V3 minixfs: add missing directory type checking

There are a few places in the Minix FS code where the "inode" field of a
minix_dir_entry is used without checking first to see if the dirent is
really a minix3_dir_entry.  The inode number in a V1/V2 dirent is 16 bits,
whereas that in a V3 dirent is 32 bits.

Accessing it as a 16 bit field when it really should be accessed as a 32
bit field probably kinda sorta works on a little-endian machine, but leads
to some rather odd behaviour on big-endian machines.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Doug Graham <dgraham@nortel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/minix/dir.c b/fs/minix/dir.c
index d407e7a..6198731 100644 (file)
--- a/fs/minix/dir.c
+++ b/fs/minix/dir.c
@@ -308,14 +308,18 @@ int minix_delete_entry(struct minix_dir_entry *de, struct page *page)
        struct inode *inode = (struct inode*)mapping->host;
        char *kaddr = page_address(page);
        loff_t pos = page_offset(page) + (char*)de - kaddr;
-       unsigned len = minix_sb(inode->i_sb)->s_dirsize;
+       struct minix_sb_info *sbi = minix_sb(inode->i_sb);
+       unsigned len = sbi->s_dirsize;
        int err;
 
        lock_page(page);
        err = __minix_write_begin(NULL, mapping, pos, len,
                                        AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
        if (err == 0) {
-               de->inode = 0;
+               if (sbi->s_version == MINIX_V3)
+                       ((minix3_dirent *) de)->inode = 0;
+               else
+                       de->inode = 0;
                err = dir_commit_chunk(page, pos, len);
        } else {
                unlock_page(page);
@@ -440,7 +444,10 @@ void minix_set_link(struct minix_dir_entry *de, struct page *page,
        err = __minix_write_begin(NULL, mapping, pos, sbi->s_dirsize,
                                        AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
        if (err == 0) {
-               de->inode = inode->i_ino;
+               if (sbi->s_version == MINIX_V3)
+                       ((minix3_dirent *) de)->inode = inode->i_ino;
+               else
+                       de->inode = inode->i_ino;
                err = dir_commit_chunk(page, pos, sbi->s_dirsize);
        } else {
                unlock_page(page);
@@ -470,7 +477,14 @@ ino_t minix_inode_by_name(struct dentry *dentry)
        ino_t res = 0;
 
        if (de) {
-               res = de->inode;
+               struct address_space *mapping = page->mapping;
+               struct inode *inode = mapping->host;
+               struct minix_sb_info *sbi = minix_sb(inode->i_sb);
+
+               if (sbi->s_version == MINIX_V3)
+                       res = ((minix3_dirent *) de)->inode;
+               else
+                       res = de->inode;
                dir_put_page(page);
        }
        return res;