Andreas Dilger wrote:
On Feb 13, 2008 18:19 +0100, Valerie Clement wrote:
From: Valerie Clement <valerie.clement@xxxxxxxx>
With the flex_bg feature enabled, a large file creation oopses the
kernel.
The BUG_ON is:
BUG_ON(len >= EXT4_BLOCKS_PER_GROUP(sb));
As the allocation of the bitmaps and the inode table can be done
outside the block group with flex_bg, this allows to allocate up to
EXT4_BLOCKS_PER_GROUP blocks in a group.
Caution is needed here. In the past we were limited to BLOCKS_PER_GROUP()
blocks per extent (32768 blocks at most, regardless of blocksize I think)
but now an extent might be larger.
Can you please verify that the extent-length limits for "initialized" vs.
"uninitialized" extents are being hit so that extents don't accidentally
grow to be > 32768 blocks long and suddenly get marked as short uninitialized
extents.
Note that the assertion can still be hit if groups are created with fewer
blocks, or with blocksize < 4096. For example, if we have blocksize = 1024
this gives BLOCKS_PER_GROUP=8192, but an extent can be up to 32768 blocks.
I think the right assertion is now:
BUG_ON(len > EXT4_INIT_MAX_LEN);
if FLEX_BG is active. I'm not sure if we want to keep the stricter assertion:
BUG_ON(len > EXT4_HAS_INCOMPAT_FEATURE_FLEX_BG(sb) ? EXT4_INIT_MAX_LEN :
EXT4_BLOCKS_PER_GROUP(sb));
but it might be worthwhile at least initially, and I don't think the CPU cost
is very high.
I agree. I'll do the changes.
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index b0f84b4..0275150 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -907,7 +907,7 @@ static void ext4_mb_mark_free_simple(struct super_block *sb,
unsigned short chunk;
unsigned short border;
- BUG_ON(len >= EXT4_BLOCKS_PER_GROUP(sb));
+ BUG_ON(len > EXT4_BLOCKS_PER_GROUP(sb));
border = 2 << sb->s_blocksize_bits;
@@ -3286,7 +3286,7 @@ static void ext4_mb_normalize_request(struct ext4_allocation_context *ac,
}
BUG_ON(start + size <= ac->ac_o_ex.fe_logical &&
start > ac->ac_o_ex.fe_logical);
- BUG_ON(size <= 0 || size >= EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
+ BUG_ON(size <= 0 || size > EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
Please separate this into two BUG_ON() statements, so it is clear which
one is being hit.
OK.
Thanks for review,
Valerie
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