On Mon, Jun 26, 2017 at 04:09:53PM +0200, David Sterba wrote: > On Fri, Jun 23, 2017 at 10:28:31PM -0600, Liu Bo wrote: > > From: Liu Bo <boliu@localhost.localdomain> Ah, my From was broken again. > > > > %search_start is calculated in a wrong way, and if %ins is a cross-stripe > > one, it'll search the same block group forever. > > That's a bit terse description, so please check if my understanding is right: > search_start advances by at least one stripe len, but the math would be wrong > as using bg_offset would not move us to the next stripe. bg_cache->key.objectid > is the full length so this will reach the next stripe and will not loop forever. Yes, it's correct, the code's logic is like, now that the returned %ins is a cross-stripe one, it then calculates a BTRFS_STRIPE_LEN aligned one as the new %search_start and see if there is any free block matching %search_start. The current code is using a wrong offset, the offset really should be the start position of a block group. > > Do you happen to have a test for that? Unfortunately it's not a test with vanilla progs. I found this when mkfs.btrfs with a 12K nodesize, but now kernel has a power_of_2 limitation for nodesize and progs code is using a weird IS_ALIGNED() which has the same effect with power_of_2(), mkfs.btrfs -n 12K is not allowed. I changed IS_ALIGNED() to (blocksize % nodesize != 0) and got the above loop. > > > Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx> > > --- > > extent-tree.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/extent-tree.c b/extent-tree.c > > index b12ee29..5e09274 100644 > > --- a/extent-tree.c > > +++ b/extent-tree.c > > @@ -2614,8 +2614,9 @@ check_failed: > > goto no_bg_cache; > > bg_offset = ins->objectid - bg_cache->key.objectid; > > > > - search_start = round_up(bg_offset + num_bytes, > > - BTRFS_STRIPE_LEN) + bg_offset; > > + search_start = round_up( > > + bg_offset + num_bytes, BTRFS_STRIPE_LEN) + > > + bg_cache->key.object; > > extent-tree.c: In function ‘find_free_extent’: > extent-tree.c:2617:18: error: ‘struct btrfs_key’ has no member named ‘object’; did you mean ‘objectid’? > bg_cache->key.object; > ^ Ouch, that's right, it's %objectid. I'll send a updated one, thanks for the comments. -liubo -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
