Commit 1638045c authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

mm: set S_SWAPFILE on blockdev swap devices 



Set S_SWAPFILE on block device inodes so that they have the same
protections as a swap flie.

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent 609488bc

mm/swapfile.c

+15 −16
Original line number Diff line number Diff line
@@ -2368,9 +2368,8 @@ EXPORT_SYMBOL_GPL(add_swap_extent); 
 * requirements, they are simply tossed out - we will never use those blocks

 * for swapping.

 *

 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon.  This

 * prevents root from shooting her foot off by ftruncating an in-use swapfile,

 * which will scribble on the fs.

 * For all swap devices we set S_SWAPFILE across the life of the swapon.  This

 * prevents users from writing to the swap device, which will corrupt memory.

 *

 * The amount of disk space which a single swap extent represents varies.

 * Typically it is in the 1-4 megabyte range.  So we can have hundreds of
@@ -2661,13 +2660,14 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) 
	inode = mapping->host;

	if (S_ISBLK(inode->i_mode)) {

		struct block_device *bdev = I_BDEV(inode);



		set_blocksize(bdev, old_block_size);

		blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);

	} else {

	}



	inode_lock(inode);

	inode->i_flags &= ~S_SWAPFILE;

	inode_unlock(inode);

	}

	filp_close(swap_file, NULL);



	/*
@@ -2890,11 +2890,11 @@ static int claim_swapfile(struct swap_info_struct *p, struct inode *inode) 
		p->flags |= SWP_BLKDEV;

	} else if (S_ISREG(inode->i_mode)) {

		p->bdev = inode->i_sb->s_bdev;

	}



	inode_lock(inode);

	if (IS_SWAPFILE(inode))

		return -EBUSY;

	} else

		return -EINVAL;



	return 0;

}
@@ -3295,7 +3295,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) 
	atomic_inc(&proc_poll_event);

	wake_up_interruptible(&proc_poll_wait);



	if (S_ISREG(inode->i_mode))

	inode->i_flags |= S_SWAPFILE;

	error = 0;

	goto out;
@@ -3318,7 +3317,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) 
	if (inced_nr_rotate_swap)

		atomic_dec(&nr_rotate_swap);

	if (swap_file) {

		if (inode && S_ISREG(inode->i_mode)) {

		if (inode) {

			inode_unlock(inode);

			inode = NULL;

		}
@@ -3331,7 +3330,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) 
	}

	if (name)

		putname(name);

	if (inode && S_ISREG(inode->i_mode))

	if (inode)

		inode_unlock(inode);

	if (!error)

		enable_swap_slots_cache();