[Galaxy Note 4 Android Development (Snapdragon)] Andycar:
Dear [MENTION=3931450]dr.ketan[/MENTION], how is it going with exFat "corrupt extsdcard" issue resolving?

Anyway, I think I may have founf a quick and ugly workaround.

Take a look at logcat below:

04-24 01:06:12.111 V/vold ( 307): ----------------
04-24 01:06:12.111 V/vold ( 307): handleBlockEvent with action 2
04-24 01:06:12.111 V/vold ( 307): void VolumeManager::handleBlockEvent(NetlinkEvent *)Throw out event : partition
04-24 01:06:12.111 V/vold ( 307): ----------------
04-24 01:06:12.111 V/vold ( 307): handleBlockEvent with action 2
04-24 01:06:12.111 V/vold ( 307): VolumeBase::destroy()++
04-24 01:06:12.111 V/vold ( 307): VolumeBase::destroy()--
04-24 01:06:12.111 D/VolumeInfo( 1184): VolumeInfo from Parcel: id public:179,65 ,type 0 ,disk DiskInfo{disk:179,64}:
04-24 01:06:12.111 D/VolumeInfo( 1184): flags=SD size=63864569856 label=
04-24 01:06:12.111 D/VolumeInfo( 1184): sysPath=/sys//devices/msm_sdcc.2/mmc_host/mmc1/mmc1:e624/block/mmcblk1
04-24 01:06:12.111 D/NetlinkEvent( 307): NL param 'DEVPATH=/devices/msm_sdcc.2/mmc_host/mmc1/mmc1:e624/block/mmcblk1/mmcblk1p1'
04-24 01:06:12.111 D/NetlinkEvent( 307): NL param 'MAJOR=179'
04-24 01:06:12.111 D/NetlinkEvent( 307): NL param 'MINOR=65'
04-24 01:06:12.111 D/NetlinkEvent( 307): NL param 'DEVNAME=mmcblk1p1'
04-24 01:06:12.111 D/NetlinkEvent( 307): NL param 'DEVTYPE=partition'
04-24 01:06:12.111 D/NetlinkEvent( 307): NL param 'PARTN=1'
04-24 01:06:12.111 D/NetlinkEvent( 307): NL param 'PARTNAME=Basic data partition'
04-24 01:06:12.111 D/NetlinkEvent( 307): NL param 'DEVPATH=/devices/msm_sdcc.2/mmc_host/mmc1/mmc1:e624/block/mmcblk1'
04-24 01:06:12.111 D/NetlinkEvent( 307): NL param 'MAJOR=179'
04-24 01:06:12.111 D/NetlinkEvent( 307): NL param 'MINOR=64'
04-24 01:06:12.111 D/NetlinkEvent( 307): NL param 'DEVNAME=mmcblk1'
04-24 01:06:12.111 D/NetlinkEvent( 307): NL param 'DEVTYPE=disk'
04-24 01:06:12.111 D/NetlinkEvent( 307): NL param 'NPARTS=0'
04-24 01:06:12.111 D/VoldConnector( 1184): RCV <- {651 public:179,65 7}
04-24 01:06:12.111 D/VoldConnector( 1184): RCV <- {659 public:179,65}
04-24 01:06:12.111 D/VoldConnector( 1184): RCV <- {649 disk:179,64}
04-24 01:06:12.111 I/MountService( 1184): onEvent:: raw= 651 public:179,65 7 cooked = 651 public:179,65 7
04-24 01:06:12.121 D/VolumeInfo( 3384): VolumeInfo from Parcel: id public:179,65 ,type 0 ,disk DiskInfo{disk:179,64}:
04-24 01:06:12.121 D/VolumeInfo( 3384): flags=SD size=63864569856 label=
04-24 01:06:12.121 D/VolumeInfo( 3384): sysPath=/sys//devices/msm_sdcc.2/mmc_host/mmc1/mmc1:e624/block/mmcblk1
04-24 01:06:12.121 D/MtpService( 3384): onStorageStateChanged /dev/null unmountable -> removed
04-24 01:06:12.121 D/VolumeInfo( 2406): VolumeInfo from Parcel: id public:179,65 ,type 0 ,disk DiskInfo{disk:179,64}:
04-24 01:06:12.121 D/VolumeInfo( 2406): flags=SD size=63864569856 label=
04-24 01:06:12.121 D/VolumeInfo( 2406): sysPath=/sys//devices/msm_sdcc.2/mmc_host/mmc1/mmc1:e624/block/mmcblk1
04-24 01:06:12.121 D/StorageNotification( 2406): Notifying about public volume: VolumeInfo{public:179,65}:
04-24 01:06:12.121 D/StorageNotification( 2406): type=PUBLIC diskId=disk:179,64 partGuid=null mountFlags=VISIBLE
04-24 01:06:12.121 D/StorageNotification( 2406): mountUserId=0 state=REMOVED
04-24 01:06:12.121 D/StorageNotification( 2406): fsType=exfat fsUuid=6425-B412 fsLabel=64Gb_exFAT
04-24 01:06:12.121 D/StorageNotification( 2406): path=null internalPath=null
04-24 01:06:12.121 I/MountService( 1184): onVolumeStateChangedLocked:: volInfo = VolumeInfo{public:179,65}:
04-24 01:06:12.121 I/MountService( 1184): type=PUBLIC diskId=disk:179,64 partGuid=null mountFlags=VISIBLE
04-24 01:06:12.121 I/MountService( 1184): mountUserId=0 state=REMOVED
04-24 01:06:12.121 I/MountService( 1184): fsType=exfat fsUuid=6425-B412 fsLabel=64Gb_exFAT
04-24 01:06:12.121 I/MountService( 1184): path=null internalPath=null
04-24 01:06:12.121 I/MountService( 1184): ,old = unmountable,new = removed
04-24 01:06:12.121 I/MountService( 1184): onEvent:: raw= 659 public:179,65 cooked = 659 public:179,65
04-24 01:06:12.121 I/MountService( 1184): onEvent:: raw= 649 disk:179,64 cooked = 649 disk:179,64
04-24 01:06:12.121 I/MountService( 1184): handleMessage :{ when=0 what=6 obj=StorageVolume:
04-24 01:06:12.121 I/MountService( 1184): mId=public:179,65 mStorageId=-860749823 mPath=/dev/null
04-24 01:06:12.121 I/MountService( 1184): mDescription=64Gb_exFAT mPrimary=false mRemovable=true mEmulated=false
04-24 01:06:12.121 I/MountService( 1184): mMtpReserveSize=0 mAllowMassStorage=false mMaxFileSize=0
04-24 01:06:12.121 I/MountService( 1184): mOwner=UserHandle{0} mFsUuid=6425-B412 mState=removed mSubSystem=sd
04-24 01:06:12.121 I/MountService( 1184): mActivitySecureContainer=true target=com.android.server.MountService$MountServiceHandler }
04-24 01:06:12.121 D/MountService( 1184): Volume public:179,65 broadcasting removed to UserHandle{0}
04-24 01:06:12.121 I/MountService( 1184): onEncryptionStatusChanged: volId = public:179,65, operation = [0] free
04-24 01:06:12.131 D/StorageNotification( 2406): isUPSModeOn false
04-24 01:06:12.131 D/StorageNotification( 2406): notifyAsUser: 378 ,id=public:179,65
04-24 01:06:12.131 D/StorageNotification( 2406): notifyAsUser: memoVolIdpublic:179,65 ,memoUuid=6425-B412
04-24 01:06:12.131 D/StorageNotification( 2406): notifyAsUser: clear old noti for volIdpublic:179,65 ,uuid=6425-B412
...

04-24 01:06:14.581 V/vold ( 307): : /dev/block/vold/public:179,65: UUID="6425-B412" LABEL="64Gb_exFAT" TYPE="exfat"
04-24 01:06:14.581 V/vold ( 307): blkid result -> fsType : exfat
04-24 01:06:14.581 V/vold ( 307): blkid result -> fsUuid : 6425-B412
04-24 01:06:14.581 V/vold ( 307): blkid result -> fsLabel : 64Gb_exFAT
04-24 01:06:14.581 V/vold ( 307): PublicVolume::readMetadata()/dev/block/vold/public:179,65 exfat 6425-B412 64Gb_exFAT
04-24 01:06:14.581 V/vold ( 307): public:179,65 PublicVolume::doMount()++ exfat
04-24 01:06:14.581 V/vold ( 307): /system/bin/fsck.exfat
04-24 01:06:14.581 V/vold ( 307): -R
04-24 01:06:14.581 V/vold ( 307): -f
04-24 01:06:14.581 V/vold ( 307): /dev/block/vold/public:179,65
04-24 01:06:14.581 D/VoldConnector( 1184): RCV <- {652 public:179,65 exfat}
04-24 01:06:14.581 D/VoldConnector( 1184): RCV <- {653 public:179,65 6425-B412}
04-24 01:06:14.581 I/MountService( 1184): onEvent:: raw= 652 public:179,65 exfat cooked = 652 public:179,65 exfat
04-24 01:06:14.581 D/VoldConnector( 1184): RCV <- {654 public:179,65 64Gb_exFAT}
04-24 01:06:14.581 I/MountService( 1184): onEvent:: raw= 653 public:179,65 6425-B412 cooked = 653 public:179,65 6425-B412
04-24 01:06:14.581 I/MountService( 1184): onEvent:: raw= 654 public:179,65 64Gb_exFAT cooked = 654 public:179,65 64Gb_exFAT
04-24 01:06:14.581 D/Vold ( 307): detected exFAT file system
04-24 01:06:14.591 I/fsck.exfat( 307): executing /system/bin/fsck.exfat failed: Permission denied
04-24 01:06:14.591 E/logwrapper( 7695): executing /system/bin/fsck.exfat failed: Permission denied
04-24 01:06:14.591 E/audit ( 3537): type=1400 msg=audit(1461449174.591:324): avc: denied { entrypoint } for pid=7695 comm="vold" path="/system/bin/fsck.exfat" dev="mmcblk0p24" ino=95485 scontext=u:r:fsck_untrusted:s0 tcontext=u:object_r:system_file:s0 tclass=file permissive=0
04-24 01:06:14.591 E/audit ( 3537): SEPF_SECMOBILE_6.0.1_0006
04-24 01:06:14.591 E/audit ( 3537): type=1300 msg=audit(1461449174.591:324): arch=40000028 syscall=11 per=800008 success=no exit=-13 a0=b457d080 a1=b3fbab00 a2=b489fdc0 a3=b457d080 items=1 ppid=307 ppcomm=vold pid=7695 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 ses=4294967295 tty=(none) comm="vold" exe="/system/bin/vold" subj=u:r:vold:s0 key=(null)
04-24 01:06:14.591 E/audit ( 3537): type=1307 msg=audit(1461449174.591:324): cwd="/"
04-24 01:06:14.591 E/audit ( 3537): type=1302 msg=audit(1461449174.591:324): item=0 name="/system/bin/fsck.exfat" inode=95485 dev=b3:18 mode=0100755 ouid=0 ogid=2000 rdev=00:00 obj=u:object_r:system_file:s0 nametype=NORMAL
04-24 01:06:14.591 E/audit ( 3537): type=1327 msg=audit(1461449174.591:324): proctitle=2F73797374656D2F62696E2F766F6C64002D2D626C6B69645F636F6E746578743D753A723A626C6B69643A7330002D2D626C6B69645F756E747275737465645F636F6E746578743D753A723A626C6B69645F756E747275737465643A7330002D2D6673636B5F636F6E746578743D753A723A6673636B3A7330002D2D6673636B
04-24 01:06:14.591 E/audit ( 3537): type=1320 msg=audit(1461449174.591:324):
04-24 01:06:14.591 I/fsck.exfat( 307): fsck.exfat terminated by exit(255)
04-24 01:06:14.591 E/vold ( 307): /dev/block/vold/public:179,65 failed FS checks (I/O error): I/O error
04-24 01:06:14.591 V/vold ( 307): public:179,65 check filesystem format: 5
04-24 01:06:14.591 E/vold ( 307): public:179,65 failed filesystem check
04-24 01:06:14.591 D/VolumeInfo( 1184): VolumeInfo from Parcel: id public:179,65 ,type 0 ,disk DiskInfo{disk:179,64}:
04-24 01:06:14.591 D/VolumeInfo( 1184): flags=SD size=63864569856 label=
04-24 01:06:14.591 D/VolumeInfo( 1184): sysPath=/sys//devices/msm_sdcc.2/mmc_host/mmc1/mmc1:e624/block/mmcblk1
04-24 01:06:14.591 D/VolumeInfo( 2406): VolumeInfo from Parcel: id public:179,65 ,type 0 ,disk DiskInfo{disk:179,64}:
04-24 01:06:14.591 D/VolumeInfo( 2406): flags=SD size=63864569856 label=
04-24 01:06:14.591 D/VolumeInfo( 2406): sysPath=/sys//devices/msm_sdcc.2/mmc_host/mmc1/mmc1:e624/block/mmcblk1
04-24 01:06:14.591 D/VolumeInfo( 3384): VolumeInfo from Parcel: id public:179,65 ,type 0 ,disk DiskInfo{disk:179,64}:
04-24 01:06:14.591 D/VolumeInfo( 3384): flags=SD size=63864569856 label=
04-24 01:06:14.591 D/VolumeInfo( 3384): sysPath=/sys//devices/msm_sdcc.2/mmc_host/mmc1/mmc1:e624/block/mmcblk1
04-24 01:06:14.591 D/MtpService( 3384): onStorageStateChanged /dev/null checking -> unmountable
04-24 01:06:14.591 E/Vold ( 307): exfat -> Filesystem check failed (unknown exit code 255)
04-24 01:06:14.591 D/VoldConnector( 1184): RCV <- {651 public:179,65 6}
04-24 01:06:14.591 D/VoldConnector( 1184): RCV <- {400 29 Command failed}
04-24 01:06:14.591 I/MountService( 1184): onEvent:: raw= 651 public:179,65 6 cooked = 651 public:179,65 6
04-24 01:06:14.591 I/MountService( 1184): handleMessage :{ when=-79ms what=7 obj=Intent { act=android.os.storage.action.VOLUME_STATE_CHANGED flg=0x4000000 (has extras) } target=com.android.server.MountService$MountServiceHandler }
04-24 01:06:14.591 I/MountService( 1184): onVolumeStateChangedLocked:: volInfo = VolumeInfo{public:179,65}:
04-24 01:06:14.591 I/MountService( 1184): type=PUBLIC diskId=disk:179,64 partGuid=null mountFlags=VISIBLE
04-24 01:06:14.591 I/MountService( 1184): mountUserId=0 state=UNMOUNTABLE
04-24 01:06:14.591 I/MountService( 1184): fsType=exfat fsUuid=6425-B412 fsLabel=64Gb_exFAT
04-24 01:06:14.591 I/MountService( 1184): path=null internalPath=null
04-24 01:06:14.591 I/MountService( 1184): ,old = checking,new = unmountable
04-24 01:06:14.591 I/MountService( 1184): handleMessage :{ when=-78ms what=7 obj=Intent { act=android.os.storage.action.DISK_SCANNED flg=0x4000000 (has extras) } target=com.android.server.MountService$MountServiceHandler }
04-24 01:06:14.591 I/MountService( 1184): handleMessage :{ when=-73ms what=6 obj=StorageVolume:
...

the bottom line: vold tries to launch fsck.exfat with arguments "-Rf /dev/block/vold/public:179,65"

So, when I tried to manually execute in terminal the same command

fsck.exfat -Rf /dev/block/vold/public:179,65
fsck.exfat v1.3.3 (lib v1.3.3)
stlog : enable
**dev_name : /dev/block/vold/public:179,65
begin(dev:/dev/block/vold/public:179,65)

Can`t open /proc/stlog(Permission denied)
Device not found.
end(ret:10, dev:/dev/block/vold/public:179,65)
Can`t open /proc/stlog(Permission denied)

I've no idea what the hell "stlog" is... Google says nothing.

But, when I deleted fsck.exfat from /system/bin, the exFat extSdCard mounts normally.

I'm not saying it's the solution. But this seems like a workaround for me. Will look more into it...