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.
This feature is enabled only when xattr_filter_reserved is non-zero.
The on-disk format for the filter map 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 <jeffl...@linux.alibaba.com>
---
fs/erofs/internal.h | 3 +++
fs/erofs/super.c | 1 +
fs/erofs/xattr.c | 13 +++++++++++++
3 files changed, 17 insertions(+)
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 36e32fa542f0..ebcad25e3750 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -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 long xattr_name_filter;
unsigned int xattr_shared_count;
unsigned int *xattr_shared_xattrs;
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 9d6a3c6158bd..72122323300e 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -388,6 +388,7 @@ 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);
diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index 40178b6e0688..eb1d1974d4b3 100644
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -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;
+ uint32_t bit;
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 +406,14 @@ int erofs_getxattr(struct inode *inode, int index, const
char *name,
if (ret)
return ret;
+ /* the reserved flag is non-zero if hashing algorithm changes */
+ if (erofs_sb_has_xattr_filter(sbi) && !sbi->xattr_filter_reserved) {
+ bit = xxh32(name, strlen(name), EROFS_XATTR_FILTER_SEED +
index);
+ bit &= EROFS_XATTR_FILTER_BITS - 1;
+ if (test_bit(bit, &vi->xattr_name_filter))
+ return -ENOATTR;
+ }
+
it.index = index;
it.name = (struct qstr)QSTR_INIT(name, strlen(name));
if (it.name.len > EROFS_NAME_LEN)
--
2.19.1.6.gb485710b
