erofs: simplify z_erofs_read_fragment()

A trivial cleanup to make the fragment handling logic more clear.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230817082813.81180-1-hsiangkao@linux.alibaba.com

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 53820271e538230a0d65abd118c1937f9e0e101f..dc104add0a99e58aad35d4a892e2bea4524e3e13 100644 (file)
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -932,34 +932,27 @@ static bool z_erofs_collector_end(struct z_erofs_decompress_frontend *fe)
        return true;
 }
 
-static int z_erofs_read_fragment(struct inode *inode, erofs_off_t pos,
-                                struct page *page, unsigned int pageofs,
-                                unsigned int len)
+static int z_erofs_read_fragment(struct super_block *sb, struct page *page,
+                       unsigned int cur, unsigned int end, erofs_off_t pos)
 {
-       struct super_block *sb = inode->i_sb;
-       struct inode *packed_inode = EROFS_I_SB(inode)->packed_inode;
+       struct inode *packed_inode = EROFS_SB(sb)->packed_inode;
        struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
-       u8 *src, *dst;
-       unsigned int i, cnt;
+       unsigned int cnt;
+       u8 *src;
 
        if (!packed_inode)
                return -EFSCORRUPTED;
 
        buf.inode = packed_inode;
-       pos += EROFS_I(inode)->z_fragmentoff;
-       for (i = 0; i < len; i += cnt) {
-               cnt = min_t(unsigned int, len - i,
+       for (; cur < end; cur += cnt, pos += cnt) {
+               cnt = min_t(unsigned int, end - cur,
                            sb->s_blocksize - erofs_blkoff(sb, pos));
                src = erofs_bread(&buf, erofs_blknr(sb, pos), EROFS_KMAP);
                if (IS_ERR(src)) {
                        erofs_put_metabuf(&buf);
                        return PTR_ERR(src);
                }
-
-               dst = kmap_local_page(page);
-               memcpy(dst + pageofs + i, src + erofs_blkoff(sb, pos), cnt);
-               kunmap_local(dst);
-               pos += cnt;
+               memcpy_to_page(page, cur, src + erofs_blkoff(sb, pos), cnt);
        }
        erofs_put_metabuf(&buf);
        return 0;
@@ -972,7 +965,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
        struct erofs_map_blocks *const map = &fe->map;
        const loff_t offset = page_offset(page);
        bool tight = true, exclusive;
-       unsigned int cur, end, spiltted;
+       unsigned int cur, end, len, spiltted;
        int err = 0;
 
        /* register locked file pages as online pages in pack */
@@ -1041,17 +1034,11 @@ hitted:
                goto next_part;
        }
        if (map->m_flags & EROFS_MAP_FRAGMENT) {
-               unsigned int pageofs, skip, len;
+               erofs_off_t fpos = offset + cur - map->m_la;
 
-               if (offset > map->m_la) {
-                       pageofs = 0;
-                       skip = offset - map->m_la;
-               } else {
-                       pageofs = map->m_la & ~PAGE_MASK;
-                       skip = 0;
-               }
-               len = min_t(unsigned int, map->m_llen - skip, end - cur);
-               err = z_erofs_read_fragment(inode, skip, page, pageofs, len);
+               len = min_t(unsigned int, map->m_llen - fpos, end - cur);
+               err = z_erofs_read_fragment(inode->i_sb, page, cur, cur + len,
+                               EROFS_I(inode)->z_fragmentoff + fpos);
                if (err)
                        goto out;
                ++spiltted;