4.19-stable patches

added patches:
	btrfs-always-log-symlinks-in-full-mode.patch

diff --git a/queue-4.19/btrfs-always-log-symlinks-in-full-mode.patch b/queue-4.19/btrfs-always-log-symlinks-in-full-mode.patch
new file mode 100644 (file)
index 0000000..4769422
--- /dev/null
+++ b/queue-4.19/btrfs-always-log-symlinks-in-full-mode.patch
@@ -0,0 +1,89 @@
+From d0e64a981fd841cb0f28fcd6afcac55e6f1e6994 Mon Sep 17 00:00:00 2001
+From: Filipe Manana <fdmanana@suse.com>
+Date: Thu, 21 Apr 2022 10:56:39 +0100
+Subject: btrfs: always log symlinks in full mode
+
+From: Filipe Manana <fdmanana@suse.com>
+
+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>
+---
+ fs/btrfs/tree-log.c |   14 +++++++++++++-
+ 1 file changed, 13 insertions(+), 1 deletion(-)
+
+--- a/fs/btrfs/tree-log.c
++++ b/fs/btrfs/tree-log.c
+@@ -4907,6 +4907,18 @@ static int btrfs_log_inode(struct btrfs_
+       }
+ 
+       /*
++       * For symlinks, we must always log their content, which is stored in an
++       * inline extent, otherwise we could end up with an empty symlink after
++       * log replay, which is invalid on linux (symlink(2) returns -ENOENT if
++       * one attempts to create an empty symlink).
++       * We don't need to worry about flushing delalloc, because when we create
++       * the inline extent when the symlink is created (we never have delalloc
++       * for symlinks).
++       */
++      if (S_ISLNK(inode->vfs_inode.i_mode))
++              inode_only = LOG_INODE_ALL;
++
++      /*
+        * a brute force approach to making sure we get the most uptodate
+        * copies of everything.
+        */
+@@ -5462,7 +5474,7 @@ process_leaf:
+                       }
+ 
+                       ctx->log_new_dentries = false;
+-                      if (type == BTRFS_FT_DIR || type == BTRFS_FT_SYMLINK)
++                      if (type == BTRFS_FT_DIR)
+                               log_mode = LOG_INODE_ALL;
+                       ret = btrfs_log_inode(trans, root, BTRFS_I(di_inode),
+                                             log_mode, 0, LLONG_MAX, ctx);

diff --git a/queue-4.19/series b/queue-4.19/series
index 3a7a6d3b0237e0622f980eea71843fe8bc93a1c7..dcee50b4c1c6402af871dd10d4eb4d1192230c9c 100644 (file)
--- a/queue-4.19/series
+++ b/queue-4.19/series
@@ -76,3 +76,4 @@ net-stmmac-dwmac-sun8i-add-missing-of_node_put-in-sun8i_dwmac_register_mdio_mux.
 net-emaclite-add-error-handling-for-of_address_to_resource.patch
 selftests-mirror_gre_bridge_1q-avoid-changing-pvid-while-interface-is-operational.patch
 smsc911x-allow-using-irq0.patch
+btrfs-always-log-symlinks-in-full-mode.patch