Messages in this thread Patch in this message |  | | | Date | Thu, 02 Jul 2009 17:13:42 -0400 | | From | "Doug Graham" <> | | Subject | V3 minixfs bug |
Is anybody interested in bugs in the minixfs V3 support that probably only turn up on big-endian machines, or on filesystems with more than 64K inodes?
The problem is that that there are a few places (three that I've found) 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.
Here's a patch:
--- linux-2.6.29.2/fs/minix/dir.c 2009/07/02 21:05:33 1.1 +++ linux-2.6.29.2/fs/minix/dir.c 2009/07/02 21:10:31 @@ -311,14 +311,18 @@ 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); @@ -443,7 +447,10 @@ 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); @@ -473,7 +480,14 @@ ino_t res = 0;
if (de) { - res = de->inode; + struct address_space *mapping = page->mapping; + struct inode *inode = (struct 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;
--Doug
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