Re: [PATCH v2 09/12] btrfs: change set_level() to bound the level passed in

Dennis Zhou
2019-02-06T16:49:01Z

From ef64a8d1f4ec44f52bd13a825288a91667121708 Mon Sep 17 00:00:00 2001
From: Dennis Zhou <dennis@kernel.org>
Date: Thu, 17 Jan 2019 12:13:27 -0800

Currently, the only user of set_level() is zlib which sets an internal
workspace parameter. As level is now plumbed into get_workspace(), this
can be handled there rather than separately.

This repurposes set_level() to bound the level passed in so it can be
used when setting the mounts compression level and as well as verifying
the level before getting a workspace. The other benefit is this divides
the meaning of compress(0) and get_workspace(0). The former means we
want to use the default compression level of the compression type. The
latter means we can use any workspace available.

Signed-off-by: Dennis Zhou <dennis@kernel.org>
---
v2:
- warn on bad level format eg: zlib:c100
- warn on level out of bounds eg: zlib:10

fs/btrfs/compression.c | 27 +++++++++++++++++++--------
fs/btrfs/compression.h | 10 ++++++++--
fs/btrfs/lzo.c | 3 ++-
fs/btrfs/super.c | 4 +++-
fs/btrfs/zlib.c | 21 ++++++++++++++-------
fs/btrfs/zstd.c | 3 ++-
6 files changed, 48 insertions(+), 20 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index a54b210739bc..560a926c2e2f 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -1007,8 +1007,6 @@ int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
int ret;

workspace = get_workspace(type, level);
-
- btrfs_compress_op[type]->set_level(workspace, level);
ret = btrfs_compress_op[type]->compress_pages(workspace, mapping,
start, pages,
out_pages,
@@ -1561,14 +1559,27 @@ int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end)
return ret;
}

-unsigned int btrfs_compress_str2level(const char *str)
+unsigned int btrfs_compress_str2level(unsigned int type, const char *str)
{
- if (strncmp(str, "zlib", 4) != 0)
+ unsigned int level = 0;
+ int ret;
+
+ if (!type)
return 0;

- /* Accepted form: zlib:1 up to zlib:9 and nothing left after the number */
- if (str[4] == ':' && '1' <= str[5] && str[5] <= '9' && str[6] == 0)
- return str[5] - '0';
+ if (str[0] == ':') {
+ if (str[1] != '+') {
+ ret = kstrtouint(str + 1, 10, &level);
+ if (!ret)
+ goto set_level;
+ }
+
+ pr_warn("BTRFS: invalid compression level %s, using default",
+ str + 1);
+ }
+
+set_level:
+ level = btrfs_compress_op[type]->set_level(level);

- return BTRFS_ZLIB_DEFAULT_LEVEL;
+ return level;
}
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index 32ba40ebae1d..3f2d36b0aabe 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -97,7 +97,7 @@ blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
int mirror_num, unsigned long bio_flags);

-unsigned btrfs_compress_str2level(const char *str);
+unsigned int btrfs_compress_str2level(unsigned int type, const char *str);

enum btrfs_compression_type {
BTRFS_COMPRESS_NONE = 0,
@@ -156,7 +156,13 @@ struct btrfs_compress_op {
unsigned long start_byte,
size_t srclen, size_t destlen);

- void (*set_level)(struct list_head *ws, unsigned int type);
+ /*
+ * This bounds the level set by the user to be within range of
+ * a particular compression type. It returns the level that
+ * will be used if the level is out of bounds or the default
+ * if 0 is passed in.
+ */
+ unsigned int (*set_level)(unsigned int level);
};

/* the heuristic workspaces are managed via the 0th workspace manager */
diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c
index f132af45a924..579d53ae256f 100644
--- a/fs/btrfs/lzo.c
+++ b/fs/btrfs/lzo.c
@@ -507,8 +507,9 @@ static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
return ret;
}

-static void lzo_set_level(struct list_head *ws, unsigned int type)
+static unsigned int lzo_set_level(unsigned int level)
{
+ return 0;
}

const struct btrfs_compress_op btrfs_lzo_compress = {
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index c5586ffd1426..b28dff207383 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -529,7 +529,9 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
if (token != Opt_compress &&
token != Opt_compress_force)
info->compress_level =
- btrfs_compress_str2level(args[0].from);
+ btrfs_compress_str2level(
+ BTRFS_COMPRESS_ZLIB,
+ args[0].from + 4);
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/zlib.c b/fs/btrfs/zlib.c
index c0ef09bef3b3..439dad221e9a 100644
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -41,7 +41,12 @@ static void zlib_cleanup_workspace_manager(void)

static struct list_head *zlib_get_workspace(unsigned int level)
{
- return btrfs_get_workspace(&wsm, level);
+ struct list_head *ws = btrfs_get_workspace(&wsm, level);
+ struct workspace *workspace = list_entry(ws, struct workspace, list);
+
+ workspace->level = level;
+
+ return ws;
}

static void zlib_put_workspace(struct list_head *ws)
@@ -413,15 +418,17 @@ static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
return ret;
}

-static void zlib_set_level(struct list_head *ws, unsigned int type)
+static unsigned int zlib_set_level(unsigned int level)
{
- struct workspace *workspace = list_entry(ws, struct workspace, list);
- unsigned int level = btrfs_compress_level(type);
-
- if (level > 9)
+ if (!level) {
+ return BTRFS_ZLIB_DEFAULT_LEVEL;
+ } else if (level > 9) {
level = 9;
+ pr_warn("BTRFS: zlib level > max level, using max level: %u",
+ level);
+ }

- workspace->level = level > 0 ? level : 3;
+ return level;
}

const struct btrfs_compress_op btrfs_zlib_compress = {
diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index 404101864220..43f3be755b8c 100644
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c
@@ -441,8 +441,9 @@ 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)
+static unsigned int zstd_set_level(unsigned int level)
{
+ return ZSTD_BTRFS_DEFAULT_LEVEL;
}

const struct btrfs_compress_op btrfs_zstd_compress = {
--
2.17.1