X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=filesetup.c;h=793b08d07549c895944f406e7afcdb7d7765e840;hp=3217e4f3080cad0e782fc22e302304e49ae6531e;hb=79591fa9555024aa9564656bbbb9d4c828a3e189;hpb=957c81b9d0d090162366dcf0bec308afb2400464

diff --git a/filesetup.c b/filesetup.c
index 3217e4f3..793b08d0 100644
--- a/filesetup.c
+++ b/filesetup.c
@@ -130,6 +130,9 @@ static int extend_file(struct thread_data *td, struct fio_file *f)
 	}
 #endif /* CONFIG_POSIX_FALLOCATE */
 
+	/*
+	 * If our jobs don't require regular files initially, we're done.
+	 */
 	if (!new_layout)
 		goto done;
 
@@ -381,6 +384,10 @@ static int get_file_size(struct thread_data *td, struct fio_file *f)
 		return 1; /* avoid offset extends end error message */
 	}
 
+	/*
+	 * Leave ->real_file_size with 0 since it could be expectation
+	 * of initial setup for regular files.
+	 */
 	if (ret)
 		return ret;
 
@@ -659,6 +666,10 @@ open_again:
 	return 0;
 }
 
+/*
+ * This function i.e. get_file_size() is the default .get_file_size
+ * implementation of majority of I/O engines.
+ */
 int generic_get_file_size(struct thread_data *td, struct fio_file *f)
 {
 	return get_file_size(td, f);
@@ -686,6 +697,13 @@ static int get_file_sizes(struct thread_data *td)
 			clear_error(td);
 		}
 
+		/*
+		 * There are corner cases where we end up with -1 for
+		 * ->real_file_size due to unsupported file type, etc.
+		 * We then just set to size option value divided by number
+		 * of files, similar to the way file ->io_size is set.
+		 * stat(2) failure doesn't set ->real_file_size to -1.
+		 */
 		if (f->real_file_size == -1ULL && td->o.size)
 			f->real_file_size = td->o.size / td->o.nr_files;
 	}
@@ -802,7 +820,9 @@ int setup_files(struct thread_data *td)
 		goto done;
 
 	/*
-	 * if ioengine defines a setup() method, it's responsible for
+	 * Find out physical size of files or devices for this thread,
+	 * before we determine I/O size and range of our targets.
+	 * If ioengine defines a setup() method, it's responsible for
 	 * opening the files and setting f->real_file_size to indicate
 	 * the valid range for that file.
 	 */
@@ -843,7 +863,7 @@ int setup_files(struct thread_data *td)
 
 	/*
 	 * Calculate per-file size and potential extra size for the
-	 * first files, if needed.
+	 * first files, if needed (i.e. if we don't have a fixed size).
 	 */
 	if (!o->file_size_low && o->nr_files) {
 		uint64_t all_fs;
@@ -865,9 +885,17 @@ int setup_files(struct thread_data *td)
 	for_each_file(td, f, i) {
 		f->file_offset = get_start_offset(td, f);
 
+		/*
+		 * Update ->io_size depending on options specified.
+		 * ->file_size_low being 0 means filesize option isn't set.
+		 * Non zero ->file_size_low equals ->file_size_high means
+		 * filesize option is set in a fixed size format.
+		 * Non zero ->file_size_low not equals ->file_size_high means
+		 * filesize option is set in a range format.
+		 */
 		if (!o->file_size_low) {
 			/*
-			 * no file size range given, file size is equal to
+			 * no file size or range given, file size is equal to
 			 * total size divided by number of files. If that is
 			 * zero, set it to the real file size. If the size
 			 * doesn't divide nicely with the min blocksize,
@@ -950,7 +978,9 @@ int setup_files(struct thread_data *td)
 	}
 
 	/*
-	 * See if we need to extend some files
+	 * See if we need to extend some files, typically needed when our
+	 * target regular files don't exist yet, but our jobs require them
+	 * initially due to read I/Os.
 	 */
 	if (need_extend) {
 		temp_stall_ts = 1;