erofs: add on-disk compression configurations
Add a bitmap for available compression algorithms and a variable-sized
on-disk table for compression options in preparation for upcoming big
pcluster and LZMA algorithm, which follows the end of super block.
To parse the compression options, the bitmap is scanned one by one.
For each available algorithm, there is data followed by 2-byte `length'
correspondingly (it's enough for most cases, or entire fs blocks should
be used.)
With such available algorithm bitmap, kernel itself can also refuse to
mount such filesystem if any unsupported compression algorithm exists.
Note that COMPR_CFGS feature will be enabled with BIG_PCLUSTER.
Link: https://lore.kernel.org/r/20210329100012.12980-1-hsiangkao@aol.com
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index b02fc64..60063bb 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -75,6 +75,7 @@ struct erofs_sb_info {
struct xarray managed_pslots;
unsigned int shrinker_run_no;
+ u16 available_compr_algs;
/* pseudo inode to manage cached pages */
struct inode *managed_cache;
@@ -90,6 +91,7 @@ struct erofs_sb_info {
/* inode slot unit size in bit shift */
unsigned char islotbits;
+ u32 sb_size; /* total superblock size */
u32 build_time_nsec;
u64 build_time;
@@ -233,6 +235,7 @@ static inline bool erofs_sb_has_##name(struct erofs_sb_info *sbi) \
}
EROFS_FEATURE_FUNCS(lz4_0padding, incompat, INCOMPAT_LZ4_0PADDING)
+EROFS_FEATURE_FUNCS(compr_cfgs, incompat, INCOMPAT_COMPR_CFGS)
EROFS_FEATURE_FUNCS(sb_chksum, compat, COMPAT_SB_CHKSUM)
/* atomic flag definitions */
@@ -452,7 +455,7 @@ static inline int z_erofs_load_lz4_config(struct super_block *sb,
struct erofs_super_block *dsb,
struct z_erofs_lz4_cfgs *lz4, int len)
{
- if (lz4 || dsb->lz4_max_distance) {
+ if (lz4 || dsb->u1.lz4_max_distance) {
erofs_err(sb, "lz4 algorithm isn't enabled");
return -EINVAL;
}