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Commit 2f120c05 authored by Josef Bacik's avatar Josef Bacik Committed by Chris Mason
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Btrfs: only map pages if we know we need them when reading the space cache 



People have been running into a warning when loading space cache because the
page is already mapped when trying to read in a bitmap.  The way we read in
entries and pages is kind of convoluted, so fix it so that io_ctl_read_entry
maps the entries if it needs to, and if it hits the end of the page it simply
unmaps the page.  That way we can unconditionally unmap the io_ctl before
reading in the bitmap and we should stop hitting these warnings.  Thanks,

Signed-off-by: default avatarJosef Bacik <josef@redhat.com>
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 76b9e23d

fs/btrfs/free-space-cache.c

+10 −7
Original line number Diff line number Diff line
@@ -537,6 +537,13 @@ static int io_ctl_read_entry(struct io_ctl *io_ctl, 
			    struct btrfs_free_space *entry, u8 *type)

{

	struct btrfs_free_space_entry *e;

	int ret;



	if (!io_ctl->cur) {

		ret = io_ctl_check_crc(io_ctl, io_ctl->index);

		if (ret)

			return ret;

	}



	e = io_ctl->cur;

	entry->offset = le64_to_cpu(e->offset);
@@ -550,10 +557,7 @@ static int io_ctl_read_entry(struct io_ctl *io_ctl, 


	io_ctl_unmap_page(io_ctl);



	if (io_ctl->index >= io_ctl->num_pages)

	return 0;



	return io_ctl_check_crc(io_ctl, io_ctl->index);

}



static int io_ctl_read_bitmap(struct io_ctl *io_ctl,
@@ -561,9 +565,6 @@ static int io_ctl_read_bitmap(struct io_ctl *io_ctl, 
{

	int ret;



	if (io_ctl->cur && io_ctl->cur != io_ctl->orig)

		io_ctl_unmap_page(io_ctl);



	ret = io_ctl_check_crc(io_ctl, io_ctl->index);

	if (ret)

		return ret;
@@ -699,6 +700,8 @@ int __load_free_space_cache(struct btrfs_root *root, struct inode *inode, 
		num_entries--;

	}



	io_ctl_unmap_page(&io_ctl);



	/*

	 * We add the bitmaps at the end of the entries in order that

	 * the bitmap entries are added to the cache.