[LTP] [PATCH v1 3/3] tst_find_backing_dev: Also check /dev/block/ for backing device

[Edward Liaw]

On Android, the backing devices are created in /dev/block/ and will not
be found using the method added in e1b1ae66b240 ("tst_find_backing_dev:
Get dev name from /sys/dev/block/*/uevent").  Adds a check for
/dev/block/%s as well as /dev/%s.

Signed-off-by: Edward Liaw <edliaw@google.com>
---
 lib/tst_device.c | 37 ++++++++++++++++++++++++++-----------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/lib/tst_device.c b/lib/tst_device.c
index ae665f7b6..14c0dd7a3 100644
--- a/lib/tst_device.c
+++ b/lib/tst_device.c
@@ -60,6 +60,11 @@ static const char *dev_loop_variants[] = {
 	"/dev/block/loop%i"
 };
 
+static const char *dev_variants[] = {
+	"/dev/%s",
+	"/dev/block/%s"
+};
+
 static int set_dev_loop_path(int dev, char *path, size_t path_len)
 {
 	unsigned int i;
@@ -75,6 +80,21 @@ static int set_dev_loop_path(int dev, char *path, size_t path_len)
 	return 1;
 }
 
+static int set_dev_path(char *dev, char *path, size_t path_len)
+{
+	unsigned int i;
+	struct stat st;
+
+	for (i = 0; i < ARRAY_SIZE(dev_variants); i++) {
+		snprintf(path, path_len, dev_variants[i], dev);
+
+		if (stat(path, &st) == 0 && S_ISBLK(st.st_mode))
+			return 0;
+	}
+
+	return 1;
+}
+
 int tst_find_free_loopdev(char *path, size_t path_len)
 {
 	int ctl_fd, dev_fd, rc, i;
@@ -511,7 +531,7 @@ unsigned long tst_dev_bytes_written(const char *dev)
 }
 
 __attribute__((nonnull))
-void tst_find_backing_dev(const char *path, char *dev)
+void tst_find_backing_dev(const char *path, char *dev, size_t dev_size)
 {
 	struct stat buf;
 	struct btrfs_ioctl_fs_info_args args = {0};
@@ -574,7 +594,7 @@ void tst_find_backing_dev(const char *path, char *dev)
 			sprintf(uevent_path, "%s/%s/uevent",
 				bdev_path, d->d_name);
 		} else {
-			tst_brkm(TBROK | TERRNO, NULL, "No backining device found while looking in %s.", bdev_path);
+			tst_brkm(TBROK | TERRNO, NULL, "No backing device found while looking in %s.", bdev_path);
 		}
 
 		if (SAFE_READDIR(NULL, dir))
@@ -590,17 +610,12 @@ void tst_find_backing_dev(const char *path, char *dev)
 	if (!access(uevent_path, R_OK)) {
 		FILE_LINES_SCANF(NULL, uevent_path, "DEVNAME=%s", dev_name);
 
-		if (dev_name[0])
-			sprintf(dev, "/dev/%s", dev_name);
+		if (!dev_name[0] || set_dev_path(dev_name, dev, dev_size) != 0)
+			tst_brkm(TBROK, NULL, "Could not stat backing device %s", dev);
+
 	} else {
 		tst_brkm(TBROK, NULL, "uevent file (%s) access failed", uevent_path);
 	}
-
-	if (stat(dev, &buf) < 0)
-		tst_brkm(TWARN | TERRNO, NULL, "stat(%s) failed", dev);
-
-	if (S_ISBLK(buf.st_mode) != 1)
-		tst_brkm(TCONF, NULL, "dev(%s) isn't a block dev", dev);
 }
 
 void tst_stat_mount_dev(const char *const mnt_path, struct stat *const st)
@@ -643,7 +658,7 @@ int tst_dev_block_size(const char *path)
 	int size;
 	char dev_name[PATH_MAX];
 
-	tst_find_backing_dev(path, dev_name);
+	tst_find_backing_dev(path, dev_name, sizeof(dev_name));
 
 	fd = SAFE_OPEN(NULL, dev_name, O_RDONLY);
 	SAFE_IOCTL(NULL, fd, BLKSSZGET, &size);
-- 
2.40.0.rc1.284.g88254d51c5-goog