[PATCH 57/78] init: refactor devt_from_partuuid

Christoph Hellwig
2020-11-16T15:11:07Z

The code in devt_from_partuuid is very convoluted. Refactor a bit by
sanitizing the goto and variable name usage.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
init/do_mounts.c | 68 ++++++++++++++++++++++--------------------------
1 file changed, 31 insertions(+), 37 deletions(-)

diff --git a/init/do_mounts.c b/init/do_mounts.c
index aef2f24461c7f1..afa26a4028d25e 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -105,13 +105,10 @@ static int match_dev_by_uuid(struct device *dev, const void *data)
*/
static dev_t devt_from_partuuid(const char *uuid_str)
{
- dev_t res = 0;
struct uuidcmp cmp;
struct device *dev = NULL;
- struct gendisk *disk;
- struct hd_struct *part;
+ dev_t devt = 0;
int offset = 0;
- bool clear_root_wait = false;
char *slash;

cmp.uuid = uuid_str;
@@ -120,52 +117,49 @@ static dev_t devt_from_partuuid(const char *uuid_str)
/* Check for optional partition number offset attributes. */
if (slash) {
char c = 0;
+
/* Explicitly fail on poor PARTUUID syntax. */
- if (sscanf(slash + 1,
- "PARTNROFF=%d%c", &offset, &c) != 1) {
- clear_root_wait = true;
- goto done;
- }
+ if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)
+ goto clear_root_wait;
cmp.len = slash - uuid_str;
} else {
cmp.len = strlen(uuid_str);
}

- if (!cmp.len) {
- clear_root_wait = true;
- goto done;
- }
+ if (!cmp.len)
+ goto clear_root_wait;

- dev = class_find_device(&block_class, NULL, &cmp,
- &match_dev_by_uuid);
+ dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
if (!dev)
- goto done;
-
- res = dev->devt;
+ return 0;

- /* Attempt to find the partition by offset. */
- if (!offset)
- goto no_offset;
+ if (offset) {
+ /*
+ * Attempt to find the requested partition by adding an offset
+ * to the partition number found by UUID.
+ */
+ struct hd_struct *part;

- res = 0;
- disk = part_to_disk(dev_to_part(dev));
- part = disk_get_part(disk, dev_to_part(dev)->partno + offset);
- if (part) {
- res = part_devt(part);
- put_device(part_to_dev(part));
+ part = disk_get_part(dev_to_disk(dev),
+ dev_to_part(dev)->partno + offset);
+ if (part) {
+ devt = part_devt(part);
+ put_device(part_to_dev(part));
+ }
+ } else {
+ devt = dev->devt;
}

-no_offset:
put_device(dev);
-done:
- if (clear_root_wait) {
- pr_err("VFS: PARTUUID= is invalid.\n"
- "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
- if (root_wait)
- pr_err("Disabling rootwait; root= is invalid.\n");
- root_wait = 0;
- }
- return res;
+ return devt;
+
+clear_root_wait:
+ pr_err("VFS: PARTUUID= is invalid.\n"
+ "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
+ if (root_wait)
+ pr_err("Disabling rootwait; root= is invalid.\n");
+ root_wait = 0;
+ return 0;
}

/**