Merge ~lfaraone/ubuntu/+source/initramfs-tools:lp798414 into ~ubuntu-kernel/ubuntu/+source/initramfs-tools:ubuntu

[Luke Faraone]

[Jarno Suni (jarnos)]

Just a note that egrep is told to be deprecated (in manual page), "grep -E" is is the recommended form. That said, grep -o '[0-9]*' would work here, too. Or awk 'NR==2{print $1}'

[Jarno Suni (jarnos)]

It might not happen with default settings, but could it happen that also a backup initrd.img file will be generated? If so, 50 MiB might not be enough.

Unmerged commits

40f5c4c... by Luke Faraone on 2016-10-25

update-initramfs: Print an error if insufficient space on $BOOTDIR

Check to see if there's a reasonable amount of free space on $BOOTDIR. If there
isn't, warn the user of this and point them to useful documentation.

A threshold of 50MiB is used since an initramfs is about 35MiB on a desktop
installation of 16.04.

LP: #798414

diff --git a/update-initramfs b/update-initramfs
index 91442a4..10de744 100755
--- a/update-initramfs
+++ b/update-initramfs
@@ -159,6 +159,22 @@ remove_initramfs_bak()
 	verbose "Removing ${initramfs_bak}"
 }
 
+# In case generating the initramfs fails due to a lack of disk space, print a
+# friendly error message.
+spacecheck()
+{
+	# Reasonable upper-bound for an initramfs.
+	MIN_FREE=50
+
+	# The available disk space in MiB
+	free_space=$(df "${BOOTDIR}" --output=avail --block-size=1M | egrep -o '[0-9]+')
+
+	if [ $free_space -lt $MIN_FREE ]; then
+		echo ""
+		echo "update-initramfs: ${BOOTDIR} has ${free_space}MiB available; at least ${MIN_FREE}MiB is recommended."
+		echo "update-initramfs: For help, see <https://help.ubuntu.com/community/LowDiskOnBoot>."
+	fi
+}
 
 generate_initramfs()
 {
@@ -177,6 +193,7 @@ generate_initramfs()
 		remove_initramfs_bak
 		rm -f "${initramfs}.new"
 		echo "update-initramfs: failed for ${initramfs} with $mkinitramfs_return." >&2
+		spacecheck
 		exit $mkinitramfs_return
 	fi
 }