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: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 7a15fcf..181760f 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -537,6 +537,13 @@
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 @@
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);
+ return 0;
}
static int io_ctl_read_bitmap(struct io_ctl *io_ctl,
@@ -561,9 +565,6 @@
{
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 @@
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.