build: Add TARGET_ROOTFS_RESERVED_PCT option to reduce wasted space

The genext2fs tool will 'reserve' 5% of the image size by default,
apparently by creating a huge lost+found directory. In fact it seemed to
be much more than 5% in practice — I saw an image with 8MiB used, and
recovered about 2MiB of it by deleting the 'empty' lost+found directory:

/dev/loop0         48377  8482     37438  19% /mnt/spare
 # rmdir lost+found/
/dev/loop0         48377  6014     39906  14% /mnt/spare

This makes it configurable, but leaves it at the genext2fs default
of 5% for now. It should probably be changed to default to zero, but
that can be a separate patch.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

SVN-Revision: 34408
v19.07.3_mercusys_ac12_duma
Gabor Juhos 11 years ago
parent 44131bd785
commit d90e805fe6

@ -125,6 +125,13 @@ menu "Target Images"
help
Allows you to change the maximum number of inodes in the root filesystem
config TARGET_ROOTFS_RESERVED_PCT
int "Percentage of reserved blocks in root filesystem"
depends TARGET_ROOTFS_EXT4FS
default 5
help
Allows you to change the percentage of reserved blocks in the root filesystem
endmenu
menu "Global build settings"

@ -124,7 +124,7 @@ ifneq ($(CONFIG_TARGET_ROOTFS_EXT4FS),)
define Image/mkfs/ext4
# generate an ext2 fs
$(STAGING_DIR_HOST)/bin/genext2fs -U -b $(E2SIZE) -N $(CONFIG_TARGET_ROOTFS_MAXINODE) -d $(TARGET_DIR)/ $(KDIR)/root.ext4
$(STAGING_DIR_HOST)/bin/genext2fs -U -b $(E2SIZE) -N $(CONFIG_TARGET_ROOTFS_MAXINODE) -d $(TARGET_DIR)/ $(KDIR)/root.ext4 -m $(CONFIG_TARGET_ROOTFS_RESERVED_PCT)
# convert it to ext4
$(STAGING_DIR_HOST)/bin/tune2fs -O extents,uninit_bg,dir_index $(KDIR)/root.ext4
# fix it up

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