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erofs: boost negative xattr lookup with bloom filter

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Optimise the negative xattr lookup with bloom filter.

The bit value for the bloom filter map has a reverse semantics for
compatibility.  That is, the bit value of 0 indicates existence, while
the bit value of 1 indicates the absence of corresponding xattr.

The initial version is _only_ enabled when xattr_filter_reserved is
zero.  The filter map internals may change in the future, in which case
the reserved flag will be set non-zero and we don't need bothering the
compatible bits again at that time.  For now disable the optimization if
this reserved flag is non-zero.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230722094538.11754-3-jefflexu@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
This commit is contained in:
Jingbo Xu 2023-07-22 17:45:38 +08:00 committed by Gao Xiang
parent 3f33992017
commit fd73a4395d
4 changed files with 19 additions and 0 deletions
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1
fs/erofs/Kconfig
View File

@ -38,6 +38,7 @@ config EROFS_FS_DEBUG
config EROFS_FS_XATTR
bool "EROFS extended attributes"
depends on EROFS_FS
select XXHASH
default y
help
Extended attributes are name:value pairs associated with inodes by

3
fs/erofs/internal.h
View File

@ -151,6 +151,7 @@ struct erofs_sb_info {
u32 xattr_prefix_start;
u8 xattr_prefix_count;
struct erofs_xattr_prefix_item *xattr_prefixes;
unsigned int xattr_filter_reserved;
#endif
u16 device_id_mask; /* valid bits of device id to be used */
@ -251,6 +252,7 @@ EROFS_FEATURE_FUNCS(fragments, incompat, INCOMPAT_FRAGMENTS)
EROFS_FEATURE_FUNCS(dedupe, incompat, INCOMPAT_DEDUPE)
EROFS_FEATURE_FUNCS(xattr_prefixes, incompat, INCOMPAT_XATTR_PREFIXES)
EROFS_FEATURE_FUNCS(sb_chksum, compat, COMPAT_SB_CHKSUM)
EROFS_FEATURE_FUNCS(xattr_filter, compat, COMPAT_XATTR_FILTER)
/* atomic flag definitions */
#define EROFS_I_EA_INITED_BIT 0
@ -270,6 +272,7 @@ struct erofs_inode {
unsigned char inode_isize;
unsigned int xattr_isize;
unsigned int xattr_name_filter;
unsigned int xattr_shared_count;
unsigned int *xattr_shared_xattrs;

1
fs/erofs/super.c
View File

@ -391,6 +391,7 @@ static int erofs_read_superblock(struct super_block *sb)
sbi->xattr_blkaddr = le32_to_cpu(dsb->xattr_blkaddr);
sbi->xattr_prefix_start = le32_to_cpu(dsb->xattr_prefix_start);
sbi->xattr_prefix_count = dsb->xattr_prefix_count;
sbi->xattr_filter_reserved = dsb->xattr_filter_reserved;
#endif
sbi->islotbits = ilog2(sizeof(struct erofs_inode_compact));
sbi->root_nid = le16_to_cpu(dsb->root_nid);

14
fs/erofs/xattr.c
View File

@ -5,6 +5,7 @@
* Copyright (C) 2021-2022, Alibaba Cloud
*/
#include <linux/security.h>
#include <linux/xxhash.h>
#include "xattr.h"
struct erofs_xattr_iter {
@ -87,6 +88,7 @@ static int erofs_init_inode_xattrs(struct inode *inode)
}
ih = it.kaddr + erofs_blkoff(sb, it.pos);
vi->xattr_name_filter = le32_to_cpu(ih->h_name_filter);
vi->xattr_shared_count = ih->h_shared_count;
vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
sizeof(uint), GFP_KERNEL);
@ -392,7 +394,10 @@ int erofs_getxattr(struct inode *inode, int index, const char *name,
void *buffer, size_t buffer_size)
{
int ret;
unsigned int hashbit;
struct erofs_xattr_iter it;
struct erofs_inode *vi = EROFS_I(inode);
struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
if (!name)
return -EINVAL;
@ -401,6 +406,15 @@ int erofs_getxattr(struct inode *inode, int index, const char *name,
if (ret)
return ret;
/* reserved flag is non-zero if there's any change of on-disk format */
if (erofs_sb_has_xattr_filter(sbi) && !sbi->xattr_filter_reserved) {
hashbit = xxh32(name, strlen(name),
EROFS_XATTR_FILTER_SEED + index);
hashbit &= EROFS_XATTR_FILTER_BITS - 1;
if (vi->xattr_name_filter & (1U << hashbit))
return -ENOATTR;
}
it.index = index;
it.name = (struct qstr)QSTR_INIT(name, strlen(name));
if (it.name.len > EROFS_NAME_LEN)