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Subject[PATCH v3] XFS: Let the broken fiemap work in query mode.
Date
> On Wed, Apr 28, 2010 at 11:00:25AM +0800, Tao Ma wrote:
>> - 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(bm.bmv_count,
>> + (__s32)(PAGE_SIZE * 16 / sizeof(struct getbmapx)));
>
> I would use min_t here instead of the case, but otherwise the patch
> looks good to me
>
>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Ok, here comes the v3. Thanks for the review.

Regards,
Tao

From c735bccfbb925841545dcb1853fa8ffb3f3c8785 Mon Sep 17 00:00:00 2001
From: Tao Ma <tao.ma@oracle.com>
Date: Wed, 28 Apr 2010 21:57:32 +0800
Subject: [PATCH v3] XFS: Let the broken 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 97db39a1f6f69e906e98118392400de5217aa33a 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>
---
fs/xfs/linux-2.6/xfs_iops.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_iops.c b/fs/xfs/linux-2.6/xfs_iops.c
index 2259460..68531fc 100644
--- a/fs/xfs/linux-2.6/xfs_iops.c
+++ b/fs/xfs/linux-2.6/xfs_iops.c
@@ -662,7 +662,10 @@ 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;
--
1.6.3.3.334.g916e1.dirty


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