Merge branch 'for-3.20/core' into for-3.20/drivers

7 files changed, 86 insertions, 58 deletions

diff --git a/Documentation/filesystems/xip.txt b/Documentation/filesystems/xip.txt
index 0466ee569278..b77472949ede 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 367533bb3d48..ee90db17b097 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 3598110d2cef..89e90ec52f28 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 b550c8c8d010..31d6884f3351 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 b48c41bf0f86..f314c2c0567d 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 e98171a11cfe..bbc5fec6ff7f 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 92f4b4b288dd..e9086be6d9a0 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;