From: Dan Williams <dan.j.williams@intel.com>
Date: Sat, 16 Jan 2016 00:55:56 +0000 (-0800)
Subject: dax: guarantee page aligned results from bdev_direct_access()
X-Git-Tag: v4.14-rc1~3996^2~68
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=fe683adabfe6629c0b6db32bbbc1ce6cacbf2117;p=platform%2Fkernel%2Flinux-rpi.git

dax: guarantee page aligned results from bdev_direct_access()

If a ->direct_access() implementation ever returns a map count less than
PAGE_SIZE, catch the error in bdev_direct_access().  This simplifies
error checking in upper layers.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 81c07055..ddc6cdd 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -494,6 +494,8 @@ long bdev_direct_access(struct block_device *bdev, sector_t sector,
 	avail = ops->direct_access(bdev, sector, addr, pfn);
 	if (!avail)
 		return -ERANGE;
+	if (avail > 0 && avail & ~PAGE_MASK)
+		return -ENXIO;
 	return min(avail, size);
 }
 EXPORT_SYMBOL_GPL(bdev_direct_access);
diff --git a/fs/dax.c b/fs/dax.c
index 11721c0..1080fb5 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -52,7 +52,6 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
 		sz = min_t(long, count, SZ_128K);
 		clear_pmem(addr, sz);
 		size -= sz;
-		BUG_ON(sz & 511);
 		sector += sz / 512;
 		cond_resched();
 	} while (size);