ext4: Fix duplicate entries returned from getdents() system call

Fix a regression caused by commit d0156417, "ext4: fix ext4_dx_readdir
hash collision handling", where deleting files in a large directory
(requiring more than one getdents system call), results in some
filenames being returned twice.  This was caused by a failure to
update info->curr_hash and info->curr_minor_hash, so that if the
directory had gotten modified since the last getdents() system call
(as would be the case if the user is running "rm -r" or "git clean"),
a directory entry would get returned twice to the userspace.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

This patch fixes the bug reported by Markus Trippelsdorf at:
http://bugzilla.kernel.org/show_bug.cgi?id=11844

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Tested-by: Markus Trippelsdorf <markus@trippelsdorf.de>

1 files changed, 8 insertions, 12 deletions

diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index 3ca6a2b7632..fed5b610df5 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -459,17 +459,8 @@ static int ext4_dx_readdir(struct file *filp,
         if (info->extra_fname) {
                 if (call_filldir(filp, dirent, filldir, info->extra_fname))
                         goto finished;
-
                 info->extra_fname = NULL;
-                info->curr_node = rb_next(info->curr_node);
-                if (!info->curr_node) {
-                        if (info->next_hash == ~0) {
-                                filp->f_pos = EXT4_HTREE_EOF;
-                                goto finished;
-                        }
-                        info->curr_hash = info->next_hash;
-                        info->curr_minor_hash = 0;
-                }
+                goto next_node;
         } else if (!info->curr_node)
                 info->curr_node = rb_first(&info->root);
 
@@ -501,9 +492,14 @@ static int ext4_dx_readdir(struct file *filp,
                 info->curr_minor_hash = fname->minor_hash;
                 if (call_filldir(filp, dirent, filldir, fname))
                         break;
-
+        next_node:
                 info->curr_node = rb_next(info->curr_node);
-                if (!info->curr_node) {
+                if (info->curr_node) {
+                        fname = rb_entry(info->curr_node, struct fname,
+                                         rb_hash);
+                        info->curr_hash = fname->hash;
+                        info->curr_minor_hash = fname->minor_hash;
+                } else {
                         if (info->next_hash == ~0) {
                                 filp->f_pos = EXT4_HTREE_EOF;
                                 break;