inline_data option on ext4 truncates symlinks

[Claes Wallin]

To replicate the bug, create two filesystems, one with `mkfs.ext4 -I 256`, one with `mkfs.ext4 -I 256 -O inline_data`. An inode size of 256 bytes is the default, but included here for clarity. To do this, you are going to need an `e2fsprogs` from trunk, or version 1.43 if it has been released.

Mount the two filesystems, in each of them do:
    $ ln -s $(for i in {1..64}; do echo -n .; done) 64
    $ ln -s $(for i in {1..128}; do echo -n .; done) 128
    $ ln -s $(for i in {1..192}; do echo -n .; done) 192
    $ ls -l 64 128 192

Both directory listings will show symlinks named `64`, `128` and `256`, each pointing to a filename with the corresponding amount of dots. This is the expected behavior.

Unmount both filesystems, mount them again. Do the `ls -l` again.

The default filesystem will show the same output as previously, the one with inline_data activated will show the `128` symlink pointing to a filename of only 64 dots.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: linux-image-3.13.0-32-generic 3.13.0-32.57
ProcVersionSignature: Ubuntu 3.13.0-32.57-generic 3.13.11.4
Uname: Linux 3.13.0-32-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: clacke 3532 F.... pulseaudio
CurrentDesktop: GNOME
Date: Sun Jul 27 00:47:06 2014
EcryptfsInUse: Yes
MachineType: LENOVO IdeaPad Z370
ProcFB:
 0 inteldrmfb
 1 nouveaufb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.13.0-32-generic root=/dev/mapper/hostname-trusty_root ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.13.0-32-generic N/A
 linux-backports-modules-3.13.0-32-generic N/A
 linux-firmware 1.127.5
SourcePackage: linux
StagingDrivers: rts5139
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 08/29/2011
dmi.bios.vendor: LENOVO
dmi.bios.version: 4ACN35WW
dmi.board.name: KL5
dmi.board.vendor: LENOVO
dmi.board.version: Rev 1.0
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Rev 1.0
dmi.modalias: dmi:bvnLENOVO:bvr4ACN35WW:bd08/29/2011:svnLENOVO:pnIdeaPadZ370:pvrRev1.0:rvnLENOVO:rnKL5:rvrRev1.0:cvnLENOVO:ct10:cvrRev1.0:
dmi.product.name: IdeaPad Z370
dmi.product.version: Rev 1.0
dmi.sys.vendor: LENOVO

[Brad Figg (brad-figg)]

This change was made by a bot.

[Luis Henriques (henrix)]

It looks like this is a bug that has already been fixed upstream by commit

commit bd9db175dde14b606265e0d37e8319d96fe1a58f
Author: Zheng Liu <email address hidden>
Date: Mon Jun 2 10:48:22 2014 -0400

    ext4: handle symlink properly with inline_data

I've uploaded a Trusty test kernel containing this commit here:

http://people.canonical.com/~henrix/lp1349020/amd64/

Could you please verify if it fixes the bug for you? Thanks!

[Claes Wallin (clacke)]

That fixes the bug. Even symlinks created by the faulty kernel will be interpreted correctly by the fixed kernel, as the fault is in reading, not in writing.

[Brad Figg (brad-figg)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-trusty' to 'verification-done-trusty'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Claes Wallin (clacke)]

The bug has been fixed in -proposed.

Performed the test in the bug description. The `128` file accurately points to a 128 bytes long filename. Double-checked that the file system was actually using -O inline_data. Disk usage reflects it as well:

# du ext4{,_inline}/test{/*,}
4 ext4/test/128
4 ext4/test/192
4 ext4/test/64
4 ext4/test
0 ext4_inline/test/128
4 ext4_inline/test/192
0 ext4_inline/test/64
0 ext4_inline/test

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 3.13.0-35.62

---------------
linux (3.13.0-35.62) trusty; urgency=low

  [ Joseph Salisbury ]

  * Release Tracking Bug
    - LP: #1357148

  [ Brad Figg ]

  * Start new release

  [ dann frazier ]

  * SAUCE: (no-up) Fix build failure on arm64
    - LP: #1353657
  * [debian] Allow for package revisions condusive for branching

  [ David Henningsson ]

  * SAUCE: Call broadwell specific functions from the hda driver
    - LP: #1317865

  [ Edward Lin ]

  * SAUCE: (no-up) Add use native backlight quirk for Dell Inspiron
    5547/5447
    - LP: #1332437

  [ Imre Deak ]

  * SAUCE: drm/i915: move power domain init earlier during system resume
    - LP: #1353405

  [ Jani Nikula ]

  * SAUCE: drm/i915: use lane count and link rate from VBT as minimums for
    eDP
    - LP: #1338582
  * SAUCE: drm/i915/dp: force eDP lane count to max available lanes on BDW
    - LP: #1338582
  * SAUCE: drm/i915: provide interface for audio driver to query cdclk
    - LP: #1188091
  * SAUCE: drm/i915: demote opregion excessive timeout WARN_ONCE to
    DRM_INFO_ONCE
    - LP: #1351014

  [ Joseph Salisbury ]

  * [Config] updateconfigs after Linux 3.13.11.6 updates

  [ Luis Henriques ]

  * Revert "[Packaging] linux-udeb-flavour -- standardise on linux prefix"

  [ Ming Lei ]

  * Revert "SAUCE: (no-up) ata: Fix the dma state machine lockup for the
    IDENTIFY DEVICE PIO mode command."
    - LP: #1335645

  [ Paulo Zanoni ]

  * SAUCE: drm/i915: consider the source max DP lane count too
    - LP: #1338582

  [ Tim Gardner ]

  * [Config] CONFIG_GPIO_SYSFS=y
    - LP: #1342153
  * [Config] CONFIG_KEYS_DEBUG_PROC_KEYS=y
    - LP: #1344405
  * [Config] updateconfigs
  * [Config] CONFIG_SCSI_IPR_TRACE=y, CONFIG_SCSI_IPR_DUMP=y
    - LP: #1343109
  * [Config] CONFIG_CONTEXT_TRACKING_FORCE=n
    - LP: #1349028

  [ Timo Aaltonen ]

  * SAUCE: Fix a typo in hda i915_bdw support.
    - LP: #1343140

  [ Upstream Kernel Changes ]

  * Revert "net/mlx4_en: Fix bad use of dev_id"
    - LP: #1347012
  * Revert "ACPI / AC: Remove AC's proc directory."
    - LP: #1356913
  * Revert "mac80211: move "bufferable MMPDU" check to fix AP mode scan"
    - LP: #1356913
  * mm, pcp: allow restoring percpu_pagelist_fraction default
    - LP: #1347088
  * net: Fix permission check in netlink_connect()
    - LP: #1312989
  * netlink: Rename netlink_capable netlink_allowed
    - LP: #1312989
  * net: Move the permission check in sock_diag_put_filterinfo to
    packet_diag_dump
    - LP: #1312989
  * net: Add variants of capable for use on on sockets
    - LP: #1312989
  * net: Add variants of capable for use on netlink messages
    - LP: #1312989
  * net: Use netlink_ns_capable to verify the permisions of netlink
    messages
    - LP: #1312989
  * netlink: Only check file credentials for implicit destinations
    - LP: #1312989
  * igb: fix stats for i210 rx_fifo_errors
    - LP: #1338893
  * HID: use multi input quirk for 22b9:2968
    - LP: #1339567
  * crypto/nx: disable NX on little endian builds
    - LP: #1338666
  * ACPI / video: Add Dell Inspiron 5737 to the blacklist
    - LP: #1250401
  * Input: elantech - deal with clickpads reportin...