[ 052/171] reiserfs: Protect reiserfs_quota_on() with write lock

[Greg Kroah-Hartman]

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@xxxxxxx>

commit b9e06ef2e8706fe669b51f4364e3aeed58639eb2 upstream.

In reiserfs_quota_on() we do quite some work - for example unpacking
tail of a quota file. Thus we have to hold write lock until a moment
we call back into the quota code.

Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/reiserfs/super.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -2170,8 +2170,11 @@ static int reiserfs_quota_on(struct supe
 	struct reiserfs_transaction_handle th;
 	int opt = type == USRQUOTA ? REISERFS_USRQUOTA : REISERFS_GRPQUOTA;
 
-	if (!(REISERFS_SB(sb)->s_mount_opt & (1 << opt)))
-		return -EINVAL;
+	reiserfs_write_lock(sb);
+	if (!(REISERFS_SB(sb)->s_mount_opt & (1 << opt))) {
+		err = -EINVAL;
+		goto out;
+	}
 
 	/* Quotafile not on the same filesystem? */
 	if (path->dentry->d_sb != sb) {
@@ -2213,8 +2216,10 @@ static int reiserfs_quota_on(struct supe
 		if (err)
 			goto out;
 	}
-	err = dquot_quota_on(sb, type, format_id, path);
+	reiserfs_write_unlock(sb);
+	return dquot_quota_on(sb, type, format_id, path);
 out:
+	reiserfs_write_unlock(sb);
 	return err;
 }
 


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