On Mon, Apr 09, 2012 at 04:06:56PM -0600, Calvin Morrow wrote:
> After a reboot however, the "flagging fs with big metadata feature"
> message no longer appears on subsequent mounts.
/*
* flag our filesystem as having big metadata blocks if
* they are bigger than the page size
*/
if (btrfs_super_leafsize(disk_super) > PAGE_CACHE_SIZE) {
if (!(features & BTRFS_FEATURE_INCOMPAT_BIG_METADATA))
printk(KERN_INFO "btrfs flagging fs with big metadata
feature\n");
features |= BTRFS_FEATURE_INCOMPAT_BIG_METADATA;
}
translation: it will print the message only the first time it's mounted and the
flag is not already stored on disk.
> Is this expected behavior?
Yes it is.
> Is there a way I can dump filesystem
> information to determine what leaf and node size the filesystem thinks
> it has?
# mkfs.btrfs -n 32k -l 32k image
WARNING! - Btrfs v0.19-152-g1957076 IS STAB^WEXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using
fs created label (null) on image
nodesize 32768 leafsize 32768 sectorsize 4096 size 300.00GB
Btrfs v0.19-152-g1957076
# file image
image: BTRFS Filesystem sectorsize 4096, nodesize 32768, leafsize 32768)
and it does it by looking to the first superblock:
/usr/share/misc/magic:
# BTRFS
0x10040 string _BHRfS_M BTRFS Filesystem
>0x1012b string >\0 (label "%s",
>0x10090 lelong x sectorsize %d,
>0x10094 lelong x nodesize %d,
>0x10098 lelong x leafsize %d)
david
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