Btrfs devel - Apr 2013 - [PATCH 1/2] btrfs-progs: replace blkid_probe_get_wholedisk_devno

blkid_probe_get_wholedisk_devno() isn''t available in some older
versions of libblkid.  It was used to work around an old
bug in blkid_devno_to_wholedisk(), but that has been fixed since
5cd0823 libblkid: fix blkid_devno_to_wholedisk(), present in
util-linux 2.17 and beyond.

If we happen to be missing that fix, the worst that happens is
that we''d fail to detect that a device is an ssd; the upside is
that this code compiles on older systems.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

diff --git a/mkfs.c b/mkfs.c
index c8cb395..7df78fc 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -1215,9 +1215,8 @@ static int check_leaf_or_node_size(u32 size, u32
sectorsize)
 
 static int is_ssd(const char *file)
 {
-	char *devname;
 	blkid_probe probe;
-	char *dev;
+	char dev[32];
 	char path[PATH_MAX];
 	dev_t disk;
 	int fd;
@@ -1227,24 +1226,16 @@ static int is_ssd(const char *file)
 	if (!probe)
 		return 0;
 
-	/*
-	 * We want to use blkid_devno_to_wholedisk() but it''s broken for some
-	 * reason on F17 at least so we''ll do this trickery
-	 */
-	disk = blkid_probe_get_wholedisk_devno(probe);
+	/* Device number of this disk (possibly a partition) */
+	disk = blkid_probe_get_devno(probe);
 	if (!disk)
 		return 0;
 
-	devname = blkid_devno_to_devname(disk);
-	if (!devname)
-		return 0;
-
-	dev = strrchr(devname, ''/'');
-	dev++;
+	/* Get whole disk name (not full path) for this devno */
+	blkid_devno_to_wholedisk(disk, dev, sizeof(dev), NULL);
 
 	snprintf(path, PATH_MAX, "/sys/block/%s/queue/rotational", dev);
 
-	free(devname);
 	blkid_free_probe(probe);
 
 	fd = open(path, O_RDONLY);


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is_ssd() uses nondescript variable names; path - to what?
disk - it''s a dev_t not a disk name, unlike dev, which is
a name not a dev_t!

Rename some vars to make things hopefully clearer:

 wholedisk - the name of the node for the entire disk
 devno - the dev_t of the device we''re mkfs''ing
 sysfs_path - the path in sysfs we ultimately check

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

Hopefully that''s slightly clearer; if not, this patch is
just cleanup, so it''s not at all critical.

diff --git a/mkfs.c b/mkfs.c
index 7df78fc..d735d65 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -1216,9 +1216,9 @@ static int check_leaf_or_node_size(u32 size, u32
sectorsize)
 static int is_ssd(const char *file)
 {
 	blkid_probe probe;
-	char dev[32];
-	char path[PATH_MAX];
-	dev_t disk;
+	char wholedisk[32];
+	char sysfs_path[PATH_MAX];
+	dev_t devno;
 	int fd;
 	char rotational;
 
@@ -1227,18 +1227,19 @@ static int is_ssd(const char *file)
 		return 0;
 
 	/* Device number of this disk (possibly a partition) */
-	disk = blkid_probe_get_devno(probe);
-	if (!disk)
+	devno= blkid_probe_get_devno(probe);
+	if (!devno)
 		return 0;
 
 	/* Get whole disk name (not full path) for this devno */
-	blkid_devno_to_wholedisk(disk, dev, sizeof(dev), NULL);
+	blkid_devno_to_wholedisk(devno, wholedisk, sizeof(wholedisk), NULL);
 
-	snprintf(path, PATH_MAX, "/sys/block/%s/queue/rotational", dev);
+	snprintf(sysfs_path, PATH_MAX, "/sys/block/%s/queue/rotational",
+		 wholedisk);
 
 	blkid_free_probe(probe);
 
-	fd = open(path, O_RDONLY);
+	fd = open(sysfs_path, O_RDONLY);
 	if (fd < 0) {
 		return 0;
 	}


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> +	devno= blkid_probe_get_devno(probe);
*gasp*

:)

- z
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