ext2: use offset_in_page() instead of open-coding it as subtraction

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Tested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index a3c77ea..5141ec6 100644 (file)
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -240,7 +240,7 @@ ext2_validate_entry(char *base, unsigned offset, unsigned mask)
                        break;
                p = ext2_next_entry(p);
        }
-       return (char *)p - base;
+       return offset_in_page(p);
 }
 
 static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
@@ -465,8 +465,7 @@ int ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
                struct page *page, void *page_addr, struct inode *inode,
                bool update_times)
 {
-       loff_t pos = page_offset(page) +
-                       (char *) de - (char *) page_addr;
+       loff_t pos = page_offset(page) + offset_in_page(de);
        unsigned len = ext2_rec_len_from_disk(de->rec_len);
        int err;
 
@@ -556,8 +555,7 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
        return -EINVAL;
 
 got_it:
-       pos = page_offset(page) +
-               (char *)de - (char *)page_addr;
+       pos = page_offset(page) + offset_in_page(de);
        err = ext2_prepare_chunk(page, pos, rec_len);
        if (err)
                goto out_unlock;
@@ -594,8 +592,8 @@ int ext2_delete_entry (struct ext2_dir_entry_2 *dir, struct page *page,
                        char *kaddr)
 {
        struct inode *inode = page->mapping->host;
-       unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
-       unsigned to = ((char *)dir - kaddr) +
+       unsigned from = offset_in_page(dir) & ~(ext2_chunk_size(inode)-1);
+       unsigned to = offset_in_page(dir) +
                                ext2_rec_len_from_disk(dir->rec_len);
        loff_t pos;
        ext2_dirent * pde = NULL;
@@ -612,7 +610,7 @@ int ext2_delete_entry (struct ext2_dir_entry_2 *dir, struct page *page,
                de = ext2_next_entry(de);
        }
        if (pde)
-               from = (char *)pde - kaddr;
+               from = offset_in_page(pde);
        pos = page_offset(page) + from;
        lock_page(page);
        err = ext2_prepare_chunk(page, pos, to - from);