Re: [PATCH v2 1/8] staging: erofs: add compacted ondisk compression indexes

From: Chao Yu
Date: Fri Jun 21 2019 - 03:46:56 EST

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On 2019/6/21 0:07, Gao Xiang wrote:
> This patch introduces new compacted compression indexes.
>
> In contract to legacy compression indexes that
> each 4k logical cluster has an 8-byte index,
> compacted ondisk compression indexes will have
> amortized 2 bytes for each 4k logical cluster (compacted 2B)
> amortized 4 bytes for each 4k logical cluster (compacted 4B)
>
> In detail, several continuous clusters will be encoded in
> a compacted pack with cluster types, offsets, and one blkaddr
> at the end of the pack to leave 4-byte margin for better
> decoding performance, as illustrated below:
> _____________________________________________
> |___@_____ encoded bits __________|_ blkaddr _|
> 0 . amortized * vcnt
> . .
> . . amortized * vcnt - 4
> . .
> .___________________.
> |_type_|_clusterofs_|
>
> Note that compacted 2 / 4B should be aligned with 32 / 8 bytes
> in order to avoid each pack crossing page boundary.
>
> Signed-off-by: Gao Xiang <gaoxiang25@xxxxxxxxxx>
> ---
> drivers/staging/erofs/data.c | 4 +--
> drivers/staging/erofs/erofs_fs.h | 57 +++++++++++++++++++++++++------
> drivers/staging/erofs/inode.c | 5 +--
> drivers/staging/erofs/internal.h | 11 ++----
> drivers/staging/erofs/unzip_vle.c | 8 ++---
> 5 files changed, 56 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/staging/erofs/data.c b/drivers/staging/erofs/data.c
> index 746685f90564..cc31c3e5984c 100644
> --- a/drivers/staging/erofs/data.c
> +++ b/drivers/staging/erofs/data.c
> @@ -124,7 +124,7 @@ static int erofs_map_blocks_flatmode(struct inode *inode,
> trace_erofs_map_blocks_flatmode_enter(inode, map, flags);
>
> nblocks = DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
> - lastblk = nblocks - is_inode_layout_inline(inode);
> + lastblk = nblocks - is_inode_flat_inline(inode);
>
> if (unlikely(offset >= inode->i_size)) {
> /* leave out-of-bound access unmapped */
> @@ -139,7 +139,7 @@ static int erofs_map_blocks_flatmode(struct inode *inode,
> if (offset < blknr_to_addr(lastblk)) {
> map->m_pa = blknr_to_addr(vi->raw_blkaddr) + map->m_la;
> map->m_plen = blknr_to_addr(lastblk) - offset;
> - } else if (is_inode_layout_inline(inode)) {
> + } else if (is_inode_flat_inline(inode)) {
> /* 2 - inode inline B: inode, [xattrs], inline last blk... */
> struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
>
> diff --git a/drivers/staging/erofs/erofs_fs.h b/drivers/staging/erofs/erofs_fs.h
> index 8ddb2b3e7d39..a05139f1df60 100644
> --- a/drivers/staging/erofs/erofs_fs.h
> +++ b/drivers/staging/erofs/erofs_fs.h
> @@ -49,19 +49,29 @@ struct erofs_super_block {
> * erofs inode data mapping:
> * 0 - inode plain without inline data A:
> * inode, [xattrs], ... | ... | no-holed data
> - * 1 - inode VLE compression B:
> + * 1 - inode VLE compression B (legacy):
> * inode, [xattrs], extents ... | ...
> * 2 - inode plain with inline data C:
> * inode, [xattrs], last_inline_data, ... | ... | no-holed data
> - * 3~7 - reserved
> + * 3 - inode compression D:
> + * inode, [xattrs], map_header, extents ... | ...
> + * 4~7 - reserved
> */
> enum {
> - EROFS_INODE_LAYOUT_PLAIN,
> - EROFS_INODE_LAYOUT_COMPRESSION,
> - EROFS_INODE_LAYOUT_INLINE,
> + EROFS_INODE_FLAT_PLAIN,
> + EROFS_INODE_FLAT_COMPRESSION_LEGACY,
> + EROFS_INODE_FLAT_INLINE,
> + EROFS_INODE_FLAT_COMPRESSION,
> EROFS_INODE_LAYOUT_MAX
> };
>
> +static bool erofs_inode_is_data_compressed(unsigned int datamode)
> +{
> + if (datamode == EROFS_INODE_FLAT_COMPRESSION)
> + return true;
> + return datamode == EROFS_INODE_FLAT_COMPRESSION_LEGACY;
> +}
> +
> /* bit definitions of inode i_advise */
> #define EROFS_I_VERSION_BITS 1
> #define EROFS_I_DATA_MAPPING_BITS 3
> @@ -176,11 +186,37 @@ struct erofs_xattr_entry {
> sizeof(struct erofs_xattr_entry) + \
> (entry)->e_name_len + le16_to_cpu((entry)->e_value_size))
>
> -/* have to be aligned with 8 bytes on disk */
> -struct erofs_extent_header {
> - __le32 eh_checksum;
> - __le32 eh_reserved[3];
> -} __packed;
> +/* available compression algorithm types */
> +enum {
> + Z_EROFS_COMPRESSION_LZ4,
> + Z_EROFS_COMPRESSION_MAX
> +};
> +
> +/*
> + * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
> + * e.g. for 4k logical cluster size, 4B if compacted 2B is off;
> + * (4B) + 2B + (4B) if compacted 2B is on.
> + */
> +#define Z_EROFS_ADVISE_COMPACTED_2B_BIT 0
> +
> +#define Z_EROFS_ADVISE_COMPACTED_2B (1 << Z_EROFS_ADVISE_COMPACTED_2B_BIT)
> +
> +struct z_erofs_map_header {
> + __le32 h_reserved1;
> + __le16 h_advise;
> + /*
> + * bit 0-3 : algorithm type of head 1 (logical cluster type 01);
> + * bit 4-7 : algorithm type of head 2 (logical cluster type 11).
> + */
> + __u8 h_algorithmtype;
> + /*
> + * bit 0-2 : logical cluster bits - 12, e.g. 0 for 4096;
> + * bit 3-4 : (physical - logical) cluster bits of head 1:
> + * For example, if logical clustersize = 4096, 1 for 8192.
> + * bit 5-7 : (physical - logical) cluster bits of head 2.
> + */
> + __u8 h_clusterbits;
> +};
>
> /*
> * Z_EROFS Variable-sized Logical Extent cluster type:
> @@ -270,7 +306,6 @@ static inline void erofs_check_ondisk_layout_definitions(void)
> BUILD_BUG_ON(sizeof(struct erofs_inode_v2) != 64);
> BUILD_BUG_ON(sizeof(struct erofs_xattr_ibody_header) != 12);
> BUILD_BUG_ON(sizeof(struct erofs_xattr_entry) != 4);
> - BUILD_BUG_ON(sizeof(struct erofs_extent_header) != 16);
> BUILD_BUG_ON(sizeof(struct z_erofs_vle_decompressed_index) != 8);
> BUILD_BUG_ON(sizeof(struct erofs_dirent) != 12);
>
> diff --git a/drivers/staging/erofs/inode.c b/drivers/staging/erofs/inode.c
> index e51348f7e838..3539290b8e45 100644
> --- a/drivers/staging/erofs/inode.c
> +++ b/drivers/staging/erofs/inode.c
> @@ -127,12 +127,9 @@ static int fill_inline_data(struct inode *inode, void *data,
> {
> struct erofs_vnode *vi = EROFS_V(inode);
> struct erofs_sb_info *sbi = EROFS_I_SB(inode);
> - const int mode = vi->datamode;
> -
> - DBG_BUGON(mode >= EROFS_INODE_LAYOUT_MAX);
>
> /* should be inode inline C */
> - if (mode != EROFS_INODE_LAYOUT_INLINE)
> + if (!is_inode_flat_inline(inode))
> return 0;
>
> /* fast symlink (following ext4) */
> diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
> index 1666cceecb3c..c851d0be6cf6 100644
> --- a/drivers/staging/erofs/internal.h
> +++ b/drivers/staging/erofs/internal.h
> @@ -382,19 +382,14 @@ static inline unsigned long inode_datablocks(struct inode *inode)
> return DIV_ROUND_UP(inode->i_size, EROFS_BLKSIZ);
> }
>
> -static inline bool is_inode_layout_plain(struct inode *inode)
> -{
> - return EROFS_V(inode)->datamode == EROFS_INODE_LAYOUT_PLAIN;
> -}
> -
> static inline bool is_inode_layout_compression(struct inode *inode)
> {
> - return EROFS_V(inode)->datamode == EROFS_INODE_LAYOUT_COMPRESSION;
> + return erofs_inode_is_data_compressed(EROFS_V(inode)->datamode);
> }
>
> -static inline bool is_inode_layout_inline(struct inode *inode)
> +static inline bool is_inode_flat_inline(struct inode *inode)
> {
> - return EROFS_V(inode)->datamode == EROFS_INODE_LAYOUT_INLINE;
> + return EROFS_V(inode)->datamode == EROFS_INODE_FLAT_INLINE;
> }
>
> extern const struct super_operations erofs_sops;
> diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
> index f3d0d2c03939..0db9bc50f67c 100644
> --- a/drivers/staging/erofs/unzip_vle.c
> +++ b/drivers/staging/erofs/unzip_vle.c
> @@ -1643,8 +1643,8 @@ vle_extent_blkaddr(struct inode *inode, pgoff_t index)
> struct erofs_vnode *vi = EROFS_V(inode);
>
> unsigned int ofs = Z_EROFS_VLE_EXTENT_ALIGN(vi->inode_isize +
> - vi->xattr_isize) + sizeof(struct erofs_extent_header) +
> - index * sizeof(struct z_erofs_vle_decompressed_index);
> + vi->xattr_isize) +
> + 16 + index * sizeof(struct z_erofs_vle_decompressed_index);
>
> return erofs_blknr(iloc(sbi, vi->nid) + ofs);
> }
> @@ -1656,8 +1656,8 @@ vle_extent_blkoff(struct inode *inode, pgoff_t index)
> struct erofs_vnode *vi = EROFS_V(inode);
>
> unsigned int ofs = Z_EROFS_VLE_EXTENT_ALIGN(vi->inode_isize +
> - vi->xattr_isize) + sizeof(struct erofs_extent_header) +
> - index * sizeof(struct z_erofs_vle_decompressed_index);
> + vi->xattr_isize) +
> + 16 + index * sizeof(struct z_erofs_vle_decompressed_index);

We can add one macro to wrap above offset (16) for better readability, anyway,
this patch looks good to me. :)

Reviewed-by: Chao Yu <yuchao0@xxxxxxxxxx>

Thanks,

>
> return erofs_blkoff(iloc(sbi, vi->nid) + ofs);
> }
>

Next message: Lowry Li (Arm Technology China): "[PATCH] drm/komeda: Adds system power management support"
Previous message: Mathieu Malaterre: "Re: [PATCH] crypto: Fix build for clang"
In reply to: Gao Xiang: "[PATCH v2 1/8] staging: erofs: add compacted ondisk compression indexes"
Next in thread: Gao Xiang: "Re: [PATCH v2 1/8] staging: erofs: add compacted ondisk compression indexes"
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