Commit 2c91943b authored Jul 18, 2014 by Qu Wenruo Committed by Chris Mason Aug 19, 2014

btrfs: Return right extent when fiemap gives unaligned offset and len.



When page aligned start and len passed to extent_fiemap(), the result is
good, but when start and len is not aligned, e.g. start = 1 and len =
4095 is passed to extent_fiemap(), it returns no extent.

The problem is that start and len is all rounded down which causes the
problem. This patch will round down start and round up (start + len) to
return right extent.

Reported-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

parent e2eca69d

fs/btrfs/extent_io.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -4213,8 +4213,8 @@ int extent_fiemap(struct inode inode, struct fiemap_extent_info fieinfo,
		return -ENOMEM;
		path->leave_spinning = 1;

		start = ALIGN(start, BTRFS_I(inode)->root->sectorsize);
		len = ALIGN(len, BTRFS_I(inode)->root->sectorsize);
		start = round_down(start, BTRFS_I(inode)->root->sectorsize);
		len = round_up(max, BTRFS_I(inode)->root->sectorsize) - start;

		/*
		* lookup the last file extent. We're not using i_size here

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