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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: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Josef Bacik 2011-11-10 20:45:05 -05:00 committed by Chris Mason
parent 76b9e23d25
commit 2f120c05e6
1 changed files with 10 additions and 7 deletions
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17
fs/btrfs/free-space-cache.c
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@ -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);
return 0;
}
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.