reiserfs: fix race in readdir

commit 01d8885785a60ae8f4c37b0ed75bdc96d0fc6a44 upstream.

jdm-20004 reiserfs_delete_xattrs: Couldn't delete all xattrs (-2)

The -ENOENT is due to readdir calling dir_emit on the same entry twice.

If the dir_emit callback sleeps and the tree is changed underneath us,
we won't be able to trust deh_offset(deh) anymore. We need to save
next_pos before we might sleep so we can find the next entry.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/reiserfs/dir.c b/fs/reiserfs/dir.c
index 6c2d136561cb..2b96b59f75da 100644
--- a/fs/reiserfs/dir.c
+++ b/fs/reiserfs/dir.c
@@ -128,6 +128,7 @@ int reiserfs_readdir_dentry(struct dentry *dentry, void *dirent,
                                 char *d_name;
                                 off_t d_off;
                                 ino_t d_ino;
+                                loff_t cur_pos = deh_offset(deh);
 
                                 if (!de_visible(deh))
                                         /* it is hidden entry */
@@ -200,8 +201,9 @@ int reiserfs_readdir_dentry(struct dentry *dentry, void *dirent,
                                 if (local_buf != small_buf) {
                                         kfree(local_buf);
                                 }
-                                // next entry should be looked for with such offset
-                                next_pos = deh_offset(deh) + 1;
+
+                                /* deh_offset(deh) may be invalid now. */
+                                next_pos = cur_pos + 1;
 
                                 if (item_moved(&tmp_ih, &path_to_entry)) {
                                         set_cpu_key_k_offset(&pos_key,