[PATCHSET 0/4 v4] brd: partition fixes

[PATCHSET 0/4 v4] brd: partition fixes

[Boaz Harrosh]

Jens Hi

Currently brd has multiple bugs when trying to use partitions. After this
set all known problems are solved. Please see individual patch for description
of the problem.
(Another merge window, another patchset send. I wish you would tell me to
 just *uck-off, instead of this silence. What is so big a deal about this
 simple bug fixes.)

These should go into current v3.19-rcXX merge window they are real bugs
solving Data corruption, when using partitions.

[v4]
- Rebase to 3.19-rc3
- Removed the getgeo patch it is no longer needed by new fdisk
- Minor change to patch: [4/4] brd: Request from fdisk 4k alignment
  As suggested by Martin

[v3]
Same exact code but some commit messages changed to try and explain better
what was fixed and why. (Rebased on 3.18-rc3 but nothing changed in brd.c
since then)

[v2]
Based on Jens's linux-next [30e996a] incorporating the brd patch by Dmitry Monakhov.
Dmitry has introduced a new part_show parameter, this parameter is now removed
and we always "part_show=1".
Scripts that did part_show=1 will work just the same but will display a
message in logs. This is harmless. (And scripts can be modified to
remove this parameter)

[v1]
Current situation is that any attempt to use partitions with brd device would
create the partition but then any use will trash the data.

See: http://www.spinics.net/lists/linux-scsi/msg76737.html

So these patches fixes up all the problems we saw with the code, but not sacrificing
any of the old fixtures. See [patch 3/4] for more explanations.

list of patches:
[PATCH 1/4] axonram: Fix bug in direct_access
[PATCH 2/4] block: Change direct_access calling convention

	These 2 above are from Matthew's DAX series latest version.
	Exactly as is, taken from the 01org/prd.git tree
	They are needed so to support direct_access with partitions.

[PATCH 3/4] brd: Fix all partitions BUGs

	This one fixes all the very HARD bugs, which today
	cause data corruption.

[PATCH 4/4] brd: Request from fdisk 4k alignment

One can fetch/view these patches from a public tree here:
  git: git://git.open-osd.org/pmem.git brd-partitions branch
  web: http://git.open-osd.org/gitweb.cgi?p=pmem.git;a=shortlog;h=refs/heads/brd-partitions

Thanks
Boaz

[PATCH 1/4 v4] axonram: Fix bug in direct_access

[Boaz Harrosh]

From: Matthew Wilcox <matthew.r.wilcox@intel.com>

The 'pfn' returned by axonram was completely bogus, and has been since
2008.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: stable@vger.kernel.org
---
 arch/powerpc/sysdev/axonram.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/sysdev/axonram.c b/arch/powerpc/sysdev/axonram.c
index f532c92..367533b 100644
--- a/arch/powerpc/sysdev/axonram.c
+++ b/arch/powerpc/sysdev/axonram.c
@@ -156,7 +156,7 @@ axon_ram_direct_access(struct block_device *device, sector_t sector,
 	}
 
 	*kaddr = (void *)(bank->ph_addr + offset);
-	*pfn = virt_to_phys(kaddr) >> PAGE_SHIFT;
+	*pfn = virt_to_phys(*kaddr) >> PAGE_SHIFT;
 
 	return 0;
 }
-- 
1.9.3

[PATCH 2/4 v4] block: Change direct_access calling convention

[Boaz Harrosh]

From: Matthew Wilcox <matthew.r.wilcox@intel.com>

In order to support accesses to larger chunks of memory, pass in a
'size' parameter (counted in bytes), and return the amount available at
that address.

Add a new helper function, bdev_direct_access(), to handle common
functionality including partition handling, checking the length requested
is positive, checking for the sector being page-aligned, and checking
the length of the request does not pass the end of the partition.

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Boaz Harrosh <boaz@plexistor.com>
---
 Documentation/filesystems/xip.txt | 15 +++++++++------
 arch/powerpc/sysdev/axonram.c     | 17 ++++-------------
 drivers/block/brd.c               | 14 +++++++-------
 drivers/s390/block/dcssblk.c      | 21 +++++++++-----------
 fs/block_dev.c                    | 40 +++++++++++++++++++++++++++++++++++++++
 fs/ext2/xip.c                     | 31 +++++++++++++-----------------
 include/linux/blkdev.h            |  6 ++++--
 7 files changed, 86 insertions(+), 58 deletions(-)

diff --git a/Documentation/filesystems/xip.txt b/Documentation/filesystems/xip.txt
index 0466ee5..b774729 100644
--- a/Documentation/filesystems/xip.txt
+++ b/Documentation/filesystems/xip.txt
@@ -28,12 +28,15 @@ Implementation
 Execute-in-place is implemented in three steps: block device operation,
 address space operation, and file operations.
 
-A block device operation named direct_access is used to retrieve a
-reference (pointer) to a block on-disk. The reference is supposed to be
-cpu-addressable, physical address and remain valid until the release operation
-is performed. A struct block_device reference is used to address the device,
-and a sector_t argument is used to identify the individual block. As an
-alternative, memory technology devices can be used for this.
+A block device operation named direct_access is used to translate the
+block device sector number to a page frame number (pfn) that identifies
+the physical page for the memory.  It also returns a kernel virtual
+address that can be used to access the memory.
+
+The direct_access method takes a 'size' parameter that indicates the
+number of bytes being requested.  The function should return the number
+of bytes that can be contiguously accessed at that offset.  It may also
+return a negative errno if an error occurs.
 
 The block device operation is optional, these block devices support it as of
 today:
diff --git a/arch/powerpc/sysdev/axonram.c b/arch/powerpc/sysdev/axonram.c
index 367533b..ee90db1 100644
--- a/arch/powerpc/sysdev/axonram.c
+++ b/arch/powerpc/sysdev/axonram.c
@@ -139,26 +139,17 @@ axon_ram_make_request(struct request_queue *queue, struct bio *bio)
  * axon_ram_direct_access - direct_access() method for block device
  * @device, @sector, @data: see block_device_operations method
  */
-static int
+static long
 axon_ram_direct_access(struct block_device *device, sector_t sector,
-		       void **kaddr, unsigned long *pfn)
+		       void **kaddr, unsigned long *pfn, long size)
 {
 	struct axon_ram_bank *bank = device->bd_disk->private_data;
-	loff_t offset;
-
-	offset = sector;
-	if (device->bd_part != NULL)
-		offset += device->bd_part->start_sect;
-	offset <<= AXON_RAM_SECTOR_SHIFT;
-	if (offset >= bank->size) {
-		dev_err(&bank->device->dev, "Access outside of address space\n");
-		return -ERANGE;
-	}
+	loff_t offset = (loff_t)sector << AXON_RAM_SECTOR_SHIFT;
 
 	*kaddr = (void *)(bank->ph_addr + offset);
 	*pfn = virt_to_phys(*kaddr) >> PAGE_SHIFT;
 
-	return 0;
+	return bank->size - offset;
 }
 
 static const struct block_device_operations axon_ram_devops = {
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 3598110..89e90ec 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -370,25 +370,25 @@ static int brd_rw_page(struct block_device *bdev, sector_t sector,
 }
 
 #ifdef CONFIG_BLK_DEV_XIP
-static int brd_direct_access(struct block_device *bdev, sector_t sector,
-			void **kaddr, unsigned long *pfn)
+static long brd_direct_access(struct block_device *bdev, sector_t sector,
+			void **kaddr, unsigned long *pfn, long size)
 {
 	struct brd_device *brd = bdev->bd_disk->private_data;
 	struct page *page;
 
 	if (!brd)
 		return -ENODEV;
-	if (sector & (PAGE_SECTORS-1))
-		return -EINVAL;
-	if (sector + PAGE_SECTORS > get_capacity(bdev->bd_disk))
-		return -ERANGE;
 	page = brd_insert_page(brd, sector);
 	if (!page)
 		return -ENOSPC;
 	*kaddr = page_address(page);
 	*pfn = page_to_pfn(page);
 
-	return 0;
+	/*
+	 * TODO: If size > PAGE_SIZE, we could look to see if the next page in
+	 * the file happens to be mapped to the next page of physical RAM.
+	 */
+	return PAGE_SIZE;
 }
 #endif
 
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index b550c8c..31d6884 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -28,8 +28,8 @@
 static int dcssblk_open(struct block_device *bdev, fmode_t mode);
 static void dcssblk_release(struct gendisk *disk, fmode_t mode);
 static void dcssblk_make_request(struct request_queue *q, struct bio *bio);
-static int dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
-				 void **kaddr, unsigned long *pfn);
+static long dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
+				 void **kaddr, unsigned long *pfn, long size);
 
 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
 
@@ -866,25 +866,22 @@ fail:
 	bio_io_error(bio);
 }
 
-static int
+static long
 dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
-			void **kaddr, unsigned long *pfn)
+			void **kaddr, unsigned long *pfn, long size)
 {
 	struct dcssblk_dev_info *dev_info;
-	unsigned long pgoff;
+	unsigned long offset, dev_sz;
 
 	dev_info = bdev->bd_disk->private_data;
 	if (!dev_info)
 		return -ENODEV;
-	if (secnum % (PAGE_SIZE/512))
-		return -EINVAL;
-	pgoff = secnum / (PAGE_SIZE / 512);
-	if ((pgoff+1)*PAGE_SIZE-1 > dev_info->end - dev_info->start)
-		return -ERANGE;
-	*kaddr = (void *) (dev_info->start+pgoff*PAGE_SIZE);
+	dev_sz = dev_info->end - dev_info->start;
+	offset = secnum * 512;
+	*kaddr = (void *) (dev_info->start + offset);
 	*pfn = virt_to_phys(*kaddr) >> PAGE_SHIFT;
 
-	return 0;
+	return dev_sz - offset;
 }
 
 static void
diff --git a/fs/block_dev.c b/fs/block_dev.c
index b48c41b..f314c2c 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -429,6 +429,46 @@ int bdev_write_page(struct block_device *bdev, sector_t sector,
 }
 EXPORT_SYMBOL_GPL(bdev_write_page);
 
+/**
+ * bdev_direct_access() - Get the address for directly-accessibly memory
+ * @bdev: The device containing the memory
+ * @sector: The offset within the device
+ * @addr: Where to put the address of the memory
+ * @pfn: The Page Frame Number for the memory
+ * @size: The number of bytes requested
+ *
+ * If a block device is made up of directly addressable memory, this function
+ * will tell the caller the PFN and the address of the memory.  The address
+ * may be directly dereferenced within the kernel without the need to call
+ * ioremap(), kmap() or similar.  The PFN is suitable for inserting into
+ * page tables.
+ *
+ * Return: negative errno if an error occurs, otherwise the number of bytes
+ * accessible at this address.
+ */
+long bdev_direct_access(struct block_device *bdev, sector_t sector,
+			void **addr, unsigned long *pfn, long size)
+{
+	long avail;
+	const struct block_device_operations *ops = bdev->bd_disk->fops;
+
+	if (size < 0)
+		return size;
+	if (!ops->direct_access)
+		return -EOPNOTSUPP;
+	if ((sector + DIV_ROUND_UP(size, 512)) >
+					part_nr_sects_read(bdev->bd_part))
+		return -ERANGE;
+	sector += get_start_sect(bdev);
+	if (sector % (PAGE_SIZE / 512))
+		return -EINVAL;
+	avail = ops->direct_access(bdev, sector, addr, pfn, size);
+	if (!avail)
+		return -ERANGE;
+	return min(avail, size);
+}
+EXPORT_SYMBOL_GPL(bdev_direct_access);
+
 /*
  * pseudo-fs
  */
diff --git a/fs/ext2/xip.c b/fs/ext2/xip.c
index e98171a..bbc5fec 100644
--- a/fs/ext2/xip.c
+++ b/fs/ext2/xip.c
@@ -13,18 +13,12 @@
 #include "ext2.h"
 #include "xip.h"
 
-static inline int
-__inode_direct_access(struct inode *inode, sector_t block,
-		      void **kaddr, unsigned long *pfn)
+static inline long __inode_direct_access(struct inode *inode, sector_t block,
+				void **kaddr, unsigned long *pfn, long size)
 {
 	struct block_device *bdev = inode->i_sb->s_bdev;
-	const struct block_device_operations *ops = bdev->bd_disk->fops;
-	sector_t sector;
-
-	sector = block * (PAGE_SIZE / 512); /* ext2 block to bdev sector */
-
-	BUG_ON(!ops->direct_access);
-	return ops->direct_access(bdev, sector, kaddr, pfn);
+	sector_t sector = block * (PAGE_SIZE / 512);
+	return bdev_direct_access(bdev, sector, kaddr, pfn, size);
 }
 
 static inline int
@@ -53,12 +47,13 @@ ext2_clear_xip_target(struct inode *inode, sector_t block)
 {
 	void *kaddr;
 	unsigned long pfn;
-	int rc;
+	long size;
 
-	rc = __inode_direct_access(inode, block, &kaddr, &pfn);
-	if (!rc)
-		clear_page(kaddr);
-	return rc;
+	size = __inode_direct_access(inode, block, &kaddr, &pfn, PAGE_SIZE);
+	if (size < 0)
+		return size;
+	clear_page(kaddr);
+	return 0;
 }
 
 void ext2_xip_verify_sb(struct super_block *sb)
@@ -77,7 +72,7 @@ void ext2_xip_verify_sb(struct super_block *sb)
 int ext2_get_xip_mem(struct address_space *mapping, pgoff_t pgoff, int create,
 				void **kmem, unsigned long *pfn)
 {
-	int rc;
+	long rc;
 	sector_t block;
 
 	/* first, retrieve the sector number */
@@ -86,6 +81,6 @@ int ext2_get_xip_mem(struct address_space *mapping, pgoff_t pgoff, int create,
 		return rc;
 
 	/* retrieve address of the target data */
-	rc = __inode_direct_access(mapping->host, block, kmem, pfn);
-	return rc;
+	rc = __inode_direct_access(mapping->host, block, kmem, pfn, PAGE_SIZE);
+	return (rc < 0) ? rc : 0;
 }
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 92f4b4b..e9086be 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1601,8 +1601,8 @@ struct block_device_operations {
 	int (*rw_page)(struct block_device *, sector_t, struct page *, int rw);
 	int (*ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
 	int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
-	int (*direct_access) (struct block_device *, sector_t,
-						void **, unsigned long *);
+	long (*direct_access)(struct block_device *, sector_t,
+					void **, unsigned long *pfn, long size);
 	unsigned int (*check_events) (struct gendisk *disk,
 				      unsigned int clearing);
 	/* ->media_changed() is DEPRECATED, use ->check_events() instead */
@@ -1620,6 +1620,8 @@ extern int __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,
 extern int bdev_read_page(struct block_device *, sector_t, struct page *);
 extern int bdev_write_page(struct block_device *, sector_t, struct page *,
 						struct writeback_control *);
+extern long bdev_direct_access(struct block_device *, sector_t, void **addr,
+						unsigned long *pfn, long size);
 #else /* CONFIG_BLOCK */
 
 struct block_device;
-- 
1.9.3

[PATCH 3/4 v4] brd: Fix all partitions BUGs

[Boaz Harrosh]

From: Boaz Harrosh <boaz@plexistor.com>

This patch fixes up brd's partitions scheme, now enjoying all worlds.

The MAIN fix here is that currently, if one fdisks some partitions,
a BAD bug will make all partitions point to the same start-end sector
ie: 0 - brd_size And an mkfs of any partition would trash the partition
table and the other partition.

Another fix is that "mount -U uuid" will not work if show_part was not
specified, because of the GENHD_FL_SUPPRESS_PARTITION_INFO flag.
We now always load without it and remove the show_part parameter.

[We remove Dmitry's new module-param part_show it is now always
 show]

So NOW the logic goes like this:
* max_part - Just says how many minors to reserve between ramX
  devices. In any way, there can be as many partition as requested.
  If minors between devices ends, then dynamic 259-major ids will
  be allocated on the fly.
  The default is now max_part=1, which means all partitions devt(s)
  will be from the dynamic (259) major-range.
  (If persistent partition minors is needed use max_part=X)
  For example with /dev/sdX max_part is hard coded 16.

* Creation of new devices on the fly still/always work:
  mknod /path/devnod b 1 X
  fdisk -l /path/devnod
  Will create a new device if [X / max_part] was not already
  created before. (Just as before)

  partitions on the dynamically created device will work as well
  Same logic applies with minors as with the pre-created ones.

TODO: dynamic grow of device size. So each device can have it's
      own size.

CC: Dmitry Monakhov <dmonakhov@openvz.org>
Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Boaz Harrosh <boaz@plexistor.com>
---
 drivers/block/brd.c | 100 ++++++++++++++++++++--------------------------------
 1 file changed, 38 insertions(+), 62 deletions(-)

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 89e90ec..a7463c959 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -438,19 +438,18 @@ static const struct block_device_operations brd_fops = {
 /*
  * And now the modules code and kernel interface.
  */
-static int rd_nr;
-int rd_size = CONFIG_BLK_DEV_RAM_SIZE;
-static int max_part;
-static int part_shift;
-static int part_show = 0;
+static int rd_nr = CONFIG_BLK_DEV_RAM_COUNT;
 module_param(rd_nr, int, S_IRUGO);
 MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices");
+
+int rd_size = CONFIG_BLK_DEV_RAM_SIZE;
 module_param(rd_size, int, S_IRUGO);
 MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes.");
+
+static int max_part = 1;
 module_param(max_part, int, S_IRUGO);
-MODULE_PARM_DESC(max_part, "Maximum number of partitions per RAM disk");
-module_param(part_show, int, S_IRUGO);
-MODULE_PARM_DESC(part_show, "Control RAM disk visibility in /proc/partitions");
+MODULE_PARM_DESC(max_part, "Num Minors to reserve between devices");
+
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR);
 MODULE_ALIAS("rd");
@@ -496,16 +495,15 @@ static struct brd_device *brd_alloc(int i)
 	brd->brd_queue->limits.discard_zeroes_data = 1;
 	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, brd->brd_queue);
 
-	disk = brd->brd_disk = alloc_disk(1 << part_shift);
+	disk = brd->brd_disk = alloc_disk(max_part);
 	if (!disk)
 		goto out_free_queue;
 	disk->major		= RAMDISK_MAJOR;
-	disk->first_minor	= i << part_shift;
+	disk->first_minor	= i * max_part;
 	disk->fops		= &brd_fops;
 	disk->private_data	= brd;
 	disk->queue		= brd->brd_queue;
-	if (!part_show)
-		disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
+	disk->flags		= GENHD_FL_EXT_DEVT;
 	sprintf(disk->disk_name, "ram%d", i);
 	set_capacity(disk, rd_size * 2);
 
@@ -527,10 +525,11 @@ static void brd_free(struct brd_device *brd)
 	kfree(brd);
 }
 
-static struct brd_device *brd_init_one(int i)
+static struct brd_device *brd_init_one(int i, bool *new)
 {
 	struct brd_device *brd;
 
+	*new = false;
 	list_for_each_entry(brd, &brd_devices, brd_list) {
 		if (brd->brd_number == i)
 			goto out;
@@ -541,6 +540,7 @@ static struct brd_device *brd_init_one(int i)
 		add_disk(brd->brd_disk);
 		list_add_tail(&brd->brd_list, &brd_devices);
 	}
+	*new = true;
 out:
 	return brd;
 }
@@ -556,70 +556,46 @@ static struct kobject *brd_probe(dev_t dev, int *part, void *data)
 {
 	struct brd_device *brd;
 	struct kobject *kobj;
+	bool new;
 
 	mutex_lock(&brd_devices_mutex);
-	brd = brd_init_one(MINOR(dev) >> part_shift);
+	brd = brd_init_one(MINOR(dev) / max_part, &new);
 	kobj = brd ? get_disk(brd->brd_disk) : NULL;
 	mutex_unlock(&brd_devices_mutex);
 
-	*part = 0;
+	if (new)
+		*part = 0;
+
 	return kobj;
 }
 
 static int __init brd_init(void)
 {
-	int i, nr;
-	unsigned long range;
 	struct brd_device *brd, *next;
+	int i;
 
 	/*
 	 * brd module now has a feature to instantiate underlying device
 	 * structure on-demand, provided that there is an access dev node.
-	 * However, this will not work well with user space tool that doesn't
-	 * know about such "feature".  In order to not break any existing
-	 * tool, we do the following:
 	 *
-	 * (1) if rd_nr is specified, create that many upfront, and this
-	 *     also becomes a hard limit.
-	 * (2) if rd_nr is not specified, create CONFIG_BLK_DEV_RAM_COUNT
-	 *     (default 16) rd device on module load, user can further
-	 *     extend brd device by create dev node themselves and have
-	 *     kernel automatically instantiate actual device on-demand.
+	 * (1) if rd_nr is specified, create that many upfront. else
+	 *     it defaults to CONFIG_BLK_DEV_RAM_COUNT
+	 * (2) User can further extend brd devices by create dev node themselves
+	 *     and have kernel automatically instantiate actual device
+	 *     on-demand. Example:
+	 *		mknod /path/devnod_name b 1 X	# 1 is the rd major
+	 *		fdisk -l /path/devnod_name
+	 *	If (X / max_part) was not already created it will be created
+	 *	dynamically.
 	 */
 
-	part_shift = 0;
-	if (max_part > 0) {
-		part_shift = fls(max_part);
-
-		/*
-		 * Adjust max_part according to part_shift as it is exported
-		 * to user space so that user can decide correct minor number
-		 * if [s]he want to create more devices.
-		 *
-		 * Note that -1 is required because partition 0 is reserved
-		 * for the whole disk.
-		 */
-		max_part = (1UL << part_shift) - 1;
-	}
-
-	if ((1UL << part_shift) > DISK_MAX_PARTS)
-		return -EINVAL;
-
-	if (rd_nr > 1UL << (MINORBITS - part_shift))
-		return -EINVAL;
-
-	if (rd_nr) {
-		nr = rd_nr;
-		range = rd_nr << part_shift;
-	} else {
-		nr = CONFIG_BLK_DEV_RAM_COUNT;
-		range = 1UL << MINORBITS;
-	}
-
 	if (register_blkdev(RAMDISK_MAJOR, "ramdisk"))
 		return -EIO;
 
-	for (i = 0; i < nr; i++) {
+	if (unlikely(!max_part))
+		max_part = 1;
+
+	for (i = 0; i < rd_nr; i++) {
 		brd = brd_alloc(i);
 		if (!brd)
 			goto out_free;
@@ -631,10 +607,10 @@ static int __init brd_init(void)
 	list_for_each_entry(brd, &brd_devices, brd_list)
 		add_disk(brd->brd_disk);
 
-	blk_register_region(MKDEV(RAMDISK_MAJOR, 0), range,
+	blk_register_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS,
 				  THIS_MODULE, brd_probe, NULL, NULL);
 
-	printk(KERN_INFO "brd: module loaded\n");
+	pr_info("brd: module loaded\n");
 	return 0;
 
 out_free:
@@ -644,21 +620,21 @@ out_free:
 	}
 	unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
 
+	pr_info("brd: module NOT loaded !!!\n");
 	return -ENOMEM;
 }
 
 static void __exit brd_exit(void)
 {
-	unsigned long range;
 	struct brd_device *brd, *next;
 
-	range = rd_nr ? rd_nr << part_shift : 1UL << MINORBITS;
-
 	list_for_each_entry_safe(brd, next, &brd_devices, brd_list)
 		brd_del_one(brd);
 
-	blk_unregister_region(MKDEV(RAMDISK_MAJOR, 0), range);
+	blk_unregister_region(MKDEV(RAMDISK_MAJOR, 0), 1UL << MINORBITS);
 	unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
+
+	pr_info("brd: module unloaded\n");
 }
 
 module_init(brd_init);
-- 
1.9.3

[PATCH 4/4 v4] brd: Request from fdisk 4k alignment

[Boaz Harrosh]

From: Boaz Harrosh <boaz@plexistor.com>

Because of the direct_access() API which returns a PFN. partitions
better start on 4K boundary, else offset ZERO of a partition will
not be aligned and blk_direct_access() will fail the call.

By setting blk_queue_physical_block_size(PAGE_SIZE) we can communicate
this to fdisk and friends.

The call to blk_queue_physical_block_size() is harmless and will
not affect the Kernel behavior in any way. It is only for
communication to user-mode.

before this patch running fdisk on a default size brd of 4M
the first sector offered is 34 (BAD), but after this patch it
will be 40, ie 8 sectors aligned. Also when entering some random
partition sizes the next partition-start sector is offered 8 sectors
aligned after this patch. (Please note that with fdisk the user
can still enter bad values, only the offered default values will
be correct)

Note that with bdev-size > 4M fdisk will try to align on a 1M
boundary (above first-sector will be 2048), in any case.

CC: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Boaz Harrosh <boaz@plexistor.com>
---
 drivers/block/brd.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index a7463c959..c01b921 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -486,10 +486,19 @@ static struct brd_device *brd_alloc(int i)
 	brd->brd_queue = blk_alloc_queue(GFP_KERNEL);
 	if (!brd->brd_queue)
 		goto out_free_dev;
+
 	blk_queue_make_request(brd->brd_queue, brd_make_request);
 	blk_queue_max_hw_sectors(brd->brd_queue, 1024);
 	blk_queue_bounce_limit(brd->brd_queue, BLK_BOUNCE_ANY);
 
+	/* This is so fdisk will align partitions on 4k, because of
+	 * direct_access API needing 4k alignment, returning a PFN
+	 * (This is only a problem on very small devices <= 4M,
+	 *  otherwise fdisk will align on 1M. Regardless this call
+	 *  is harmless)
+	 */
+	blk_queue_physical_block_size(brd->brd_queue, PAGE_SIZE);
+
 	brd->brd_queue->limits.discard_granularity = PAGE_SIZE;
 	brd->brd_queue->limits.max_discard_sectors = UINT_MAX;
 	brd->brd_queue->limits.discard_zeroes_data = 1;
-- 
1.9.3

Re: [PATCH 4/4 v4] brd: Request from fdisk 4k alignment

[Martin K. Petersen]

>>>>> "Boaz" == Boaz Harrosh <boaz@plexistor.com> writes:

Boaz> Because of the direct_access() API which returns a PFN. partitions
Boaz> better start on 4K boundary, else offset ZERO of a partition will
Boaz> not be aligned and blk_direct_access() will fail the call.

Boaz> By setting blk_queue_physical_block_size(PAGE_SIZE) we can
Boaz> communicate this to fdisk and friends.

Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCHSET 0/4 v4] brd: partition fixes

[Jens Axboe]

On 01/07/2015 09:02 AM, Boaz Harrosh wrote:
> Jens Hi
> 
> Currently brd has multiple bugs when trying to use partitions. After this
> set all known problems are solved. Please see individual patch for description
> of the problem.
> (Another merge window, another patchset send. I wish you would tell me to
>  just *uck-off, instead of this silence. What is so big a deal about this
>  simple bug fixes.)

Calm down. All previous series posted have needed changes. And you
always seem to post after a merge window has closed, so your timing is
bad. Finally looks like it's good to go, so I've merged it for this series.

-- 
Jens Axboe

Re: [PATCHSET 0/4 v4] brd: partition fixes

[Boaz Harrosh]

On 01/08/2015 10:56 PM, Jens Axboe wrote:
> On 01/07/2015 09:02 AM, Boaz Harrosh wrote:
>> Jens Hi
>>
>> Currently brd has multiple bugs when trying to use partitions. After this
>> set all known problems are solved. Please see individual patch for description
>> of the problem.
>> (Another merge window, another patchset send. I wish you would tell me to
>>  just *uck-off, instead of this silence. What is so big a deal about this
>>  simple bug fixes.)
> 
> Calm down. All previous series posted have needed changes. And you
> always seem to post after a merge window has closed, so your timing is
> bad. Finally looks like it's good to go, so I've merged it for this series.
> 

Thanks
Boaz

Re: [PATCH 3/4 v4] brd: Fix all partitions BUGs

[Tony Luck]

On Wed, Jan 7, 2015 at 8:07 AM, Boaz Harrosh <boaz@plexistor.com> wrote:
> From: Boaz Harrosh <boaz@plexistor.com>
>
> This patch fixes up brd's partitions scheme, now enjoying all worlds.

linux-next-20150116 includes this as commit
937af5ecd0591e84ee54180fa97dcbe9bbe5fed6

On ia64 I'm seeing:
ram0: unknown partition table
ram1: unknown partition table
...
ram15: unknown partition table

At first I blamed c8fa31730fc7 "brd: Request from fdisk 4k alignment" because it
has all sorts of comments about PAGE_SIZE and 4k ... and my page size isn't
4k.  But, reverting that one didn't help.

reverting 937af5ecd0 does make the message go away.

-Tony

Re: [PATCH 3/4 v4] brd: Fix all partitions BUGs

[Jens Axboe]

On 01/16/2015 03:32 PM, Tony Luck wrote:
> On Wed, Jan 7, 2015 at 8:07 AM, Boaz Harrosh <boaz@plexistor.com> wrote:
>> From: Boaz Harrosh <boaz@plexistor.com>
>>
>> This patch fixes up brd's partitions scheme, now enjoying all worlds.
> 
> linux-next-20150116 includes this as commit
> 937af5ecd0591e84ee54180fa97dcbe9bbe5fed6
> 
> On ia64 I'm seeing:
> ram0: unknown partition table
> ram1: unknown partition table
> ...
> ram15: unknown partition table
> 
> At first I blamed c8fa31730fc7 "brd: Request from fdisk 4k alignment" because it
> has all sorts of comments about PAGE_SIZE and 4k ... and my page size isn't
> 4k.  But, reverting that one didn't help.
> 
> reverting 937af5ecd0 does make the message go away.

Boaz, why wasn't GENHD_FL_SUPPRESS_PARTITION_INFO retained?

-- 
Jens Axboe

Re: [PATCH 3/4 v4] brd: Fix all partitions BUGs

[Boaz Harrosh]

On 01/17/2015 12:49 AM, Jens Axboe wrote:
> On 01/16/2015 03:32 PM, Tony Luck wrote:
>> On Wed, Jan 7, 2015 at 8:07 AM, Boaz Harrosh <boaz@plexistor.com> wrote:
>>> From: Boaz Harrosh <boaz@plexistor.com>
>>>
>>> This patch fixes up brd's partitions scheme, now enjoying all worlds.
>>
>> linux-next-20150116 includes this as commit
>> 937af5ecd0591e84ee54180fa97dcbe9bbe5fed6
>>
>> On ia64 I'm seeing:
>> ram0: unknown partition table
>> ram1: unknown partition table
>> ...
>> ram15: unknown partition table
>>
>> At first I blamed c8fa31730fc7 "brd: Request from fdisk 4k alignment" because it
>> has all sorts of comments about PAGE_SIZE and 4k ... and my page size isn't
>> 4k.  But, reverting that one didn't help.
>>
>> reverting 937af5ecd0 does make the message go away.
> 
> Boaz, why wasn't GENHD_FL_SUPPRESS_PARTITION_INFO retained?
> 

OK. This message is completely harmless. My vm's 3 FSfull devices
print this message day in and day out. Its when you have an FS on
a partition-less device.

Dmitry had a module param "show_partition" which controls the addition
of this flag. The reason to remove it is because for some reason
with it, mount by UUID would not work, same reason lsblk would not see
the partition on this device even with -a.

For some reason GENHD_FL_SUPPRESS_PARTITION_INFO does not only shut up
that harmless message above, it interferes with any partition operations.
(As well as any udev operation on the device)

Do you want that I add back Dmitry's "show_partition" module param? Or should
I add a new flag that would behave exactly as a regular device but only
suppress the above harmless and annoying message like:
	GENHD_FL_PARTITION_LESS_OK (Or something like that)

Your call, Tell me which way you want to go. For me the message above is a
daily routine with many other devices not only brd. 
(I would even just remove the message above, what is it for at all? What error
condition does it uncover? So OK I have plugged a new device and it is
uninitialized yet, how the "unknown partition table" helps me in anyway?
I'm not complaining I would really like to understand.)

Thanks
Boaz

Re: [PATCH 3/4 v4] brd: Fix all partitions BUGs

[Christoph Hellwig]

Can we just get rid of the warnings?  It's fairly annoying as devices
without partitions are perfectly fine and very useful.

[RFC] block: Remove annoying "unknown partition table" message

[Boaz Harrosh]

From: Boaz Harrosh <boaz@plexistor.com>

As Christoph put it best:
  Can we just get rid of the warnings?  It's fairly annoying as devices
  without partitions are perfectly fine and very useful.

Me too I see this message every VM boot for ages on all my
devices. Would love to just remove it. For me a partition-table
is only needed for a booting BIOS, grub, and stuff.

(NOT Yet Tested)

CC: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Boaz Harrosh <boaz@plexistor.com>
---
 block/partitions/check.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/block/partitions/check.c b/block/partitions/check.c
index 9ac1df7..e3a9077 100644
--- a/block/partitions/check.c
+++ b/block/partitions/check.c
@@ -184,9 +184,7 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
 	if (err)
 	/* The partition is unrecognized. So report I/O errors if there were any */
 		res = err;
-	if (!res)
-		strlcat(state->pp_buf, " unknown partition table\n", PAGE_SIZE);
-	else if (warn_no_part)
+	if (warn_no_part)
 		strlcat(state->pp_buf, " unable to read partition table\n", PAGE_SIZE);
 
 	printk(KERN_INFO "%s", state->pp_buf);

Re: [RFC] block: Remove annoying "unknown partition table" message

[Boaz Harrosh]

On 01/18/2015 05:32 PM, Boaz Harrosh wrote:
> From: Boaz Harrosh <boaz@plexistor.com>
> 
> As Christoph put it best:
>   Can we just get rid of the warnings?  It's fairly annoying as devices
>   without partitions are perfectly fine and very useful.
> 
> Me too I see this message every VM boot for ages on all my
> devices. Would love to just remove it. For me a partition-table
> is only needed for a booting BIOS, grub, and stuff.
> 
> (NOT Yet Tested)
> 
> CC: Christoph Hellwig <hch@infradead.org>
> Signed-off-by: Boaz Harrosh <boaz@plexistor.com>
> ---
>  block/partitions/check.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/block/partitions/check.c b/block/partitions/check.c
> index 9ac1df7..e3a9077 100644
> --- a/block/partitions/check.c
> +++ b/block/partitions/check.c
> @@ -184,9 +184,7 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
>  	if (err)
>  	/* The partition is unrecognized. So report I/O errors if there were any */
>  		res = err;
> -	if (!res)
> -		strlcat(state->pp_buf, " unknown partition table\n", PAGE_SIZE);
> -	else if (warn_no_part)
> +	if (warn_no_part)
>  		strlcat(state->pp_buf, " unable to read partition table\n", PAGE_SIZE);
>  
>  	printk(KERN_INFO "%s", state->pp_buf);
> 

Off course that was untested crap something like:
---
diff --git a/block/partitions/check.c b/block/partitions/check.c
index 9ac1df7..16118d1 100644
--- a/block/partitions/check.c
+++ b/block/partitions/check.c
@@ -184,12 +184,12 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
 	if (err)
 	/* The partition is unrecognized. So report I/O errors if there were any */
 		res = err;
-	if (!res)
-		strlcat(state->pp_buf, " unknown partition table\n", PAGE_SIZE);
-	else if (warn_no_part)
-		strlcat(state->pp_buf, " unable to read partition table\n", PAGE_SIZE);
-
-	printk(KERN_INFO "%s", state->pp_buf);
+	if (res) {
+		if (warn_no_part)
+			strlcat(state->pp_buf,
+				" unable to read partition table\n", PAGE_SIZE);
+		printk(KERN_INFO "%s", state->pp_buf);
+	}
 
 	free_page((unsigned long)state->pp_buf);
 	free_partitions(state);
---
Not-Signed-off-yet: Boaz Harrosh <boaz@plexistor.com>

Re: [RFC] block: Remove annoying "unknown partition table" message

[Jens Axboe]

On 01/18/2015 08:48 AM, Boaz Harrosh wrote:
> On 01/18/2015 05:32 PM, Boaz Harrosh wrote:
>> From: Boaz Harrosh <boaz@plexistor.com>
>>
>> As Christoph put it best:
>>   Can we just get rid of the warnings?  It's fairly annoying as devices
>>   without partitions are perfectly fine and very useful.
>>
>> Me too I see this message every VM boot for ages on all my
>> devices. Would love to just remove it. For me a partition-table
>> is only needed for a booting BIOS, grub, and stuff.
>>
>> (NOT Yet Tested)
>>
>> CC: Christoph Hellwig <hch@infradead.org>
>> Signed-off-by: Boaz Harrosh <boaz@plexistor.com>
>> ---
>>  block/partitions/check.c | 4 +---
>>  1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/block/partitions/check.c b/block/partitions/check.c
>> index 9ac1df7..e3a9077 100644
>> --- a/block/partitions/check.c
>> +++ b/block/partitions/check.c
>> @@ -184,9 +184,7 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
>>  	if (err)
>>  	/* The partition is unrecognized. So report I/O errors if there were any */
>>  		res = err;
>> -	if (!res)
>> -		strlcat(state->pp_buf, " unknown partition table\n", PAGE_SIZE);
>> -	else if (warn_no_part)
>> +	if (warn_no_part)
>>  		strlcat(state->pp_buf, " unable to read partition table\n", PAGE_SIZE);
>>  
>>  	printk(KERN_INFO "%s", state->pp_buf);
>>
> 
> Off course that was untested crap something like:
> ---
> diff --git a/block/partitions/check.c b/block/partitions/check.c
> index 9ac1df7..16118d1 100644
> --- a/block/partitions/check.c
> +++ b/block/partitions/check.c
> @@ -184,12 +184,12 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
>  	if (err)
>  	/* The partition is unrecognized. So report I/O errors if there were any */
>  		res = err;
> -	if (!res)
> -		strlcat(state->pp_buf, " unknown partition table\n", PAGE_SIZE);
> -	else if (warn_no_part)
> -		strlcat(state->pp_buf, " unable to read partition table\n", PAGE_SIZE);
> -
> -	printk(KERN_INFO "%s", state->pp_buf);
> +	if (res) {
> +		if (warn_no_part)
> +			strlcat(state->pp_buf,
> +				" unable to read partition table\n", PAGE_SIZE);
> +		printk(KERN_INFO "%s", state->pp_buf);
> +	}
>  
>  	free_page((unsigned long)state->pp_buf);
>  	free_partitions(state);
> ---
> Not-Signed-off-yet: Boaz Harrosh <boaz@plexistor.com>

Were you going to send a tested patch with the commit message?

-- 
Jens Axboe

[PATCH] block: Remove annoying "unknown partition table" message

[Boaz Harrosh]

From: Boaz Harrosh <boaz@plexistor.com>

As Christoph put it:
  Can we just get rid of the warnings?  It's fairly annoying as devices
  without partitions are perfectly fine and very useful.

Me too I see this message every VM boot for ages on all my
devices. Would love to just remove it. For me a partition-table
is only needed for a booting BIOS, grub, and stuff.

CC: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Boaz Harrosh <boaz@plexistor.com>
---
 block/partitions/check.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/block/partitions/check.c b/block/partitions/check.c
index 9ac1df7..16118d1 100644
--- a/block/partitions/check.c
+++ b/block/partitions/check.c
@@ -184,12 +184,12 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
 	if (err)
 	/* The partition is unrecognized. So report I/O errors if there were any */
 		res = err;
-	if (!res)
-		strlcat(state->pp_buf, " unknown partition table\n", PAGE_SIZE);
-	else if (warn_no_part)
-		strlcat(state->pp_buf, " unable to read partition table\n", PAGE_SIZE);
-
-	printk(KERN_INFO "%s", state->pp_buf);
+	if (res) {
+		if (warn_no_part)
+			strlcat(state->pp_buf,
+				" unable to read partition table\n", PAGE_SIZE);
+		printk(KERN_INFO "%s", state->pp_buf);
+	}
 
 	free_page((unsigned long)state->pp_buf);
 	free_partitions(state);
-- 
1.9.3

Re: [PATCH] block: Remove annoying "unknown partition table" message

[Boaz Harrosh]

On 01/22/2015 02:39 PM, Boaz Harrosh wrote:
> From: Boaz Harrosh <boaz@plexistor.com>
> 
> As Christoph put it:
>   Can we just get rid of the warnings?  It's fairly annoying as devices
>   without partitions are perfectly fine and very useful.
> 
> Me too I see this message every VM boot for ages on all my
> devices. Would love to just remove it. For me a partition-table
> is only needed for a booting BIOS, grub, and stuff.
> 
> CC: Christoph Hellwig <hch@infradead.org>
> Signed-off-by: Boaz Harrosh <boaz@plexistor.com>

Jens Hi

Sorry for the delay, was unavailable from beginning of the week.

I have tested this. The message no longer shows.

I also hacked to return -EIO if sector ZERO is read, and
the "unable to read partition table" will show, (as well as 16
other messages complaining at other places). So I guess it is
test.

Thanks
Boaz

> ---
>  block/partitions/check.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/block/partitions/check.c b/block/partitions/check.c
> index 9ac1df7..16118d1 100644
> --- a/block/partitions/check.c
> +++ b/block/partitions/check.c
> @@ -184,12 +184,12 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
>  	if (err)
>  	/* The partition is unrecognized. So report I/O errors if there were any */
>  		res = err;
> -	if (!res)
> -		strlcat(state->pp_buf, " unknown partition table\n", PAGE_SIZE);
> -	else if (warn_no_part)
> -		strlcat(state->pp_buf, " unable to read partition table\n", PAGE_SIZE);
> -
> -	printk(KERN_INFO "%s", state->pp_buf);
> +	if (res) {
> +		if (warn_no_part)
> +			strlcat(state->pp_buf,
> +				" unable to read partition table\n", PAGE_SIZE);
> +		printk(KERN_INFO "%s", state->pp_buf);
> +	}
>  
>  	free_page((unsigned long)state->pp_buf);
>  	free_partitions(state);
>