linux-ext4 - [FOR-STABLE 14/20] ext4: Fix duplicate entries returned from getdents() system call

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Date:	Sun, 16 Nov 2008 11:05:34 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	stable@...nel.org
Cc:	Ext4 Developers List <linux-ext4@...r.kernel.org>,
	Theodore Ts'o <tytso@....edu>
Subject: [FOR-STABLE 14/20] 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@....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@....edu>
Tested-by: Markus Trippelsdorf <markus@...ppelsdorf.de>
(cherry picked from commit 3c37fc86d20fe35be656f070997d62f75c2e4874)
---
 fs/ext4/dir.c |   20 ++++++++------------
 1 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index ec8e33b..0f2bbda 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -453,17 +453,8 @@ 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);
 
@@ -495,9 +486,14 @@ 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;
-- 
1.6.0.4.8.g36f27.dirty

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