reiserfs: fix race in readdir
Jeff Mahoney [Wed, 2 Apr 2014 18:40:26 +0000 (14:40 -0400)]
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>

fs/reiserfs/dir.c

index 6c2d136..2b96b59 100644 (file)
@@ -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,