commit f968c2dbcf62347953b6dcf4197e308ec1e8b2e4
author Daniel Rosenberg <drosen@google.com> Thu Aug 27 13:42:20 2015 -0700
committer Daniel Rosenberg <drosen@google.com> Mon Aug 31 15:18:05 2015 -0700
tree 0e105020995b14928f61bcd6dc71e935bae9d828
parent 45e5e4778b8508c54525705727974c8cc2de682a

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 8b0f714..d77d41f 100644
--- a/fs_mgr/fs_mgr_fstab.c
+++ b/fs_mgr/fs_mgr_fstab.c
@@ -20,6 +20,8 @@
 #include <string.h>
 #include <sys/mount.h>
 
+#include <cutils/properties.h>
+
 #include "fs_mgr_priv.h"
 
 struct fs_mgr_flag_values {
@@ -70,6 +72,7 @@
     { "zramsize=",   MF_ZRAMSIZE },
     { "verify",      MF_VERIFY },
     { "noemulatedsd", MF_NOEMULATEDSD },
+    { "slotselect",  MF_SLOTSELECT },
     { "defaults",    0 },
     { 0,             0 },
 };
@@ -307,6 +310,23 @@
         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);
@@ -448,3 +468,8 @@
 {
     return fstab->fs_mgr_flags & MF_NOEMULATEDSD;
 }
+
+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 d56111a..cc02bac 100644
--- a/fs_mgr/fs_mgr_priv.h
+++ b/fs_mgr/fs_mgr_priv.h
@@ -77,6 +77,7 @@
 #define MF_NOEMULATEDSD 0x800 /* no emulated sdcard daemon, sd card is the only
                                  external storage */
 #define MF_FILEENCRYPTION 0x2000
+#define MF_SLOTSELECT   0x8000
 
 #define DM_BUF_SIZE 4096