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mkfs.btrfs on arm

PATCH Tobias Arp 1 participant 1 message Apr 24, 2012 Btrfs file system

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Tobias Arp

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Hi,

yesterday i tried mkfs.btrfs on my embedded arm system without success (git clone from 2012-04-24). I got always this error message (this "bug" where already mentioned some month ago)

mkfs.btrfs /dev/sda1

WARNING! - Btrfs Btrfs v0.19-dirty IS EPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using mkfs.btrfs: volumes.c:843: btrfs_alloc_chunk: Assertion `!(ret)' failed. Aborted

I turned aligment warnings on:

echo 1 > /proc/cpu/aligment

so i got this messages:

mkfs.btrfs /dev/sda1

WARNING! - Btrfs Btrfs v0.19-dirty IS EXPERIMENTAL WARNING! - see http://btrfs.wiki.kernel.org before using

Alignment trap: mkfs.btrfs (70) PC=0x00039f4c Instr=0xe8820018 Address=0xbebbbae9 FSR 0x813 Alignment trap: mkfs.btrfs (70) PC=0x00039f4c Instr=0xe8820018 Address=0xbebbbae9 FSR 0x813

mkfs.btrfs: volumes.c:843: btrfs_alloc_chunk: Assertion `!(ret)' failed. Aborted

I tracked down the problem and changed this:

btrfs-progs-test/volumes.c 2012-04-24 15:20:09.492181736 +0200 renamed from volumes.c 2012-04-24 15:20:51.404182411 +0200 +3 -1
@@ -402,6 +402,7 @@
     struct btrfs_key key;
     struct btrfs_chunk *chunk;
     struct btrfs_key found_key;
+    u64 u64temp;
 
     path = btrfs_alloc_path();
     BUG_ON(!path);
@@ -427,8 +428,9 @@
         else {
             chunk = btrfs_item_ptr(path->nodes[0], path->slots[0],
                            struct btrfs_chunk);
-            *offset = found_key.offset +
+            u64temp = found_key.offset +
                 btrfs_chunk_length(path->nodes[0], chunk);
+            memcpy(offset,&u64temp,sizeof(u64));
         }
     }
     ret = 0;

But there are many other places where an aligment trap could occur, particularly where packed structures are used
(we will get often elements with adresses which are unaligned). So how can i fix it easily? I don't know much about btrfs so i cannot estimate where it is allowed to change...

Best regards

Tobias

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