[PATCH] erofs-utils: introduce xattr support
Gao Xiang
hsiangkao at aol.com
Tue Aug 6 03:30:30 AEST 2019
Hi Guifu,
On Mon, Aug 05, 2019 at 10:54:52PM +0800, Li Guifu wrote:
> Hi
> It seems look good, a great step.
> A new develop branch is a googd choice to make this more stable
> and the hash function would better use a light weight one like
> full_name_hash in the kernel
Yes, you are right. it seems a great baby step of xattr.
I will make a new branch to test this of course.
BTW, Guifu, please help review this patch as well, and
don't forget to tag "Reviewed-by:" if it looks good to you.
Thanks,
Gao Xiang
>
> ?? 2019/7/26 19:50, htyuxe+dhbrei4sq0df8 at grr.la ????:
> > load xattrs from source files and pack them into target image.
> > ---
> > include/erofs/hashtable.h | 502 ++++++++++++++++++++++++++++++++++++++
> > include/erofs/internal.h | 2 +-
> > include/erofs/xattr.h | 22 ++
> > lib/Makefile.am | 3 +-
> > lib/inode.c | 23 ++
> > lib/xattr.c | 319 ++++++++++++++++++++++++
> > 6 files changed, 869 insertions(+), 2 deletions(-)
> > create mode 100644 include/erofs/hashtable.h
> > create mode 100644 include/erofs/xattr.h
> > create mode 100644 lib/xattr.c
> >
> > diff --git a/include/erofs/hashtable.h b/include/erofs/hashtable.h
> > new file mode 100644
> > index 0000000..349a655
> > --- /dev/null
> > +++ b/include/erofs/hashtable.h
> > @@ -0,0 +1,502 @@
> > +/* SPDX-License-Identifier: GPL-2.0+ */
> > +/*
> > + * include/erofs/hashtable.h
> > + *
> > + */
> > +
> > +#ifndef __EROFS_HASHTABLE_H
> > +#define __EROFS_HASHTABLE_H
> > +
> > +#define BITS_PER_LONG 32
> > +#ifndef __always_inline
> > +#define __always_inline inline
> > +#endif
> > +
> > +/* 2^31 + 2^29 - 2^25 + 2^22 - 2^19 - 2^16 + 1 */
> > +#define GOLDEN_RATIO_PRIME_32 0x9e370001UL
> > +/* 2^63 + 2^61 - 2^57 + 2^54 - 2^51 - 2^18 + 1 */
> > +#define GOLDEN_RATIO_PRIME_64 0x9e37fffffffc0001UL
> > +
> > +#if BITS_PER_LONG == 32
> > +#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_PRIME_32
> > +#define hash_long(val, bits) hash_32(val, bits)
> > +#elif BITS_PER_LONG == 64
> > +#define hash_long(val, bits) hash_64(val, bits)
> > +#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_PRIME_64
> > +#else
> > +#error Wordsize not 32 or 64
> > +#endif
> > +
> > +struct hlist_head {
> > + struct hlist_node *first;
> > +};
> > +
> > +struct hlist_node {
> > + struct hlist_node *next, **pprev;
> > +};
> > +
> > +/*
> > + * Architectures might want to move the poison pointer offset
> > + * into some well-recognized area such as 0xdead000000000000,
> > + * that is also not mappable by user-space exploits:
> > + */
> > +#ifdef CONFIG_ILLEGAL_POINTER_VALUE
> > +# define POISON_POINTER_DELTA _AC(CONFIG_ILLEGAL_POINTER_VALUE, UL)
> > +#else
> > +# define POISON_POINTER_DELTA 0
> > +#endif
> > +
> > +/*
> > + * These are non-NULL pointers that will result in page faults
> > + * under normal circumstances, used to verify that nobody uses
> > + * non-initialized list entries.
> > + */
> > +#define LIST_POISON1 ((void *) 0x00100100 + POISON_POINTER_DELTA)
> > +#define LIST_POISON2 ((void *) 0x00200200 + POISON_POINTER_DELTA)
> > +
> > +#undef offsetof
> > +#ifdef __compiler_offsetof
> > +#define offsetof(TYPE, MEMBER) __compiler_offsetof(TYPE, MEMBER)
> > +#else
> > +#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
> > +#endif
> > +
> > +/*
> > + * Double linked lists with a single pointer list head.
> > + * Mostly useful for hash tables where the two pointer list head is
> > + * too wasteful.
> > + * You lose the ability to access the tail in O(1).
> > + */
> > +
> > +#define HLIST_HEAD_INIT { .first = NULL }
> > +#define HLIST_HEAD(name) struct hlist_head name = { .first = NULL }
> > +#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
> > +static inline void INIT_HLIST_NODE(struct hlist_node *h)
> > +{
> > + h->next = NULL;
> > + h->pprev = NULL;
> > +}
> > +
> > +static inline int hlist_unhashed(const struct hlist_node *h)
> > +{
> > + return !h->pprev;
> > +}
> > +
> > +static inline int hlist_empty(const struct hlist_head *h)
> > +{
> > + return !h->first;
> > +}
> > +
> > +static inline void __hlist_del(struct hlist_node *n)
> > +{
> > + struct hlist_node *next = n->next;
> > + struct hlist_node **pprev = n->pprev;
> > +
> > + *pprev = next;
> > + if (next)
> > + next->pprev = pprev;
> > +}
> > +
> > +static inline void hlist_del(struct hlist_node *n)
> > +{
> > + __hlist_del(n);
> > + n->next = LIST_POISON1;
> > + n->pprev = LIST_POISON2;
> > +}
> > +
> > +static inline void hlist_del_init(struct hlist_node *n)
> > +{
> > + if (!hlist_unhashed(n)) {
> > + __hlist_del(n);
> > + INIT_HLIST_NODE(n);
> > + }
> > +}
> > +
> > +static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
> > +{
> > + struct hlist_node *first = h->first;
> > +
> > + n->next = first;
> > + if (first)
> > + first->pprev = &n->next;
> > + h->first = n;
> > + n->pprev = &h->first;
> > +}
> > +
> > +/* next must be != NULL */
> > +static inline void hlist_add_before(struct hlist_node *n,
> > + struct hlist_node *next)
> > +{
> > + n->pprev = next->pprev;
> > + n->next = next;
> > + next->pprev = &n->next;
> > + *(n->pprev) = n;
> > +}
> > +
> > +static inline void hlist_add_behind(struct hlist_node *n,
> > + struct hlist_node *prev)
> > +{
> > + n->next = prev->next;
> > + prev->next = n;
> > + n->pprev = &prev->next;
> > +
> > + if (n->next)
> > + n->next->pprev = &n->next;
> > +}
> > +
> > +/* after that we'll appear to be on some hlist and hlist_del will work */
> > +static inline void hlist_add_fake(struct hlist_node *n)
> > +{
> > + n->pprev = &n->next;
> > +}
> > +
> > +/*
> > + * Move a list from one list head to another. Fixup the pprev
> > + * reference of the first entry if it exists.
> > + */
> > +static inline void hlist_move_list(struct hlist_head *old,
> > + struct hlist_head *new)
> > +{
> > + new->first = old->first;
> > + if (new->first)
> > + new->first->pprev = &new->first;
> > + old->first = NULL;
> > +}
> > +
> > +#define hlist_entry(ptr, type, member) container_of(ptr, type, member)
> > +
> > +#define hlist_for_each(pos, head) \
> > + for (pos = (head)->first; pos; pos = pos->next)
> > +
> > +#define hlist_for_each_safe(pos, n, head) \
> > + for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
> > + pos = n)
> > +
> > +#define hlist_entry_safe(ptr, type, member) \
> > + ({ typeof(ptr) ____ptr = (ptr); \
> > + ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
> > + })
> > +
> > +/**
> > + * hlist_for_each_entry - iterate over list of given type
> > + * @pos:the type * to use as a loop cursor.
> > + * @head:the head for your list.
> > + * @member:the name of the hlist_node within the struct.
> > + */
> > +#define hlist_for_each_entry(pos, head, member) \
> > + for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
> > + pos; \
> > + pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
> > +
> > +/**
> > + * hlist_for_each_entry_continue
> > + * iterate over a hlist continuing after current point
> > + * @pos:the type * to use as a loop cursor.
> > + * @member:the name of the hlist_node within the struct.
> > + */
> > +#define hlist_for_each_entry_continue(pos, member) \
> > + for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\
> > + pos; \
> > + pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
> > +
> > +/**
> > + * hlist_for_each_entry_from
> > + * iterate over a hlist continuing from current point
> > + * @pos: the type * to use as a loop cursor.
> > + * @member: the name of the hlist_node within the struct.
> > + */
> > +#define hlist_for_each_entry_from(pos, member) \
> > + for (; pos; \
> > + pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
> > +
> > +/**
> > + * hlist_for_each_entry_safe
> > + * iterate over list of given type safe against removal of list entry
> > + * @pos:the type * to use as a loop cursor.
> > + * @n:another &struct hlist_node to use as temporary storage
> > + * @head:the head for your list.
> > + * @member:the name of the hlist_node within the struct.
> > + */
> > +#define hlist_for_each_entry_safe(pos, n, head, member) \
> > + for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
> > + pos && ({ n = pos->member.next; 1; }); \
> > + pos = hlist_entry_safe(n, typeof(*pos), member))
> > +
> > +static __always_inline u64 hash_64(u64 val, unsigned int bits)
> > +{
> > + u64 hash = val;
> > +
> > +#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
> > + hash = hash * GOLDEN_RATIO_PRIME_64;
> > +#else
> > + /* Sigh, gcc can't optimise this alone like it does for 32 bits. */
> > + u64 n = hash;
> > +
> > + n <<= 18;
> > + hash -= n;
> > + n <<= 33;
> > + hash -= n;
> > + n <<= 3;
> > + hash += n;
> > + n <<= 3;
> > + hash -= n;
> > + n <<= 4;
> > + hash += n;
> > + n <<= 2;
> > + hash += n;
> > +#endif
> > +
> > + /* High bits are more random, so use them. */
> > + return hash >> (64 - bits);
> > +}
> > +
> > +static inline u32 hash_32(u32 val, unsigned int bits)
> > +{
> > + /* On some cpus multiply is faster, on others gcc will do shifts */
> > + u32 hash = val * GOLDEN_RATIO_PRIME_32;
> > +
> > + /* High bits are more random, so use them. */
> > + return hash >> (32 - bits);
> > +}
> > +
> > +/**
> > + * ilog2 - log of base 2 of 32-bit or a 64-bit unsigned value
> > + * @n - parameter
> > + *
> > + * constant-capable log of base 2 calculation
> > + * - this can be used to initialise global variables from constant data, hence
> > + * the massive ternary operator construction
> > + *
> > + * selects the appropriately-sized optimised version depending on sizeof(n)
> > + */
> > +#define ilog2(n) \
> > +( \
> > + (n) & (1ULL << 63) ? 63 : \
> > + (n) & (1ULL << 62) ? 62 : \
> > + (n) & (1ULL << 61) ? 61 : \
> > + (n) & (1ULL << 60) ? 60 : \
> > + (n) & (1ULL << 59) ? 59 : \
> > + (n) & (1ULL << 58) ? 58 : \
> > + (n) & (1ULL << 57) ? 57 : \
> > + (n) & (1ULL << 56) ? 56 : \
> > + (n) & (1ULL << 55) ? 55 : \
> > + (n) & (1ULL << 54) ? 54 : \
> > + (n) & (1ULL << 53) ? 53 : \
> > + (n) & (1ULL << 52) ? 52 : \
> > + (n) & (1ULL << 51) ? 51 : \
> > + (n) & (1ULL << 50) ? 50 : \
> > + (n) & (1ULL << 49) ? 49 : \
> > + (n) & (1ULL << 48) ? 48 : \
> > + (n) & (1ULL << 47) ? 47 : \
> > + (n) & (1ULL << 46) ? 46 : \
> > + (n) & (1ULL << 45) ? 45 : \
> > + (n) & (1ULL << 44) ? 44 : \
> > + (n) & (1ULL << 43) ? 43 : \
> > + (n) & (1ULL << 42) ? 42 : \
> > + (n) & (1ULL << 41) ? 41 : \
> > + (n) & (1ULL << 40) ? 40 : \
> > + (n) & (1ULL << 39) ? 39 : \
> > + (n) & (1ULL << 38) ? 38 : \
> > + (n) & (1ULL << 37) ? 37 : \
> > + (n) & (1ULL << 36) ? 36 : \
> > + (n) & (1ULL << 35) ? 35 : \
> > + (n) & (1ULL << 34) ? 34 : \
> > + (n) & (1ULL << 33) ? 33 : \
> > + (n) & (1ULL << 32) ? 32 : \
> > + (n) & (1ULL << 31) ? 31 : \
> > + (n) & (1ULL << 30) ? 30 : \
> > + (n) & (1ULL << 29) ? 29 : \
> > + (n) & (1ULL << 28) ? 28 : \
> > + (n) & (1ULL << 27) ? 27 : \
> > + (n) & (1ULL << 26) ? 26 : \
> > + (n) & (1ULL << 25) ? 25 : \
> > + (n) & (1ULL << 24) ? 24 : \
> > + (n) & (1ULL << 23) ? 23 : \
> > + (n) & (1ULL << 22) ? 22 : \
> > + (n) & (1ULL << 21) ? 21 : \
> > + (n) & (1ULL << 20) ? 20 : \
> > + (n) & (1ULL << 19) ? 19 : \
> > + (n) & (1ULL << 18) ? 18 : \
> > + (n) & (1ULL << 17) ? 17 : \
> > + (n) & (1ULL << 16) ? 16 : \
> > + (n) & (1ULL << 15) ? 15 : \
> > + (n) & (1ULL << 14) ? 14 : \
> > + (n) & (1ULL << 13) ? 13 : \
> > + (n) & (1ULL << 12) ? 12 : \
> > + (n) & (1ULL << 11) ? 11 : \
> > + (n) & (1ULL << 10) ? 10 : \
> > + (n) & (1ULL << 9) ? 9 : \
> > + (n) & (1ULL << 8) ? 8 : \
> > + (n) & (1ULL << 7) ? 7 : \
> > + (n) & (1ULL << 6) ? 6 : \
> > + (n) & (1ULL << 5) ? 5 : \
> > + (n) & (1ULL << 4) ? 4 : \
> > + (n) & (1ULL << 3) ? 3 : \
> > + (n) & (1ULL << 2) ? 2 : \
> > + (n) & (1ULL << 1) ? 1 : 0 \
> > +)
> > +
> > +static const uint16_t crc16tab[256] = {
> > + 0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
> > + 0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
> > + 0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
> > + 0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
> > + 0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
> > + 0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
> > + 0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
> > + 0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
> > + 0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
> > + 0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
> > + 0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
> > + 0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
> > + 0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
> > + 0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
> > + 0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
> > + 0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
> > + 0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
> > + 0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
> > + 0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
> > + 0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
> > + 0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
> > + 0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
> > + 0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
> > + 0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
> > + 0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
> > + 0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
> > + 0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
> > + 0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
> > + 0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
> > + 0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
> > + 0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
> > + 0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
> > +};
> > +
> > +uint16_t crc16(const char *buf, int len)
> > +{
> > + int counter;
> > + uint16_t crc = 0;
> > +
> > + for (counter = 0; counter < len; counter++)
> > + crc = (crc<<8) ^ crc16tab[((crc>>8) ^ *buf++)&0x00FF];
> > + return crc;
> > +}
> > +
> > +#define DEFINE_HASHTABLE(name, bits) \
> > + struct hlist_head name[1 << (bits)] = \
> > + { [0 ... ((1 << (bits)) - 1)] = HLIST_HEAD_INIT }
> > +
> > +#define DECLARE_HASHTABLE(name, bits) \
> > + struct hlist_head name[1 << (bits)]
> > +
> > +#define HASH_SIZE(name) (ARRAY_SIZE(name))
> > +#define HASH_BITS(name) ilog2(HASH_SIZE(name))
> > +
> > +/* Use hash_32 when possible to allow for fast 32bit hashing in 64bit kernels*/
> > +#define hash_min(val, bits) \
> > + (sizeof(val) <= 4 ? hash_32(val, bits) : hash_long(val, bits))
> > +
> > +static inline void __hash_init(struct hlist_head *ht, unsigned int sz)
> > +{
> > + unsigned int i;
> > +
> > + for (i = 0; i < sz; i++)
> > + INIT_HLIST_HEAD(&ht[i]);
> > +}
> > +
> > +/**
> > + * hash_init - initialize a hash table
> > + * @hashtable: hashtable to be initialized
> > + *
> > + * Calculates the size of the hashtable from the given parameter, otherwise
> > + * same as hash_init_size.
> > + *
> > + * This has to be a macro since HASH_BITS() will not work on pointers since
> > + * it calculates the size during preprocessing.
> > + */
> > +#define hash_init(hashtable) __hash_init(hashtable, HASH_SIZE(hashtable))
> > +
> > +/**
> > + * hash_add - add an object to a hashtable
> > + * @hashtable: hashtable to add to
> > + * @node: the &struct hlist_node of the object to be added
> > + * @key: the key of the object to be added
> > + */
> > +#define hash_add(hashtable, node, key) \
> > + hlist_add_head(node, &hashtable[hash_min(key, HASH_BITS(hashtable))])
> > +
> > +/**
> > + * hash_hashed - check whether an object is in any hashtable
> > + * @node: the &struct hlist_node of the object to be checked
> > + */
> > +static inline bool hash_hashed(struct hlist_node *node)
> > +{
> > + return !hlist_unhashed(node);
> > +}
> > +
> > +static inline bool __hash_empty(struct hlist_head *ht, unsigned int sz)
> > +{
> > + unsigned int i;
> > +
> > + for (i = 0; i < sz; i++)
> > + if (!hlist_empty(&ht[i]))
> > + return false;
> > +
> > + return true;
> > +}
> > +
> > +/**
> > + * hash_empty - check whether a hashtable is empty
> > + * @hashtable: hashtable to check
> > + *
> > + * This has to be a macro since HASH_BITS() will not work on pointers since
> > + * it calculates the size during preprocessing.
> > + */
> > +#define hash_empty(hashtable) __hash_empty(hashtable, HASH_SIZE(hashtable))
> > +
> > +/**
> > + * hash_del - remove an object from a hashtable
> > + * @node: &struct hlist_node of the object to remove
> > + */
> > +static inline void hash_del(struct hlist_node *node)
> > +{
> > + hlist_del_init(node);
> > +}
> > +
> > +/**
> > + * hash_for_each - iterate over a hashtable
> > + * @name: hashtable to iterate
> > + * @bkt: integer to use as bucket loop cursor
> > + * @obj: the type * to use as a loop cursor for each entry
> > + * @member: the name of the hlist_node within the struct
> > + */
> > +#define hash_for_each(name, bkt, obj, member) \
> > + for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\
> > + (bkt)++)\
> > + hlist_for_each_entry(obj, &name[bkt], member)
> > +
> > +/**
> > + * hash_for_each_safe - iterate over a hashtable safe against removal of
> > + * hash entry
> > + * @name: hashtable to iterate
> > + * @bkt: integer to use as bucket loop cursor
> > + * @tmp: a &struct used for temporary storage
> > + * @obj: the type * to use as a loop cursor for each entry
> > + * @member: the name of the hlist_node within the struct
> > + */
> > +#define hash_for_each_safe(name, bkt, tmp, obj, member) \
> > + for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\
> > + (bkt)++)\
> > + hlist_for_each_entry_safe(obj, tmp, &name[bkt], member)
> > +
> > +/**
> > + * hash_for_each_possible - iterate over all possible objects hashing to the
> > + * same bucket
> > + * @name: hashtable to iterate
> > + * @obj: the type * to use as a loop cursor for each entry
> > + * @member: the name of the hlist_node within the struct
> > + * @key: the key of the objects to iterate over
> > + */
> > +#define hash_for_each_possible(name, obj, member, key) \
> > + hlist_for_each_entry(obj, &name[hash_min(key, HASH_BITS(name))], member)
> > +
> > +#endif
> > diff --git a/include/erofs/internal.h b/include/erofs/internal.h
> > index b7ce6f8..33a72b5 100644
> > --- a/include/erofs/internal.h
> > +++ b/include/erofs/internal.h
> > @@ -59,7 +59,7 @@ struct erofs_sb_info {
> > extern struct erofs_sb_info sbi;
> > struct erofs_inode {
> > - struct list_head i_hash, i_subdirs;
> > + struct list_head i_hash, i_subdirs, i_xattrs;
> > unsigned int i_count;
> > struct erofs_inode *i_parent;
> > diff --git a/include/erofs/xattr.h b/include/erofs/xattr.h
> > new file mode 100644
> > index 0000000..dff9fd6
> > --- /dev/null
> > +++ b/include/erofs/xattr.h
> > @@ -0,0 +1,22 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * include/erofs/xattr.h
> > + *
> > + */
> > +
> > +#ifndef __EROFS_XATTR_H
> > +#define __EROFS_XATTR_H
> > +
> > +#define XATTR_COUNT(_size) ({\
> > + u32 __size = le16_to_cpu(_size); \
> > + ((__size) == 0) ? 0 : \
> > + (_size - sizeof(struct erofs_xattr_ibody_header)) / \
> > + sizeof(struct erofs_xattr_entry) + 1; })
> > +
> > +
> > +int cust_xattr(struct list_head *hlist);
> > +int read_xattr_from_src(const char *path, struct list_head *hlist);
> > +int xattr_entry_size(struct list_head *hlist);
> > +char *xattr_data(struct list_head *hlist, int size);
> > +
> > +#endif
> > diff --git a/lib/Makefile.am b/lib/Makefile.am
> > index dea82f7..cbe3243 100644
> > --- a/lib/Makefile.am
> > +++ b/lib/Makefile.am
> > @@ -2,7 +2,8 @@
> > # Makefile.am
> > noinst_LTLIBRARIES = liberofs.la
> > -liberofs_la_SOURCES = config.c io.c cache.c inode.c compress.c compressor.c
> > +liberofs_la_SOURCES = config.c io.c cache.c inode.c compress.c compressor.c \
> > + xattr.c
> > liberofs_la_CFLAGS = -Wall -Werror -I$(top_srcdir)/include
> > if ENABLE_LZ4
> > liberofs_la_CFLAGS += ${LZ4_CFLAGS}
> > diff --git a/lib/inode.c b/lib/inode.c
> > index 8b38270..615f117 100644
> > --- a/lib/inode.c
> > +++ b/lib/inode.c
> > @@ -18,6 +18,7 @@
> > #include "erofs/cache.h"
> > #include "erofs/io.h"
> > #include "erofs/compress.h"
> > +#include "erofs/xattr.h"
> > struct erofs_sb_info sbi;
> > @@ -364,8 +365,10 @@ static bool erofs_bh_flush_write_inode(struct erofs_buffer_head *bh)
> > /* let's support v1 currently */
> > struct erofs_inode_v1 v1 = {0};
> > int ret;
> > + uint16_t count = XATTR_COUNT(inode->xattr_isize);
> > v1.i_advise = cpu_to_le16(0 | (inode->data_mapping_mode << 1));
> > + v1.i_xattr_icount = cpu_to_le16(count);
> > v1.i_mode = cpu_to_le16(inode->i_mode);
> > v1.i_nlink = cpu_to_le16(inode->i_nlink);
> > v1.i_size = cpu_to_le32((u32)inode->i_size);
> > @@ -399,6 +402,20 @@ static bool erofs_bh_flush_write_inode(struct erofs_buffer_head *bh)
> > return false;
> > off += inode->inode_isize;
> > + if (inode->xattr_isize) {
> > + char *pbuf = xattr_data(&inode->i_xattrs, inode->xattr_isize);
> > +
> > + if (IS_ERR(pbuf))
> > + return false;
> > +
> > + ret = dev_write(pbuf, off, inode->xattr_isize);
> > + free(pbuf);
> > + if (ret)
> > + return false;
> > +
> > + off += inode->xattr_isize;
> > + }
> > +
> > if (inode->extent_isize) {
> > /* write compression metadata */
> > off = Z_EROFS_VLE_EXTENT_ALIGN(off);
> > @@ -452,6 +469,7 @@ int erofs_prepare_inode_buffer(struct erofs_inode *inode)
> > DBG_BUGON(inode->bh || inode->bh_inline);
> > + inode->xattr_isize = xattr_entry_size(&inode->i_xattrs);
> > inodesize = inode->inode_isize + inode->xattr_isize +
> > inode->extent_isize;
> > @@ -612,6 +630,7 @@ struct erofs_inode *erofs_new_inode(void)
> > inode->i_count = 1;
> > init_list_head(&inode->i_subdirs);
> > + init_list_head(&inode->i_xattrs);
> > inode->xattr_isize = 0;
> > inode->extent_isize = 0;
> > @@ -699,6 +718,10 @@ struct erofs_inode *erofs_mkfs_build_tree(struct erofs_inode *dir)
> > struct dirent *dp;
> > struct erofs_dentry *d;
> > + ret = read_xattr_from_src(dir->i_srcpath, &dir->i_xattrs);
> > + if (ret)
> > + return ERR_PTR(ret);
> > +
> > if (!S_ISDIR(dir->i_mode)) {
> > if (S_ISLNK(dir->i_mode)) {
> > char *const symlink = malloc(dir->i_size);
> > diff --git a/lib/xattr.c b/lib/xattr.c
> > new file mode 100644
> > index 0000000..6278abc
> > --- /dev/null
> > +++ b/lib/xattr.c
> > @@ -0,0 +1,319 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * lib/xattr.c
> > + *
> > + */
> > +
> > +#include <stdlib.h>
> > +#include <sys/types.h>
> > +#include <sys/xattr.h>
> > +#include <linux/xattr.h>
> > +#include <errno.h>
> > +#include <string.h>
> > +
> > +#include "erofs/defs.h"
> > +#include "erofs/print.h"
> > +#include "erofs/list.h"
> > +#include "erofs/internal.h"
> > +#include "erofs/hashtable.h"
> > +#include "err.h"
> > +#define EROFS_XATTR_HASH_TABLE_BITS 16
> > +
> > +struct xattr_item {
> > + const char *buf;
> > + unsigned int keylen;
> > + unsigned int vallen;
> > + unsigned int count;
> > + u8 index;
> > + struct hlist_node node;
> > +};
> > +
> > +struct xattr_list {
> > + struct xattr_item *item;
> > + struct list_head list;
> > +};
> > +
> > +DECLARE_HASHTABLE(my_hash_table, EROFS_XATTR_HASH_TABLE_BITS);
> > +
> > +struct xattr_prefix {
> > + const char *prefix;
> > + uint16_t prefix_len;
> > + u8 index;
> > +} prefix[] = {
> > + {
> > + XATTR_USER_PREFIX,
> > + XATTR_USER_PREFIX_LEN,
> > + EROFS_XATTR_INDEX_USER
> > + },
> > + {
> > + XATTR_SECURITY_PREFIX,
> > + XATTR_SYSTEM_PREFIX_LEN,
> > + EROFS_XATTR_INDEX_SECURITY
> > + },
> > + {
> > + XATTR_TRUSTED_PREFIX,
> > + XATTR_TRUSTED_PREFIX_LEN,
> > + EROFS_XATTR_INDEX_TRUSTED
> > + },
> > + {NULL, 0, 0},
> > +};
> > +
> > +static inline void hxattr_add(struct hlist_node *node, uint16_t key)
> > +{
> > + hash_add(my_hash_table, node, key);
> > +}
> > +
> > +static inline void hxattr_del(struct hlist_node *node)
> > +{
> > + hash_del(node);
> > +}
> > +
> > +static struct xattr_item *hxattr_match(const char *buf, int len, u8 index)
> > +{
> > + struct xattr_item *item;
> > + uint16_t mkey = crc16(buf, len);
> > +
> > + hash_for_each_possible(my_hash_table, item, node, mkey) {
> > + if (index == item->index &&
> > + len == (item->keylen + item->vallen) &&
> > + !memcmp(buf, item->buf, len)) {
> > + return item;
> > + }
> > + }
> > +
> > + return ERR_PTR(-ENOENT);
> > +}
> > +
> > +static bool match_index(const char *key, u8 *index, uint16_t *len)
> > +{
> > + struct xattr_prefix *p = prefix;
> > +
> > + while (p->prefix) {
> > + if (strncmp(p->prefix, key, p->prefix_len)) {
> > + *len = p->prefix_len;
> > + *index = p->index;
> > + return true;
> > + }
> > + p++;
> > + }
> > +
> > + return false;
> > +}
> > +
> > +static struct xattr_item *new_xattr(const char *buf, u8 index,
> > + int keylen, int vallen)
> > +{
> > + struct xattr_item *item = malloc(sizeof(*item));
> > +
> > + if (!item)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + memset(item, 0, sizeof(*item));
> > + INIT_HLIST_NODE(&item->node);
> > + item->buf = buf;
> > + item->keylen = keylen;
> > + item->vallen = vallen;
> > + item->count = 1;
> > + item->index = index;
> > + if (!item->index)
> > + return ERR_PTR(-EPERM);
> > +
> > + return item;
> > +}
> > +
> > +static int xattr_add(struct list_head *hlist, struct xattr_item *item)
> > +{
> > + struct xattr_list *mlist = malloc(sizeof(*mlist));
> > +
> > + if (!mlist)
> > + return -ENOMEM;
> > +
> > + init_list_head(&mlist->list);
> > + mlist->item = item;
> > + list_add(&mlist->list, hlist);
> > + return 0;
> > +}
> > +
> > +static struct xattr_item *list_xattr_value(const char *path, const char *key)
> > +{
> > + ssize_t keylen, vallen;
> > + char *kxattr;
> > + struct xattr_item *item;
> > + u8 index;
> > + uint16_t prelen, suflen;
> > +
> > + /* Output attribute key.*/
> > + erofs_info("path:%s key: [%s] ", path, key);
> > +
> > + keylen = strlen(key);
> > + if (!match_index(key, &index, &prelen))
> > + return ERR_PTR(-ENODATA);
> > +
> > + BUG_ON(keylen < prelen);
> > + /* Determine length of the value.*/
> > + vallen = lgetxattr(path, key, NULL, 0);
> > + if (vallen == -1)
> > + return ERR_PTR(-errno);
> > +
> > + /*
> > + * Allocate value buffer.
> > + * One extra byte is needed to append 0x00.
> > + */
> > + suflen = keylen - prelen;
> > + kxattr = malloc(suflen + vallen + 1);
> > + if (!kxattr)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + if (vallen == 0)
> > + goto value_0;
> > +
> > + /* Copy value to buffer.*/
> > + vallen = lgetxattr(path, key, kxattr + suflen, vallen);
> > + if (vallen == -1) {
> > + free(kxattr);
> > + return ERR_PTR(-errno);
> > + }
> > +
> > +value_0:
> > + memcpy(kxattr, key + prelen, suflen);
> > + /* Output attribute value.*/
> > + kxattr[suflen + vallen] = '\0';
> > + erofs_info("value: [%s]", kxattr + suflen);
> > +
> > + /* kxattr is used at xattr_add(), neednt free if SUCCESS */
> > + item = hxattr_match(kxattr, suflen + vallen, index);
> > + if (!IS_ERR(item)) {
> > + item->count++;
> > + free(kxattr);
> > + return item;
> > + }
> > +
> > + item = new_xattr(kxattr, index, suflen, vallen);
> > + if (IS_ERR(item))
> > + free(kxattr);
> > +
> > + return item;
> > +}
> > +
> > +int read_xattr_from_src(const char *path, struct list_head *hlist)
> > +{
> > + int ret = 0;
> > + char *kbuf, *key;
> > + ssize_t buflen = llistxattr(path, NULL, 0);
> > +
> > + if (buflen == -1)
> > + return -errno;
> > + else if (buflen == 0)
> > + return 0;
> > +
> > + /* Allocate the buffer.*/
> > + kbuf = malloc(buflen);
> > + if (!kbuf)
> > + return -errno;
> > +
> > + /* Copy the list of attribute keys to the buffer.*/
> > + buflen = llistxattr(path, kbuf, buflen);
> > + if (buflen == -1) {
> > + ret = -errno;
> > + goto exit_err;
> > + }
> > +
> > + /*
> > + * Loop over the list of zero terminated strings with the
> > + * attribute keys. Use the remaining buffer length to determine
> > + * the end of the list.
> > + */
> > + key = kbuf;
> > + while (buflen > 0) {
> > + size_t keylen = strlen(key) + 1;
> > + struct xattr_item *item = list_xattr_value(path, key);
> > +
> > + if (!item) {
> > + ret = -errno;
> > + goto exit_err;
> > + }
> > +
> > + if (!hash_hashed(&item->node)) {
> > + uint16_t mkey;
> > +
> > + mkey = crc16(item->buf, item->keylen + item->vallen);
> > + hxattr_add(&item->node, mkey);
> > + }
> > +
> > + if (hlist) {
> > + ret = xattr_add(hlist, item);
> > + if (ret < 0)
> > + goto exit_err;
> > + }
> > +
> > + buflen -= keylen;
> > + key += keylen;
> > + }
> > +
> > +exit_err:
> > + free(kbuf);
> > + return ret;
> > +
> > +}
> > +
> > +int xattr_entry_size(struct list_head *hlist)
> > +{
> > + int sum = 0;
> > + struct xattr_list *lst;
> > +
> > + if (list_empty(hlist))
> > + return 0;
> > +
> > + list_for_each_entry(lst, hlist, list) {
> > + struct xattr_item *item = lst->item;
> > +
> > + sum += sizeof(struct erofs_xattr_entry);
> > + sum += item->keylen + item->vallen;
> > + sum = EROFS_XATTR_ALIGN(sum);
> > + }
> > +
> > + sum += sizeof(struct erofs_xattr_ibody_header);
> > +
> > + return EROFS_XATTR_ALIGN(sum);
> > +}
> > +
> > +char *xattr_data(struct list_head *hlist, int xattr_size)
> > +{
> > + struct xattr_list *lst;
> > + char *buf, *pbuf;
> > + unsigned int size = 0;
> > + struct erofs_xattr_ibody_header header = {
> > + .h_checksum = 0,
> > + .h_shared_count = 0,
> > + };
> > +
> > + erofs_info("xattr_size=%d", xattr_size);
> > + buf = malloc(xattr_size);
> > + if (!buf)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + memset(buf, 0, xattr_size);
> > + pbuf = buf + sizeof(struct erofs_xattr_ibody_header);
> > +
> > + list_for_each_entry(lst, hlist, list) {
> > + struct erofs_xattr_entry entry;
> > + struct xattr_item *item = lst->item;
> > +
> > + entry.e_name_index = item->index;
> > + entry.e_name_len = item->keylen;
> > + entry.e_value_size = cpu_to_le16(item->vallen);
> > +
> > + BUG_ON(size > xattr_size);
> > + memcpy(pbuf + size, &entry, sizeof(entry));
> > +
> > + size += sizeof(struct erofs_xattr_entry);
> > + memcpy(pbuf + size, item->buf, item->keylen + item->vallen);
> > + size += item->keylen + item->vallen;
> > + size = EROFS_XATTR_ALIGN(size);
> > + }
> > +
> > + memcpy(buf, &header, sizeof(header));
> > +
> > + return buf;
> > +}
> > +
> >
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