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author | Matthew Wilcox <matthew.r.wilcox@intel.com> | 2015-01-07 18:05:34 +0200 |
---|---|---|
committer | Jens Axboe <axboe@fb.com> | 2015-01-13 21:58:11 -0700 |
commit | dd22f551ac0ad366f92f601835f6623b83adc331 (patch) | |
tree | 47f6c4f274b3b6989869734b32afdc2e5d85769d /fs/block_dev.c | |
parent | c761d96b079e99d106fa4064e730ef7d0f312f9d (diff) | |
download | linux-dd22f551ac0ad366f92f601835f6623b83adc331.tar.bz2 |
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@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Boaz Harrosh <boaz@plexistor.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'fs/block_dev.c')
-rw-r--r-- | fs/block_dev.c | 40 |
1 files changed, 40 insertions, 0 deletions
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 */ |