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[PATCH 4.5 125/128] Btrfs: fix empty symlink after creating symlink and fsync parent dir

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4.5-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Filipe Manana <fdmanana@suse.com>

commit 3f9749f6e9edcf8ec569fb542efc3be35e06e84a upstream.

If we create a symlink, fsync its parent directory, crash/power fail and
mount the filesystem, we end up with an empty symlink, which not only is
useless it's also not allowed in linux (the man page symlink(2) is well
explicit about that).  So we just need to make sure to fully log an inode
if it's a symlink, to ensure its inline extent gets logged, ensuring the
same behaviour as ext3, ext4, xfs, reiserfs, f2fs, nilfs2, etc.

Example reproducer:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /mnt
  $ mkdir /mnt/testdir
  $ sync
  $ ln -s /mnt/foo /mnt/testdir/bar
  $ xfs_io -c fsync /mnt/testdir
  <power fail>
  $ mount /dev/sdb /mnt
  $ readlink /mnt/testdir/bar
  <empty string>

A test case for fstests follows soon.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/btrfs/tree-log.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -5157,7 +5157,7 @@ process_leaf:
 			}
 
 			ctx->log_new_dentries = false;
-			if (type == BTRFS_FT_DIR)
+			if (type == BTRFS_FT_DIR || type == BTRFS_FT_SYMLINK)
 				log_mode = LOG_INODE_ALL;
 			btrfs_release_path(path);
 			ret = btrfs_log_inode(trans, root, di_inode,

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[PATCH 4.5 000/128] 4.5.7-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 01:00 +0200
  [PATCH 4.5 126/128] Btrfs: fix unexpected return value of fiemap Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 127/128] btrfs: scrub: Set bbio to NULL before calling btrfs_map_block Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 098/128] PM / sleep: Handle failures in device_suspend_late() consistently Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 093/128] ext4: fix check of dqget() return value in ext4_ioctl_setproject() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 110/128] btrfs: allow balancing to dup with multi-device Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 128/128] btrfs: make state preallocation more speculative in __set_extent_bit Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 120/128] btrfs: fix int32 overflow in shrink_delalloc(). Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 095/128] ext4: address UBSAN warning in mb_find_order_for_block() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 102/128] gcov: disable tree-loop-im to reduce stack usage Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 097/128] nfs: avoid race that crashes nfs_init_commit Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 100/128] scripts/package/Makefile: rpmbuild add support of RPMOPTS Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 115/128] btrfs: add check to sysfs handler of label Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 096/128] ext4: silence UBSAN in ext4_mb_init() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 116/128] Btrfs: fix divide error upon chunks stripe_len Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 123/128] btrfs: pass the right error code to the btrfs_std_error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 113/128] btrfs: fix lock dep warning, move scratch dev out of device_list_mutex and uuid_mutex Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 122/128] btrfs: fix memory leak during RAID 5/6 device replacement Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 109/128] Btrfs: do not create empty block group if we have allocated data Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 114/128] btrfs: add read-only check to sysfs handler of features Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 119/128] btrfs: add write protection to SET_FEATURES ioctl Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 117/128] Btrfs: remove BUG_ON()s in btrfs_map_block Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 111/128] btrfs: fix mixed block count of available space Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 118/128] btrfs: fix lock dep warning move scratch super outside of chunk_mutex Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 125/128] Btrfs: fix empty symlink after creating symlink and fsync parent dir Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 101/128] mm: thp: avoid false positive VM_BUG_ON_PAGE in page_move_anon_rmap() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:40 +0200
  [PATCH 4.5 112/128] btrfs: avoid overflowing f_bfree Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-06 16:50 +0200
  Re: [PATCH 4.5 000/128] 4.5.7-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2016-06-06 19:30 +0200
  Re: [PATCH 4.5 000/128] 4.5.7-stable review Guenter Roeck <linux@roeck-us.net> - 2016-06-07 15:40 +0200

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