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

Dave Hansen
2007-02-09T22:58:49Z

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@us.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
_