diff options
| -rw-r--r-- | fs/xfs/xfs_log_cil.c | 46 |
1 files changed, 35 insertions, 11 deletions
diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c index b59cc9c0961c..83a039762b81 100644 --- a/fs/xfs/xfs_log_cil.c +++ b/fs/xfs/xfs_log_cil.c @@ -103,6 +103,39 @@ xlog_cil_iovec_space( } /* + * shadow buffers can be large, so we need to use kvmalloc() here to ensure + * success. Unfortunately, kvmalloc() only allows GFP_KERNEL contexts to fall + * back to vmalloc, so we can't actually do anything useful with gfp flags to + * control the kmalloc() behaviour within kvmalloc(). Hence kmalloc() will do + * direct reclaim and compaction in the slow path, both of which are + * horrendously expensive. We just want kmalloc to fail fast and fall back to + * vmalloc if it can't get somethign straight away from the free lists or buddy + * allocator. Hence we have to open code kvmalloc outselves here. + * + * Also, we are in memalloc_nofs_save task context here, so despite the use of + * GFP_KERNEL here, we are actually going to be doing GFP_NOFS allocations. This + * is actually the only way to make vmalloc() do GFP_NOFS allocations, so lets + * just all pretend this is a GFP_KERNEL context operation.... + */ +static inline void * +xlog_cil_kvmalloc( + size_t buf_size) +{ + gfp_t flags = GFP_KERNEL; + void *p; + + flags &= ~__GFP_DIRECT_RECLAIM; + flags |= __GFP_NOWARN | __GFP_NORETRY; + do { + p = kmalloc(buf_size, flags); + if (!p) + p = vmalloc(buf_size); + } while (!p); + + return p; +} + +/* * Allocate or pin log vector buffers for CIL insertion. * * The CIL currently uses disposable buffers for copying a snapshot of the @@ -203,25 +236,16 @@ xlog_cil_alloc_shadow_bufs( */ if (!lip->li_lv_shadow || buf_size > lip->li_lv_shadow->lv_size) { - /* * We free and allocate here as a realloc would copy - * unnecessary data. We don't use kmem_zalloc() for the + * unnecessary data. We don't use kvzalloc() for the * same reason - we don't need to zero the data area in * the buffer, only the log vector header and the iovec * storage. */ kmem_free(lip->li_lv_shadow); + lv = xlog_cil_kvmalloc(buf_size); - /* - * We are in transaction context, which means this - * allocation will pick up GFP_NOFS from the - * memalloc_nofs_save/restore context the transaction - * holds. This means we can use GFP_KERNEL here so the - * generic kvmalloc() code will run vmalloc on - * contiguous page allocation failure as we require. - */ - lv = kvmalloc(buf_size, GFP_KERNEL); memset(lv, 0, xlog_cil_iovec_space(niovecs)); lv->lv_item = lip; |