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Subject[PATCH 3/4] erofs: introduce on-disk lz4 fs configurations
Date
From: Gao Xiang <hsiangkao@redhat.com>

Introduce z_erofs_lz4_cfgs to store all lz4 configurations.
Currently it's only max_distance, but will be used for new
features later.

Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
---
fs/erofs/decompressor.c | 15 +++++++++++++--
fs/erofs/erofs_fs.h | 6 ++++++
fs/erofs/internal.h | 8 +++++---
fs/erofs/super.c | 2 +-
4 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index 93411e9df9b6..97538ff24a19 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -29,9 +29,20 @@ struct z_erofs_decompressor {
};

int z_erofs_load_lz4_config(struct super_block *sb,
- struct erofs_super_block *dsb)
+ struct erofs_super_block *dsb,
+ struct z_erofs_lz4_cfgs *lz4, int size)
{
- u16 distance = le16_to_cpu(dsb->lz4_max_distance);
+ u16 distance;
+
+ if (lz4) {
+ if (size < sizeof(struct z_erofs_lz4_cfgs)) {
+ erofs_err(sb, "invalid lz4 cfgs, size=%u", size);
+ return -EINVAL;
+ }
+ distance = le16_to_cpu(lz4->max_distance);
+ } else {
+ distance = le16_to_cpu(dsb->lz4_max_distance);
+ }

EROFS_SB(sb)->lz4.max_distance_pages = distance ?
DIV_ROUND_UP(distance, PAGE_SIZE) + 1 :
diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h
index b27d0e4e4ab5..1322ae63944b 100644
--- a/fs/erofs/erofs_fs.h
+++ b/fs/erofs/erofs_fs.h
@@ -196,6 +196,12 @@ enum {
Z_EROFS_COMPRESSION_MAX
};

+/* 14 bytes (+ length field = 16 bytes) */
+struct z_erofs_lz4_cfgs {
+ __le16 max_distance;
+ u8 reserved[12];
+} __packed;
+
/*
* bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
* e.g. for 4k logical cluster size, 4B if compacted 2B is off;
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 1de60992c3dd..46b977f348eb 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -441,7 +441,8 @@ int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
int erofs_try_to_free_cached_page(struct address_space *mapping,
struct page *page);
int z_erofs_load_lz4_config(struct super_block *sb,
- struct erofs_super_block *dsb);
+ struct erofs_super_block *dsb,
+ struct z_erofs_lz4_cfgs *lz4, int len);
#else
static inline void erofs_shrinker_register(struct super_block *sb) {}
static inline void erofs_shrinker_unregister(struct super_block *sb) {}
@@ -450,9 +451,10 @@ static inline void erofs_exit_shrinker(void) {}
static inline int z_erofs_init_zip_subsystem(void) { return 0; }
static inline void z_erofs_exit_zip_subsystem(void) {}
static inline int z_erofs_load_lz4_config(struct super_block *sb,
- struct erofs_super_block *dsb)
+ struct erofs_super_block *dsb,
+ struct z_erofs_lz4_cfgs *lz4, int len)
{
- if (dsb->lz4_max_distance) {
+ if (lz4 || dsb->lz4_max_distance) {
erofs_err(sb, "lz4 algorithm isn't enabled");
return -EINVAL;
}
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 3212e4f73f85..1ca8da3f2125 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -189,7 +189,7 @@ static int erofs_read_superblock(struct super_block *sb)
}

/* parse on-disk compression configurations */
- ret = z_erofs_load_lz4_config(sb, dsb);
+ ret = z_erofs_load_lz4_config(sb, dsb, NULL, 0);
out:
kunmap(page);
put_page(page);
--
2.20.1
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