On Thu, Feb 02, 2012 at 10:05:55AM +0100, Lukas Czerner wrote: > When resizing file system in the way that the new size of the file > system is still in the same group (no new groups are added), then we can > hit a BUG_ON in ext4_alloc_group_tables() > > BUG_ON(flex_gd->count == 0 || group_data == NULL); > > because flex_gd->count is zero. The reason is the missing check for such > case, so the code always extend the last group fully and then attempt to > add more groups, but at that time n_blocks_count is actually smaller > than o_blocks_count. > > It can be easily reproduced like this: > > mkfs.ext4 -b 4096 /dev/sda 30M > mount /dev/sda /mnt/test > resize2fs /dev/sda 50M > > Fix this by checking whether the resize happens within the singe group > and only add that many blocks into the last group to satisfy user > request. Then o_blocks_count == n_blocks_count and the resize will exit > successfully without and attempt to add more groups into the fs. > > Also fix mixing together block number and blocks count which might be > confusing and can easily lead to off-by-one errors (but it is actually > not the case here since the two occurrence of this mix-up will cancel > each other). > > Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx> > Reported-by: Milan Broz <mbroz@xxxxxxxxxx> Thanks, applied. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
