Greetings, I am testing the 3.4.0(rc) btrfs patches backported to a 3.3.1 kernel. I''m particularly interested in the large metadata features for help with fragmentation issues. After merging, installing, and booting the new kernel, I created several btrfs filesystems with leaf size 32768 and node size 32768. Mounting the filesystem gives the expected behavior with the following messages in syslog: Apr 9 14:56:18 app-cluster1 kernel: [ 1872.279286] device fsid 48be2eaf-f2af-444a-a440-ae0ed555f1e7 devid 1 transid 7 /dev/sdd Apr 9 14:56:18 app-cluster1 kernel: [ 1872.281352] btrfs flagging fs with big metadata feature After a reboot however, the "flagging fs with big metadata feature" message no longer appears on subsequent mounts. Apr 9 15:03:28 app-cluster1 kernel: [ 12.083827] device fsid 48be2eaf-f2af-444a-a440-ae0ed555f1e7 devid 1 transid 11 /dev/sdd Apr 9 15:03:28 app-cluster1 kernel: [ 12.118204] device fsid 078b5f99-89ba-4e46-9ed9-26895d188a3e devid 1 transid 11 /dev/sde Apr 9 15:03:28 app-cluster1 kernel: [ 12.136635] device fsid ca2fd449-d582-4d46-ab9a-c89c17762f8d devid 1 transid 11 /dev/sdf I''ve verified I''m rebooting into the correct kernel: Linux app-cluster1 3.3.1.app.btrfs-backports #1 SMP Sun Apr 8 19:33:29 MDT 2012 x86_64 x86_64 x86_64 GNU/Linux Is this expected behavior? Is there a way I can dump filesystem information to determine what leaf and node size the filesystem thinks it has? Calvin -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html