Re: [PATCH v4 5/5] erofs: use separate xattr parsers for listxattr/getxattr
From: Jingbo Xu
Date: Wed May 31 2023 - 04:31:29 EST
On 5/31/23 3:18 PM, Gao Xiang wrote:
>
>
> On 2023/5/31 11:13, Jingbo Xu wrote:
>> There's a callback styled xattr parser, i.e. xattr_foreach(), which is
>> shared among listxattr and getxattr. Convert it to two separate xattr
>> parsers for listxattr and getxattr.
>>
>> Signed-off-by: Jingbo Xu <jefflexu@xxxxxxxxxxxxxxxxx>
>> ---
>> fs/erofs/xattr.c | 372 ++++++++++++++++++++---------------------------
>> 1 file changed, 155 insertions(+), 217 deletions(-)
>>
>> diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
>> index 074743e2b271..438fcf22b230 100644
>> --- a/fs/erofs/xattr.c
>> +++ b/fs/erofs/xattr.c
>> @@ -12,7 +12,7 @@ struct erofs_xattr_iter {
>> struct erofs_buf buf;
>> void *kaddr;
>> erofs_blk_t blkaddr;
>> - unsigned int ofs;
>> + unsigned int ofs, next_ofs;
>> char *buffer;
>> int buffer_size, buffer_ofs;
>> @@ -141,183 +141,6 @@ static int erofs_init_inode_xattrs(struct inode
>> *inode)
>> return ret;
>> }
>> -/*
>> - * the general idea for these return values is
>> - * if 0 is returned, go on processing the current xattr;
>> - * 1 (> 0) is returned, skip this round to process the next xattr;
>> - * -err (< 0) is returned, an error (maybe ENOXATTR) occurred
>> - * and need to be handled
>> - */
>> -struct xattr_iter_handlers {
>> - int (*entry)(struct erofs_xattr_iter *it, struct
>> erofs_xattr_entry *entry);
>> - int (*name)(struct erofs_xattr_iter *it, unsigned int processed,
>> char *buf,
>> - unsigned int len);
>> - int (*alloc_buffer)(struct erofs_xattr_iter *it, unsigned int
>> value_sz);
>> - void (*value)(struct erofs_xattr_iter *it, unsigned int
>> processed, char *buf,
>> - unsigned int len);
>> -};
>> -
>> -/*
>> - * Regardless of success or failure, `xattr_foreach' will end up with
>> - * `ofs' pointing to the next xattr item rather than an arbitrary
>> position.
>> - */
>> -static int xattr_foreach(struct erofs_xattr_iter *it,
>> - const struct xattr_iter_handlers *op,
>> - unsigned int *tlimit)
>> -{
>> - struct erofs_xattr_entry entry;
>> - unsigned int value_sz, processed, slice;
>> - int err;
>> -
>> - /* 0. fixup blkaddr, ofs, ipage */
>> - err = erofs_xattr_iter_fixup(it, false);
>> - if (err)
>> - return err;
>> -
>> - /*
>> - * 1. read xattr entry to the memory,
>> - * since we do EROFS_XATTR_ALIGN
>> - * therefore entry should be in the page
>> - */
>> - entry = *(struct erofs_xattr_entry *)(it->kaddr + it->ofs);
>> - if (tlimit) {
>> - unsigned int entry_sz = erofs_xattr_entry_size(&entry);
>> -
>> - /* xattr on-disk corruption: xattr entry beyond xattr_isize */
>> - if (*tlimit < entry_sz) {
>> - DBG_BUGON(1);
>> - return -EFSCORRUPTED;
>> - }
>> - *tlimit -= entry_sz;
>> - }
>> -
>> - it->ofs += sizeof(struct erofs_xattr_entry);
>> - value_sz = le16_to_cpu(entry.e_value_size);
>> -
>> - /* handle entry */
>> - err = op->entry(it, &entry);
>> - if (err) {
>> - it->ofs += entry.e_name_len + value_sz;
>> - goto out;
>> - }
>> -
>> - /* 2. handle xattr name (ofs will finally be at the end of name) */
>> - processed = 0;
>> -
>> - while (processed < entry.e_name_len) {
>> - err = erofs_xattr_iter_fixup(it, true);
>> - if (err)
>> - goto out;
>> -
>> - slice = min_t(unsigned int, it->sb->s_blocksize - it->ofs,
>> - entry.e_name_len - processed);
>> -
>> - /* handle name */
>> - err = op->name(it, processed, it->kaddr + it->ofs, slice);
>> - if (err) {
>> - it->ofs += entry.e_name_len - processed + value_sz;
>> - goto out;
>> - }
>> -
>> - it->ofs += slice;
>> - processed += slice;
>> - }
>> -
>> - /* 3. handle xattr value */
>> - processed = 0;
>> -
>> - if (op->alloc_buffer) {
>> - err = op->alloc_buffer(it, value_sz);
>> - if (err) {
>> - it->ofs += value_sz;
>> - goto out;
>> - }
>> - }
>> -
>> - while (processed < value_sz) {
>> - err = erofs_xattr_iter_fixup(it, true);
>> - if (err)
>> - goto out;
>> -
>> - slice = min_t(unsigned int, it->sb->s_blocksize - it->ofs,
>> - value_sz - processed);
>> - op->value(it, processed, it->kaddr + it->ofs, slice);
>> - it->ofs += slice;
>> - processed += slice;
>> - }
>> -
>> -out:
>> - /* xattrs should be 4-byte aligned (on-disk constraint) */
>> - it->ofs = EROFS_XATTR_ALIGN(it->ofs);
>> - return err < 0 ? err : 0;
>> -}
>> -
>> -static int erofs_xattr_long_entrymatch(struct erofs_xattr_iter *it,
>> - struct erofs_xattr_entry *entry)
>> -{
>> - struct erofs_sb_info *sbi = EROFS_SB(it->sb);
>> - struct erofs_xattr_prefix_item *pf = sbi->xattr_prefixes +
>> - (entry->e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
>> -
>> - if (pf >= sbi->xattr_prefixes + sbi->xattr_prefix_count)
>> - return -ENOATTR;
>> -
>> - if (it->index != pf->prefix->base_index ||
>> - it->name.len != entry->e_name_len + pf->infix_len)
>> - return -ENOATTR;
>> -
>> - if (memcmp(it->name.name, pf->prefix->infix, pf->infix_len))
>> - return -ENOATTR;
>> -
>> - it->infix_len = pf->infix_len;
>> - return 0;
>> -}
>> -
>> -static int xattr_entrymatch(struct erofs_xattr_iter *it,
>> - struct erofs_xattr_entry *entry)
>> -{
>> - /* should also match the infix for long name prefixes */
>> - if (entry->e_name_index & EROFS_XATTR_LONG_PREFIX)
>> - return erofs_xattr_long_entrymatch(it, entry);
>> -
>> - if (it->index != entry->e_name_index ||
>> - it->name.len != entry->e_name_len)
>> - return -ENOATTR;
>> - it->infix_len = 0;
>> - return 0;
>> -}
>> -
>> -static int xattr_namematch(struct erofs_xattr_iter *it,
>> - unsigned int processed, char *buf, unsigned int len)
>> -{
>> - if (memcmp(buf, it->name.name + it->infix_len + processed, len))
>> - return -ENOATTR;
>> - return 0;
>> -}
>> -
>> -static int xattr_checkbuffer(struct erofs_xattr_iter *it,
>> - unsigned int value_sz)
>> -{
>> - int err = it->buffer_size < value_sz ? -ERANGE : 0;
>> -
>> - it->buffer_ofs = value_sz;
>> - return !it->buffer ? 1 : err;
>> -}
>> -
>> -static void xattr_copyvalue(struct erofs_xattr_iter *it,
>> - unsigned int processed,
>> - char *buf, unsigned int len)
>> -{
>> - memcpy(it->buffer + processed, buf, len);
>> -}
>> -
>> -static const struct xattr_iter_handlers find_xattr_handlers = {
>> - .entry = xattr_entrymatch,
>> - .name = xattr_namematch,
>> - .alloc_buffer = xattr_checkbuffer,
>> - .value = xattr_copyvalue
>> -};
>> -
>> static bool erofs_xattr_user_list(struct dentry *dentry)
>> {
>> return test_opt(&EROFS_SB(dentry->d_sb)->opt, XATTR_USER);
>> @@ -370,20 +193,70 @@ const struct xattr_handler
>> *erofs_xattr_handlers[] = {
>> NULL,
>> };
>> -static int xattr_entrylist(struct erofs_xattr_iter *it,
>> - struct erofs_xattr_entry *entry)
>> +typedef int (*erofs_xattr_body_handler)(struct erofs_xattr_iter *it,
>> + unsigned int processed, char *buf, unsigned int len);
>> +
>> +static int erofs_xattr_namematch(struct erofs_xattr_iter *it,
>> + unsigned int processed, char *buf, unsigned int len)
>> +{
>> + if (memcmp(buf, it->name.name + it->infix_len + processed, len))
>> + return -ENOATTR;
>> + return 0;
>> +}
>> +
>> +static int erofs_xattr_copy(struct erofs_xattr_iter *it,
>> + unsigned int unused, char *buf, unsigned int len)
>> +{
>> + memcpy(it->buffer + it->buffer_ofs, buf, len);
>> + it->buffer_ofs += len;
>> + return 0;
>> +}
>> +
>> +static int erofs_xattr_body(struct erofs_xattr_iter *it, unsigned int
>> len,
>> + erofs_xattr_body_handler handler)
>
>
> could we change erofs_xattr_body_handler into a bool (e.g.
> bool copy_or_match)?
>
>> +{
>> + unsigned int slice, processed = 0;
>> +
>> + while (processed < len) {
>> + int err = erofs_xattr_iter_fixup(it, true);
>> + if (err)
>> + return err;
>> +
>> + slice = min_t(unsigned int, it->sb->s_blocksize - it->ofs,
>> + len - processed);
>> + err = handler(it, processed, it->kaddr + it->ofs, slice);
>
> So that an indirect call could be avoided, as:
>
> if (copy_or_match) {
> memcpy(it->buffer + it->buffer_ofs, buf, len);
> it->buffer_ofs += len;
> } else if (memcmp(buf,
> it->name.name + it->infix_len + processed, len)) {
> return -ENOATTR;
> }
>
> ?
Okay. Will be fixed in the next version.
--
Thanks,
Jingbo