Permission denied to resize filesystem

Solution 1:

Same problem -- turned out my FS had some inconsistencies:

# resize2fs /dev/blah/lvol0
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/blah/lvol0 is mounted on /mnt/lvol0; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
resize2fs: Permission denied to resize filesystem

# umount /mnt/lvol0

# resize2fs /dev/blah/lvol0
resize2fs 1.42.9 (28-Dec-2013)
Please run 'e2fsck -f /dev/blah/lvol0' first.

# fsck /dev/blah/lvol0
fsck from util-linux 2.23.2
e2fsck 1.42.9 (28-Dec-2013)
/dev/mapper/blah-lvol0 contains a file system with errors, check forced.
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/mapper/blah-lvol0: 513/3072 files (2.9% non-contiguous), 12288/12288 blocks

# mount /dev/blah/lvol0 /mnt/lvol0

# resize2fs /dev/blah/lvol0
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/blah/lvol0 is mounted on /mnt/lvol0; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
The filesystem on /dev/blah/lvol0 is now 225280 blocks long.

Solution 2:

/dev/mapper/ may contain block devices instead of symlinks. If so, remove them, run udevadm trigger. Worked for Debian 7.8.