linux-kernel - [PATCH 22/22] kill open files traverse on remount ro

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Message-Id: <20070209225345.D9BAC383@localhost.localdomain>
Date:	Fri, 09 Feb 2007 14:53:45 -0800
From:	Dave Hansen <hansendc@...ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	akpm@...l.org, hch@...radead.org, Dave Hansen <hansendc@...ibm.com>
Subject: [PATCH 22/22] kill open files traverse on remount ro


Now that we have the sb writer count, and all of the
writers marked with mnt_want_write(), we don't need to
go looking at all of the individual open files.

Kill the open files walk, and use the sb writer count.

Signed-off-by: Dave Hansen <haveblue@...ibm.com>
---

 lxc-dave/fs/file_table.c    |   25 -------------------------
 lxc-dave/fs/super.c         |   13 ++++++++++++-
 lxc-dave/include/linux/fs.h |    2 --
 3 files changed, 12 insertions(+), 28 deletions(-)

diff -puN fs/file_table.c~24-24-kill-open-files-traverse-on-remount-ro fs/file_table.c
--- lxc/fs/file_table.c~24-24-kill-open-files-traverse-on-remount-ro	2007-02-09 14:27:01.000000000 -0800
+++ lxc-dave/fs/file_table.c	2007-02-09 14:27:01.000000000 -0800
@@ -308,31 +308,6 @@ void file_kill(struct file *file)
 	}
 }
 
-int fs_may_remount_ro(struct super_block *sb)
-{
-	struct list_head *p;
-
-	/* Check that no files are currently opened for writing. */
-	file_list_lock();
-	list_for_each(p, &sb->s_files) {
-		struct file *file = list_entry(p, struct file, f_u.fu_list);
-		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;
-	}
-	file_list_unlock();
-	return 1; /* Tis' cool bro. */
-too_bad:
-	file_list_unlock();
-	return 0;
-}
-
 void __init files_init(unsigned long mempages)
 { 
 	int n; 
diff -puN fs/super.c~24-24-kill-open-files-traverse-on-remount-ro fs/super.c
--- lxc/fs/super.c~24-24-kill-open-files-traverse-on-remount-ro	2007-02-09 14:27:01.000000000 -0800
+++ lxc-dave/fs/super.c	2007-02-09 14:27:01.000000000 -0800
@@ -580,7 +580,18 @@ static void mark_files_ro(struct super_b
 
 static int sb_remount_ro(struct super_block *sb)
 {
-	return fs_may_remount_ro(sb);
+	int ret = 0;
+
+	/*
+	 * The r/o flag actually gets set
+	 * by the caller.
+	 */
+	spin_lock(&sb->s_mnt_writers_lock);
+	if (sb->s_writers)
+		ret = -EBUSY;
+	spin_unlock(&sb->s_mnt_writers_lock);
+
+	return ret;
 }
 
 /**
diff -puN include/linux/fs.h~24-24-kill-open-files-traverse-on-remount-ro include/linux/fs.h
--- lxc/include/linux/fs.h~24-24-kill-open-files-traverse-on-remount-ro	2007-02-09 14:27:01.000000000 -0800
+++ lxc-dave/include/linux/fs.h	2007-02-09 14:27:01.000000000 -0800
@@ -1657,8 +1657,6 @@ extern const struct file_operations read
 extern const struct file_operations write_fifo_fops;
 extern const struct file_operations rdwr_fifo_fops;
 
-extern int fs_may_remount_ro(struct super_block *);
-
 #ifdef CONFIG_BLOCK
 /*
  * return READ, READA, or WRITE
_
-
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