Re: btrfs kernel oops on mount

[Jeff Mahoney <jeffm@suse.com>]

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On 9/9/16 8:47 PM, Austin S. Hemmelgarn wrote:
> A couple of other things to comment about on this:
> 1. 'can_overcommit' (the function that the Arch kernel choked on) is
> from the memory management subsystem.  The fact that that's throwing a
> null pointer says to me either your hardware has issues, or the Arch
> kernel itself has problems (which would probably mean the kernel image
> is corrupted).

fs/btrfs/extent-tree.c:
static int can_overcommit(struct btrfs_root *root,
                          struct btrfs_space_info *space_info, u64 bytes,
                          enum btrfs_reserve_flush_enum flush)

> 3. In general, it's a good idea to keep an eye on space usage on your
> filesystems.  If it's getting to be more than about 95% full, you should
> be looking at getting some more storage space.  This is especially true
> for BTRFS, as a 100% full BTRFS filesystem functionally becomes
> permanently read-only because there's nowhere for the copy-on-write
> updates to write to.

The entire point of having the global metadata reserve is to avoid that
situation.

-Jeff

-- 
Jeff Mahoney
SUSE Labs


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