[PATCH v4 1/5] erofs: enhance erofs_xattr_iter_fixup() helper

[Jingbo Xu]

Enhance erofs_xattr_iter_fixup() helper so that it could be reused in
the situation where it.ofs could not span the block boundary.

Besides call erofs_init_metabuf() and erofs_bread() separately to avoid
the repetition of assigning buf->inode when iterating xattrs.

Signed-off-by: Jingbo Xu <jefflexu@xxxxxxxxxxxxxxxxx>
---
 fs/erofs/xattr.c | 82 +++++++++++++++++++++---------------------------
 1 file changed, 35 insertions(+), 47 deletions(-)

diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index bbfe7ce170d2..df6c4e6f1f4e 100644
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -29,6 +29,24 @@ struct xattr_iter {
 	unsigned int ofs;
 };
 
+static inline int erofs_xattr_iter_fixup(struct xattr_iter *it, bool nospan)
+{
+	if (it->ofs < it->sb->s_blocksize)
+		return 0;
+
+	if (nospan && it->ofs != it->sb->s_blocksize) {
+		DBG_BUGON(1);
+		return -EFSCORRUPTED;
+	}
+
+	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 erofs_init_inode_xattrs(struct inode *inode)
 {
 	struct erofs_inode *const vi = EROFS_I(inode);
@@ -80,6 +98,7 @@ static int erofs_init_inode_xattrs(struct inode *inode)
 		goto out_unlock;
 	}
 
+	it.sb = sb;
 	it.buf = __EROFS_BUF_INITIALIZER;
 	it.blkaddr = erofs_blknr(sb, erofs_iloc(inode) + vi->inode_isize);
 	it.ofs = erofs_blkoff(sb, erofs_iloc(inode) + vi->inode_isize);
@@ -105,19 +124,11 @@ static int erofs_init_inode_xattrs(struct inode *inode)
 	it.ofs += 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_read_metabuf(&it.buf, sb, ++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;
+		ret = erofs_xattr_iter_fixup(&it, true);
+		if (ret) {
+			kfree(vi->xattr_shared_xattrs);
+			vi->xattr_shared_xattrs = NULL;
+			goto out_unlock;
 		}
 		vi->xattr_shared_xattrs[i] =
 			le32_to_cpu(*(__le32 *)(it.kaddr + it.ofs));
@@ -150,20 +161,6 @@ 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_read_metabuf(&it->buf, it->sb, 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)
 {
@@ -201,7 +198,7 @@ static int xattr_foreach(struct xattr_iter *it,
 	int err;
 
 	/* 0. fixup blkaddr, ofs, ipage */
-	err = xattr_iter_fixup(it);
+	err = erofs_xattr_iter_fixup(it, false);
 	if (err)
 		return err;
 
@@ -236,14 +233,9 @@ static int xattr_foreach(struct xattr_iter *it,
 	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;
-		}
+		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);
@@ -271,14 +263,9 @@ static int xattr_foreach(struct xattr_iter *it,
 	}
 
 	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;
-		}
+		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);
@@ -444,13 +431,14 @@ int erofs_getxattr(struct inode *inode, int index,
 	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.buffer = buffer;
 	it.buffer_size = buffer_size;
 
-	it.it.sb = inode->i_sb;
 	ret = inline_getxattr(inode, &it);
 	if (ret == -ENOATTR)
 		ret = shared_getxattr(inode, &it);
@@ -632,14 +620,14 @@ 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.dentry = dentry;
 	it.buffer = buffer;
 	it.buffer_size = buffer_size;
 	it.buffer_ofs = 0;
 
-	it.it.sb = dentry->d_sb;
-
 	ret = inline_listxattr(&it);
 	if (ret >= 0 || ret == -ENOATTR)
 		ret = shared_listxattr(&it);
-- 
2.19.1.6.gb485710b