Commits
Chris Mason committed e3f24cc521c
Btrfs: don't release pages when we can't clear the uptodate bits Btrfs tracks uptodate state in an rbtree as well as in the page bits. This is supposed to enable us to use block sizes other than the page size, but there are a few parts still missing before that completely works. But, our readpage routine trusts this additional range based tracking of uptodateness, much in the same way the buffer head up to date bits are trusted for the other filesystems. The problem is that sometimes we need to allocate memory in order to split records in the rbtree, even when we are just clearing bits. This can be difficult when our clearing function is called GFP_ATOMIC, which can happen in the releasepage path. So, what happens today looks like this: releasepage called with GFP_ATOMIC btrfs_releasepage calls clear_extent_bit clear_extent_bit fails to allocate ram, leaving the up to date bit set btrfs_releasepage returns success The end result is the page being gone, but btrfs thinking the range is up to date. Later on if someone tries to read that same page, the btrfs readpage code will return immediately thinking the page is already up to date. This commit fixes things to fail the releasepage when we can't clear the extent state bits. It covers both data pages and metadata tree blocks. Signed-off-by: Chris Mason <chris.mason@oracle.com>