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Filename Latest commit message Latest commit date
Filipe Manana 2b99ff4c3e btrfs: always log symlinks in full mode
commit d0e64a981fd841cb0f28fcd6afcac55e6f1e6994 upstream.

On Linux, empty symlinks are invalid, and attempting to create one with
the system call symlink(2) results in an -ENOENT error and this is
explicitly documented in the man page.

If we rename a symlink that was created in the current transaction and its
parent directory was logged before, we actually end up logging the symlink
without logging its content, which is stored in an inline extent. That
means that after a power failure we can end up with an empty symlink,
having no content and an i_size of 0 bytes.

It can be easily reproduced like this:

  $ mkfs.btrfs -f /dev/sdc
  $ mount /dev/sdc /mnt

  $ mkdir /mnt/testdir
  $ sync

  # Create a file inside the directory and fsync the directory.
  $ touch /mnt/testdir/foo
  $ xfs_io -c "fsync" /mnt/testdir

  # Create a symlink inside the directory and then rename the symlink.
  $ ln -s /mnt/testdir/foo /mnt/testdir/bar
  $ mv /mnt/testdir/bar /mnt/testdir/baz

  # Now fsync again the directory, this persist the log tree.
  $ xfs_io -c "fsync" /mnt/testdir

  <power failure>

  $ mount /dev/sdc /mnt
  $ stat -c %s /mnt/testdir/baz
  0
  $ readlink /mnt/testdir/baz
  $

Fix this by always logging symlinks in full mode (LOG_INODE_ALL), so that
their content is also logged.

A test case for fstests will follow.

CC: stable@vger.kernel.org # 4.9+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-05-12 12:23:46 +02:00
arch parisc: Merge model and model name into one line in /proc/cpuinfo 2022-05-12 12:23:40 +02:00
block block/compat_ioctl: fix range check in BLKGETSIZE 2022-04-27 13:50:50 +02:00
certs
crypto crypto: authenc - Fix sleep in atomic context in decrypt_tail 2022-04-15 14:18:04 +02:00
Documentation ext4, doc: fix incorrect h_reserved size 2022-04-27 13:50:50 +02:00
drivers smsc911x: allow using IRQ0 2022-05-12 12:23:46 +02:00
fs btrfs: always log symlinks in full mode 2022-05-12 12:23:46 +02:00
include mm, hugetlb: allow for "high" userspace addresses 2022-05-09 09:03:28 +02:00
init init/main.c: return 1 from handled __setup() functions 2022-04-15 14:18:35 +02:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-12-01 09:23:35 +01:00
kernel genirq: Synchronize interrupt thread startup 2022-05-12 12:23:41 +02:00
lib hex2bin: fix access beyond string end 2022-05-09 09:03:22 +02:00
LICENSES
mm mm, hugetlb: allow for "high" userspace addresses 2022-05-09 09:03:28 +02:00
net NFC: netlink: fix sleep in atomic bug when firmware download timeout 2022-05-12 12:23:44 +02:00
samples samples/kretprobes: Fix return value if register_kretprobe() failed 2021-11-17 09:48:39 +01:00
scripts gcc-plugins: latent_entropy: use /dev/urandom 2022-04-20 09:19:38 +02:00
security Fix incorrect type in assignment of ipv6 port for audit 2022-04-15 14:18:22 +02:00
sound ASoC: dmaengine: Restore NULL prepare_slave_config() callback 2022-05-12 12:23:44 +02:00
tools selftests: mirror_gre_bridge_1q: Avoid changing PVID while interface is operational 2022-05-12 12:23:46 +02:00
usr
virt KVM: Prevent module exit until all VMs are freed 2022-04-15 14:18:27 +02:00
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.cocciconfig
.get_maintainer.ignore
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COPYING
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Makefile Linux 5.4.192 2022-05-09 09:03:28 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.