parameters zstd_get_btrfs_parameters(size_t src_len) +static ZSTD_parameters zstd_get_btrfs_parameters(size_t src_len, int level) { - ZSTD_parameters params = ZSTD_getParams(ZSTD_BTRFS_DEFAULT_LEVEL, - src_len, 0); + ZSTD_parameters params = ZSTD_getParams(level, src_len, 0); + BUG_ON(level > ZSTD_maxCLevel()); if (params.cParams.windowLog > ZSTD_BTRFS_MAX_WINDOWLOG) params.cParams.windowLog = ZSTD_BTRFS_MAX_WINDOWLOG;
@@ -43,6 +46,7 @@ struct workspace { size_t size; char *buf; struct list_head list; + int level; }; static void zstd_free_workspace(struct list_head *ws)
@@ -57,7 +61,8 @@ static void zstd_free_workspace(struct list_head *ws) static struct list_head *zstd_alloc_workspace(void) { ZSTD_parameters params = - zstd_get_btrfs_parameters(ZSTD_BTRFS_MAX_INPUT); + zstd_get_btrfs_parameters(ZSTD_BTRFS_MAX_INPUT, + ZSTD_BTRFS_MAX_LEVEL); struct workspace *workspace; workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
@@ -101,7 +106,7 @@ static int zstd_compress_pages(struct list_head *ws, unsigned long len = *total_out; const unsigned long nr_dest_pages = *out_pages; unsigned long max_out = nr_dest_pages * PAGE_SIZE; - ZSTD_parameters params = zstd_get_btrfs_parameters(len); + ZSTD_parameters params = zstd_get_btrfs_parameters(len, workspace->level); *out_pages = 0; *total_out = 0;
@@ -423,10 +428,19 @@ static int zstd_decompress(struct list_head *ws, unsigned char *data_in, return ret; } +static void zstd_set_level(struct list_head *ws, unsigned int type) +{ + struct workspace *workspace = list_entry(ws, struct workspace, list); + unsigned level = (type & 0xF0) >> 4; + + workspace->level = level > 0 ? level : ZSTD_BTRFS_DEFAULT_LEVEL; +} + const struct btrfs_compress_op btrfs_zstd_compress = { .alloc_workspace = zstd_alloc_workspace, .free_workspace = zstd_free_workspace, .compress_pages = zstd_compress_pages, .decompress_bio = zstd_decompress_bio, .decompress = zstd_decompress, + .set_level = zstd_set_level, };
--
2.14.1