mkfs.btrfs broken

Commit Message

Mitch Harder March 7, 2013, 9:38 p.m. UTC

On Thu, Mar 7, 2013 at 12:10 PM, Swâmi Petaramesh <[e-mail]> wrote:
> Le 07/03/2013 19:06, Jérôme Poulin a écrit :
>> mkfs.btrfs tries to lookup loop devices by their filenames and fails
>> if any loop device file is missing.
>
> Hmm.... Why would mkfs.btrfs want to lookup anything else but the device
> we're trying to format, to check if it's mounted or not ?
>

At Sabayon, we pretty-much hacked our way around this with a
"make-it-go" kind of patch.

Otherwise, our installation would break with btrfs on our
Live-[CD/DVD/USB] media.

I know we should have taken the time to put together a proper
solution, but I could never figure out the  reasoning for needing to
scan every device either.

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Patch

--- btrfs-progs-0.19.orig/utils.c
+++ btrfs-progs-0.19/utils.c
@@ -708,6 +708,21 @@  int is_same_blk_file(const char* a, cons
 	return 0;
 }

+/* Checks if a file exists and is a block or regular file*/
+int is_existing_blk_or_reg_file(const char* filename)
+{
+	struct stat st_buf;
+
+	if(stat(filename, &st_buf) < 0) {
+		if(errno == ENOENT)
+			return 0;
+		else
+			return -errno;
+	}
+
+	return (S_ISBLK(st_buf.st_mode) || S_ISREG(st_buf.st_mode));
+}
+
 /* checks if a and b are identical or device
  * files associated with the same block device or
  * if one file is a loop device that uses the other
@@ -727,7 +742,10 @@  int is_same_loop_file(const char* a, con
 	} else if(ret) {
 		if((ret = resolve_loop_device(a, res_a, sizeof(res_a))) < 0)
 			return ret;
-
+		/* if the resolved path is not available, there is nothing
+		   we can do */
+		if((ret = is_existing_blk_or_reg_file(res_a)) == 0)
+			return ret;
 		final_a = res_a;
 	} else {
 		final_a = a;
@@ -739,6 +757,10 @@  int is_same_loop_file(const char* a, con
 	} else if(ret) {
 		if((ret = resolve_loop_device(b, res_b, sizeof(res_b))) < 0)
 			return ret;
+		/* if the resolved path is not available, there is nothing
+		   we can do */
+		if((ret = is_existing_blk_or_reg_file(res_b)) == 0)
+			return ret;

 		final_b = res_b;
 	} else {
@@ -748,21 +770,6 @@  int is_same_loop_file(const char* a, con
 	return is_same_blk_file(final_a, final_b);
 }

-/* Checks if a file exists and is a block or regular file*/
-int is_existing_blk_or_reg_file(const char* filename)
-{
-	struct stat st_buf;
-
-	if(stat(filename, &st_buf) < 0) {
-		if(errno == ENOENT)
-			return 0;
-		else
-			return -errno;
-	}
-
-	return (S_ISBLK(st_buf.st_mode) || S_ISREG(st_buf.st_mode));
-}
-
 /* Checks if a file is used (directly or indirectly via a loop device)
  * by a device in fs_devices
  */