From 011fa99404bea3f5d897c4983f6bd51170e3b18f Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Fri, 26 Dec 2014 23:58:21 -0500 Subject: [PATCH] ext4: prevent online resize with backup superblock Prevent BUG or corrupted file systems after the following: mkfs.ext4 /dev/vdc 100M mount -t ext4 -o sb=40961 /dev/vdc /vdc resize2fs /dev/vdc We previously prevented online resizing using the old resize ioctl. Move the code to ext4_resize_begin(), so the check applies for all of the resize ioctl's. Reported-by: Maxim Malkov Signed-off-by: Theodore Ts'o --- fs/ext4/resize.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index bf76f405a5f9..8a8ec6293b19 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -23,6 +23,18 @@ int ext4_resize_begin(struct super_block *sb) if (!capable(CAP_SYS_RESOURCE)) return -EPERM; + /* + * If we are not using the primary superblock/GDT copy don't resize, + * because the user tools have no way of handling this. Probably a + * bad time to do it anyways. + */ + if (EXT4_SB(sb)->s_sbh->b_blocknr != + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) { + ext4_warning(sb, "won't resize using backup superblock at %llu", + (unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr); + return -EPERM; + } + /* * We are not allowed to do online-resizing on a filesystem mounted * with error, because it can destroy the filesystem easily. @@ -758,18 +770,6 @@ static int add_new_gdb(handle_t *handle, struct inode *inode, "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n", gdb_num); - /* - * If we are not using the primary superblock/GDT copy don't resize, - * because the user tools have no way of handling this. Probably a - * bad time to do it anyways. - */ - if (EXT4_SB(sb)->s_sbh->b_blocknr != - le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) { - ext4_warning(sb, "won't resize using backup superblock at %llu", - (unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr); - return -EPERM; - } - gdb_bh = sb_bread(sb, gdblock); if (!gdb_bh) return -EIO; -- 2.30.2