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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 <malkov@ispras.ru>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2014-12-26 23:58:21 -05:00
parent 50db71abc5
commit 011fa99404
1 changed files with 12 additions and 12 deletions
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24
fs/ext4/resize.c
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@ -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;