Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

Pull quota, fsnotify and ext2 updates from Jan Kara:
 "Changes to locking of some quota operations from dedicated quota mutex
  to s_umount semaphore, a fsnotify fix and a simple ext2 fix"

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  quota: Fix bogus warning in dquot_disable()
  fsnotify: Fix possible use-after-free in inode iteration on umount
  ext2: reject inodes with negative size
  quota: Remove dqonoff_mutex
  ocfs2: Use s_umount for quota recovery protection
  quota: Remove dqonoff_mutex from dquot_scan_active()
  ocfs2: Protect periodic quota syncing with s_umount semaphore
  quota: Use s_umount protection for quota operations
  quota: Hold s_umount in exclusive mode when enabling / disabling quotas
  fs: Provide function to get superblock with exclusive s_umount

3 files changed, 16 insertions, 6 deletions

diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index 87e577a49b0d..cec495a921e3 100644
--- a/fs/ocfs2/quota_global.c
+++ b/fs/ocfs2/quota_global.c
@@ -634,7 +634,15 @@ static void qsync_work_fn(struct work_struct *work)
 						      dqi_sync_work.work);
 	struct super_block *sb = oinfo->dqi_gqinode->i_sb;
 
-	dquot_scan_active(sb, ocfs2_sync_dquot_helper, oinfo->dqi_type);
+	/*
+	 * We have to be careful here not to deadlock on s_umount as umount
+	 * disabling quotas may be in progress and it waits for this work to
+	 * complete. If trylock fails, we'll do the sync next time...
+	 */
+	if (down_read_trylock(&sb->s_umount)) {
+		dquot_scan_active(sb, ocfs2_sync_dquot_helper, oinfo->dqi_type);
+		up_read(&sb->s_umount);
+	}
 	schedule_delayed_work(&oinfo->dqi_sync_work,
 			      msecs_to_jiffies(oinfo->dqi_syncms));
 }
diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
index 8a54fd8a4fa5..32c5a40c1257 100644
--- a/fs/ocfs2/quota_local.c
+++ b/fs/ocfs2/quota_local.c
@@ -454,7 +454,7 @@ out:
 /* Sync changes in local quota file into global quota file and
  * reinitialize local quota file.
  * The function expects local quota file to be already locked and
- * dqonoff_mutex locked. */
+ * s_umount locked in shared mode. */
 static int ocfs2_recover_local_quota_file(struct inode *lqinode,
 					  int type,
 					  struct ocfs2_quota_recovery *rec)
@@ -597,7 +597,7 @@ int ocfs2_finish_quota_recovery(struct ocfs2_super *osb,
 	printk(KERN_NOTICE "ocfs2: Finishing quota recovery on device (%s) for "
 	       "slot %u\n", osb->dev_str, slot_num);
 
-	mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
+	down_read(&sb->s_umount);
 	for (type = 0; type < OCFS2_MAXQUOTAS; type++) {
 		if (list_empty(&(rec->r_list[type])))
 			continue;
@@ -674,7 +674,7 @@ out_put:
 			break;
 	}
 out:
-	mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
+	up_read(&sb->s_umount);
 	kfree(rec);
 	return status;
 }
@@ -840,7 +840,10 @@ static int ocfs2_local_free_info(struct super_block *sb, int type)
 	}
 	ocfs2_release_local_quota_bitmaps(&oinfo->dqi_chunk);
 
-	/* dqonoff_mutex protects us against racing with recovery thread... */
+	/*
+	 * s_umount held in exclusive mode protects us against racing with
+	 * recovery thread...
+	 */
 	if (oinfo->dqi_rec) {
 		ocfs2_free_quota_recovery(oinfo->dqi_rec);
 		mark_clean = 0;
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index c894d945b084..a24e42f95341 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -985,7 +985,6 @@ static void ocfs2_disable_quotas(struct ocfs2_super *osb)
 	for (type = 0; type < OCFS2_MAXQUOTAS; type++) {
 		if (!sb_has_quota_loaded(sb, type))
 			continue;
-		/* Cancel periodic syncing before we grab dqonoff_mutex */
 		oinfo = sb_dqinfo(sb, type)->dqi_priv;
 		cancel_delayed_work_sync(&oinfo->dqi_sync_work);
 		inode = igrab(sb->s_dquot.files[type]);