vfs: prevent remount read-only if pending removes
If there are any inodes on the super block that have been unlinked
(i_nlink == 0) but have not yet been deleted then prevent the
remounting the super block read-only.
Reported-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/file_table.c b/fs/file_table.c
index c322794..20002e3 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -474,29 +474,6 @@
#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/fs/namespace.c b/fs/namespace.c
index 98ebc78..7e6f2c9 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -449,6 +449,10 @@
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 @@
}
}
}
+ if (!err && atomic_long_read(&sb->s_remove_count))
+ err = -EBUSY;
+
if (!err) {
sb->s_readonly_remount = 1;
smp_wmb();
diff --git a/fs/super.c b/fs/super.c
index 6acc022..de41e1e 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -729,10 +729,6 @@
retval = sb_prepare_remount_readonly(sb);
if (retval)
return retval;
-
- retval = -EBUSY;
- if (!fs_may_remount_ro(sb))
- goto cancel_readonly;
}
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 8ac4092..7aacf31 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2150,8 +2150,6 @@
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