[RFC PATCH 1/4] init: move block device helpers from init/do_mounts.c

Daniel Golle
2022-11-17T00:43:09Z

In init/do_mounts.c there are helper functions devt_from_partuuid,
devt_from_partlabel and devt_from_devname. In order to make these
functions available to other users, move them to block/bdev.c.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
block/bdev.c | 166 +++++++++++++++++++++++++++++++++++++++++
include/linux/blkdev.h | 15 ++++
init/do_mounts.c | 166 +----------------------------------------
3 files changed, 183 insertions(+), 164 deletions(-)

diff --git a/block/bdev.c b/block/bdev.c
index d699ecdb3260..92e3e5c81337 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -1092,3 +1092,169 @@ void bdev_statx_dioalign(struct inode *inode, struct kstat *stat)

blkdev_put_no_open(bdev);
}
+
+struct uuidcmp {
+ const char *uuid;
+ int len;
+};
+
+/**
+ * match_dev_by_uuid - callback for finding a partition using its uuid
+ * @dev: device passed in by the caller
+ * @data: opaque pointer to the desired struct uuidcmp to match
+ *
+ * Returns 1 if the device matches, and 0 otherwise.
+ */
+static int match_dev_by_uuid(struct device *dev, const void *data)
+{
+ struct block_device *bdev = dev_to_bdev(dev);
+ const struct uuidcmp *cmp = data;
+
+ if (!bdev->bd_meta_info ||
+ strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))
+ return 0;
+ return 1;
+}
+
+/**
+ * devt_from_partuuid - looks up the dev_t of a partition by its UUID
+ * @uuid_str: char array containing ascii UUID
+ *
+ * The function will return the first partition which contains a matching
+ * UUID value in its partition_meta_info struct. This does not search
+ * by filesystem UUIDs.
+ *
+ * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
+ * extracted and used as an offset from the partition identified by the UUID.
+ *
+ * Returns the matching dev_t on success or 0 on failure.
+ */
+dev_t devt_from_partuuid(const char *uuid_str, int *root_wait)
+{
+ struct uuidcmp cmp;
+ struct device *dev = NULL;
+ dev_t devt = 0;
+ int offset = 0;
+ char *slash;
+
+ cmp.uuid = uuid_str;
+
+ slash = strchr(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)
+ goto clear_root_wait;
+ cmp.len = slash - uuid_str;
+ } else {
+ cmp.len = strlen(uuid_str);
+ }
+
+ if (!cmp.len)
+ goto clear_root_wait;
+
+ dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
+ if (!dev)
+ return 0;
+
+ if (offset) {
+ /*
+ * Attempt to find the requested partition by adding an offset
+ * to the partition number found by UUID.
+ */
+ devt = part_devt(dev_to_disk(dev),
+ dev_to_bdev(dev)->bd_partno + offset);
+ } else {
+ devt = dev->devt;
+ }
+
+ put_device(dev);
+ return devt;
+
+clear_root_wait:
+ pr_err("VFS: PARTUUID= is invalid.\n"
+ "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
+ if (root_wait && *root_wait) {
+ pr_err("Disabling rootwait; root= is invalid.\n");
+ *root_wait = 0;
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(devt_from_partuuid);
+
+/**
+ * match_dev_by_label - callback for finding a partition using its label
+ * @dev: device passed in by the caller
+ * @data: opaque pointer to the label to match
+ *
+ * Returns 1 if the device matches, and 0 otherwise.
+ */
+static int match_dev_by_label(struct device *dev, const void *data)
+{
+ struct block_device *bdev = dev_to_bdev(dev);
+ const char *label = data;
+
+ if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))
+ return 0;
+ return 1;
+}
+
+dev_t devt_from_partlabel(const char *label)
+{
+ struct device *dev;
+ dev_t devt = 0;
+
+ dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
+ if (dev) {
+ devt = dev->devt;
+ put_device(dev);
+ }
+
+ return devt;
+}
+EXPORT_SYMBOL_GPL(devt_from_partlabel);
+
+dev_t devt_from_devname(const char *name)
+{
+ dev_t devt = 0;
+ int part;
+ char s[32];
+ char *p;
+
+ if (strlen(name) > 31)
+ return 0;
+ strcpy(s, name);
+ for (p = s; *p; p++) {
+ if (*p == '/')
+ *p = '!';
+ }
+
+ devt = blk_lookup_devt(s, 0);
+ if (devt)
+ return devt;
+
+ /*
+ * Try non-existent, but valid partition, which may only exist after
+ * opening the device, like partitioned md devices.
+ */
+ while (p > s && isdigit(p[-1]))
+ p--;
+ if (p == s || !*p || *p == '0')
+ return 0;
+
+ /* try disk name without <part number> */
+ part = simple_strtoul(p, NULL, 10);
+ *p = '\0';
+ devt = blk_lookup_devt(s, part);
+ if (devt)
+ return devt;
+
+ /* try disk name without p<part number> */
+ if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
+ return 0;
+ p[-1] = '\0';
+ return blk_lookup_devt(s, part);
+}
+EXPORT_SYMBOL_GPL(devt_from_devname);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index fb27dfaaaf85..b45cdcdccc6d 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1494,6 +1494,9 @@ int truncate_bdev_range(struct block_device *bdev, fmode_t mode, loff_t lstart,
loff_t lend);

#ifdef CONFIG_BLOCK
+dev_t devt_from_partuuid(const char *uuid_str, int *root_wait);
+dev_t devt_from_partlabel(const char *label);
+dev_t devt_from_devname(const char *name);
void invalidate_bdev(struct block_device *bdev);
int sync_blockdev(struct block_device *bdev);
int sync_blockdev_range(struct block_device *bdev, loff_t lstart, loff_t lend);
@@ -1502,6 +1505,18 @@ void sync_bdevs(bool wait);
void bdev_statx_dioalign(struct inode *inode, struct kstat *stat);
void printk_all_partitions(void);
#else
+static inline dev_t devt_from_partuuid(const char *uuid_str, int *root_wait)
+{
+ return MKDEV(0, 0);
+}
+static inline dev_t devt_from_partlabel(const char *label);
+{
+ return MKDEV(0, 0);
+}
+static inline dev_t devt_from_devname(const char *name);
+{
+ return MKDEV(0, 0);
+}
static inline void invalidate_bdev(struct block_device *bdev)
{
}
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 811e94daf0a8..d55e34994f18 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/sched.h>
+#include <linux/blkdev.h>
#include <linux/ctype.h>
#include <linux/fd.h>
#include <linux/tty.h>
@@ -60,169 +61,6 @@ static int __init readwrite(char *str)
__setup("ro", readonly);
__setup("rw", readwrite);

-#ifdef CONFIG_BLOCK
-struct uuidcmp {
- const char *uuid;
- int len;
-};
-
-/**
- * match_dev_by_uuid - callback for finding a partition using its uuid
- * @dev: device passed in by the caller
- * @data: opaque pointer to the desired struct uuidcmp to match
- *
- * Returns 1 if the device matches, and 0 otherwise.
- */
-static int match_dev_by_uuid(struct device *dev, const void *data)
-{
- struct block_device *bdev = dev_to_bdev(dev);
- const struct uuidcmp *cmp = data;
-
- if (!bdev->bd_meta_info ||
- strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))
- return 0;
- return 1;
-}
-
-/**
- * devt_from_partuuid - looks up the dev_t of a partition by its UUID
- * @uuid_str: char array containing ascii UUID
- *
- * The function will return the first partition which contains a matching
- * UUID value in its partition_meta_info struct. This does not search
- * by filesystem UUIDs.
- *
- * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
- * extracted and used as an offset from the partition identified by the UUID.
- *
- * Returns the matching dev_t on success or 0 on failure.
- */
-static dev_t devt_from_partuuid(const char *uuid_str)
-{
- struct uuidcmp cmp;
- struct device *dev = NULL;
- dev_t devt = 0;
- int offset = 0;
- char *slash;
-
- cmp.uuid = uuid_str;
-
- slash = strchr(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)
- goto clear_root_wait;
- cmp.len = slash - uuid_str;
- } else {
- cmp.len = strlen(uuid_str);
- }
-
- if (!cmp.len)
- goto clear_root_wait;
-
- dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
- if (!dev)
- return 0;
-
- if (offset) {
- /*
- * Attempt to find the requested partition by adding an offset
- * to the partition number found by UUID.
- */
- devt = part_devt(dev_to_disk(dev),
- dev_to_bdev(dev)->bd_partno + offset);
- } else {
- devt = dev->devt;
- }
-
- put_device(dev);
- 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;
-}
-
-/**
- * match_dev_by_label - callback for finding a partition using its label
- * @dev: device passed in by the caller
- * @data: opaque pointer to the label to match
- *
- * Returns 1 if the device matches, and 0 otherwise.
- */
-static int match_dev_by_label(struct device *dev, const void *data)
-{
- struct block_device *bdev = dev_to_bdev(dev);
- const char *label = data;
-
- if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))
- return 0;
- return 1;
-}
-
-static dev_t devt_from_partlabel(const char *label)
-{
- struct device *dev;
- dev_t devt = 0;
-
- dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
- if (dev) {
- devt = dev->devt;
- put_device(dev);
- }
-
- return devt;
-}
-
-static dev_t devt_from_devname(const char *name)
-{
- dev_t devt = 0;
- int part;
- char s[32];
- char *p;
-
- if (strlen(name) > 31)
- return 0;
- strcpy(s, name);
- for (p = s; *p; p++) {
- if (*p == '/')
- *p = '!';
- }
-
- devt = blk_lookup_devt(s, 0);
- if (devt)
- return devt;
-
- /*
- * Try non-existent, but valid partition, which may only exist after
- * opening the device, like partitioned md devices.
- */
- while (p > s && isdigit(p[-1]))
- p--;
- if (p == s || !*p || *p == '0')
- return 0;
-
- /* try disk name without <part number> */
- part = simple_strtoul(p, NULL, 10);
- *p = '\0';
- devt = blk_lookup_devt(s, part);
- if (devt)
- return devt;
-
- /* try disk name without p<part number> */
- if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
- return 0;
- p[-1] = '\0';
- return blk_lookup_devt(s, part);
-}
-#endif /* CONFIG_BLOCK */

static dev_t devt_from_devnum(const char *name)
{
@@ -284,7 +122,7 @@ dev_t name_to_dev_t(const char *name)
return Root_RAM0;
#ifdef CONFIG_BLOCK
if (strncmp(name, "PARTUUID=", 9) == 0)
- return devt_from_partuuid(name + 9);
+ return devt_from_partuuid(name + 9, &root_wait);
if (strncmp(name, "PARTLABEL=", 10) == 0)
return devt_from_partlabel(name + 10);
if (strncmp(name, "/dev/", 5) == 0)
--
2.38.1