From: Sitsofe Wheeler <sitsofe@yahoo.com>
Date: Fri, 30 Jun 2017 06:32:19 +0000 (+0100)
Subject: filesetup: add native fallocate
X-Git-Tag: fio-2.99~11^2~1
X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=2c3e17be

filesetup: add native fallocate

- Implement a native fallocate mode that only logs an error (if it's
  implemented) and falls back to the same behaviour as fallocate=none if
  it fails
- Add a native OSX and Linux fallocate
- Update man page and HOWTO with new native and defaults

v4:
- Update commit message
- Update man page and HOWTO

Fixes https://github.com/axboe/fio/issues/22 - we now print a message if
fallocate fails which gives the user a hint that behaviour might differ
from other case along with a workaround suggestion (fallocate=none).

Fixes https://github.com/axboe/fio/issues/376 - we now have
fallocate=none fallback behaviour if native fallocate fails. On at least
glibc platforms, posix_fallocate emulates fallocate if the
platform/filesystem doesn't support it (see
https://www.gnu.org/software/libc/manual/html_node/Storage-Allocation.html#index-posix_005ffallocate
for some of the caveats) resulting in strange layout performance thus
making it less attractive than fallocate=none behaviour for fio.

Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>
---

diff --git a/HOWTO b/HOWTO
index 6e53cff8..cf463492 100644
--- a/HOWTO
+++ b/HOWTO
@@ -1049,6 +1049,10 @@ I/O type
 		**none**
 			Do not pre-allocate space.
 
+		**native**
+			Use a platform's native pre-allocation call but fall back to
+			**none** behavior if it fails/is not implemented.
+
 		**posix**
 			Pre-allocate via :manpage:`posix_fallocate(3)`.
 
@@ -1063,8 +1067,9 @@ I/O type
 			Backward-compatible alias for **posix**.
 
 	May not be available on all supported platforms. **keep** is only available
-	on Linux. If using ZFS on Solaris this must be set to **none** because ZFS
-	doesn't support it. Default: **posix**.
+	on Linux. If using ZFS on Solaris this cannot be set to **posix**
+	because ZFS doesn't support pre-allocation. Default: **native** if any
+	pre-allocation methods are available, **none** if not.
 
 .. option:: fadvise_hint=str
 
diff --git a/file.h b/file.h
index 9801bb58..84daa5f6 100644
--- a/file.h
+++ b/file.h
@@ -63,6 +63,7 @@ enum fio_fallocate_mode {
 	FIO_FALLOCATE_NONE	= 1,
 	FIO_FALLOCATE_POSIX	= 2,
 	FIO_FALLOCATE_KEEP_SIZE	= 3,
+	FIO_FALLOCATE_NATIVE	= 4,
 };
 
 /*
diff --git a/filesetup.c b/filesetup.c
index f3e3865e..38ad9edc 100644
--- a/filesetup.c
+++ b/filesetup.c
@@ -38,6 +38,25 @@ static inline void clear_error(struct thread_data *td)
 	td->verror[0] = '\0';
 }
 
+static inline int native_fallocate(struct thread_data *td, struct fio_file *f)
+{
+	bool success;
+
+	success = fio_fallocate(f, 0, f->real_file_size);
+	dprint(FD_FILE, "native fallocate of file %s size %llu was "
+			"%ssuccessful\n", f->file_name,
+			(unsigned long long) f->real_file_size,
+			!success ? "un": "");
+
+	if (success)
+		return 0;
+
+	if (errno == ENOSYS)
+		dprint(FD_FILE, "native fallocate is not implemented\n");
+
+	return -1;
+}
+
 static void fallocate_file(struct thread_data *td, struct fio_file *f)
 {
 	int r;
@@ -45,10 +64,16 @@ static void fallocate_file(struct thread_data *td, struct fio_file *f)
 	if (td->o.fill_device)
 		return;
 
-#ifdef CONFIG_POSIX_FALLOCATE
 	switch (td->o.fallocate_mode) {
+	case FIO_FALLOCATE_NATIVE:
+		r = native_fallocate(td, f);
+		if (r != 0)
+			log_err("fio: native_fallocate call failed: %s\n",
+					strerror(errno));
+		break;
 	case FIO_FALLOCATE_NONE:
 		break;
+#ifdef CONFIG_POSIX_FALLOCATE
 	case FIO_FALLOCATE_POSIX:
 		dprint(FD_FILE, "posix_fallocate file %s size %llu\n",
 				 f->file_name,
@@ -58,6 +83,7 @@ static void fallocate_file(struct thread_data *td, struct fio_file *f)
 		if (r > 0)
 			log_err("fio: posix_fallocate fails: %s\n", strerror(r));
 		break;
+#endif /* CONFIG_POSIX_FALLOCATE */
 #ifdef CONFIG_LINUX_FALLOCATE
 	case FIO_FALLOCATE_KEEP_SIZE:
 		dprint(FD_FILE, "fallocate(FALLOC_FL_KEEP_SIZE) "
@@ -74,7 +100,7 @@ static void fallocate_file(struct thread_data *td, struct fio_file *f)
 		log_err("fio: unknown fallocate mode: %d\n", td->o.fallocate_mode);
 		assert(0);
 	}
-#endif /* CONFIG_POSIX_FALLOCATE */
+
 }
 
 /*
diff --git a/fio.1 b/fio.1
index ab042081..9783646d 100644
--- a/fio.1
+++ b/fio.1
@@ -436,6 +436,10 @@ are:
 .B none
 Do not pre-allocate space.
 .TP
+.B native
+Use a platform's native pre-allocation call but fall back to 'none' behavior if
+it fails/is not implemented.
+.TP
 .B posix
 Pre-allocate via \fBposix_fallocate\fR\|(3).
 .TP
@@ -450,8 +454,9 @@ Backward-compatible alias for 'posix'.
 .RE
 .P
 May not be available on all supported platforms. 'keep' is only
-available on Linux. If using ZFS on Solaris this must be set to 'none'
-because ZFS doesn't support it. Default: 'posix'.
+available on Linux. If using ZFS on Solaris this cannot be set to 'posix'
+because ZFS doesn't support it. Default: 'native' if any pre-allocation methods
+are available, 'none' if not.
 .RE
 .TP
 .BI fadvise_hint \fR=\fPstr
diff --git a/options.c b/options.c
index 09a21af0..b21f09ae 100644
--- a/options.c
+++ b/options.c
@@ -2289,14 +2289,14 @@ struct fio_option fio_options[FIO_MAX_OPTS] = {
 		.parent = "nrfiles",
 		.hide	= 1,
 	},
-#ifdef CONFIG_POSIX_FALLOCATE
+#if defined(CONFIG_POSIX_FALLOCATE) || defined(FIO_HAVE_NATIVE_FALLOCATE)
 	{
 		.name	= "fallocate",
 		.lname	= "Fallocate",
 		.type	= FIO_OPT_STR,
 		.off1	= offsetof(struct thread_options, fallocate_mode),
 		.help	= "Whether pre-allocation is performed when laying out files",
-		.def	= "posix",
+		.def	= "native",
 		.category = FIO_OPT_C_FILE,
 		.group	= FIO_OPT_G_INVALID,
 		.posval	= {
@@ -2304,10 +2304,16 @@ struct fio_option fio_options[FIO_MAX_OPTS] = {
 			    .oval = FIO_FALLOCATE_NONE,
 			    .help = "Do not pre-allocate space",
 			  },
+			  { .ival = "native",
+			    .oval = FIO_FALLOCATE_NATIVE,
+			    .help = "Use native pre-allocation if possible",
+			  },
+#ifdef CONFIG_POSIX_FALLOCATE
 			  { .ival = "posix",
 			    .oval = FIO_FALLOCATE_POSIX,
 			    .help = "Use posix_fallocate()",
 			  },
+#endif
 #ifdef CONFIG_LINUX_FALLOCATE
 			  { .ival = "keep",
 			    .oval = FIO_FALLOCATE_KEEP_SIZE,
@@ -2319,10 +2325,12 @@ struct fio_option fio_options[FIO_MAX_OPTS] = {
 			    .oval = FIO_FALLOCATE_NONE,
 			    .help = "Alias for 'none'",
 			  },
+#ifdef CONFIG_POSIX_FALLOCATE
 			  { .ival = "1",
 			    .oval = FIO_FALLOCATE_POSIX,
 			    .help = "Alias for 'posix'",
 			  },
+#endif
 		},
 	},
 #else	/* CONFIG_POSIX_FALLOCATE */
@@ -2332,7 +2340,7 @@ struct fio_option fio_options[FIO_MAX_OPTS] = {
 		.type	= FIO_OPT_UNSUPPORTED,
 		.help	= "Your platform does not support fallocate",
 	},
-#endif /* CONFIG_POSIX_FALLOCATE */
+#endif /* CONFIG_POSIX_FALLOCATE || FIO_HAVE_NATIVE_FALLOCATE */
 	{
 		.name	= "fadvise_hint",
 		.lname	= "Fadvise hint",
diff --git a/os/os-linux.h b/os/os-linux.h
index 8c1e93be..e7d600dd 100644
--- a/os/os-linux.h
+++ b/os/os-linux.h
@@ -392,4 +392,22 @@ static inline int shm_attach_to_open_removed(void)
 	return 1;
 }
 
+#ifdef CONFIG_LINUX_FALLOCATE
+#define FIO_HAVE_NATIVE_FALLOCATE
+static inline bool fio_fallocate(struct fio_file *f, uint64_t offset,
+				 uint64_t len)
+{
+	int ret;
+	ret = fallocate(f->fd, 0, 0, len);
+	if (ret == 0)
+		return true;
+
+	/* Work around buggy old glibc versions... */
+	if (ret > 0)
+		errno = ret;
+
+	return false;
+}
+#endif
+
 #endif
diff --git a/os/os-mac.h b/os/os-mac.h
index 7de36ea7..a1536c70 100644
--- a/os/os-mac.h
+++ b/os/os-mac.h
@@ -20,6 +20,7 @@
 #define FIO_USE_GENERIC_INIT_RANDOM_STATE
 #define FIO_HAVE_GETTID
 #define FIO_HAVE_CHARDEV_SIZE
+#define FIO_HAVE_NATIVE_FALLOCATE
 
 #define OS_MAP_ANON		MAP_ANON
 
@@ -101,4 +102,15 @@ static inline int gettid(void)
  */
 extern int fdatasync(int fd);
 
+static inline bool fio_fallocate(struct fio_file *f, uint64_t offset, uint64_t len)
+{
+	fstore_t store = {F_ALLOCATEALL, F_PEOFPOSMODE, offset, len};
+	if (fcntl(f->fd, F_PREALLOCATE, &store) != -1) {
+		if (ftruncate(f->fd, len) == 0)
+			return true;
+	}
+
+	return false;
+}
+
 #endif
diff --git a/os/os.h b/os/os.h
index 1d400c8f..afee9f9c 100644
--- a/os/os.h
+++ b/os/os.h
@@ -361,4 +361,12 @@ static inline int shm_attach_to_open_removed(void)
 }
 #endif
 
+#ifndef FIO_HAVE_NATIVE_FALLOCATE
+static inline bool fio_fallocate(struct fio_file *f, uint64_t offset, uint64_t len)
+{
+	errno = ENOSYS;
+	return false;
+}
+#endif
+
 #endif