Commit e82c9362 authored by Filipe Manana's avatar Filipe Manana Committed by David Sterba
Browse files

btrfs: send: check for read-only send root under critical section 



We're checking if the send root is read-only without being under the
protection of the root's root_item_lock spinlock, which is what protects
the root's flags when clearing the read-only flag, done at
btrfs_ioctl_subvol_setflags(). Furthermore, it should be done in the
same critical section that increments the root's send_in_progress counter,
as btrfs_ioctl_subvol_setflags() clears the read-only flag in the same
critical section that checks the counter's value.

So fix this by moving the read-only check under the critical section
delimited by the root's root_item_lock which also increments the root's
send_in_progress counter.

Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent dc058f5f

fs/btrfs/send.c

+6 −10
Original line number Diff line number Diff line
@@ -8133,7 +8133,12 @@ long btrfs_ioctl_send(struct btrfs_inode *inode, const struct btrfs_ioctl_send_a 
		spin_unlock(&send_root->root_item_lock);

		return -EPERM;

	}

	if (btrfs_root_readonly(send_root) && send_root->dedupe_in_progress) {

	/* Userspace tools do the checks and warn the user if it's not RO. */

	if (!btrfs_root_readonly(send_root)) {

		spin_unlock(&send_root->root_item_lock);

		return -EPERM;

	}

	if (send_root->dedupe_in_progress) {

		dedupe_in_progress_warn(send_root);

		spin_unlock(&send_root->root_item_lock);

		return -EAGAIN;
@@ -8141,15 +8146,6 @@ long btrfs_ioctl_send(struct btrfs_inode *inode, const struct btrfs_ioctl_send_a 
	send_root->send_in_progress++;

	spin_unlock(&send_root->root_item_lock);



	/*

	 * Userspace tools do the checks and warn the user if it's

	 * not RO.

	 */

	if (!btrfs_root_readonly(send_root)) {

		ret = -EPERM;

		goto out;

	}



	/*

	 * Check that we don't overflow at later allocations, we request

	 * clone_sources_count + 1 items, and compare to unsigned long inside