releases/2.6.34.8/ext4-Fix-remaining-racy-updates-of-EXT4_I-inode-i_fl.patch

From 252ff9f1dbd312207c9a2db7d0135df759aacfe4 Mon Sep 17 00:00:00 2001
From: Dmitry Monakhov <dmonakhov@openvz.org>
Date: Sat, 5 Jun 2010 11:51:27 -0400
Subject: [PATCH] ext4: Fix remaining racy updates of EXT4_I(inode)->i_flags

commit 84a8dce2710cc425089a2b92acc354d4fbb5788d upstream.

A few functions were still modifying i_flags in a racy manner.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
 fs/ext4/inode.c |   40 +++++++++++++++++++++++-----------------
 1 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 3fd683f..4eced51 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4932,20 +4932,26 @@ void ext4_set_inode_flags(struct inode *inode)
 /* Propagate flags from i_flags to EXT4_I(inode)->i_flags */
 void ext4_get_inode_flags(struct ext4_inode_info *ei)
 {
-	unsigned int flags = ei->vfs_inode.i_flags;
-
-	ei->i_flags &= ~(EXT4_SYNC_FL|EXT4_APPEND_FL|
-			EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|EXT4_DIRSYNC_FL);
-	if (flags & S_SYNC)
-		ei->i_flags |= EXT4_SYNC_FL;
-	if (flags & S_APPEND)
-		ei->i_flags |= EXT4_APPEND_FL;
-	if (flags & S_IMMUTABLE)
-		ei->i_flags |= EXT4_IMMUTABLE_FL;
-	if (flags & S_NOATIME)
-		ei->i_flags |= EXT4_NOATIME_FL;
-	if (flags & S_DIRSYNC)
-		ei->i_flags |= EXT4_DIRSYNC_FL;
+	unsigned int vfs_fl;
+	unsigned long old_fl, new_fl;
+
+	do {
+		vfs_fl = ei->vfs_inode.i_flags;
+		old_fl = ei->i_flags;
+		new_fl = old_fl & ~(EXT4_SYNC_FL|EXT4_APPEND_FL|
+				EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|
+				EXT4_DIRSYNC_FL);
+		if (vfs_fl & S_SYNC)
+			new_fl |= EXT4_SYNC_FL;
+		if (vfs_fl & S_APPEND)
+			new_fl |= EXT4_APPEND_FL;
+		if (vfs_fl & S_IMMUTABLE)
+			new_fl |= EXT4_IMMUTABLE_FL;
+		if (vfs_fl & S_NOATIME)
+			new_fl |= EXT4_NOATIME_FL;
+		if (vfs_fl & S_DIRSYNC)
+			new_fl |= EXT4_DIRSYNC_FL;
+	} while (cmpxchg(&ei->i_flags, old_fl, new_fl) != old_fl);
 }
 
 static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
@@ -5182,7 +5188,7 @@ static int ext4_inode_blocks_set(handle_t *handle,
 		 */
 		raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
 		raw_inode->i_blocks_high = 0;
-		ei->i_flags &= ~EXT4_HUGE_FILE_FL;
+		ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
 		return 0;
 	}
 	if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_HUGE_FILE))
@@ -5195,9 +5201,9 @@ static int ext4_inode_blocks_set(handle_t *handle,
 		 */
 		raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
 		raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
-		ei->i_flags &= ~EXT4_HUGE_FILE_FL;
+		ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
 	} else {
-		ei->i_flags |= EXT4_HUGE_FILE_FL;
+		ext4_set_inode_flag(inode, EXT4_INODE_HUGE_FILE);
 		/* i_block is stored in file system block size */
 		i_blocks = i_blocks >> (inode->i_blkbits - 9);
 		raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
-- 
1.7.0.4