quota: Convert dqio_mutex to rwsem

Convert dqio_mutex to rwsem and call it dqio_sem. No functional changes
yet.

Signed-off-by: Jan Kara <jack@suse.cz>

7 files changed, 36 insertions, 41 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index d61a70e2..4c168b9 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5263,18 +5263,13 @@ static int ext4_statfs(struct dentry *dentry, struct kstatfs *buf)
 	return 0;
 }
 
-/* Helper function for writing quotas on sync - we need to start transaction
- * before quota file is locked for write. Otherwise the are possible deadlocks:
- * Process 1                         Process 2
- * ext4_create()                     quota_sync()
- *   jbd2_journal_start()                  write_dquot()
- *   dquot_initialize()                         down(dqio_mutex)
- *     down(dqio_mutex)                    jbd2_journal_start()
- *
- */
 
 #ifdef CONFIG_QUOTA
 
+/*
+ * Helper functions so that transaction is started before we acquire dqio_sem
+ * to keep correct lock ordering of transaction > dqio_sem
+ */
 static inline struct inode *dquot_to_inode(struct dquot *dquot)
 {
 	return sb_dqopt(dquot->dq_sb)->files[dquot->dq_id.type];
diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index cec495a..4134d55 100644
--- a/fs/ocfs2/quota_global.c
+++ b/fs/ocfs2/quota_global.c
@@ -33,7 +33,7 @@
  * Locking of quotas with OCFS2 is rather complex. Here are rules that
  * should be obeyed by all the functions:
  * - any write of quota structure (either to local or global file) is protected
- *   by dqio_mutex or dquot->dq_lock.
+ *   by dqio_sem or dquot->dq_lock.
  * - any modification of global quota file holds inode cluster lock, i_mutex,
  *   and ip_alloc_sem of the global quota file (achieved by
  *   ocfs2_lock_global_qf). It also has to hold qinfo_lock.
@@ -42,9 +42,9 @@
  *
  * A rough sketch of locking dependencies (lf = local file, gf = global file):
  * Normal filesystem operation:
- *   start_trans -> dqio_mutex -> write to lf
+ *   start_trans -> dqio_sem -> write to lf
  * Syncing of local and global file:
- *   ocfs2_lock_global_qf -> start_trans -> dqio_mutex -> qinfo_lock ->
+ *   ocfs2_lock_global_qf -> start_trans -> dqio_sem -> qinfo_lock ->
  *     write to gf
  *						       -> write to lf
  * Acquire dquot for the first time:
@@ -60,7 +60,7 @@
  * Recovery:
  *   inode cluster lock of recovered lf
  *     -> read bitmaps -> ip_alloc_sem of lf
- *     -> ocfs2_lock_global_qf -> start_trans -> dqio_mutex -> qinfo_lock ->
+ *     -> ocfs2_lock_global_qf -> start_trans -> dqio_sem -> qinfo_lock ->
  *        write to gf
  */
 
@@ -611,7 +611,7 @@ static int ocfs2_sync_dquot_helper(struct dquot *dquot, unsigned long type)
 		mlog_errno(status);
 		goto out_ilock;
 	}
-	mutex_lock(&sb_dqopt(sb)->dqio_mutex);
+	down_write(&sb_dqopt(sb)->dqio_sem);
 	status = ocfs2_sync_dquot(dquot);
 	if (status < 0)
 		mlog_errno(status);
@@ -619,7 +619,7 @@ static int ocfs2_sync_dquot_helper(struct dquot *dquot, unsigned long type)
 	status = ocfs2_local_write_dquot(dquot);
 	if (status < 0)
 		mlog_errno(status);
-	mutex_unlock(&sb_dqopt(sb)->dqio_mutex);
+	up_write(&sb_dqopt(sb)->dqio_sem);
 	ocfs2_commit_trans(osb, handle);
 out_ilock:
 	ocfs2_unlock_global_qf(oinfo, 1);
@@ -666,9 +666,9 @@ static int ocfs2_write_dquot(struct dquot *dquot)
 		mlog_errno(status);
 		goto out;
 	}
-	mutex_lock(&sb_dqopt(dquot->dq_sb)->dqio_mutex);
+	down_write(&sb_dqopt(dquot->dq_sb)->dqio_sem);
 	status = ocfs2_local_write_dquot(dquot);
-	mutex_unlock(&sb_dqopt(dquot->dq_sb)->dqio_mutex);
+	up_write(&sb_dqopt(dquot->dq_sb)->dqio_sem);
 	ocfs2_commit_trans(osb, handle);
 out:
 	return status;
@@ -939,7 +939,7 @@ static int ocfs2_mark_dquot_dirty(struct dquot *dquot)
 		mlog_errno(status);
 		goto out_ilock;
 	}
-	mutex_lock(&sb_dqopt(sb)->dqio_mutex);
+	down_write(&sb_dqopt(sb)->dqio_sem);
 	status = ocfs2_sync_dquot(dquot);
 	if (status < 0) {
 		mlog_errno(status);
@@ -948,7 +948,7 @@ static int ocfs2_mark_dquot_dirty(struct dquot *dquot)
 	/* Now write updated local dquot structure */
 	status = ocfs2_local_write_dquot(dquot);
 out_dlock:
-	mutex_unlock(&sb_dqopt(sb)->dqio_mutex);
+	up_write(&sb_dqopt(sb)->dqio_sem);
 	ocfs2_commit_trans(osb, handle);
 out_ilock:
 	ocfs2_unlock_global_qf(oinfo, 1);
diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
index 32c5a40..1311eff 100644
--- a/fs/ocfs2/quota_local.c
+++ b/fs/ocfs2/quota_local.c
@@ -520,7 +520,7 @@ static int ocfs2_recover_local_quota_file(struct inode *lqinode,
 				mlog_errno(status);
 				goto out_drop_lock;
 			}
-			mutex_lock(&sb_dqopt(sb)->dqio_mutex);
+			down_write(&sb_dqopt(sb)->dqio_sem);
 			spin_lock(&dq_data_lock);
 			/* Add usage from quota entry into quota changes
 			 * of our node. Auxiliary variables are important
@@ -553,7 +553,7 @@ static int ocfs2_recover_local_quota_file(struct inode *lqinode,
 			unlock_buffer(qbh);
 			ocfs2_journal_dirty(handle, qbh);
 out_commit:
-			mutex_unlock(&sb_dqopt(sb)->dqio_mutex);
+			up_write(&sb_dqopt(sb)->dqio_sem);
 			ocfs2_commit_trans(OCFS2_SB(sb), handle);
 out_drop_lock:
 			ocfs2_unlock_global_qf(oinfo, 1);
@@ -693,7 +693,7 @@ static int ocfs2_local_read_info(struct super_block *sb, int type)
 
 	/* We don't need the lock and we have to acquire quota file locks
 	 * which will later depend on this lock */
-	mutex_unlock(&sb_dqopt(sb)->dqio_mutex);
+	up_write(&sb_dqopt(sb)->dqio_sem);
 	info->dqi_max_spc_limit = 0x7fffffffffffffffLL;
 	info->dqi_max_ino_limit = 0x7fffffffffffffffLL;
 	oinfo = kmalloc(sizeof(struct ocfs2_mem_dqinfo), GFP_NOFS);
@@ -772,7 +772,7 @@ static int ocfs2_local_read_info(struct super_block *sb, int type)
 		goto out_err;
 	}
 
-	mutex_lock(&sb_dqopt(sb)->dqio_mutex);
+	down_write(&sb_dqopt(sb)->dqio_sem);
 	return 0;
 out_err:
 	if (oinfo) {
@@ -786,7 +786,7 @@ out_err:
 		kfree(oinfo);
 	}
 	brelse(bh);
-	mutex_lock(&sb_dqopt(sb)->dqio_mutex);
+	down_write(&sb_dqopt(sb)->dqio_sem);
 	return -1;
 }
 
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 53a1749..29d4475 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -120,7 +120,7 @@
  * spinlock to internal buffers before writing.
  *
  * Lock ordering (including related VFS locks) is the following:
- *   s_umount > i_mutex > journal_lock > dquot->dq_lock > dqio_mutex
+ *   s_umount > i_mutex > journal_lock > dquot->dq_lock > dqio_sem
  */
 
 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dq_list_lock);
@@ -406,7 +406,7 @@ int dquot_acquire(struct dquot *dquot)
 	struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
 
 	mutex_lock(&dquot->dq_lock);
-	mutex_lock(&dqopt->dqio_mutex);
+	down_write(&dqopt->dqio_sem);
 	if (!test_bit(DQ_READ_B, &dquot->dq_flags))
 		ret = dqopt->ops[dquot->dq_id.type]->read_dqblk(dquot);
 	if (ret < 0)
@@ -436,7 +436,7 @@ int dquot_acquire(struct dquot *dquot)
 	smp_mb__before_atomic();
 	set_bit(DQ_ACTIVE_B, &dquot->dq_flags);
 out_iolock:
-	mutex_unlock(&dqopt->dqio_mutex);
+	up_write(&dqopt->dqio_sem);
 	mutex_unlock(&dquot->dq_lock);
 	return ret;
 }
@@ -450,7 +450,7 @@ int dquot_commit(struct dquot *dquot)
 	int ret = 0;
 	struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
 
-	mutex_lock(&dqopt->dqio_mutex);
+	down_write(&dqopt->dqio_sem);
 	spin_lock(&dq_list_lock);
 	if (!clear_dquot_dirty(dquot)) {
 		spin_unlock(&dq_list_lock);
@@ -464,7 +464,7 @@ int dquot_commit(struct dquot *dquot)
 	else
 		ret = -EIO;
 out_sem:
-	mutex_unlock(&dqopt->dqio_mutex);
+	up_write(&dqopt->dqio_sem);
 	return ret;
 }
 EXPORT_SYMBOL(dquot_commit);
@@ -481,7 +481,7 @@ int dquot_release(struct dquot *dquot)
 	/* Check whether we are not racing with some other dqget() */
 	if (atomic_read(&dquot->dq_count) > 1)
 		goto out_dqlock;
-	mutex_lock(&dqopt->dqio_mutex);
+	down_write(&dqopt->dqio_sem);
 	if (dqopt->ops[dquot->dq_id.type]->release_dqblk) {
 		ret = dqopt->ops[dquot->dq_id.type]->release_dqblk(dquot);
 		/* Write the info */
@@ -493,7 +493,7 @@ int dquot_release(struct dquot *dquot)
 			ret = ret2;
 	}
 	clear_bit(DQ_ACTIVE_B, &dquot->dq_flags);
-	mutex_unlock(&dqopt->dqio_mutex);
+	up_write(&dqopt->dqio_sem);
 out_dqlock:
 	mutex_unlock(&dquot->dq_lock);
 	return ret;
@@ -2060,9 +2060,9 @@ int dquot_commit_info(struct super_block *sb, int type)
 	int ret;
 	struct quota_info *dqopt = sb_dqopt(sb);
 
-	mutex_lock(&dqopt->dqio_mutex);
+	down_write(&dqopt->dqio_sem);
 	ret = dqopt->ops[type]->write_file_info(sb, type);
-	mutex_unlock(&dqopt->dqio_mutex);
+	up_write(&dqopt->dqio_sem);
 	return ret;
 }
 EXPORT_SYMBOL(dquot_commit_info);
@@ -2076,9 +2076,9 @@ int dquot_get_next_id(struct super_block *sb, struct kqid *qid)
 		return -ESRCH;
 	if (!dqopt->ops[qid->type]->get_next_id)
 		return -ENOSYS;
-	mutex_lock(&dqopt->dqio_mutex);
+	down_write(&dqopt->dqio_sem);
 	err = dqopt->ops[qid->type]->get_next_id(sb, qid);
-	mutex_unlock(&dqopt->dqio_mutex);
+	up_write(&dqopt->dqio_sem);
 	return err;
 }
 EXPORT_SYMBOL(dquot_get_next_id);
@@ -2328,15 +2328,15 @@ static int vfs_load_quota_inode(struct inode *inode, int type, int format_id,
 	dqopt->info[type].dqi_format = fmt;
 	dqopt->info[type].dqi_fmt_id = format_id;
 	INIT_LIST_HEAD(&dqopt->info[type].dqi_dirty_list);
-	mutex_lock(&dqopt->dqio_mutex);
+	down_write(&dqopt->dqio_sem);
 	error = dqopt->ops[type]->read_file_info(sb, type);
 	if (error < 0) {
-		mutex_unlock(&dqopt->dqio_mutex);
+		up_write(&dqopt->dqio_sem);
 		goto out_file_init;
 	}
 	if (dqopt->flags & DQUOT_QUOTA_SYS_FILE)
 		dqopt->info[type].dqi_flags |= DQF_SYS_FILE;
-	mutex_unlock(&dqopt->dqio_mutex);
+	up_write(&dqopt->dqio_sem);
 	spin_lock(&dq_state_lock);
 	dqopt->flags |= dquot_state_flag(flags, type);
 	spin_unlock(&dq_state_lock);
diff --git a/fs/quota/quota_tree.c b/fs/quota/quota_tree.c
index 0738972..54f85eb 100644
--- a/fs/quota/quota_tree.c
+++ b/fs/quota/quota_tree.c
@@ -379,7 +379,7 @@ int qtree_write_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot)
 	if (!ddquot)
 		return -ENOMEM;
 
-	/* dq_off is guarded by dqio_mutex */
+	/* dq_off is guarded by dqio_sem */
 	if (!dquot->dq_off) {
 		ret = dq_insert_tree(info, dquot);
 		if (ret < 0) {
diff --git a/fs/super.c b/fs/super.c
index 6bc3352..221cfa1 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -242,7 +242,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
 	atomic_set(&s->s_active, 1);
 	mutex_init(&s->s_vfs_rename_mutex);
 	lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
-	mutex_init(&s->s_dquot.dqio_mutex);
+	init_rwsem(&s->s_dquot.dqio_sem);
 	s->s_maxbytes = MAX_NON_LFS;
 	s->s_op = &default_op;
 	s->s_time_gran = 1000000000;
diff --git a/include/linux/quota.h b/include/linux/quota.h
index bfd077c..3a6df74 100644
--- a/include/linux/quota.h
+++ b/include/linux/quota.h
@@ -521,7 +521,7 @@ static inline void quota_send_warning(struct kqid qid, dev_t dev,
 
 struct quota_info {
 	unsigned int flags;			/* Flags for diskquotas on this device */
-	struct mutex dqio_mutex;		/* lock device while I/O in progress */
+	struct rw_semaphore dqio_sem;		/* Lock quota file while I/O in progress */
 	struct inode *files[MAXQUOTAS];		/* inodes of quotafiles */
 	struct mem_dqinfo info[MAXQUOTAS];	/* Information for each quota type */
 	const struct quota_format_ops *ops[MAXQUOTAS];	/* Operations for each type */