reduce readahead for ext4 filesystems

bug 27381069

Change-Id: I8f2be28687c8de953d2942dc9ee5d4ef78ce0355
diff --git a/fstab.bullhead b/fstab.bullhead
index 624fe94..8fb67f8 100644
--- a/fstab.bullhead
+++ b/fstab.bullhead
@@ -3,9 +3,9 @@
 # The filesystem that contains the filesystem checker binary (typically /system) cannot
 # specify MF_CHECK, and must come before any filesystems that do specify MF_CHECK
 
-/dev/block/platform/soc.0/f9824900.sdhci/by-name/system       /system         ext4    ro,barrier=1                                                    wait,verify=/dev/block/platform/soc.0/f9824900.sdhci/by-name/metadata
-/dev/block/platform/soc.0/f9824900.sdhci/by-name/vendor       /vendor         ext4    ro,barrier=1                                                    wait,verify=/dev/block/platform/soc.0/f9824900.sdhci/by-name/metadata
-/dev/block/platform/soc.0/f9824900.sdhci/by-name/userdata     /data           ext4    noatime,nosuid,nodev,barrier=1,data=ordered,nomblk_io_submit,noauto_da_alloc,errors=panic wait,check,forcefdeorfbe=/dev/block/platform/soc.0/f9824900.sdhci/by-name/metadata
+/dev/block/platform/soc.0/f9824900.sdhci/by-name/system       /system         ext4    ro,barrier=1,inode_readahead_blks=8                             wait,verify=/dev/block/platform/soc.0/f9824900.sdhci/by-name/metadata
+/dev/block/platform/soc.0/f9824900.sdhci/by-name/vendor       /vendor         ext4    ro,barrier=1,inode_readahead_blks=8                             wait,verify=/dev/block/platform/soc.0/f9824900.sdhci/by-name/metadata
+/dev/block/platform/soc.0/f9824900.sdhci/by-name/userdata     /data           ext4    noatime,nosuid,nodev,barrier=1,data=ordered,nomblk_io_submit,noauto_da_alloc,errors=panic,inode_readahead_blks=8 wait,check,forcefdeorfbe=/dev/block/platform/soc.0/f9824900.sdhci/by-name/metadata
 /dev/block/platform/soc.0/f9824900.sdhci/by-name/cache        /cache          ext4    noatime,nosuid,nodev,barrier=1,data=ordered,nomblk_io_submit,noauto_da_alloc,errors=panic wait,check
 /dev/block/platform/soc.0/f9824900.sdhci/by-name/persist      /persist        ext4    nosuid,nodev,barrier=1,data=ordered,nodelalloc,nomblk_io_submit,errors=panic wait,notrim
 /dev/block/platform/soc.0/f9824900.sdhci/by-name/modem        /firmware       vfat    ro,shortname=lower,uid=1000,gid=1000,dmask=227,fmask=337,context=u:object_r:firmware_file:s0        wait