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Commit 8e8b8796 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Al Viro
Browse files

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: default avatarToshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Tested-by: default avatarToshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 7ada4db8

fs/file_table.c

+0 −23
Original line number Diff line number Diff line
@@ -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

fs/namespace.c

+7 −0
Original line number Diff line number Diff line
@@ -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();

fs/super.c

+0 −4
Original line number Diff line number Diff line
@@ -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;

		}

	}

include/linux/fs.h

+0 −2
Original line number Diff line number Diff line
@@ -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