The patch titled
Subject: block: change direct_access calling convention
has been added to the -mm tree. Its filename is
block-change-direct_access-calling-convention.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/block-change-direct_access-calling-convention.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/block-change-direct_access-calling-convention.patch
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------------------------------------------------------
From: Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx>
Subject: block: change direct_access calling convention
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@xxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
Cc: Andreas Dilger <andreas.dilger@xxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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 -puN Documentation/filesystems/xip.txt~block-change-direct_access-calling-convention Documentation/filesystems/xip.txt
--- a/Documentation/filesystems/xip.txt~block-change-direct_access-calling-convention
+++ a/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 -puN arch/powerpc/sysdev/axonram.c~block-change-direct_access-calling-convention arch/powerpc/sysdev/axonram.c
--- a/arch/powerpc/sysdev/axonram.c~block-change-direct_access-calling-convention
+++ a/arch/powerpc/sysdev/axonram.c
@@ -139,26 +139,17 @@ axon_ram_make_request(struct request_que
* 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 -puN drivers/block/brd.c~block-change-direct_access-calling-convention drivers/block/brd.c
--- a/drivers/block/brd.c~block-change-direct_access-calling-convention
+++ a/drivers/block/brd.c
@@ -370,25 +370,25 @@ static int brd_rw_page(struct block_devi
}
#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 -puN drivers/s390/block/dcssblk.c~block-change-direct_access-calling-convention drivers/s390/block/dcssblk.c
--- a/drivers/s390/block/dcssblk.c~block-change-direct_access-calling-convention
+++ a/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 -puN fs/block_dev.c~block-change-direct_access-calling-convention fs/block_dev.c
--- a/fs/block_dev.c~block-change-direct_access-calling-convention
+++ a/fs/block_dev.c
@@ -429,6 +429,46 @@ int bdev_write_page(struct block_device
}
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 -puN fs/ext2/xip.c~block-change-direct_access-calling-convention fs/ext2/xip.c
--- a/fs/ext2/xip.c~block-change-direct_access-calling-convention
+++ a/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 *inod
{
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_blo
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_spac
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 -puN include/linux/blkdev.h~block-change-direct_access-calling-convention include/linux/blkdev.h
--- a/include/linux/blkdev.h~block-change-direct_access-calling-convention
+++ a/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
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;
_
Patches currently in -mm which might be from matthew.r.wilcox@xxxxxxxxx are
axonram-fix-bug-in-direct_access.patch
block-change-direct_access-calling-convention.patch
mm-fix-xip-fault-vs-truncate-race.patch
mm-fix-xip-fault-vs-truncate-race-fix.patch
mm-allow-page-fault-handlers-to-perform-the-cow.patch
mm-allow-page-fault-handlers-to-perform-the-cow-fix.patch
vfsext2-introduce-is_daxinode.patch
daxext2-replace-xip-read-and-write-with-dax-i-o.patch
daxext2-replace-ext2_clear_xip_target-with-dax_clear_blocks.patch
daxext2-replace-the-xip-page-fault-handler-with-the-dax-page-fault-handler.patch
daxext2-replace-the-xip-page-fault-handler-with-the-dax-page-fault-handler-fix.patch
daxext2-replace-xip_truncate_page-with-dax_truncate_page.patch
vfs-remove-get_xip_mem.patch
ext2-remove-ext2_xip_verify_sb.patch
ext2-remove-ext2_use_xip.patch
ext2-remove-xipc-and-xiph.patch
vfsext2-remove-config_ext2_fs_xip-and-rename-config_fs_xip-to-config_fs_dax.patch
ext2-remove-ext2_aops_xip.patch
ext2-get-rid-of-most-mentions-of-xip-in-ext2.patch
dax-add-dax_zero_page_range.patch
dax-add-dax_zero_page_range-fix.patch
ext4-add-dax-functionality.patch
brd-rename-xip-to-dax.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
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