--- /dev/null
+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
+@@ -5484,6 +5484,18 @@ 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;
++
++ /*
+ * This is for cases where logging a directory could result in losing a
+ * a file after replaying the log. For example, if we move a file from a
+ * directory A to a directory B, then fsync directory A, we have no way
+@@ -5853,7 +5865,7 @@ 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, ctx);
--- /dev/null
+From 9f73f1aef98b2fa7252c0a89be64840271ce8ea0 Mon Sep 17 00:00:00 2001
+From: Qu Wenruo <wqu@suse.com>
+Date: Fri, 1 Apr 2022 15:29:37 +0800
+Subject: btrfs: force v2 space cache usage for subpage mount
+
+From: Qu Wenruo <wqu@suse.com>
+
+commit 9f73f1aef98b2fa7252c0a89be64840271ce8ea0 upstream.
+
+[BUG]
+For a 4K sector sized btrfs with v1 cache enabled and only mounted on
+systems with 4K page size, if it's mounted on subpage (64K page size)
+systems, it can cause the following warning on v1 space cache:
+
+ BTRFS error (device dm-1): csum mismatch on free space cache
+ BTRFS warning (device dm-1): failed to load free space cache for block group 84082688, rebuilding it now
+
+Although not a big deal, as kernel can rebuild it without problem, such
+warning will bother end users, especially if they want to switch the
+same btrfs seamlessly between different page sized systems.
+
+[CAUSE]
+V1 free space cache is still using fixed PAGE_SIZE for various bitmap,
+like BITS_PER_BITMAP.
+
+Such hard-coded PAGE_SIZE usage will cause various mismatch, from v1
+cache size to checksum.
+
+Thus kernel will always reject v1 cache with a different PAGE_SIZE with
+csum mismatch.
+
+[FIX]
+Although we should fix v1 cache, it's already going to be marked
+deprecated soon.
+
+And we have v2 cache based on metadata (which is already fully subpage
+compatible), and it has almost everything superior than v1 cache.
+
+So just force subpage mount to use v2 cache on mount.
+
+Reported-by: Matt Corallo <blnxfsl@bluematt.me>
+CC: stable@vger.kernel.org # 5.15+
+Link: https://lore.kernel.org/linux-btrfs/61aa27d1-30fc-c1a9-f0f4-9df544395ec3@bluematt.me/
+Reviewed-by: Josef Bacik <josef@toxicpanda.com>
+Signed-off-by: Qu Wenruo <wqu@suse.com>
+Signed-off-by: David Sterba <dsterba@suse.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/btrfs/disk-io.c | 11 +++++++++++
+ 1 file changed, 11 insertions(+)
+
+--- a/fs/btrfs/disk-io.c
++++ b/fs/btrfs/disk-io.c
+@@ -3415,6 +3415,17 @@ int __cold open_ctree(struct super_block
+ }
+
+ if (sectorsize != PAGE_SIZE) {
++ /*
++ * V1 space cache has some hardcoded PAGE_SIZE usage, and is
++ * going to be deprecated.
++ *
++ * Force to use v2 cache for subpage case.
++ */
++ btrfs_clear_opt(fs_info->mount_opt, SPACE_CACHE);
++ btrfs_set_and_info(fs_info, FREE_SPACE_TREE,
++ "forcing free space tree for sector size %u with page size %lu",
++ sectorsize, PAGE_SIZE);
++
+ btrfs_warn(fs_info,
+ "read-write for sector size %u with page size %lu is experimental",
+ sectorsize, PAGE_SIZE);
projects / thirdparty / kernel / stable-queue.git / commitdiff
