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. > 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. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc. - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
