From: Christoph Hellwig Date: Tue, 7 Apr 2026 14:05:24 +0000 (+0200) Subject: xfs: fix number of GC bvecs X-Git-Tag: v7.1-rc1~233^2~15 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=452c8f6cbd0ef1408474a875c5c4149a02c7610f;p=thirdparty%2Fkernel%2Flinux.git xfs: fix number of GC bvecs GC scratch allocations can wrap around and use the same buffer twice, and the current code fails to account for that. So far this worked due to rounding in the block layer, but changes to the bio allocator drop the over-provisioning and generic/256 or generic/361 will now usually fail when running against the current block tree. Simplify the allocation to always pass the maximum value that is easier to verify, as a saving of up to one bvec per allocation isn't worth the effort to verify a complicated calculated value. Fixes: 102f444b57b3 ("xfs: rework zone GC buffer management") Signed-off-by: Christoph Hellwig Reviewed-by: Damien Le Moal Reviewed-by: Hans Holmberg Link: https://patch.msgid.link/20260407140538.633364-2-hch@lst.de Signed-off-by: Jens Axboe --- diff --git a/fs/xfs/xfs_zone_gc.c b/fs/xfs/xfs_zone_gc.c index 7efeecd2d85f5..f279dcca53cc2 100644 --- a/fs/xfs/xfs_zone_gc.c +++ b/fs/xfs/xfs_zone_gc.c @@ -671,7 +671,6 @@ xfs_zone_gc_start_chunk( struct xfs_inode *ip; struct bio *bio; xfs_daddr_t daddr; - unsigned int len; bool is_seq; if (xfs_is_shutdown(mp)) @@ -686,15 +685,16 @@ xfs_zone_gc_start_chunk( return false; } - len = XFS_FSB_TO_B(mp, irec.rm_blockcount); - bio = bio_alloc_bioset(bdev, - min(howmany(len, XFS_GC_BUF_SIZE) + 1, XFS_GC_NR_BUFS), - REQ_OP_READ, GFP_NOFS, &data->bio_set); - + /* + * Scratch allocation can wrap around to the same buffer again, + * provision an extra bvec for that case. + */ + bio = bio_alloc_bioset(bdev, XFS_GC_NR_BUFS + 1, REQ_OP_READ, GFP_NOFS, + &data->bio_set); chunk = container_of(bio, struct xfs_gc_bio, bio); chunk->ip = ip; chunk->offset = XFS_FSB_TO_B(mp, irec.rm_offset); - chunk->len = len; + chunk->len = XFS_FSB_TO_B(mp, irec.rm_blockcount); chunk->old_startblock = xfs_rgbno_to_rtb(iter->victim_rtg, irec.rm_startblock); chunk->new_daddr = daddr; @@ -708,8 +708,9 @@ xfs_zone_gc_start_chunk( bio->bi_iter.bi_sector = xfs_rtb_to_daddr(mp, chunk->old_startblock); bio->bi_end_io = xfs_zone_gc_end_io; xfs_zone_gc_add_data(chunk); - data->scratch_head = (data->scratch_head + len) % data->scratch_size; - data->scratch_available -= len; + data->scratch_head = + (data->scratch_head + chunk->len) % data->scratch_size; + data->scratch_available -= chunk->len; XFS_STATS_INC(mp, xs_gc_read_calls);