On 07/25/2017 01:29 AM, David Sterba wrote:
> Preliminary support for setting compression level for zlib, the
> following works:
Thanks for working on this, I think it is a great feature.
I have a few comments relating to how it would work with zstd.
>
> $ 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 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@xxxxxxxx>
> ---
> fs/btrfs/compression.c | 20 +++++++++++++++++++-
> fs/btrfs/compression.h | 6 +++++-
> fs/btrfs/ctree.h | 1 +
> fs/btrfs/inode.c | 5 ++++-
> fs/btrfs/lzo.c | 5 +++++
> fs/btrfs/super.c | 7 +++++--
> fs/btrfs/zlib.c | 12 +++++++++++-
> 7 files changed, 50 insertions(+), 6 deletions(-)
>
> diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
> index 8ba1b86c9b72..142206d68495 100644
> --- a/fs/btrfs/compression.c
> +++ b/fs/btrfs/compression.c
> @@ -866,6 +866,11 @@ static void free_workspaces(void)
> * Given an address space and start and length, compress the bytes into @pages
> * that are allocated on demand.
> *
> + * @type_level is encoded algorithm and level, where level 0 means whatever
> + * default the algorithm chooses and is opaque here;
> + * - compression algo are 0-3
> + * - the level are bits 4-7
zstd has 19 levels, but we can either only allow the first 15 + default, or
provide a mapping from zstd-level to BtrFS zstd-level.
> + *
> * @out_pages is an in/out parameter, holds maximum number of pages to allocate
> * and returns number of actually allocated pages
> *
> @@ -880,7 +885,7 @@ static void free_workspaces(void)
> * @max_out tells us the max number of bytes that we're allowed to
> * stuff into pages
> */
> -int btrfs_compress_pages(int type, struct address_space *mapping,
> +int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
> u64 start, struct page **pages,
> unsigned long *out_pages,
> unsigned long *total_in,
> @@ -888,9 +893,11 @@ int btrfs_compress_pages(int type, struct address_space *mapping,
> {
> struct list_head *workspace;
> int ret;
> + int type = type_level & 0xF;
>
> workspace = find_workspace(type);
>
> + btrfs_compress_op[type - 1]->set_level(workspace, type_level);
zlib uses the same amount of memory independently of the compression level,
but zstd uses a different amount of memory for each level. zstd will have
to allocate memory here if it doesn't have enough (or has way to much),
will that be okay?
> ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
> start, pages,
> out_pages,
> @@ -1047,3 +1054,14 @@ int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
>
> return 1;
> }
> +
> +unsigned int btrfs_compress_str2level(const char *str)
> +{
> + if (strncmp(str, "zlib", 4) != 0)
> + return 0;
> +
> + if ('1' <= str[4] && str[4] <= '9' )
> + return str[4] - '0';
> +
> + return 0;
> +}
> diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
> index 89bcf975efb8..8a6db02d8732 100644
> --- a/fs/btrfs/compression.h
> +++ b/fs/btrfs/compression.h
> @@ -76,7 +76,7 @@ struct compressed_bio {
> void btrfs_init_compress(void);
> void btrfs_exit_compress(void);
>
> -int btrfs_compress_pages(int type, struct address_space *mapping,
> +int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
> u64 start, struct page **pages,
> unsigned long *out_pages,
> unsigned long *total_in,
> @@ -95,6 +95,8 @@ int btrfs_submit_compressed_write(struct inode *inode, u64 start,
> int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
> int mirror_num, unsigned long bio_flags);
>
> +unsigned btrfs_compress_str2level(const char *str);
> +
> enum btrfs_compression_type {
> BTRFS_COMPRESS_NONE = 0,
> BTRFS_COMPRESS_ZLIB = 1,
> @@ -124,6 +126,8 @@ struct btrfs_compress_op {
> struct page *dest_page,
> unsigned long start_byte,
> size_t srclen, size_t destlen);
> +
> + void (*set_level)(struct list_head *ws, unsigned int type);
> };
>
> extern const struct btrfs_compress_op btrfs_zlib_compress;
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 5bdd36664421..3393aed07132 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -791,6 +791,7 @@ struct btrfs_fs_info {
> */
> unsigned long pending_changes;
> unsigned long compress_type:4;
> + unsigned int compress_level;
> int commit_interval;
> /*
> * It is a suggestive number, the read side is safe even it gets a
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index eb495e956d53..a832bf8cebab 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -525,7 +525,10 @@ static noinline void compress_file_range(struct inode *inode,
> */
> extent_range_clear_dirty_for_io(inode, start, end);
> redirty = 1;
> - ret = btrfs_compress_pages(compress_type,
> +
> + /* Compression level is applied here and only here */
> + ret = btrfs_compress_pages(
> + compress_type | (fs_info->compress_level << 4),
> inode->i_mapping, start,
> pages,
> &nr_pages,
> diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c
> index d433e75d489a..6c7f18cd3b61 100644
> --- a/fs/btrfs/lzo.c
> +++ b/fs/btrfs/lzo.c
> @@ -430,10 +430,15 @@ 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)
> +{
> +}
> +
> const struct btrfs_compress_op btrfs_lzo_compress = {
> .alloc_workspace = lzo_alloc_workspace,
> .free_workspace = lzo_free_workspace,
> .compress_pages = lzo_compress_pages,
> .decompress_bio = lzo_decompress_bio,
> .decompress = lzo_decompress,
> + .set_level = lzo_set_level,
> };
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 147330454c17..25ffebb101c9 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -501,6 +501,7 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
> strncmp(args[0].from, "zlib", 4) == 0) {
> compress_type = "zlib";
> info->compress_type = BTRFS_COMPRESS_ZLIB;
> + 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);
> @@ -540,9 +541,9 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
> compress_force != saved_compress_force)) ||
> (!btrfs_test_opt(info, COMPRESS) &&
> no_compress == 1)) {
> - btrfs_info(info, "%s %s compression",
> + btrfs_info(info, "%s %s compression, level %d",
> (compress_force) ? "force" : "use",
> - compress_type);
> + compress_type, info->compress_level);
> }
> compress_force = false;
> break;
> @@ -1234,6 +1235,8 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
> seq_printf(seq, ",compress-force=%s", compress_type);
> else
> seq_printf(seq, ",compress=%s", compress_type);
> + if (info->compress_level)
> + seq_printf(seq, "%d", info->compress_level);
> }
> if (btrfs_test_opt(info, NOSSD))
> seq_puts(seq, ",nossd");
> diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
> index c248f9286366..c890032e680f 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 +403,19 @@ 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)
> +{
> + struct workspace *workspace = list_entry(ws, struct workspace, list);
> + unsigned level = (type & 0xF0) >> 4;
> +
> + 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,
> };
> --
> 2.13.0
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