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btrfs: switch compression callbacks to direct calls

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The indirect calls bring some overhead due to spectre vulnerability
mitigations. The number of cases is small and below the threshold
(10-20) where indirect call would be better.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba
2019-10-02 00:06:15 +02:00
parent c4bf665a31
commit 1e4eb74654
5 changed files with 69 additions and 34 deletions
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77
fs/btrfs/compression.c
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@@ -86,6 +86,70 @@ bool btrfs_compress_is_valid_type(const char *str, size_t len)
return false;
}
static int compression_compress_pages(int type, struct list_head *ws,
struct address_space *mapping, u64 start, struct page **pages,
unsigned long *out_pages, unsigned long *total_in,
unsigned long *total_out)
{
switch (type) {
case BTRFS_COMPRESS_ZLIB:
return zlib_compress_pages(ws, mapping, start, pages,
out_pages, total_in, total_out);
case BTRFS_COMPRESS_LZO:
return lzo_compress_pages(ws, mapping, start, pages,
out_pages, total_in, total_out);
case BTRFS_COMPRESS_ZSTD:
return zstd_compress_pages(ws, mapping, start, pages,
out_pages, total_in, total_out);
case BTRFS_COMPRESS_NONE:
default:
/*
* This can't happen, the type is validated several times
* before we get here. As a sane fallback, return what the
* callers will understand as 'no compression happened'.
*/
return -E2BIG;
}
}
static int compression_decompress_bio(int type, struct list_head *ws,
struct compressed_bio *cb)
{
switch (type) {
case BTRFS_COMPRESS_ZLIB: return zlib_decompress_bio(ws, cb);
case BTRFS_COMPRESS_LZO: return lzo_decompress_bio(ws, cb);
case BTRFS_COMPRESS_ZSTD: return zstd_decompress_bio(ws, cb);
case BTRFS_COMPRESS_NONE:
default:
/*
* This can't happen, the type is validated several times
* before we get here.
*/
BUG();
}
}
static int compression_decompress(int type, struct list_head *ws,
unsigned char *data_in, struct page *dest_page,
unsigned long start_byte, size_t srclen, size_t destlen)
{
switch (type) {
case BTRFS_COMPRESS_ZLIB: return zlib_decompress(ws, data_in, dest_page,
start_byte, srclen, destlen);
case BTRFS_COMPRESS_LZO: return lzo_decompress(ws, data_in, dest_page,
start_byte, srclen, destlen);
case BTRFS_COMPRESS_ZSTD: return zstd_decompress(ws, data_in, dest_page,
start_byte, srclen, destlen);
case BTRFS_COMPRESS_NONE:
default:
/*
* This can't happen, the type is validated several times
* before we get here.
*/
BUG();
}
}
static int btrfs_decompress_bio(struct compressed_bio *cb);
static inline int compressed_bio_size(struct btrfs_fs_info *fs_info,
@@ -1074,10 +1138,8 @@ int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
level = btrfs_compress_set_level(type, level);
workspace = get_workspace(type, level);
ret = btrfs_compress_op[type]->compress_pages(workspace, mapping,
start, pages,
out_pages,
total_in, total_out);
ret = compression_compress_pages(type, workspace, mapping, start, pages,
out_pages, total_in, total_out);
put_workspace(type, workspace);
return ret;
}
@@ -1103,7 +1165,7 @@ static int btrfs_decompress_bio(struct compressed_bio *cb)
int type = cb->compress_type;
workspace = get_workspace(type, 0);
ret = btrfs_compress_op[type]->decompress_bio(workspace, cb);
ret = compression_decompress_bio(type, workspace, cb);
put_workspace(type, workspace);
return ret;
@@ -1121,9 +1183,8 @@ int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
int ret;
workspace = get_workspace(type, 0);
ret = btrfs_compress_op[type]->decompress(workspace, data_in,
dest_page, start_byte,
srclen, destlen);
ret = compression_decompress(type, workspace, data_in, dest_page,
start_byte, srclen, destlen);
put_workspace(type, workspace);
return ret;