reiserfs: Protect reiserfs_quota_on() with write lock

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.

CC: stable@vger.kernel.org # >= 3.0
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 5372980..e59d6dd 100644 (file)
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -2216,8 +2216,11 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id,
        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) {
@@ -2259,8 +2262,10 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id,
                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;
 }