Simplified sendfile(SF_NODISKIO) usage.

Starting with FreeBSD 11, there is no need to use AIO operations to preload
data into cache for sendfile(SF_NODISKIO) to work.  Instead, sendfile()
handles non-blocking loading data from disk by itself.  It still can, however,
return EBUSY if a page is already being loaded (for example, by a different
process).  If this happens, we now post an event for the next event loop
iteration, so sendfile() is retried "after a short period", as manpage
recommends.

The limit of the number of EBUSY tolerated without any progress is preserved,
but now it does not result in an alert, since on an idle system event loop
iteration might be very short and EBUSY can happen many times in a row.
Instead, SF_NODISKIO is simply disabled for one call once the limit is
reached.

With this change, sendfile(SF_NODISKIO) is now used automatically as long as
sendfile() is enabled, and no longer requires "aio on;".

4 files changed, 2 insertions, 37 deletions

diff --git a/src/core/ngx_buf.h b/src/core/ngx_buf.h
index 4b665629c..fdcd0cddf 100644
--- a/src/core/ngx_buf.h
+++ b/src/core/ngx_buf.h
@@ -90,9 +90,6 @@ struct ngx_output_chain_ctx_s {
 
 #if (NGX_HAVE_FILE_AIO || NGX_COMPAT)
     ngx_output_chain_aio_pt      aio_handler;
-#if (NGX_HAVE_AIO_SENDFILE || NGX_COMPAT)
-    ssize_t                    (*aio_preload)(ngx_buf_t *file);
-#endif
 #endif
 
 #if (NGX_THREADS || NGX_COMPAT)
diff --git a/src/core/ngx_connection.h b/src/core/ngx_connection.h
index 4716da492..8cc14755a 100644
--- a/src/core/ngx_connection.h
+++ b/src/core/ngx_connection.h
@@ -185,7 +185,7 @@ struct ngx_connection_s {
 
     unsigned            need_last_buf:1;
 
-#if (NGX_HAVE_AIO_SENDFILE || NGX_COMPAT)
+#if (NGX_HAVE_SENDFILE_NODISKIO || NGX_COMPAT)
     unsigned            busy_count:2;
 #endif
 
diff --git a/src/core/ngx_module.h b/src/core/ngx_module.h
index 8cf3210e8..6fb455426 100644
--- a/src/core/ngx_module.h
+++ b/src/core/ngx_module.h
@@ -41,7 +41,7 @@
 #define NGX_MODULE_SIGNATURE_3   "0"
 #endif
 
-#if (NGX_HAVE_AIO_SENDFILE || NGX_COMPAT)
+#if (NGX_HAVE_SENDFILE_NODISKIO || NGX_COMPAT)
 #define NGX_MODULE_SIGNATURE_4   "1"
 #else
 #define NGX_MODULE_SIGNATURE_4   "0"
diff --git a/src/core/ngx_output_chain.c b/src/core/ngx_output_chain.c
index fd4603b19..41267eeff 100644
--- a/src/core/ngx_output_chain.c
+++ b/src/core/ngx_output_chain.c
@@ -29,10 +29,6 @@
 
 static ngx_inline ngx_int_t
     ngx_output_chain_as_is(ngx_output_chain_ctx_t *ctx, ngx_buf_t *buf);
-#if (NGX_HAVE_AIO_SENDFILE)
-static ngx_int_t ngx_output_chain_aio_setup(ngx_output_chain_ctx_t *ctx,
-    ngx_file_t *file);
-#endif
 static ngx_int_t ngx_output_chain_add_copy(ngx_pool_t *pool,
     ngx_chain_t **chain, ngx_chain_t *in);
 static ngx_int_t ngx_output_chain_align_file_buf(ngx_output_chain_ctx_t *ctx,
@@ -283,12 +279,6 @@ ngx_output_chain_as_is(ngx_output_chain_ctx_t *ctx, ngx_buf_t *buf)
         buf->in_file = 0;
     }
 
-#if (NGX_HAVE_AIO_SENDFILE)
-    if (ctx->aio_preload && buf->in_file) {
-        (void) ngx_output_chain_aio_setup(ctx, buf->file);
-    }
-#endif
-
     if (ctx->need_in_memory && !ngx_buf_in_memory(buf)) {
         return 0;
     }
@@ -301,28 +291,6 @@ ngx_output_chain_as_is(ngx_output_chain_ctx_t *ctx, ngx_buf_t *buf)
 }
 
 
-#if (NGX_HAVE_AIO_SENDFILE)
-
-static ngx_int_t
-ngx_output_chain_aio_setup(ngx_output_chain_ctx_t *ctx, ngx_file_t *file)
-{
-    ngx_event_aio_t  *aio;
-
-    if (file->aio == NULL && ngx_file_aio_init(file, ctx->pool) != NGX_OK) {
-        return NGX_ERROR;
-    }
-
-    aio = file->aio;
-
-    aio->data = ctx->filter_ctx;
-    aio->preload_handler = ctx->aio_preload;
-
-    return NGX_OK;
-}
-
-#endif
-
-
 static ngx_int_t
 ngx_output_chain_add_copy(ngx_pool_t *pool, ngx_chain_t **chain,
     ngx_chain_t *in)