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authorTao Ma <tao.ma@oracle.com>2010-08-30 02:44:03 +0000
committerAlex Elder <aelder@sgi.com>2010-09-03 09:02:11 -0500
commit9af25465081480a75824fd7a16a37a5cfebeede9 (patch)
tree475ea0ef9247b65b0ce8997ba581a87bd71c11b6 /fs/xfs
parent23963e54ce187ca6e907c83176c15508b0f6e60d (diff)
xfs: Make fiemap work with sparse files
In xfs_vn_fiemap, we set bvm_count to fi_extent_max + 1 and want to return fi_extent_max extents, but actually it won't work for a sparse file. The reason is that in xfs_getbmap we will calculate holes and set it in 'out', while out is malloced by bmv_count(fi_extent_max+1) which didn't consider holes. So in the worst case, if 'out' vector looks like [hole, extent, hole, extent, hole, ... hole, extent, hole], we will only return half of fi_extent_max extents. This patch add a new parameter BMV_IF_NO_HOLES for bvm_iflags. So with this flags, we don't use our 'out' in xfs_getbmap for a hole. The solution is a bit ugly by just don't increasing index of 'out' vector. I felt that it is not easy to skip it at the very beginning since we have the complicated check and some function like xfs_getbmapx_fix_eof_hole to adjust 'out'. Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Tao Ma <tao.ma@oracle.com> Signed-off-by: Alex Elder <aelder@sgi.com>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/linux-2.6/xfs_iops.c2
-rw-r--r--fs/xfs/xfs_bmap.c14
-rw-r--r--fs/xfs/xfs_fs.h4
3 files changed, 17 insertions, 3 deletions
diff --git a/fs/xfs/linux-2.6/xfs_iops.c b/fs/xfs/linux-2.6/xfs_iops.c
index 68be25dcd301..b1fc2a6bfe83 100644
--- a/fs/xfs/linux-2.6/xfs_iops.c
+++ b/fs/xfs/linux-2.6/xfs_iops.c
@@ -664,7 +664,7 @@ xfs_vn_fiemap(
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;
+ bm.bmv_iflags = BMV_IF_PREALLOC | BMV_IF_NO_HOLES;
if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR)
bm.bmv_iflags |= BMV_IF_ATTRFORK;
if (!(fieinfo->fi_flags & FIEMAP_FLAG_SYNC))
diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 23f14e595c18..f90dadd5a968 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -5533,12 +5533,24 @@ xfs_getbmap(
map[i].br_startblock))
goto out_free_map;
- nexleft--;
bmv->bmv_offset =
out[cur_ext].bmv_offset +
out[cur_ext].bmv_length;
bmv->bmv_length =
max_t(__int64_t, 0, bmvend - bmv->bmv_offset);
+
+ /*
+ * In case we don't want to return the hole,
+ * don't increase cur_ext so that we can reuse
+ * it in the next loop.
+ */
+ if ((iflags & BMV_IF_NO_HOLES) &&
+ map[i].br_startblock == HOLESTARTBLOCK) {
+ memset(&out[cur_ext], 0, sizeof(out[cur_ext]));
+ continue;
+ }
+
+ nexleft--;
bmv->bmv_entries++;
cur_ext++;
}
diff --git a/fs/xfs/xfs_fs.h b/fs/xfs/xfs_fs.h
index 7cf7220e7d5f..87c2e9d02288 100644
--- a/fs/xfs/xfs_fs.h
+++ b/fs/xfs/xfs_fs.h
@@ -114,8 +114,10 @@ struct getbmapx {
#define BMV_IF_NO_DMAPI_READ 0x2 /* Do not generate DMAPI read event */
#define BMV_IF_PREALLOC 0x4 /* rtn status BMV_OF_PREALLOC if req */
#define BMV_IF_DELALLOC 0x8 /* rtn status BMV_OF_DELALLOC if req */
+#define BMV_IF_NO_HOLES 0x10 /* Do not return holes */
#define BMV_IF_VALID \
- (BMV_IF_ATTRFORK|BMV_IF_NO_DMAPI_READ|BMV_IF_PREALLOC|BMV_IF_DELALLOC)
+ (BMV_IF_ATTRFORK|BMV_IF_NO_DMAPI_READ|BMV_IF_PREALLOC| \
+ BMV_IF_DELALLOC|BMV_IF_NO_HOLES)
/* bmv_oflags values - returned for each non-header segment */
#define BMV_OF_PREALLOC 0x1 /* segment = unwritten pre-allocation */