From 0ab7620a0cefe6982b914a830a41f65ecccd74bd Mon Sep 17 00:00:00 2001 From: Erik van der Kouwe Date: Wed, 26 May 2010 12:03:23 +0200 Subject: [PATCH] fs/minix: bugfix, number of indirect block ptrs per block depends on block size The MINIX filesystem driver used a constant number of indirect block pointers in an indirect block. This worked only for filesystems with 1kb block, while the MINIX default block size is now 4kb. As a consequence, large files were read incorrectly on such filesystems and writing a large file would cause the filesystem to become corrupted. This patch computes the number of indirect block pointers based on the block size, making the driver work for each block size. I would like to thank Feiran Zheng ('Fam') for pointing out the cause of the corruption. Signed-off-by: Erik van der Kouwe Signed-off-by: Al Viro --- fs/minix/itree_v2.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-) diff --git a/fs/minix/itree_v2.c b/fs/minix/itree_v2.c index f23010969369..13487ad16894 100644 --- a/fs/minix/itree_v2.c +++ b/fs/minix/itree_v2.c @@ -20,6 +20,9 @@ static inline block_t *i_data(struct inode *inode) return (block_t *)minix_i(inode)->u.i2_data; } +#define DIRCOUNT 7 +#define INDIRCOUNT(sb) (1 << ((sb)->s_blocksize_bits - 2)) + static int block_to_path(struct inode * inode, long block, int offsets[DEPTH]) { int n = 0; @@ -34,21 +37,21 @@ static int block_to_path(struct inode * inode, long block, int offsets[DEPTH]) printk("MINIX-fs: block_to_path: " "block %ld too big on dev %s\n", block, bdevname(sb->s_bdev, b)); - } else if (block < 7) { + } else if (block < DIRCOUNT) { offsets[n++] = block; - } else if ((block -= 7) < 256) { - offsets[n++] = 7; + } else if ((block -= DIRCOUNT) < INDIRCOUNT(sb)) { + offsets[n++] = DIRCOUNT; offsets[n++] = block; - } else if ((block -= 256) < 256*256) { - offsets[n++] = 8; - offsets[n++] = block>>8; - offsets[n++] = block & 255; + } else if ((block -= INDIRCOUNT(sb)) < INDIRCOUNT(sb) * INDIRCOUNT(sb)) { + offsets[n++] = DIRCOUNT + 1; + offsets[n++] = block / INDIRCOUNT(sb); + offsets[n++] = block % INDIRCOUNT(sb); } else { - block -= 256*256; - offsets[n++] = 9; - offsets[n++] = block>>16; - offsets[n++] = (block>>8) & 255; - offsets[n++] = block & 255; + block -= INDIRCOUNT(sb) * INDIRCOUNT(sb); + offsets[n++] = DIRCOUNT + 2; + offsets[n++] = (block / INDIRCOUNT(sb)) / INDIRCOUNT(sb); + offsets[n++] = (block / INDIRCOUNT(sb)) % INDIRCOUNT(sb); + offsets[n++] = block % INDIRCOUNT(sb); } return n; }