From 41b8c853a495438208faa5be03bbb0050859163b Mon Sep 17 00:00:00 2001 From: Neil Brown Date: Wed, 18 Feb 2009 10:33:59 +0100 Subject: block: fix booting from partitioned md array Hi Tejun, it looks like your commit: block: don't depend on consecutive minor space f331c0296f2a9fee0d396a70598b954062603015 broke a particular case for booting from partitioned md/raid devices. That is the second time this has been broken recently. The previous time was fixed by block: do_mounts - accept root= 30f2f0eb4bd2c43d10a8b0d872c6e5ad8f31c9a0 Because the data isn't available when an md device is first created (we add disks and set it up after creation), the initial partition scan finds nothing. It is not until the device is opened that another partition scan happens and finds something. So at the point where the kernel parameter "root=/dev/md_d0p1" is being parsed, md_d0 exists, but md_d0p1 does not. However if we let blk_lookup_devt return the correct device number even though the device doesn't exist, then the attempt to mount it will successfully find the partition. I have tried in the past to find a way to get the partition table to be read as soon as the array is assembled but that proved impossible (at the time). I don't remember the details, and could possibly revisit it. However it would be really nice if blk_lookup_devt could be adjusted to again accept non existant partitions. Signed-off-by: Jens Axboe --- block/genhd.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'block/genhd.c') diff --git a/block/genhd.c b/block/genhd.c index 397960cf26a..e1eadcc9546 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1087,6 +1087,14 @@ dev_t blk_lookup_devt(const char *name, int partno) if (strcmp(dev_name(dev), name)) continue; + if (partno < disk->minors) { + /* We need to return the right devno, even + * if the partition doesn't exist yet. + */ + devt = MKDEV(MAJOR(dev->devt), + MINOR(dev->devt) + partno); + break; + } part = disk_get_part(disk, partno); if (part) { devt = part_devt(part); -- cgit v1.2.2 From 9e8c0bccdc944bd09361672d47660810c027bcaa Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?M=C3=A1rton=20N=C3=A9meth?= Date: Fri, 20 Feb 2009 08:12:51 +0100 Subject: block: add documentation for register_blkdev() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add documentation for register_blkdev() function and for the parameters. Signed-off-by: Márton Németh Cc: Greg Kroah-Hartman Signed-off-by: Jens Axboe --- block/genhd.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'block/genhd.c') diff --git a/block/genhd.c b/block/genhd.c index e1eadcc9546..a9ec910974c 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -256,6 +256,22 @@ void blkdev_show(struct seq_file *seqf, off_t offset) } #endif /* CONFIG_PROC_FS */ +/** + * register_blkdev - register a new block device + * + * @major: the requested major device number [1..255]. If @major=0, try to + * allocate any unused major number. + * @name: the name of the new block device as a zero terminated string + * + * The @name must be unique within the system. + * + * The return value depends on the @major input parameter. + * - if a major device number was requested in range [1..255] then the + * function returns zero on success, or a negative error code + * - if any unused major number was requested with @major=0 parameter + * then the return value is the allocated major number in range + * [1..255] or a negative error code otherwise + */ int register_blkdev(unsigned int major, const char *name) { struct blk_major_name **n, *p; -- cgit v1.2.2