Commit 293a8489 authored by Mark Fasheh's avatar Mark Fasheh Committed by Chris Mason
Browse files

btrfs: fix clone / extent-same deadlocks 



Clone and extent same lock their source and target inodes in opposite order.
In addition to this, the range locking in clone doesn't take ordering into
account. Fix this by having clone use the same locking helpers as
btrfs-extent-same.

In addition, I do a small cleanup of the locking helpers, removing a case
(both inodes being the same) which was poorly accounted for and never
actually used by the callers.

Signed-off-by: default avatarMark Fasheh <mfasheh@suse.de>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.cz>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent 4a3560c4

fs/btrfs/ioctl.c

+8 −26
Original line number Diff line number Diff line
@@ -2852,7 +2852,6 @@ static void btrfs_double_inode_lock(struct inode *inode1, struct inode *inode2) 
		swap(inode1, inode2);



	mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);

	if (inode1 != inode2)

	mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);

}
@@ -2871,7 +2870,6 @@ static void btrfs_double_extent_lock(struct inode *inode1, u64 loff1, 
		swap(loff1, loff2);

	}

	lock_extent_range(inode1, loff1, len);

	if (inode1 != inode2)

	lock_extent_range(inode2, loff2, len);

}
@@ -3797,13 +3795,7 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd, 
		goto out_fput;



	if (!same_inode) {

		if (inode < src) {

			mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);

			mutex_lock_nested(&src->i_mutex, I_MUTEX_CHILD);

		} else {

			mutex_lock_nested(&src->i_mutex, I_MUTEX_PARENT);

			mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);

		}

		btrfs_double_inode_lock(src, inode);

	} else {

		mutex_lock(&src->i_mutex);

	}
@@ -3853,8 +3845,7 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd, 


		lock_extent_range(src, lock_start, lock_len);

	} else {

		lock_extent_range(src, off, len);

		lock_extent_range(inode, destoff, len);

		btrfs_double_extent_lock(src, off, inode, destoff, len);

	}



	ret = btrfs_clone(src, inode, off, olen, len, destoff, 0);
@@ -3865,9 +3856,7 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd, 


		unlock_extent(&BTRFS_I(src)->io_tree, lock_start, lock_end);

	} else {

		unlock_extent(&BTRFS_I(src)->io_tree, off, off + len - 1);

		unlock_extent(&BTRFS_I(inode)->io_tree, destoff,

			      destoff + len - 1);

		btrfs_double_extent_unlock(src, off, inode, destoff, len);

	}

	/*

	 * Truncate page cache pages so that future reads will see the cloned
@@ -3876,17 +3865,10 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd, 
	truncate_inode_pages_range(&inode->i_data, destoff,

				   PAGE_CACHE_ALIGN(destoff + len) - 1);

out_unlock:

	if (!same_inode) {

		if (inode < src) {

			mutex_unlock(&src->i_mutex);

			mutex_unlock(&inode->i_mutex);

		} else {

			mutex_unlock(&inode->i_mutex);

			mutex_unlock(&src->i_mutex);

		}

	} else {

	if (!same_inode)

		btrfs_double_inode_unlock(src, inode);

	else

		mutex_unlock(&src->i_mutex);

	}

out_fput:

	fdput(src_file);

out_drop_write:

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