From: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
This helpers allows to trim an extent to a subset of it's original range
while making sure the block numbers in it remain valid,
In the future xfs_trim_extent and xfs_bmapi_trim_map should probably be
merged in some form.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
[hch: split from a previous patch from Darrick, moved around and added
support for "raw" delayed extents"]
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/xfs/libxfs/xfs_bmap.c | 33 +++++++++++++++++++++++++++++++++
fs/xfs/libxfs/xfs_bmap.h | 2 ++
2 files changed, 35 insertions(+)
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index c27344c..016dacc 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -3999,6 +3999,39 @@ xfs_bmap_alloc(
return xfs_bmap_btalloc(ap);
}
+/* Trim extent to fit a logical block range. */
+void
+xfs_trim_extent(
+ struct xfs_bmbt_irec *irec,
+ xfs_fileoff_t bno,
+ xfs_filblks_t len)
+{
+ xfs_fileoff_t distance;
+ xfs_fileoff_t end = bno + len;
+
+ if (irec->br_startoff + irec->br_blockcount <= bno ||
+ irec->br_startoff >= end) {
+ irec->br_blockcount = 0;
+ return;
+ }
+
+ if (irec->br_startoff < bno) {
+ distance = bno - irec->br_startoff;
+ if (isnullstartblock(irec->br_startblock))
+ irec->br_startblock = DELAYSTARTBLOCK;
+ if (irec->br_startblock != DELAYSTARTBLOCK &&
+ irec->br_startblock != HOLESTARTBLOCK)
+ irec->br_startblock += distance;
+ irec->br_startoff += distance;
+ irec->br_blockcount -= distance;
+ }
+
+ if (end < irec->br_startoff + irec->br_blockcount) {
+ distance = irec->br_startoff + irec->br_blockcount - end;
+ irec->br_blockcount -= distance;
+ }
+}
+
/*
* Trim the returned map to the required bounds
*/
diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
index f97db71..eb86af0 100644
--- a/fs/xfs/libxfs/xfs_bmap.h
+++ b/fs/xfs/libxfs/xfs_bmap.h
@@ -190,6 +190,8 @@ void xfs_bmap_trace_exlist(struct xfs_inode *ip, xfs_extnum_t cnt,
#define XFS_BMAP_TRACE_EXLIST(ip,c,w)
#endif
+void xfs_trim_extent(struct xfs_bmbt_irec *irec, xfs_fileoff_t bno,
+ xfs_filblks_t len);
int xfs_bmap_add_attrfork(struct xfs_inode *ip, int size, int rsvd);
void xfs_bmap_local_to_extents_empty(struct xfs_inode *ip, int whichfork);
void xfs_bmap_add_free(struct xfs_mount *mp, struct xfs_defer_ops *dfops,
--
2.10.1.382.ga23ca1b
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