Btrfs: remove deleted xattrs on fsync log replay

If we deleted xattrs from a file and fsynced the file, after a log replay
the xattrs would remain associated to the file. This was an unexpected
behaviour and differs from what other filesystems do, such as for example
xfs and ext3/4.

Fix this by, on fsync log replay, check if every xattr in the fs/subvol
tree (that belongs to a logged inode) has a matching xattr in the log,
and if it does not, delete it from the fs/subvol tree. This is a similar
approach to what we do for dentries when we replay a directory from the
fsync log.

This issue is trivial to reproduce, and the following excerpt from my
test for xfstests triggers the issue:

  _crash_and_mount()
  {
       # Simulate a crash/power loss.
       _load_flakey_table $FLAKEY_DROP_WRITES
       _unmount_flakey
       _load_flakey_table $FLAKEY_ALLOW_WRITES
       _mount_flakey
  }

  rm -f $seqres.full

  _scratch_mkfs >> $seqres.full 2>&1
  _init_flakey
  _mount_flakey

  # Create out test file and add 3 xattrs to it.
  touch $SCRATCH_MNT/foobar
  $SETFATTR_PROG -n user.attr1 -v val1 $SCRATCH_MNT/foobar
  $SETFATTR_PROG -n user.attr2 -v val2 $SCRATCH_MNT/foobar
  $SETFATTR_PROG -n user.attr3 -v val3 $SCRATCH_MNT/foobar

  # Make sure everything is durably persisted.
  sync

  # Now delete the second xattr and fsync the inode.
  $SETFATTR_PROG -x user.attr2 $SCRATCH_MNT/foobar
  $XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foobar

  _crash_and_mount

  # After the fsync log is replayed, the file should have only 2 xattrs, the ones
  # named user.attr1 and user.attr3. The btrfs fsync log replay bug left the file
  # with the 3 xattrs that we had before deleting the second one and fsyncing the
  # file.
  echo "xattr names and values after first fsync log replay:"
  $GETFATTR_PROG --absolute-names --dump $SCRATCH_MNT/foobar | _filter_scratch

  # Now write some data to our file, fsync it, remove the first xattr, add a new
  # hard link to our file and commit the fsync log by fsyncing some other new
  # file. This is to verify that after log replay our first xattr does not exist
  # anymore.
  echo "hello world!" >> $SCRATCH_MNT/foobar
  $XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foobar
  $SETFATTR_PROG -x user.attr1 $SCRATCH_MNT/foobar
  ln $SCRATCH_MNT/foobar $SCRATCH_MNT/foobar_link
  touch $SCRATCH_MNT/qwerty
  $XFS_IO_PROG -c "fsync" $SCRATCH_MNT/qwerty

  _crash_and_mount

  # Now only the xattr with name user.attr3 should be set in our file.
  echo "xattr names and values after second fsync log replay:"
  $GETFATTR_PROG --absolute-names --dump $SCRATCH_MNT/foobar | _filter_scratch

  status=0
  exit

The expected golden output, which is produced with this patch applied or
when testing against xfs or ext3/4, is:

  xattr names and values after first fsync log replay:
  # file: SCRATCH_MNT/foobar
  user.attr1="val1"
  user.attr3="val3"

  xattr names and values after second fsync log replay:
  # file: SCRATCH_MNT/foobar
  user.attr3="val3"

Without this patch applied, the output is:

  xattr names and values after first fsync log replay:
  # file: SCRATCH_MNT/foobar
  user.attr1="val1"
  user.attr2="val2"
  user.attr3="val3"

  xattr names and values after second fsync log replay:
  # file: SCRATCH_MNT/foobar
  user.attr1="val1"
  user.attr2="val2"
  user.attr3="val3"

A patch with a test case for xfstests follows soon.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 109 insertions, 14 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 066e754b1294..6c95159302dd 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -1951,6 +1951,104 @@ out:
         return ret;
 }
 
+static int replay_xattr_deletes(struct btrfs_trans_handle *trans,
+                              struct btrfs_root *root,
+                              struct btrfs_root *log,
+                              struct btrfs_path *path,
+                              const u64 ino)
+{
+        struct btrfs_key search_key;
+        struct btrfs_path *log_path;
+        int i;
+        int nritems;
+        int ret;
+
+        log_path = btrfs_alloc_path();
+        if (!log_path)
+                return -ENOMEM;
+
+        search_key.objectid = ino;
+        search_key.type = BTRFS_XATTR_ITEM_KEY;
+        search_key.offset = 0;
+again:
+        ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
+        if (ret < 0)
+                goto out;
+process_leaf:
+        nritems = btrfs_header_nritems(path->nodes[0]);
+        for (i = path->slots[0]; i < nritems; i++) {
+                struct btrfs_key key;
+                struct btrfs_dir_item *di;
+                struct btrfs_dir_item *log_di;
+                u32 total_size;
+                u32 cur;
+
+                btrfs_item_key_to_cpu(path->nodes[0], &key, i);
+                if (key.objectid != ino || key.type != BTRFS_XATTR_ITEM_KEY) {
+                        ret = 0;
+                        goto out;
+                }
+
+                di = btrfs_item_ptr(path->nodes[0], i, struct btrfs_dir_item);
+                total_size = btrfs_item_size_nr(path->nodes[0], i);
+                cur = 0;
+                while (cur < total_size) {
+                        u16 name_len = btrfs_dir_name_len(path->nodes[0], di);
+                        u16 data_len = btrfs_dir_data_len(path->nodes[0], di);
+                        u32 this_len = sizeof(*di) + name_len + data_len;
+                        char *name;
+
+                        name = kmalloc(name_len, GFP_NOFS);
+                        if (!name) {
+                                ret = -ENOMEM;
+                                goto out;
+                        }
+                        read_extent_buffer(path->nodes[0], name,
+                                           (unsigned long)(di + 1), name_len);
+
+                        log_di = btrfs_lookup_xattr(NULL, log, log_path, ino,
+                                                    name, name_len, 0);
+                        btrfs_release_path(log_path);
+                        if (!log_di) {
+                                /* Doesn't exist in log tree, so delete it. */
+                                btrfs_release_path(path);
+                                di = btrfs_lookup_xattr(trans, root, path, ino,
+                                                        name, name_len, -1);
+                                kfree(name);
+                                if (IS_ERR(di)) {
+                                        ret = PTR_ERR(di);
+                                        goto out;
+                                }
+                                ASSERT(di);
+                                ret = btrfs_delete_one_dir_name(trans, root,
+                                                                path, di);
+                                if (ret)
+                                        goto out;
+                                btrfs_release_path(path);
+                                search_key = key;
+                                goto again;
+                        }
+                        kfree(name);
+                        if (IS_ERR(log_di)) {
+                                ret = PTR_ERR(log_di);
+                                goto out;
+                        }
+                        cur += this_len;
+                        di = (struct btrfs_dir_item *)((char *)di + this_len);
+                }
+        }
+        ret = btrfs_next_leaf(root, path);
+        if (ret > 0)
+                ret = 0;
+        else if (ret == 0)
+                goto process_leaf;
+out:
+        btrfs_free_path(log_path);
+        btrfs_release_path(path);
+        return ret;
+}
+
+
 /*
  * deletion replay happens before we copy any new directory items
  * out of the log or out of backreferences from inodes.  It
@@ -2104,6 +2202,10 @@ static int replay_one_buffer(struct btrfs_root *log, struct extent_buffer *eb,
 
                         inode_item = btrfs_item_ptr(eb, i,
                                             struct btrfs_inode_item);
+                        ret = replay_xattr_deletes(wc->trans, root, log,
+                                                   path, key.objectid);
+                        if (ret)
+                                break;
                         mode = btrfs_inode_mode(eb, inode_item);
                         if (S_ISDIR(mode)) {
                                 ret = replay_dir_deletes(wc->trans,
@@ -4072,10 +4174,8 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans,
         if (S_ISDIR(inode->i_mode)) {
                 int max_key_type = BTRFS_DIR_LOG_INDEX_KEY;
 
-                if (inode_only == LOG_INODE_EXISTS) {
-                        max_key_type = BTRFS_INODE_EXTREF_KEY;
-                        max_key.type = max_key_type;
-                }
+                if (inode_only == LOG_INODE_EXISTS)
+                        max_key_type = BTRFS_XATTR_ITEM_KEY;
                 ret = drop_objectid_items(trans, log, path, ino, max_key_type);
         } else {
                 if (inode_only == LOG_INODE_EXISTS) {
@@ -4100,7 +4200,7 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans,
                 if (test_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
                              &BTRFS_I(inode)->runtime_flags)) {
                         if (inode_only == LOG_INODE_EXISTS) {
-                                max_key.type = BTRFS_INODE_EXTREF_KEY;
+                                max_key.type = BTRFS_XATTR_ITEM_KEY;
                                 ret = drop_objectid_items(trans, log, path, ino,
                                                           max_key.type);
                         } else {
@@ -4111,17 +4211,12 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans,
                                 ret = btrfs_truncate_inode_items(trans, log,
                                                                  inode, 0, 0);
                         }
-                } else if (test_bit(BTRFS_INODE_COPY_EVERYTHING,
-                                    &BTRFS_I(inode)->runtime_flags) ||
+                } else if (test_and_clear_bit(BTRFS_INODE_COPY_EVERYTHING,
+                                              &BTRFS_I(inode)->runtime_flags) ||
                            inode_only == LOG_INODE_EXISTS) {
-                        if (inode_only == LOG_INODE_ALL) {
-                                clear_bit(BTRFS_INODE_COPY_EVERYTHING,
-                                          &BTRFS_I(inode)->runtime_flags);
+                        if (inode_only == LOG_INODE_ALL)
                                 fast_search = true;
-                                max_key.type = BTRFS_XATTR_ITEM_KEY;
-                        } else {
-                                max_key.type = BTRFS_INODE_EXTREF_KEY;
-                        }
+                        max_key.type = BTRFS_XATTR_ITEM_KEY;
                         ret = drop_objectid_items(trans, log, path, ino,
                                                   max_key.type);
                 } else {