Re: [PATCH] btrfs: block group: do not exclude bytenr adjacent to block group

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On 2019/11/18 5:56 PM, Nikolay Borisov wrote:


On 18.11.19 г. 7:56 ч., damenly.su@xxxxxxxxx wrote:
From: Su Yue <Damenly_Su@xxxxxxx>

while excluding super stripes from one block group, the logical bytenr
should not be excluded if the block group's start + length equals the
bytenr since the bytenr is not belong to the block group.

This is insipred by same bugous code of btrfs-progs.
The fuzz image is rejected to be mounted by tree-checker, but not
bad to enhance the check in practice.

Signed-off-by: Su Yue <Damenly_Su@xxxxxxx>
---
  fs/btrfs/block-group.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 1e521db3ef56..54f970f459f5 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1539,7 +1539,7 @@ static int exclude_super_stripes(struct btrfs_block_group_cache *cache)
  		while (nr--) {
  			u64 start, len;

-			if (logical[nr] > cache->start + cache->length)
+			if (logical[nr] >= cache->start + cache->length)
  				continue;

  			if (logical[nr] + stripe_len <= cache->start)


Is this check necessary at all, since btrfs_rmap_block already contains
a check which ensures the physical address passed is withing the range
of the given chunk, which in turn means all logical addresses derived in
btrfs_rmap_block with:

                bytenr = chunk_start + stripe_nr * rmap_len;

will be within this block group?


Yes, you're right. Drop this bad patch.

Got sick, sorry for the late reply.




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