From b2e87c203c9f362e41ca6214836f589868d20a7c Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@suse.cz>
Date: Mon, 21 Nov 2011 12:11:33 +0100
Subject: [PATCH] --- yaml --- r: 280302 b: refs/heads/master c:
 8e8b87964bc8dc5c14b6543fc933b7725f07d3ac h: refs/heads/master v: v3

---
 [refs]                   |  2 +-
 trunk/fs/file_table.c    | 23 -----------------------
 trunk/fs/namespace.c     |  7 +++++++
 trunk/fs/super.c         |  4 ----
 trunk/include/linux/fs.h |  2 --
 5 files changed, 8 insertions(+), 30 deletions(-)

diff --git a/[refs] b/[refs]
index 1b35383213ac..508d39830549 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7ada4db88634429f4da690ad1c4eb73c93085f0c
+refs/heads/master: 8e8b87964bc8dc5c14b6543fc933b7725f07d3ac
diff --git a/trunk/fs/file_table.c b/trunk/fs/file_table.c
index c322794f7360..20002e39754d 100644
--- a/trunk/fs/file_table.c
+++ b/trunk/fs/file_table.c
@@ -474,29 +474,6 @@ void file_sb_list_del(struct file *file)
 
 #endif
 
-int fs_may_remount_ro(struct super_block *sb)
-{
-	struct file *file;
-	/* Check that no files are currently opened for writing. */
-	lg_global_lock(files_lglock);
-	do_file_list_for_each_entry(sb, file) {
-		struct inode *inode = file->f_path.dentry->d_inode;
-
-		/* File with pending delete? */
-		if (inode->i_nlink == 0)
-			goto too_bad;
-
-		/* Writeable file? */
-		if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
-			goto too_bad;
-	} while_file_list_for_each_entry;
-	lg_global_unlock(files_lglock);
-	return 1; /* Tis' cool bro. */
-too_bad:
-	lg_global_unlock(files_lglock);
-	return 0;
-}
-
 /**
  *	mark_files_ro - mark all files read-only
  *	@sb: superblock in question
diff --git a/trunk/fs/namespace.c b/trunk/fs/namespace.c
index 98ebc78b21ab..7e6f2c9dc7c4 100644
--- a/trunk/fs/namespace.c
+++ b/trunk/fs/namespace.c
@@ -449,6 +449,10 @@ int sb_prepare_remount_readonly(struct super_block *sb)
 	struct mount *mnt;
 	int err = 0;
 
+	/* Racy optimization.  Recheck the counter under MNT_WRITE_HOLD */
+	if (atomic_long_read(&sb->s_remove_count))
+		return -EBUSY;
+
 	br_write_lock(vfsmount_lock);
 	list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) {
 		if (!(mnt->mnt.mnt_flags & MNT_READONLY)) {
@@ -460,6 +464,9 @@ int sb_prepare_remount_readonly(struct super_block *sb)
 			}
 		}
 	}
+	if (!err && atomic_long_read(&sb->s_remove_count))
+		err = -EBUSY;
+
 	if (!err) {
 		sb->s_readonly_remount = 1;
 		smp_wmb();
diff --git a/trunk/fs/super.c b/trunk/fs/super.c
index 6acc02237e3e..de41e1e46f09 100644
--- a/trunk/fs/super.c
+++ b/trunk/fs/super.c
@@ -729,10 +729,6 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
 			retval = sb_prepare_remount_readonly(sb);
 			if (retval)
 				return retval;
-
-			retval = -EBUSY;
-			if (!fs_may_remount_ro(sb))
-				goto cancel_readonly;
 		}
 	}
 
diff --git a/trunk/include/linux/fs.h b/trunk/include/linux/fs.h
index 8ac40921f5ac..7aacf31418fe 100644
--- a/trunk/include/linux/fs.h
+++ b/trunk/include/linux/fs.h
@@ -2150,8 +2150,6 @@ extern const struct file_operations read_pipefifo_fops;
 extern const struct file_operations write_pipefifo_fops;
 extern const struct file_operations rdwr_pipefifo_fops;
 
-extern int fs_may_remount_ro(struct super_block *);
-
 #ifdef CONFIG_BLOCK
 /*
  * return READ, READA, or WRITE