[PATCH v6 0/5] erofs: cleanup of xattr handling

[PATCH v6 0/5] erofs: cleanup of xattr handling

[Jingbo Xu]

changes since v5:
- patch 1: newly added into this series, in preparation for the
  following cleanup
- patch 5: rename erofs_xattr_body() to erofs_xattr_handle_string()

changes since v4:
- patch 1: make conversions from erofs_read_metabuf() in xattr.c
  to "erofs_init_metabuf() + erofs_bread()" a separate patch
- patch 6: add "bool copy" function parameter to erofs_xattr_body(), and
  thus make erofs_xattr_namematch() and erofs_xattr_copy() inlined
  inside erofs_xattr_body()

changes since v3:
- patch 1: make a unified erofs_xattr_iter_fixup() API with newly
  introduced "bool nospan" argument; call erofs_init_metabuf() and
  erofs_bread() separately instead of erofs_read_metabuf()
- patch 2: avoid duplicated strlen() calculation in erofs_getxattr(); no
  need zeroing other fields when initializing 'struct erofs_xattr_iter'
- patch 4: don't explode 'struct erofs_xattr_iter' with inode/getxattr
  fields; instead pass inode/getxattr parameters through function
  parameters of erofs_iter_[inline|shared]_xattr()
- patch 5: don't explode 'struct erofs_xattr_iter' with remaining field;
  instead  calculate and check the remaining inside
  erofs_iter_inline_xattr()

changes since v2:
- rebase to v6.4-rc2
- passes xattr tests (erofs/019,020,021) of erofs-utils [1]

[1] https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs-utils.git/log/?h=experimental-tests

v5: https://lore.kernel.org/all/20230601024347.108469-1-jefflexu@linux.alibaba.com/
v4: https://lore.kernel.org/all/20230531031330.3504-1-jefflexu@linux.alibaba.com/
v3: https://lore.kernel.org/lkml/20230518024551.123990-1-jefflexu@linux.alibaba.com/
v2: https://lore.kernel.org/all/20230330082910.125374-1-jefflexu@linux.alibaba.com/
v1: https://lore.kernel.org/all/20230323000949.57608-1-jefflexu@linux.alibaba.com/


Jingbo Xu (5):
  erofs: use absolute position in xattr iterator
  erofs: unify xattr_iter structures
  erofs: make the size of read data stored in buffer_ofs
  erofs: unify inline/share xattr iterators for listxattr/getxattr
  erofs: use separate xattr parsers for listxattr/getxattr

 fs/erofs/xattr.c | 652 +++++++++++++++++------------------------------
 1 file changed, 227 insertions(+), 425 deletions(-)

-- 
2.19.1.6.gb485710b

[PATCH v6 1/5] erofs: use absolute position in xattr iterator

[Jingbo Xu]

Replace blkaddr/ofs with pos in 'struct erofs_xattr_iter'.

After erofs_bread() is introduced to replace raw page cache APIs for
metadata I/Os handling, xattr_iter_fixup() is no longer needed anymore.

In addition, it is also unnecessary to check if the iterated position is
span over the block boundary as absolute offset is used instead of
blkaddr + offset pairs.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
---
 fs/erofs/xattr.c | 154 +++++++++++++++++++----------------------------
 1 file changed, 61 insertions(+), 93 deletions(-)

diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index d9e041d27a35..d9aaa8016eea 100644
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -7,26 +7,11 @@
 #include <linux/security.h>
 #include "xattr.h"
 
-static inline erofs_blk_t erofs_xattr_blkaddr(struct super_block *sb,
-					      unsigned int xattr_id)
-{
-	return EROFS_SB(sb)->xattr_blkaddr +
-	       erofs_blknr(sb, xattr_id * sizeof(__u32));
-}
-
-static inline unsigned int erofs_xattr_blkoff(struct super_block *sb,
-					      unsigned int xattr_id)
-{
-	return erofs_blkoff(sb, xattr_id * sizeof(__u32));
-}
-
 struct xattr_iter {
 	struct super_block *sb;
 	struct erofs_buf buf;
+	erofs_off_t pos;
 	void *kaddr;
-
-	erofs_blk_t blkaddr;
-	unsigned int ofs;
 };
 
 static int erofs_init_inode_xattrs(struct inode *inode)
@@ -82,17 +67,16 @@ static int erofs_init_inode_xattrs(struct inode *inode)
 
 	it.buf = __EROFS_BUF_INITIALIZER;
 	erofs_init_metabuf(&it.buf, sb);
-	it.blkaddr = erofs_blknr(sb, erofs_iloc(inode) + vi->inode_isize);
-	it.ofs = erofs_blkoff(sb, erofs_iloc(inode) + vi->inode_isize);
+	it.pos = erofs_iloc(inode) + vi->inode_isize;
 
 	/* read in shared xattr array (non-atomic, see kmalloc below) */
-	it.kaddr = erofs_bread(&it.buf, it.blkaddr, EROFS_KMAP);
+	it.kaddr = erofs_bread(&it.buf, erofs_blknr(sb, it.pos), EROFS_KMAP);
 	if (IS_ERR(it.kaddr)) {
 		ret = PTR_ERR(it.kaddr);
 		goto out_unlock;
 	}
 
-	ih = (struct erofs_xattr_ibody_header *)(it.kaddr + it.ofs);
+	ih = it.kaddr + erofs_blkoff(sb, it.pos);
 	vi->xattr_shared_count = ih->h_shared_count;
 	vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
 						sizeof(uint), GFP_KERNEL);
@@ -103,25 +87,20 @@ static int erofs_init_inode_xattrs(struct inode *inode)
 	}
 
 	/* let's skip ibody header */
-	it.ofs += sizeof(struct erofs_xattr_ibody_header);
+	it.pos += sizeof(struct erofs_xattr_ibody_header);
 
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
-		if (it.ofs >= sb->s_blocksize) {
-			/* cannot be unaligned */
-			DBG_BUGON(it.ofs != sb->s_blocksize);
-
-			it.kaddr = erofs_bread(&it.buf, ++it.blkaddr, EROFS_KMAP);
-			if (IS_ERR(it.kaddr)) {
-				kfree(vi->xattr_shared_xattrs);
-				vi->xattr_shared_xattrs = NULL;
-				ret = PTR_ERR(it.kaddr);
-				goto out_unlock;
-			}
-			it.ofs = 0;
+		it.kaddr = erofs_bread(&it.buf, erofs_blknr(sb, it.pos),
+				       EROFS_KMAP);
+		if (IS_ERR(it.kaddr)) {
+			kfree(vi->xattr_shared_xattrs);
+			vi->xattr_shared_xattrs = NULL;
+			ret = PTR_ERR(it.kaddr);
+			goto out_unlock;
 		}
-		vi->xattr_shared_xattrs[i] =
-			le32_to_cpu(*(__le32 *)(it.kaddr + it.ofs));
-		it.ofs += sizeof(__le32);
+		vi->xattr_shared_xattrs[i] = le32_to_cpu(*(__le32 *)
+				(it.kaddr + erofs_blkoff(sb, it.pos)));
+		it.pos += sizeof(__le32);
 	}
 	erofs_put_metabuf(&it.buf);
 
@@ -150,24 +129,11 @@ struct xattr_iter_handlers {
 		      unsigned int len);
 };
 
-static inline int xattr_iter_fixup(struct xattr_iter *it)
-{
-	if (it->ofs < it->sb->s_blocksize)
-		return 0;
-
-	it->blkaddr += erofs_blknr(it->sb, it->ofs);
-	it->kaddr = erofs_bread(&it->buf, it->blkaddr, EROFS_KMAP);
-	if (IS_ERR(it->kaddr))
-		return PTR_ERR(it->kaddr);
-	it->ofs = erofs_blkoff(it->sb, it->ofs);
-	return 0;
-}
-
 static int inline_xattr_iter_begin(struct xattr_iter *it,
 				   struct inode *inode)
 {
 	struct erofs_inode *const vi = EROFS_I(inode);
-	unsigned int xattr_header_sz, inline_xattr_ofs;
+	unsigned int xattr_header_sz;
 
 	xattr_header_sz = sizeof(struct erofs_xattr_ibody_header) +
 			  sizeof(u32) * vi->xattr_shared_count;
@@ -176,11 +142,9 @@ static int inline_xattr_iter_begin(struct xattr_iter *it,
 		return -ENOATTR;
 	}
 
-	inline_xattr_ofs = vi->inode_isize + xattr_header_sz;
-
-	it->blkaddr = erofs_blknr(it->sb, erofs_iloc(inode) + inline_xattr_ofs);
-	it->ofs = erofs_blkoff(it->sb, erofs_iloc(inode) + inline_xattr_ofs);
-	it->kaddr = erofs_bread(&it->buf, it->blkaddr, EROFS_KMAP);
+	it->pos = erofs_iloc(inode) + vi->inode_isize + xattr_header_sz;
+	it->kaddr = erofs_bread(&it->buf, erofs_blknr(it->sb, it->pos),
+				EROFS_KMAP);
 	if (IS_ERR(it->kaddr))
 		return PTR_ERR(it->kaddr);
 	return vi->xattr_isize - xattr_header_sz;
@@ -188,27 +152,29 @@ static int inline_xattr_iter_begin(struct xattr_iter *it,
 
 /*
  * Regardless of success or failure, `xattr_foreach' will end up with
- * `ofs' pointing to the next xattr item rather than an arbitrary position.
+ * `pos' pointing to the next xattr item rather than an arbitrary position.
  */
 static int xattr_foreach(struct xattr_iter *it,
 			 const struct xattr_iter_handlers *op,
 			 unsigned int *tlimit)
 {
 	struct erofs_xattr_entry entry;
+	struct super_block *sb = it->sb;
 	unsigned int value_sz, processed, slice;
 	int err;
 
-	/* 0. fixup blkaddr, ofs, ipage */
-	err = xattr_iter_fixup(it);
-	if (err)
-		return err;
+	/* 0. fixup blkaddr, pos */
+	it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos), EROFS_KMAP);
+	if (IS_ERR(it->kaddr))
+		return PTR_ERR(it->kaddr);
 
 	/*
 	 * 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);
+	entry = *(struct erofs_xattr_entry *)
+		(it->kaddr + erofs_blkoff(sb, it->pos));
 	if (tlimit) {
 		unsigned int entry_sz = erofs_xattr_entry_size(&entry);
 
@@ -220,40 +186,40 @@ static int xattr_foreach(struct xattr_iter *it,
 		*tlimit -= entry_sz;
 	}
 
-	it->ofs += sizeof(struct erofs_xattr_entry);
+	it->pos += 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;
+		it->pos += entry.e_name_len + value_sz;
 		goto out;
 	}
 
-	/* 2. handle xattr name (ofs will finally be at the end of name) */
+	/* 2. handle xattr name (pos will finally be at the end of name) */
 	processed = 0;
 
 	while (processed < entry.e_name_len) {
-		if (it->ofs >= it->sb->s_blocksize) {
-			DBG_BUGON(it->ofs > it->sb->s_blocksize);
-
-			err = xattr_iter_fixup(it);
-			if (err)
-				goto out;
-			it->ofs = 0;
+		it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
+					EROFS_KMAP);
+		if (IS_ERR(it->kaddr)) {
+			err = PTR_ERR(it->kaddr);
+			goto out;
 		}
 
-		slice = min_t(unsigned int, it->sb->s_blocksize - it->ofs,
+		slice = min_t(unsigned int,
+			      sb->s_blocksize - erofs_blkoff(sb, it->pos),
 			      entry.e_name_len - processed);
 
 		/* handle name */
-		err = op->name(it, processed, it->kaddr + it->ofs, slice);
+		err = op->name(it, processed,
+			       it->kaddr + erofs_blkoff(sb, it->pos), slice);
 		if (err) {
-			it->ofs += entry.e_name_len - processed + value_sz;
+			it->pos += entry.e_name_len - processed + value_sz;
 			goto out;
 		}
 
-		it->ofs += slice;
+		it->pos += slice;
 		processed += slice;
 	}
 
@@ -263,31 +229,31 @@ static int xattr_foreach(struct xattr_iter *it,
 	if (op->alloc_buffer) {
 		err = op->alloc_buffer(it, value_sz);
 		if (err) {
-			it->ofs += value_sz;
+			it->pos += value_sz;
 			goto out;
 		}
 	}
 
 	while (processed < value_sz) {
-		if (it->ofs >= it->sb->s_blocksize) {
-			DBG_BUGON(it->ofs > it->sb->s_blocksize);
-
-			err = xattr_iter_fixup(it);
-			if (err)
-				goto out;
-			it->ofs = 0;
+		it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
+					EROFS_KMAP);
+		if (IS_ERR(it->kaddr)) {
+			err = PTR_ERR(it->kaddr);
+			goto out;
 		}
 
-		slice = min_t(unsigned int, it->sb->s_blocksize - it->ofs,
+		slice = min_t(unsigned int,
+			      sb->s_blocksize - erofs_blkoff(sb, it->pos),
 			      value_sz - processed);
-		op->value(it, processed, it->kaddr + it->ofs, slice);
-		it->ofs += slice;
+		op->value(it, processed, it->kaddr + erofs_blkoff(sb, it->pos),
+			  slice);
+		it->pos += slice;
 		processed += slice;
 	}
 
 out:
 	/* xattrs should be 4-byte aligned (on-disk constraint) */
-	it->ofs = EROFS_XATTR_ALIGN(it->ofs);
+	it->pos = EROFS_XATTR_ALIGN(it->pos);
 	return err < 0 ? err : 0;
 }
 
@@ -399,9 +365,10 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
 
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
 		xsid = vi->xattr_shared_xattrs[i];
-		it->it.blkaddr = erofs_xattr_blkaddr(sb, xsid);
-		it->it.ofs = erofs_xattr_blkoff(sb, xsid);
-		it->it.kaddr = erofs_bread(&it->it.buf, it->it.blkaddr, EROFS_KMAP);
+		it->it.pos = erofs_pos(sb, EROFS_SB(sb)->xattr_blkaddr) +
+				       xsid * sizeof(__u32);
+		it->it.kaddr = erofs_bread(&it->it.buf,
+				erofs_blknr(sb, it->it.pos), EROFS_KMAP);
 		if (IS_ERR(it->it.kaddr))
 			return PTR_ERR(it->it.kaddr);
 
@@ -604,9 +571,10 @@ static int shared_listxattr(struct listxattr_iter *it)
 
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
 		xsid = vi->xattr_shared_xattrs[i];
-		it->it.blkaddr = erofs_xattr_blkaddr(sb, xsid);
-		it->it.ofs = erofs_xattr_blkoff(sb, xsid);
-		it->it.kaddr = erofs_bread(&it->it.buf, it->it.blkaddr, EROFS_KMAP);
+		it->it.pos = erofs_pos(sb, EROFS_SB(sb)->xattr_blkaddr) +
+				       xsid * sizeof(__u32);
+		it->it.kaddr = erofs_bread(&it->it.buf,
+				erofs_blknr(sb, it->it.pos), EROFS_KMAP);
 		if (IS_ERR(it->it.kaddr))
 			return PTR_ERR(it->it.kaddr);
 
-- 
2.19.1.6.gb485710b

[PATCH v6 2/5] erofs: unify xattr_iter structures

[Jingbo Xu]

Unify xattr_iter/listxattr_iter/getxattr_iter structures into
erofs_xattr_iter structure.

This is in preparation for the following further cleanup.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 fs/erofs/xattr.c | 154 ++++++++++++++++++++---------------------------
 1 file changed, 66 insertions(+), 88 deletions(-)

diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index d9aaa8016eea..e9bc81846722 100644
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -7,17 +7,27 @@
 #include <linux/security.h>
 #include "xattr.h"
 
-struct xattr_iter {
+struct erofs_xattr_iter {
 	struct super_block *sb;
 	struct erofs_buf buf;
 	erofs_off_t pos;
 	void *kaddr;
+
+	char *buffer;
+	int buffer_size, buffer_ofs;
+
+	/* getxattr */
+	int index, infix_len;
+	struct qstr name;
+
+	/* listxattr */
+	struct dentry *dentry;
 };
 
 static int erofs_init_inode_xattrs(struct inode *inode)
 {
 	struct erofs_inode *const vi = EROFS_I(inode);
-	struct xattr_iter it;
+	struct erofs_xattr_iter it;
 	unsigned int i;
 	struct erofs_xattr_ibody_header *ih;
 	struct super_block *sb = inode->i_sb;
@@ -121,15 +131,15 @@ static int erofs_init_inode_xattrs(struct inode *inode)
  *                            and need to be handled
  */
 struct xattr_iter_handlers {
-	int (*entry)(struct xattr_iter *_it, struct erofs_xattr_entry *entry);
-	int (*name)(struct xattr_iter *_it, unsigned int processed, char *buf,
+	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 xattr_iter *_it, unsigned int value_sz);
-	void (*value)(struct xattr_iter *_it, unsigned int processed, char *buf,
+	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);
 };
 
-static int inline_xattr_iter_begin(struct xattr_iter *it,
+static int inline_xattr_iter_begin(struct erofs_xattr_iter *it,
 				   struct inode *inode)
 {
 	struct erofs_inode *const vi = EROFS_I(inode);
@@ -154,7 +164,7 @@ static int inline_xattr_iter_begin(struct xattr_iter *it,
  * Regardless of success or failure, `xattr_foreach' will end up with
  * `pos' pointing to the next xattr item rather than an arbitrary position.
  */
-static int xattr_foreach(struct xattr_iter *it,
+static int xattr_foreach(struct erofs_xattr_iter *it,
 			 const struct xattr_iter_handlers *op,
 			 unsigned int *tlimit)
 {
@@ -257,18 +267,10 @@ static int xattr_foreach(struct xattr_iter *it,
 	return err < 0 ? err : 0;
 }
 
-struct getxattr_iter {
-	struct xattr_iter it;
-
-	char *buffer;
-	int buffer_size, index, infix_len;
-	struct qstr name;
-};
-
-static int erofs_xattr_long_entrymatch(struct getxattr_iter *it,
+static int erofs_xattr_long_entrymatch(struct erofs_xattr_iter *it,
 				       struct erofs_xattr_entry *entry)
 {
-	struct erofs_sb_info *sbi = EROFS_SB(it->it.sb);
+	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);
 
@@ -286,11 +288,9 @@ static int erofs_xattr_long_entrymatch(struct getxattr_iter *it,
 	return 0;
 }
 
-static int xattr_entrymatch(struct xattr_iter *_it,
+static int xattr_entrymatch(struct erofs_xattr_iter *it,
 			    struct erofs_xattr_entry *entry)
 {
-	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
-
 	/* 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);
@@ -302,32 +302,27 @@ static int xattr_entrymatch(struct xattr_iter *_it,
 	return 0;
 }
 
-static int xattr_namematch(struct xattr_iter *_it,
+static int xattr_namematch(struct erofs_xattr_iter *it,
 			   unsigned int processed, char *buf, unsigned int len)
 {
-	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
-
 	if (memcmp(buf, it->name.name + it->infix_len + processed, len))
 		return -ENOATTR;
 	return 0;
 }
 
-static int xattr_checkbuffer(struct xattr_iter *_it,
+static int xattr_checkbuffer(struct erofs_xattr_iter *it,
 			     unsigned int value_sz)
 {
-	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
 	int err = it->buffer_size < value_sz ? -ERANGE : 0;
 
 	it->buffer_size = value_sz;
 	return !it->buffer ? 1 : err;
 }
 
-static void xattr_copyvalue(struct xattr_iter *_it,
+static void xattr_copyvalue(struct erofs_xattr_iter *it,
 			    unsigned int processed,
 			    char *buf, unsigned int len)
 {
-	struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
-
 	memcpy(it->buffer + processed, buf, len);
 }
 
@@ -338,41 +333,41 @@ static const struct xattr_iter_handlers find_xattr_handlers = {
 	.value = xattr_copyvalue
 };
 
-static int inline_getxattr(struct inode *inode, struct getxattr_iter *it)
+static int inline_getxattr(struct inode *inode, struct erofs_xattr_iter *it)
 {
 	int ret;
 	unsigned int remaining;
 
-	ret = inline_xattr_iter_begin(&it->it, inode);
+	ret = inline_xattr_iter_begin(it, inode);
 	if (ret < 0)
 		return ret;
 
 	remaining = ret;
 	while (remaining) {
-		ret = xattr_foreach(&it->it, &find_xattr_handlers, &remaining);
+		ret = xattr_foreach(it, &find_xattr_handlers, &remaining);
 		if (ret != -ENOATTR)
 			break;
 	}
 	return ret ? ret : it->buffer_size;
 }
 
-static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
+static int shared_getxattr(struct inode *inode, struct erofs_xattr_iter *it)
 {
 	struct erofs_inode *const vi = EROFS_I(inode);
-	struct super_block *const sb = it->it.sb;
+	struct super_block *const sb = it->sb;
 	unsigned int i, xsid;
 	int ret = -ENOATTR;
 
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
 		xsid = vi->xattr_shared_xattrs[i];
-		it->it.pos = erofs_pos(sb, EROFS_SB(sb)->xattr_blkaddr) +
-				       xsid * sizeof(__u32);
-		it->it.kaddr = erofs_bread(&it->it.buf,
-				erofs_blknr(sb, it->it.pos), EROFS_KMAP);
-		if (IS_ERR(it->it.kaddr))
-			return PTR_ERR(it->it.kaddr);
-
-		ret = xattr_foreach(&it->it, &find_xattr_handlers, NULL);
+		it->pos = erofs_pos(sb, EROFS_SB(sb)->xattr_blkaddr) +
+				    xsid * sizeof(__u32);
+		it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
+					EROFS_KMAP);
+		if (IS_ERR(it->kaddr))
+			return PTR_ERR(it->kaddr);
+
+		ret = xattr_foreach(it, &find_xattr_handlers, NULL);
 		if (ret != -ENOATTR)
 			break;
 	}
@@ -394,7 +389,7 @@ int erofs_getxattr(struct inode *inode, int index,
 		   void *buffer, size_t buffer_size)
 {
 	int ret;
-	struct getxattr_iter it;
+	struct erofs_xattr_iter it;
 
 	if (!name)
 		return -EINVAL;
@@ -404,22 +399,21 @@ int erofs_getxattr(struct inode *inode, int index,
 		return ret;
 
 	it.index = index;
-	it.name.len = strlen(name);
+	it.name = (struct qstr)QSTR_INIT(name, strlen(name));
 	if (it.name.len > EROFS_NAME_LEN)
 		return -ERANGE;
 
-	it.it.sb = inode->i_sb;
-	it.it.buf = __EROFS_BUF_INITIALIZER;
-	erofs_init_metabuf(&it.it.buf, it.it.sb);
-	it.name.name = name;
-
+	it.sb = inode->i_sb;
+	it.buf = __EROFS_BUF_INITIALIZER;
+	erofs_init_metabuf(&it.buf, it.sb);
 	it.buffer = buffer;
 	it.buffer_size = buffer_size;
+	it.buffer_ofs = 0;
 
 	ret = inline_getxattr(inode, &it);
 	if (ret == -ENOATTR)
 		ret = shared_getxattr(inode, &it);
-	erofs_put_metabuf(&it.it.buf);
+	erofs_put_metabuf(&it.buf);
 	return ret;
 }
 
@@ -465,25 +459,15 @@ const struct xattr_handler *erofs_xattr_handlers[] = {
 	NULL,
 };
 
-struct listxattr_iter {
-	struct xattr_iter it;
-
-	struct dentry *dentry;
-	char *buffer;
-	int buffer_size, buffer_ofs;
-};
-
-static int xattr_entrylist(struct xattr_iter *_it,
+static int xattr_entrylist(struct erofs_xattr_iter *it,
 			   struct erofs_xattr_entry *entry)
 {
-	struct listxattr_iter *it =
-		container_of(_it, struct listxattr_iter, it);
 	unsigned int base_index = entry->e_name_index;
 	unsigned int prefix_len, infix_len = 0;
 	const char *prefix, *infix = NULL;
 
 	if (entry->e_name_index & EROFS_XATTR_LONG_PREFIX) {
-		struct erofs_sb_info *sbi = EROFS_SB(_it->sb);
+		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);
 
@@ -515,23 +499,17 @@ static int xattr_entrylist(struct xattr_iter *_it,
 	return 0;
 }
 
-static int xattr_namelist(struct xattr_iter *_it,
+static int xattr_namelist(struct erofs_xattr_iter *it,
 			  unsigned int processed, char *buf, unsigned int len)
 {
-	struct listxattr_iter *it =
-		container_of(_it, struct listxattr_iter, it);
-
 	memcpy(it->buffer + it->buffer_ofs, buf, len);
 	it->buffer_ofs += len;
 	return 0;
 }
 
-static int xattr_skipvalue(struct xattr_iter *_it,
+static int xattr_skipvalue(struct erofs_xattr_iter *it,
 			   unsigned int value_sz)
 {
-	struct listxattr_iter *it =
-		container_of(_it, struct listxattr_iter, it);
-
 	it->buffer[it->buffer_ofs++] = '\0';
 	return 1;
 }
@@ -543,42 +521,42 @@ static const struct xattr_iter_handlers list_xattr_handlers = {
 	.value = NULL
 };
 
-static int inline_listxattr(struct listxattr_iter *it)
+static int inline_listxattr(struct erofs_xattr_iter *it)
 {
 	int ret;
 	unsigned int remaining;
 
-	ret = inline_xattr_iter_begin(&it->it, d_inode(it->dentry));
+	ret = inline_xattr_iter_begin(it, d_inode(it->dentry));
 	if (ret < 0)
 		return ret;
 
 	remaining = ret;
 	while (remaining) {
-		ret = xattr_foreach(&it->it, &list_xattr_handlers, &remaining);
+		ret = xattr_foreach(it, &list_xattr_handlers, &remaining);
 		if (ret)
 			break;
 	}
 	return ret ? ret : it->buffer_ofs;
 }
 
-static int shared_listxattr(struct listxattr_iter *it)
+static int shared_listxattr(struct erofs_xattr_iter *it)
 {
 	struct inode *const inode = d_inode(it->dentry);
 	struct erofs_inode *const vi = EROFS_I(inode);
-	struct super_block *const sb = it->it.sb;
+	struct super_block *const sb = it->sb;
 	unsigned int i, xsid;
 	int ret = 0;
 
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
 		xsid = vi->xattr_shared_xattrs[i];
-		it->it.pos = erofs_pos(sb, EROFS_SB(sb)->xattr_blkaddr) +
-				       xsid * sizeof(__u32);
-		it->it.kaddr = erofs_bread(&it->it.buf,
-				erofs_blknr(sb, it->it.pos), EROFS_KMAP);
-		if (IS_ERR(it->it.kaddr))
-			return PTR_ERR(it->it.kaddr);
-
-		ret = xattr_foreach(&it->it, &list_xattr_handlers, NULL);
+		it->pos = erofs_pos(sb, EROFS_SB(sb)->xattr_blkaddr) +
+				    xsid * sizeof(__u32);
+		it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
+					EROFS_KMAP);
+		if (IS_ERR(it->kaddr))
+			return PTR_ERR(it->kaddr);
+
+		ret = xattr_foreach(it, &list_xattr_handlers, NULL);
 		if (ret)
 			break;
 	}
@@ -589,7 +567,7 @@ ssize_t erofs_listxattr(struct dentry *dentry,
 			char *buffer, size_t buffer_size)
 {
 	int ret;
-	struct listxattr_iter it;
+	struct erofs_xattr_iter it;
 
 	ret = erofs_init_inode_xattrs(d_inode(dentry));
 	if (ret == -ENOATTR)
@@ -597,9 +575,9 @@ ssize_t erofs_listxattr(struct dentry *dentry,
 	if (ret)
 		return ret;
 
-	it.it.sb = dentry->d_sb;
-	it.it.buf = __EROFS_BUF_INITIALIZER;
-	erofs_init_metabuf(&it.it.buf, it.it.sb);
+	it.sb = dentry->d_sb;
+	it.buf = __EROFS_BUF_INITIALIZER;
+	erofs_init_metabuf(&it.buf, it.sb);
 	it.dentry = dentry;
 	it.buffer = buffer;
 	it.buffer_size = buffer_size;
@@ -608,7 +586,7 @@ ssize_t erofs_listxattr(struct dentry *dentry,
 	ret = inline_listxattr(&it);
 	if (ret >= 0 || ret == -ENOATTR)
 		ret = shared_listxattr(&it);
-	erofs_put_metabuf(&it.it.buf);
+	erofs_put_metabuf(&it.buf);
 	return ret;
 }
 
-- 
2.19.1.6.gb485710b

[PATCH v6 3/5] erofs: make the size of read data stored in buffer_ofs

[Jingbo Xu]

Since now xattr_iter structures have been unified, make the size of the
read data stored in buffer_ofs.  Don't bother reusing buffer_size for
this use, which may be confusing.

This is in preparation for the following further cleanup.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 fs/erofs/xattr.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index e9bc81846722..4ae9b7cdd3ac 100644
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -315,7 +315,7 @@ static int xattr_checkbuffer(struct erofs_xattr_iter *it,
 {
 	int err = it->buffer_size < value_sz ? -ERANGE : 0;
 
-	it->buffer_size = value_sz;
+	it->buffer_ofs = value_sz;
 	return !it->buffer ? 1 : err;
 }
 
@@ -348,7 +348,7 @@ static int inline_getxattr(struct inode *inode, struct erofs_xattr_iter *it)
 		if (ret != -ENOATTR)
 			break;
 	}
-	return ret ? ret : it->buffer_size;
+	return ret ? ret : it->buffer_ofs;
 }
 
 static int shared_getxattr(struct inode *inode, struct erofs_xattr_iter *it)
@@ -371,7 +371,7 @@ static int shared_getxattr(struct inode *inode, struct erofs_xattr_iter *it)
 		if (ret != -ENOATTR)
 			break;
 	}
-	return ret ? ret : it->buffer_size;
+	return ret ? ret : it->buffer_ofs;
 }
 
 static bool erofs_xattr_user_list(struct dentry *dentry)
-- 
2.19.1.6.gb485710b

[PATCH v6 4/5] erofs: unify inline/share xattr iterators for listxattr/getxattr

[Jingbo Xu]

Make inline_getxattr() and inline_listxattr() unified as
iter_inline_xattr(), shared_getxattr() and shared_listxattr() unified as
iter_shared_xattr().

After the unification, both iter_inline_xattr() and iter_shared_xattr()
return 0 on success, and negative error on failure.

One thing worth noting is that, the logic of returning it->buffer_ofs
when there's no shared xattrs in shared_listxattr() is moved to
erofs_listxattr() to make the unification possible.  The only difference
is that, semantically the old behavior will return ENOATTR rather than
it->buffer_ofs if ENOATTR encountered when listxattr is parsing upon a
specific shared xattr, while now the new behavior will return
it->buffer_ofs in this case.  This is not an issue, as listxattr upon a
specific xattr won't return ENOATTR.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
---
 fs/erofs/xattr.c | 188 ++++++++++++++++++-----------------------------
 1 file changed, 73 insertions(+), 115 deletions(-)

diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index 4ae9b7cdd3ac..15a1a4042205 100644
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -139,27 +139,6 @@ struct xattr_iter_handlers {
 		      unsigned int len);
 };
 
-static int inline_xattr_iter_begin(struct erofs_xattr_iter *it,
-				   struct inode *inode)
-{
-	struct erofs_inode *const vi = EROFS_I(inode);
-	unsigned int xattr_header_sz;
-
-	xattr_header_sz = sizeof(struct erofs_xattr_ibody_header) +
-			  sizeof(u32) * vi->xattr_shared_count;
-	if (xattr_header_sz >= vi->xattr_isize) {
-		DBG_BUGON(xattr_header_sz > vi->xattr_isize);
-		return -ENOATTR;
-	}
-
-	it->pos = erofs_iloc(inode) + vi->inode_isize + xattr_header_sz;
-	it->kaddr = erofs_bread(&it->buf, erofs_blknr(it->sb, it->pos),
-				EROFS_KMAP);
-	if (IS_ERR(it->kaddr))
-		return PTR_ERR(it->kaddr);
-	return vi->xattr_isize - xattr_header_sz;
-}
-
 /*
  * Regardless of success or failure, `xattr_foreach' will end up with
  * `pos' pointing to the next xattr item rather than an arbitrary position.
@@ -333,47 +312,6 @@ static const struct xattr_iter_handlers find_xattr_handlers = {
 	.value = xattr_copyvalue
 };
 
-static int inline_getxattr(struct inode *inode, struct erofs_xattr_iter *it)
-{
-	int ret;
-	unsigned int remaining;
-
-	ret = inline_xattr_iter_begin(it, inode);
-	if (ret < 0)
-		return ret;
-
-	remaining = ret;
-	while (remaining) {
-		ret = xattr_foreach(it, &find_xattr_handlers, &remaining);
-		if (ret != -ENOATTR)
-			break;
-	}
-	return ret ? ret : it->buffer_ofs;
-}
-
-static int shared_getxattr(struct inode *inode, struct erofs_xattr_iter *it)
-{
-	struct erofs_inode *const vi = EROFS_I(inode);
-	struct super_block *const sb = it->sb;
-	unsigned int i, xsid;
-	int ret = -ENOATTR;
-
-	for (i = 0; i < vi->xattr_shared_count; ++i) {
-		xsid = vi->xattr_shared_xattrs[i];
-		it->pos = erofs_pos(sb, EROFS_SB(sb)->xattr_blkaddr) +
-				    xsid * sizeof(__u32);
-		it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
-					EROFS_KMAP);
-		if (IS_ERR(it->kaddr))
-			return PTR_ERR(it->kaddr);
-
-		ret = xattr_foreach(it, &find_xattr_handlers, NULL);
-		if (ret != -ENOATTR)
-			break;
-	}
-	return ret ? ret : it->buffer_ofs;
-}
-
 static bool erofs_xattr_user_list(struct dentry *dentry)
 {
 	return test_opt(&EROFS_SB(dentry->d_sb)->opt, XATTR_USER);
@@ -384,39 +322,6 @@ static bool erofs_xattr_trusted_list(struct dentry *dentry)
 	return capable(CAP_SYS_ADMIN);
 }
 
-int erofs_getxattr(struct inode *inode, int index,
-		   const char *name,
-		   void *buffer, size_t buffer_size)
-{
-	int ret;
-	struct erofs_xattr_iter it;
-
-	if (!name)
-		return -EINVAL;
-
-	ret = erofs_init_inode_xattrs(inode);
-	if (ret)
-		return ret;
-
-	it.index = index;
-	it.name = (struct qstr)QSTR_INIT(name, strlen(name));
-	if (it.name.len > EROFS_NAME_LEN)
-		return -ERANGE;
-
-	it.sb = inode->i_sb;
-	it.buf = __EROFS_BUF_INITIALIZER;
-	erofs_init_metabuf(&it.buf, it.sb);
-	it.buffer = buffer;
-	it.buffer_size = buffer_size;
-	it.buffer_ofs = 0;
-
-	ret = inline_getxattr(inode, &it);
-	if (ret == -ENOATTR)
-		ret = shared_getxattr(inode, &it);
-	erofs_put_metabuf(&it.buf);
-	return ret;
-}
-
 static int erofs_xattr_generic_get(const struct xattr_handler *handler,
 				   struct dentry *unused, struct inode *inode,
 				   const char *name, void *buffer, size_t size)
@@ -521,31 +426,48 @@ static const struct xattr_iter_handlers list_xattr_handlers = {
 	.value = NULL
 };
 
-static int inline_listxattr(struct erofs_xattr_iter *it)
+static int erofs_iter_inline_xattr(struct erofs_xattr_iter *it,
+				   struct inode *inode, bool getxattr)
 {
+	struct erofs_inode *const vi = EROFS_I(inode);
+	const struct xattr_iter_handlers *op;
+	unsigned int xattr_header_sz, remaining;
 	int ret;
-	unsigned int remaining;
 
-	ret = inline_xattr_iter_begin(it, d_inode(it->dentry));
-	if (ret < 0)
-		return ret;
+	xattr_header_sz = sizeof(struct erofs_xattr_ibody_header) +
+			  sizeof(u32) * vi->xattr_shared_count;
+	if (xattr_header_sz >= vi->xattr_isize) {
+		DBG_BUGON(xattr_header_sz > vi->xattr_isize);
+		return -ENOATTR;
+	}
+
+	it->pos = erofs_iloc(inode) + vi->inode_isize + xattr_header_sz;
+	it->kaddr = erofs_bread(&it->buf, erofs_blknr(it->sb, it->pos),
+				EROFS_KMAP);
+	if (IS_ERR(it->kaddr))
+		return PTR_ERR(it->kaddr);
+
+	remaining = vi->xattr_isize - xattr_header_sz;
+	op = getxattr ? &find_xattr_handlers : &list_xattr_handlers;
 
-	remaining = ret;
 	while (remaining) {
-		ret = xattr_foreach(it, &list_xattr_handlers, &remaining);
-		if (ret)
+		ret = xattr_foreach(it, op, &remaining);
+		if ((getxattr && ret != -ENOATTR) || (!getxattr && ret))
 			break;
 	}
-	return ret ? ret : it->buffer_ofs;
+	return ret;
 }
 
-static int shared_listxattr(struct erofs_xattr_iter *it)
+static int erofs_iter_shared_xattr(struct erofs_xattr_iter *it,
+				   struct inode *inode, bool getxattr)
 {
-	struct inode *const inode = d_inode(it->dentry);
 	struct erofs_inode *const vi = EROFS_I(inode);
 	struct super_block *const sb = it->sb;
+	const struct xattr_iter_handlers *op;
 	unsigned int i, xsid;
-	int ret = 0;
+	int ret = -ENOATTR;
+
+	op = getxattr ? &find_xattr_handlers : &list_xattr_handlers;
 
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
 		xsid = vi->xattr_shared_xattrs[i];
@@ -556,11 +478,44 @@ static int shared_listxattr(struct erofs_xattr_iter *it)
 		if (IS_ERR(it->kaddr))
 			return PTR_ERR(it->kaddr);
 
-		ret = xattr_foreach(it, &list_xattr_handlers, NULL);
-		if (ret)
+		ret = xattr_foreach(it, op, NULL);
+		if ((getxattr && ret != -ENOATTR) || (!getxattr && ret))
 			break;
 	}
-	return ret ? ret : it->buffer_ofs;
+	return ret;
+}
+
+int erofs_getxattr(struct inode *inode, int index,
+		   const char *name,
+		   void *buffer, size_t buffer_size)
+{
+	int ret;
+	struct erofs_xattr_iter it;
+
+	if (!name)
+		return -EINVAL;
+
+	ret = erofs_init_inode_xattrs(inode);
+	if (ret)
+		return ret;
+
+	it.index = index;
+	it.name = (struct qstr)QSTR_INIT(name, strlen(name));
+	if (it.name.len > EROFS_NAME_LEN)
+		return -ERANGE;
+
+	it.sb = inode->i_sb;
+	it.buf = __EROFS_BUF_INITIALIZER;
+	erofs_init_metabuf(&it.buf, it.sb);
+	it.buffer = buffer;
+	it.buffer_size = buffer_size;
+	it.buffer_ofs = 0;
+
+	ret = erofs_iter_inline_xattr(&it, inode, true);
+	if (ret == -ENOATTR)
+		ret = erofs_iter_shared_xattr(&it, inode, true);
+	erofs_put_metabuf(&it.buf);
+	return ret ? ret : it.buffer_ofs;
 }
 
 ssize_t erofs_listxattr(struct dentry *dentry,
@@ -568,8 +523,9 @@ ssize_t erofs_listxattr(struct dentry *dentry,
 {
 	int ret;
 	struct erofs_xattr_iter it;
+	struct inode *inode = d_inode(dentry);
 
-	ret = erofs_init_inode_xattrs(d_inode(dentry));
+	ret = erofs_init_inode_xattrs(inode);
 	if (ret == -ENOATTR)
 		return 0;
 	if (ret)
@@ -583,11 +539,13 @@ ssize_t erofs_listxattr(struct dentry *dentry,
 	it.buffer_size = buffer_size;
 	it.buffer_ofs = 0;
 
-	ret = inline_listxattr(&it);
-	if (ret >= 0 || ret == -ENOATTR)
-		ret = shared_listxattr(&it);
+	ret = erofs_iter_inline_xattr(&it, inode, false);
+	if (!ret || ret == -ENOATTR)
+		ret = erofs_iter_shared_xattr(&it, inode, false);
+	if (ret == -ENOATTR)
+		ret = 0;
 	erofs_put_metabuf(&it.buf);
-	return ret;
+	return ret ? ret : it.buffer_ofs;
 }
 
 void erofs_xattr_prefixes_cleanup(struct super_block *sb)
-- 
2.19.1.6.gb485710b

[PATCH v6 5/5] erofs: use separate xattr parsers for listxattr/getxattr

[Jingbo Xu]

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@linux.alibaba.com>
---
 fs/erofs/xattr.c | 364 +++++++++++++++++------------------------------
 1 file changed, 131 insertions(+), 233 deletions(-)

diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index 15a1a4042205..bfee11ee7fcf 100644
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -123,195 +123,6 @@ 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
- * `pos' 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;
-	struct super_block *sb = it->sb;
-	unsigned int value_sz, processed, slice;
-	int err;
-
-	/* 0. fixup blkaddr, pos */
-	it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos), EROFS_KMAP);
-	if (IS_ERR(it->kaddr))
-		return PTR_ERR(it->kaddr);
-
-	/*
-	 * 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 + erofs_blkoff(sb, it->pos));
-	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->pos += sizeof(struct erofs_xattr_entry);
-	value_sz = le16_to_cpu(entry.e_value_size);
-
-	/* handle entry */
-	err = op->entry(it, &entry);
-	if (err) {
-		it->pos += entry.e_name_len + value_sz;
-		goto out;
-	}
-
-	/* 2. handle xattr name (pos will finally be at the end of name) */
-	processed = 0;
-
-	while (processed < entry.e_name_len) {
-		it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
-					EROFS_KMAP);
-		if (IS_ERR(it->kaddr)) {
-			err = PTR_ERR(it->kaddr);
-			goto out;
-		}
-
-		slice = min_t(unsigned int,
-			      sb->s_blocksize - erofs_blkoff(sb, it->pos),
-			      entry.e_name_len - processed);
-
-		/* handle name */
-		err = op->name(it, processed,
-			       it->kaddr + erofs_blkoff(sb, it->pos), slice);
-		if (err) {
-			it->pos += entry.e_name_len - processed + value_sz;
-			goto out;
-		}
-
-		it->pos += slice;
-		processed += slice;
-	}
-
-	/* 3. handle xattr value */
-	processed = 0;
-
-	if (op->alloc_buffer) {
-		err = op->alloc_buffer(it, value_sz);
-		if (err) {
-			it->pos += value_sz;
-			goto out;
-		}
-	}
-
-	while (processed < value_sz) {
-		it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
-					EROFS_KMAP);
-		if (IS_ERR(it->kaddr)) {
-			err = PTR_ERR(it->kaddr);
-			goto out;
-		}
-
-		slice = min_t(unsigned int,
-			      sb->s_blocksize - erofs_blkoff(sb, it->pos),
-			      value_sz - processed);
-		op->value(it, processed, it->kaddr + erofs_blkoff(sb, it->pos),
-			  slice);
-		it->pos += slice;
-		processed += slice;
-	}
-
-out:
-	/* xattrs should be 4-byte aligned (on-disk constraint) */
-	it->pos = EROFS_XATTR_ALIGN(it->pos);
-	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);
@@ -364,20 +175,55 @@ const struct xattr_handler *erofs_xattr_handlers[] = {
 	NULL,
 };
 
-static int xattr_entrylist(struct erofs_xattr_iter *it,
-			   struct erofs_xattr_entry *entry)
+static int erofs_xattr_handle_string(struct erofs_xattr_iter *it,
+				     unsigned int len, bool copy)
 {
-	unsigned int base_index = entry->e_name_index;
-	unsigned int prefix_len, infix_len = 0;
+	unsigned int slice, processed = 0;
+	struct super_block *sb = it->sb;
+	void *buf;
+
+	while (processed < len) {
+		it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
+					EROFS_KMAP);
+		if (IS_ERR(it->kaddr))
+			return PTR_ERR(it->kaddr);
+
+		buf = it->kaddr + erofs_blkoff(sb, it->pos);
+		slice = min_t(unsigned int, sb->s_blocksize -
+				erofs_blkoff(sb, it->pos), len - processed);
+		if (copy) {
+			memcpy(it->buffer + it->buffer_ofs, buf, slice);
+			it->buffer_ofs += slice;
+		} else if (memcmp(it->name.name + it->infix_len + processed,
+				  buf, slice)) {
+			return -ENOATTR;
+		}
+		it->pos += slice;
+		processed += slice;
+	}
+	return 0;
+}
+
+static int erofs_listxattr_foreach(struct erofs_xattr_iter *it)
+{
+	struct erofs_xattr_entry entry;
+	unsigned int base_index, prefix_len, infix_len = 0;
 	const char *prefix, *infix = NULL;
+	int err;
 
-	if (entry->e_name_index & EROFS_XATTR_LONG_PREFIX) {
+	/* 1. handle xattr entry */
+	entry = *(struct erofs_xattr_entry *)
+			(it->kaddr + erofs_blkoff(it->sb, it->pos));
+	it->pos += sizeof(struct erofs_xattr_entry);
+
+	base_index = entry.e_name_index;
+	if (entry.e_name_index & EROFS_XATTR_LONG_PREFIX) {
 		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);
+			(entry.e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
 
 		if (pf >= sbi->xattr_prefixes + sbi->xattr_prefix_count)
-			return 1;
+			return 0;
 		infix = pf->prefix->infix;
 		infix_len = pf->infix_len;
 		base_index = pf->prefix->base_index;
@@ -385,53 +231,91 @@ static int xattr_entrylist(struct erofs_xattr_iter *it,
 
 	prefix = erofs_xattr_prefix(base_index, it->dentry);
 	if (!prefix)
-		return 1;
+		return 0;
 	prefix_len = strlen(prefix);
 
 	if (!it->buffer) {
-		it->buffer_ofs += prefix_len + infix_len +
-					entry->e_name_len + 1;
-		return 1;
+		it->buffer_ofs += prefix_len + infix_len + entry.e_name_len + 1;
+		return 0;
 	}
 
 	if (it->buffer_ofs + prefix_len + infix_len +
-		+ entry->e_name_len + 1 > it->buffer_size)
+		entry.e_name_len + 1 > it->buffer_size)
 		return -ERANGE;
 
 	memcpy(it->buffer + it->buffer_ofs, prefix, prefix_len);
 	memcpy(it->buffer + it->buffer_ofs + prefix_len, infix, infix_len);
 	it->buffer_ofs += prefix_len + infix_len;
-	return 0;
-}
 
-static int xattr_namelist(struct erofs_xattr_iter *it,
-			  unsigned int processed, char *buf, unsigned int len)
-{
-	memcpy(it->buffer + it->buffer_ofs, buf, len);
-	it->buffer_ofs += len;
+	/* 2. handle xattr name */
+	err = erofs_xattr_handle_string(it, entry.e_name_len, true);
+	if (err)
+		return err;
+
+	it->buffer[it->buffer_ofs++] = '\0';
 	return 0;
 }
 
-static int xattr_skipvalue(struct erofs_xattr_iter *it,
-			   unsigned int value_sz)
+static int erofs_getxattr_foreach(struct erofs_xattr_iter *it)
 {
-	it->buffer[it->buffer_ofs++] = '\0';
-	return 1;
-}
+	struct erofs_xattr_entry entry;
+	unsigned int value_sz;
+	int err;
 
-static const struct xattr_iter_handlers list_xattr_handlers = {
-	.entry = xattr_entrylist,
-	.name = xattr_namelist,
-	.alloc_buffer = xattr_skipvalue,
-	.value = NULL
-};
+	/* 1. handle xattr entry */
+	entry = *(struct erofs_xattr_entry *)
+			(it->kaddr + erofs_blkoff(it->sb, it->pos));
+	it->pos += sizeof(struct erofs_xattr_entry);
+	value_sz = le16_to_cpu(entry.e_value_size);
+
+	/* should also match the infix for long name prefixes */
+	if (entry.e_name_index & EROFS_XATTR_LONG_PREFIX) {
+		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;
+	} else {
+		if (it->index != entry.e_name_index ||
+		    it->name.len != entry.e_name_len)
+			return -ENOATTR;
+
+		it->infix_len = 0;
+	}
+
+	/* 2. handle xattr name */
+	err = erofs_xattr_handle_string(it, entry.e_name_len, false);
+	if (err)
+		return err;
+
+	/* 3. handle xattr value */
+	if (!it->buffer) {
+		it->buffer_ofs = value_sz;
+		return 0;
+	}
+
+	if (it->buffer_size < value_sz)
+		return -ERANGE;
+
+	return erofs_xattr_handle_string(it, value_sz, true);
+}
 
 static int erofs_iter_inline_xattr(struct erofs_xattr_iter *it,
 				   struct inode *inode, bool getxattr)
 {
 	struct erofs_inode *const vi = EROFS_I(inode);
-	const struct xattr_iter_handlers *op;
-	unsigned int xattr_header_sz, remaining;
+	unsigned int xattr_header_sz, remaining, entry_sz;
+	erofs_off_t next_pos;
 	int ret;
 
 	xattr_header_sz = sizeof(struct erofs_xattr_ibody_header) +
@@ -441,19 +325,33 @@ static int erofs_iter_inline_xattr(struct erofs_xattr_iter *it,
 		return -ENOATTR;
 	}
 
-	it->pos = erofs_iloc(inode) + vi->inode_isize + xattr_header_sz;
-	it->kaddr = erofs_bread(&it->buf, erofs_blknr(it->sb, it->pos),
-				EROFS_KMAP);
-	if (IS_ERR(it->kaddr))
-		return PTR_ERR(it->kaddr);
-
 	remaining = vi->xattr_isize - xattr_header_sz;
-	op = getxattr ? &find_xattr_handlers : &list_xattr_handlers;
+	it->pos = erofs_iloc(inode) + vi->inode_isize + xattr_header_sz;
 
 	while (remaining) {
-		ret = xattr_foreach(it, op, &remaining);
+		it->kaddr = erofs_bread(&it->buf, erofs_blknr(it->sb, it->pos),
+					EROFS_KMAP);
+		if (IS_ERR(it->kaddr))
+			return PTR_ERR(it->kaddr);
+
+		entry_sz = erofs_xattr_entry_size(it->kaddr +
+				erofs_blkoff(it->sb, it->pos));
+		/* xattr on-disk corruption: xattr entry beyond xattr_isize */
+		if (remaining < entry_sz) {
+			DBG_BUGON(1);
+			return -EFSCORRUPTED;
+		}
+		remaining -= entry_sz;
+		next_pos = it->pos + entry_sz;
+
+		if (getxattr)
+			ret = erofs_getxattr_foreach(it);
+		else
+			ret = erofs_listxattr_foreach(it);
 		if ((getxattr && ret != -ENOATTR) || (!getxattr && ret))
 			break;
+
+		it->pos = next_pos;
 	}
 	return ret;
 }
@@ -463,12 +361,9 @@ static int erofs_iter_shared_xattr(struct erofs_xattr_iter *it,
 {
 	struct erofs_inode *const vi = EROFS_I(inode);
 	struct super_block *const sb = it->sb;
-	const struct xattr_iter_handlers *op;
 	unsigned int i, xsid;
 	int ret = -ENOATTR;
 
-	op = getxattr ? &find_xattr_handlers : &list_xattr_handlers;
-
 	for (i = 0; i < vi->xattr_shared_count; ++i) {
 		xsid = vi->xattr_shared_xattrs[i];
 		it->pos = erofs_pos(sb, EROFS_SB(sb)->xattr_blkaddr) +
@@ -478,7 +373,10 @@ static int erofs_iter_shared_xattr(struct erofs_xattr_iter *it,
 		if (IS_ERR(it->kaddr))
 			return PTR_ERR(it->kaddr);
 
-		ret = xattr_foreach(it, op, NULL);
+		if (getxattr)
+			ret = erofs_getxattr_foreach(it);
+		else
+			ret = erofs_listxattr_foreach(it);
 		if ((getxattr && ret != -ENOATTR) || (!getxattr && ret))
 			break;
 	}
-- 
2.19.1.6.gb485710b

Re: [PATCH v6 1/5] erofs: use absolute position in xattr iterator

[Gao Xiang]

On 2023/6/8 19:30, Jingbo Xu wrote:
> Replace blkaddr/ofs with pos in 'struct erofs_xattr_iter'.
> 
> After erofs_bread() is introduced to replace raw page cache APIs for
> metadata I/Os handling, xattr_iter_fixup() is no longer needed anymore.
> 
> In addition, it is also unnecessary to check if the iterated position is
> span over the block boundary as absolute offset is used instead of
> blkaddr + offset pairs.
> 
> Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>

...

>   
> @@ -399,9 +365,10 @@ static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
>   
>   	for (i = 0; i < vi->xattr_shared_count; ++i) {
>   		xsid = vi->xattr_shared_xattrs[i];
> -		it->it.blkaddr = erofs_xattr_blkaddr(sb, xsid);
> -		it->it.ofs = erofs_xattr_blkoff(sb, xsid);
> -		it->it.kaddr = erofs_bread(&it->it.buf, it->it.blkaddr, EROFS_KMAP);
> +		it->it.pos = erofs_pos(sb, EROFS_SB(sb)->xattr_blkaddr) +
> +				       xsid * sizeof(__u32);

					^ sizeof(__le32); ?

> +		it->it.kaddr = erofs_bread(&it->it.buf,
> +				erofs_blknr(sb, it->it.pos), EROFS_KMAP);
>   		if (IS_ERR(it->it.kaddr))
>   			return PTR_ERR(it->it.kaddr);
>   
> @@ -604,9 +571,10 @@ static int shared_listxattr(struct listxattr_iter *it)
>   
>   	for (i = 0; i < vi->xattr_shared_count; ++i) {
>   		xsid = vi->xattr_shared_xattrs[i];
> -		it->it.blkaddr = erofs_xattr_blkaddr(sb, xsid);
> -		it->it.ofs = erofs_xattr_blkoff(sb, xsid);
> -		it->it.kaddr = erofs_bread(&it->it.buf, it->it.blkaddr, EROFS_KMAP);
> +		it->it.pos = erofs_pos(sb, EROFS_SB(sb)->xattr_blkaddr) +
> +				       xsid * sizeof(__u32);

					^ sizeof(__le32); ?


Otherwise it looks good to me.

Thanks,
Gao Xiang

Re: [PATCH v6 4/5] erofs: unify inline/share xattr iterators for listxattr/getxattr

[Gao Xiang]

On 2023/6/8 19:30, Jingbo Xu wrote:
> Make inline_getxattr() and inline_listxattr() unified as
> iter_inline_xattr(), shared_getxattr() and shared_listxattr() unified as

erofs_xattr_iter_inline() as well as shared_getxattr() and
shared_listxattr() unified as erofs_xattr_iter_shared() ?

> iter_shared_xattr().
> 
> After the unification, both iter_inline_xattr() and iter_shared_xattr()
> return 0 on success, and negative error on failure.

After these changes, both erofs_xattr_iter_{inline,shared} return 0 on
success, and negative values on failure.

> 
> One thing worth noting is that, the logic of returning it->buffer_ofs
> when there's no shared xattrs in shared_listxattr() is moved to
> erofs_listxattr() to make the unification possible.  The only difference
> is that, semantically the old behavior will return ENOATTR rather than
> it->buffer_ofs if ENOATTR encountered when listxattr is parsing upon a
> specific shared xattr, while now the new behavior will return
> it->buffer_ofs in this case.  This is not an issue, as listxattr upon a
> specific xattr won't return ENOATTR.
> 
> Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>

Otherwise it looks good to me.

Thanks,
Gao Xiang

> ---
>   fs/erofs/xattr.c | 188 ++++++++++++++++++-----------------------------
>   1 file changed, 73 insertions(+), 115 deletions(-)
> 
> diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
> index 4ae9b7cdd3ac..15a1a4042205 100644
> --- a/fs/erofs/xattr.c
> +++ b/fs/erofs/xattr.c
> @@ -139,27 +139,6 @@ struct xattr_iter_handlers {
>   		      unsigned int len);
>   };
>   
> -static int inline_xattr_iter_begin(struct erofs_xattr_iter *it,
> -				   struct inode *inode)
> -{
> -	struct erofs_inode *const vi = EROFS_I(inode);
> -	unsigned int xattr_header_sz;
> -
> -	xattr_header_sz = sizeof(struct erofs_xattr_ibody_header) +
> -			  sizeof(u32) * vi->xattr_shared_count;
> -	if (xattr_header_sz >= vi->xattr_isize) {
> -		DBG_BUGON(xattr_header_sz > vi->xattr_isize);
> -		return -ENOATTR;
> -	}
> -
> -	it->pos = erofs_iloc(inode) + vi->inode_isize + xattr_header_sz;
> -	it->kaddr = erofs_bread(&it->buf, erofs_blknr(it->sb, it->pos),
> -				EROFS_KMAP);
> -	if (IS_ERR(it->kaddr))
> -		return PTR_ERR(it->kaddr);
> -	return vi->xattr_isize - xattr_header_sz;
> -}
> -
>   /*
>    * Regardless of success or failure, `xattr_foreach' will end up with
>    * `pos' pointing to the next xattr item rather than an arbitrary position.
> @@ -333,47 +312,6 @@ static const struct xattr_iter_handlers find_xattr_handlers = {
>   	.value = xattr_copyvalue
>   };
>   
> -static int inline_getxattr(struct inode *inode, struct erofs_xattr_iter *it)
> -{
> -	int ret;
> -	unsigned int remaining;
> -
> -	ret = inline_xattr_iter_begin(it, inode);
> -	if (ret < 0)
> -		return ret;
> -
> -	remaining = ret;
> -	while (remaining) {
> -		ret = xattr_foreach(it, &find_xattr_handlers, &remaining);
> -		if (ret != -ENOATTR)
> -			break;
> -	}
> -	return ret ? ret : it->buffer_ofs;
> -}
> -
> -static int shared_getxattr(struct inode *inode, struct erofs_xattr_iter *it)
> -{
> -	struct erofs_inode *const vi = EROFS_I(inode);
> -	struct super_block *const sb = it->sb;
> -	unsigned int i, xsid;
> -	int ret = -ENOATTR;
> -
> -	for (i = 0; i < vi->xattr_shared_count; ++i) {
> -		xsid = vi->xattr_shared_xattrs[i];
> -		it->pos = erofs_pos(sb, EROFS_SB(sb)->xattr_blkaddr) +
> -				    xsid * sizeof(__u32);
> -		it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
> -					EROFS_KMAP);
> -		if (IS_ERR(it->kaddr))
> -			return PTR_ERR(it->kaddr);
> -
> -		ret = xattr_foreach(it, &find_xattr_handlers, NULL);
> -		if (ret != -ENOATTR)
> -			break;
> -	}
> -	return ret ? ret : it->buffer_ofs;
> -}
> -
>   static bool erofs_xattr_user_list(struct dentry *dentry)
>   {
>   	return test_opt(&EROFS_SB(dentry->d_sb)->opt, XATTR_USER);
> @@ -384,39 +322,6 @@ static bool erofs_xattr_trusted_list(struct dentry *dentry)
>   	return capable(CAP_SYS_ADMIN);
>   }
>   
> -int erofs_getxattr(struct inode *inode, int index,
> -		   const char *name,
> -		   void *buffer, size_t buffer_size)
> -{
> -	int ret;
> -	struct erofs_xattr_iter it;
> -
> -	if (!name)
> -		return -EINVAL;
> -
> -	ret = erofs_init_inode_xattrs(inode);
> -	if (ret)
> -		return ret;
> -
> -	it.index = index;
> -	it.name = (struct qstr)QSTR_INIT(name, strlen(name));
> -	if (it.name.len > EROFS_NAME_LEN)
> -		return -ERANGE;
> -
> -	it.sb = inode->i_sb;
> -	it.buf = __EROFS_BUF_INITIALIZER;
> -	erofs_init_metabuf(&it.buf, it.sb);
> -	it.buffer = buffer;
> -	it.buffer_size = buffer_size;
> -	it.buffer_ofs = 0;
> -
> -	ret = inline_getxattr(inode, &it);
> -	if (ret == -ENOATTR)
> -		ret = shared_getxattr(inode, &it);
> -	erofs_put_metabuf(&it.buf);
> -	return ret;
> -}
> -
>   static int erofs_xattr_generic_get(const struct xattr_handler *handler,
>   				   struct dentry *unused, struct inode *inode,
>   				   const char *name, void *buffer, size_t size)
> @@ -521,31 +426,48 @@ static const struct xattr_iter_handlers list_xattr_handlers = {
>   	.value = NULL
>   };
>   
> -static int inline_listxattr(struct erofs_xattr_iter *it)
> +static int erofs_iter_inline_xattr(struct erofs_xattr_iter *it,
> +				   struct inode *inode, bool getxattr)
>   {
> +	struct erofs_inode *const vi = EROFS_I(inode);
> +	const struct xattr_iter_handlers *op;
> +	unsigned int xattr_header_sz, remaining;
>   	int ret;
> -	unsigned int remaining;
>   
> -	ret = inline_xattr_iter_begin(it, d_inode(it->dentry));
> -	if (ret < 0)
> -		return ret;
> +	xattr_header_sz = sizeof(struct erofs_xattr_ibody_header) +
> +			  sizeof(u32) * vi->xattr_shared_count;
> +	if (xattr_header_sz >= vi->xattr_isize) {
> +		DBG_BUGON(xattr_header_sz > vi->xattr_isize);
> +		return -ENOATTR;
> +	}
> +
> +	it->pos = erofs_iloc(inode) + vi->inode_isize + xattr_header_sz;
> +	it->kaddr = erofs_bread(&it->buf, erofs_blknr(it->sb, it->pos),
> +				EROFS_KMAP);
> +	if (IS_ERR(it->kaddr))
> +		return PTR_ERR(it->kaddr);
> +
> +	remaining = vi->xattr_isize - xattr_header_sz;
> +	op = getxattr ? &find_xattr_handlers : &list_xattr_handlers;
>   
> -	remaining = ret;
>   	while (remaining) {
> -		ret = xattr_foreach(it, &list_xattr_handlers, &remaining);
> -		if (ret)
> +		ret = xattr_foreach(it, op, &remaining);
> +		if ((getxattr && ret != -ENOATTR) || (!getxattr && ret))
>   			break;
>   	}
> -	return ret ? ret : it->buffer_ofs;
> +	return ret;
>   }
>   
> -static int shared_listxattr(struct erofs_xattr_iter *it)
> +static int erofs_iter_shared_xattr(struct erofs_xattr_iter *it,
> +				   struct inode *inode, bool getxattr)
>   {
> -	struct inode *const inode = d_inode(it->dentry);
>   	struct erofs_inode *const vi = EROFS_I(inode);
>   	struct super_block *const sb = it->sb;
> +	const struct xattr_iter_handlers *op;
>   	unsigned int i, xsid;
> -	int ret = 0;
> +	int ret = -ENOATTR;
> +
> +	op = getxattr ? &find_xattr_handlers : &list_xattr_handlers;
>   
>   	for (i = 0; i < vi->xattr_shared_count; ++i) {
>   		xsid = vi->xattr_shared_xattrs[i];
> @@ -556,11 +478,44 @@ static int shared_listxattr(struct erofs_xattr_iter *it)
>   		if (IS_ERR(it->kaddr))
>   			return PTR_ERR(it->kaddr);
>   
> -		ret = xattr_foreach(it, &list_xattr_handlers, NULL);
> -		if (ret)
> +		ret = xattr_foreach(it, op, NULL);
> +		if ((getxattr && ret != -ENOATTR) || (!getxattr && ret))
>   			break;
>   	}
> -	return ret ? ret : it->buffer_ofs;
> +	return ret;
> +}
> +
> +int erofs_getxattr(struct inode *inode, int index,
> +		   const char *name,
> +		   void *buffer, size_t buffer_size)
> +{
> +	int ret;
> +	struct erofs_xattr_iter it;
> +
> +	if (!name)
> +		return -EINVAL;
> +
> +	ret = erofs_init_inode_xattrs(inode);
> +	if (ret)
> +		return ret;
> +
> +	it.index = index;
> +	it.name = (struct qstr)QSTR_INIT(name, strlen(name));
> +	if (it.name.len > EROFS_NAME_LEN)
> +		return -ERANGE;
> +
> +	it.sb = inode->i_sb;
> +	it.buf = __EROFS_BUF_INITIALIZER;
> +	erofs_init_metabuf(&it.buf, it.sb);
> +	it.buffer = buffer;
> +	it.buffer_size = buffer_size;
> +	it.buffer_ofs = 0;
> +
> +	ret = erofs_iter_inline_xattr(&it, inode, true);
> +	if (ret == -ENOATTR)
> +		ret = erofs_iter_shared_xattr(&it, inode, true);
> +	erofs_put_metabuf(&it.buf);
> +	return ret ? ret : it.buffer_ofs;
>   }
>   
>   ssize_t erofs_listxattr(struct dentry *dentry,
> @@ -568,8 +523,9 @@ ssize_t erofs_listxattr(struct dentry *dentry,
>   {
>   	int ret;
>   	struct erofs_xattr_iter it;
> +	struct inode *inode = d_inode(dentry);
>   
> -	ret = erofs_init_inode_xattrs(d_inode(dentry));
> +	ret = erofs_init_inode_xattrs(inode);
>   	if (ret == -ENOATTR)
>   		return 0;
>   	if (ret)
> @@ -583,11 +539,13 @@ ssize_t erofs_listxattr(struct dentry *dentry,
>   	it.buffer_size = buffer_size;
>   	it.buffer_ofs = 0;
>   
> -	ret = inline_listxattr(&it);
> -	if (ret >= 0 || ret == -ENOATTR)
> -		ret = shared_listxattr(&it);
> +	ret = erofs_iter_inline_xattr(&it, inode, false);
> +	if (!ret || ret == -ENOATTR)
> +		ret = erofs_iter_shared_xattr(&it, inode, false);
> +	if (ret == -ENOATTR)
> +		ret = 0;
>   	erofs_put_metabuf(&it.buf);
> -	return ret;
> +	return ret ? ret : it.buffer_ofs;
>   }
>   
>   void erofs_xattr_prefixes_cleanup(struct super_block *sb)