commit 8a94fba7d4917c77a10b8497f260c02d9e000a2e
author Daniel Rosenberg <drosen@google.com> Thu Aug 27 13:42:20 2015 -0700
committer Rom Lemarchand <romlem@google.com> Mon Nov 16 08:53:04 2015 -0800
tree 18fbc7dac7a2d67d8c8192e9ba9a91f0ce5a92e3
parent 15ceeca4cbcb9bda717fbfdfecd160633168bcd5

fs_mgr: Add support for A/B partitions

Allow partitions to be marked as A/B partitions
using the slotselect flag in fstab. The partitions
can be identified by appending the correct suffix
to the block device listed in the fstab. The suffix
is provided by the bootloader through a command line
parameter or the device tree, and can be found in
ro.boot.slot_suffix or read from the boot_control HAL.

Change-Id: I6846d80e857f95bfb8f282f4ab81167394613bbe
Signed-off-by: Daniel Rosenberg <drosen@google.com>

fs_mgr/fs_mgr_fstab.c

diff --git a/fs_mgr/fs_mgr_fstab.c b/fs_mgr/fs_mgr_fstab.c
index f24af1f..a44d034 100644
--- a/fs_mgr/fs_mgr_fstab.c
+++ b/fs_mgr/fs_mgr_fstab.c
@@ -22,6 +22,8 @@
 #include <sys/mount.h>
 #include <unistd.h>
 
+#include <cutils/properties.h>
+
 #include "fs_mgr_priv.h"
 
 struct fs_mgr_flag_values {
@@ -74,6 +76,7 @@
     { "noemulatedsd", MF_NOEMULATEDSD },
     { "notrim",       MF_NOTRIM },
     { "formattable", MF_FORMATTABLE },
+    { "slotselect",  MF_SLOTSELECT },
     { "defaults",    0 },
     { 0,             0 },
 };
@@ -329,6 +332,23 @@
         fstab->recs[cnt].partnum = flag_vals.partnum;
         fstab->recs[cnt].swap_prio = flag_vals.swap_prio;
         fstab->recs[cnt].zram_size = flag_vals.zram_size;
+
+        /* If an A/B partition, modify block device to be the real block device */
+        if (fstab->recs[cnt].fs_mgr_flags & MF_SLOTSELECT) {
+            char propbuf[PROPERTY_VALUE_MAX];
+            char *tmp;
+
+            /* use the kernel parameter if set */
+            property_get("ro.boot.slot_suffix", propbuf, "");
+
+            if (asprintf(&tmp, "%s%s", fstab->recs[cnt].blk_device, propbuf) > 0) {
+                free(fstab->recs[cnt].blk_device);
+                fstab->recs[cnt].blk_device = tmp;
+            } else {
+                ERROR("Error updating block device name\n");
+                goto err;
+            }
+        }
         cnt++;
     }
     fclose(fstab_file);
@@ -480,3 +500,8 @@
 {
     return fstab->fs_mgr_flags & (MF_FORMATTABLE);
 }
+
+int fs_mgr_is_slotselect(struct fstab_rec *fstab)
+{
+    return fstab->fs_mgr_flags & MF_SLOTSELECT;
+}

fs_mgr/fs_mgr_priv.h

diff --git a/fs_mgr/fs_mgr_priv.h b/fs_mgr/fs_mgr_priv.h
index 682fd11..a87092e 100644
--- a/fs_mgr/fs_mgr_priv.h
+++ b/fs_mgr/fs_mgr_priv.h
@@ -79,6 +79,7 @@
 #define MF_NOTRIM       0x1000
 #define MF_FILEENCRYPTION 0x2000
 #define MF_FORMATTABLE  0x4000
+#define MF_SLOTSELECT   0x8000
 
 #define DM_BUF_SIZE 4096