Commit 2d1ff3c7 authored Apr 29, 2010 by Tao Ma Committed by Alex Elder May 19, 2010

xfs: Make fiemap work in query mode.



According to Documentation/filesystems/fiemap.txt, If fm_extent_count
is zero, then the fm_extents[] array is ignored (no extents will be
returned), and the fm_mapped_extents count will hold the number of
extents needed.

But as the commit 97db39a1 has changed
bmv_count to the caller's input buffer, this number query function can't
work any more. As this commit is written to change bmv_count from
MAXEXTNUM because of ENOMEM.

This patch just try to  set bm.bmv_count to something sane.
Thanks to Dave Chinner <david@fromorbit.com> for the suggestion.

Cc: Eric Sandeen <sandeen@redhat.com>
Cc: Alex Elder <aelder@sgi.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Tao Ma <tao.ma@oracle.com>

parent 48389ef1

fs/xfs/linux-2.6/xfs_iops.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -673,7 +673,10 @@ xfs_vn_fiemap(
		bm.bmv_length = BTOBB(length);

		/* We add one because in getbmap world count includes the header */
		bm.bmv_count = fieinfo->fi_extents_max + 1;
		bm.bmv_count = !fieinfo->fi_extents_max ? MAXEXTNUM :
		fieinfo->fi_extents_max + 1;
		bm.bmv_count = min_t(__s32, bm.bmv_count,
		(PAGE_SIZE * 16 / sizeof(struct getbmapx)));
		bm.bmv_iflags = BMV_IF_PREALLOC;
		if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR)
		bm.bmv_iflags \|= BMV_IF_ATTRFORK;

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