[PATCH 03/18] xfs: simplify xfs_bmap_punch_delalloc_range

Christoph Hellwig
2018-05-30T10:00:32Z

Instead of using xfs_bmapi_read to find delalloc extents and then punch
them out using xfs_bunmapi, opencode the loop to iterate over the extents
and call xfs_bmap_del_extent_delay directly. This both simplifies the
code and reduces the number of extent tree lookups required.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/xfs/xfs_bmap_util.c | 84 ++++++++++++++----------------------------
1 file changed, 28 insertions(+), 56 deletions(-)

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 06badcbadeb4..f2b87873612d 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -695,12 +695,10 @@ xfs_getbmap(
}

/*
- * dead simple method of punching delalyed allocation blocks from a range in
- * the inode. Walks a block at a time so will be slow, but is only executed in
- * rare error cases so the overhead is not critical. This will always punch out
- * both the start and end blocks, even if the ranges only partially overlap
- * them, so it is up to the caller to ensure that partial blocks are not
- * passed in.
+ * Dead simple method of punching delalyed allocation blocks from a range in
+ * the inode. This will always punch out both the start and end blocks, even
+ * if the ranges only partially overlap them, so it is up to the caller to
+ * ensure that partial blocks are not passed in.
*/
int
xfs_bmap_punch_delalloc_range(
@@ -708,63 +706,37 @@ xfs_bmap_punch_delalloc_range(
xfs_fileoff_t start_fsb,
xfs_fileoff_t length)
{
- xfs_fileoff_t remaining = length;
+ struct xfs_ifork *ifp = &ip->i_df;
+ xfs_fileoff_t end_fsb = start_fsb + length;
+ struct xfs_bmbt_irec got, del;
+ struct xfs_iext_cursor icur;
int error = 0;

ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));

- do {
- int done;
- xfs_bmbt_irec_t imap;
- int nimaps = 1;
- xfs_fsblock_t firstblock;
- struct xfs_defer_ops dfops;
-
- /*
- * Map the range first and check that it is a delalloc extent
- * before trying to unmap the range. Otherwise we will be
- * trying to remove a real extent (which requires a
- * transaction) or a hole, which is probably a bad idea...
- */
- error = xfs_bmapi_read(ip, start_fsb, 1, &imap, &nimaps,
- XFS_BMAPI_ENTIRE);
+ if (!(ifp->if_flags & XFS_IFEXTENTS)) {
+ error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
+ if (error)
+ return error;
+ }

- if (error) {
- /* something screwed, just bail */
- if (!XFS_FORCED_SHUTDOWN(ip->i_mount)) {
- xfs_alert(ip->i_mount,
- "Failed delalloc mapping lookup ino %lld fsb %lld.",
- ip->i_ino, start_fsb);
- }
- break;
- }
- if (!nimaps) {
- /* nothing there */
- goto next_block;
- }
- if (imap.br_startblock != DELAYSTARTBLOCK) {
- /* been converted, ignore */
- goto next_block;
- }
- WARN_ON(imap.br_blockcount == 0);
+ if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &icur, &got))
+ return 0;

- /*
- * Note: while we initialise the firstblock/dfops pair, they
- * should never be used because blocks should never be
- * allocated or freed for a delalloc extent and hence we need
- * don't cancel or finish them after the xfs_bunmapi() call.
- */
- xfs_defer_init(&dfops, &firstblock);
- error = xfs_bunmapi(NULL, ip, start_fsb, 1, 0, 1, &firstblock,
- &dfops, &done);
- if (error)
- break;
+ while (got.br_startoff + got.br_blockcount > start_fsb) {
+ del = got;
+ xfs_trim_extent(&del, start_fsb, length);

- ASSERT(!xfs_defer_has_unfinished_work(&dfops));
-next_block:
- start_fsb++;
- remaining--;
- } while(remaining > 0);
+ if (del.br_blockcount && isnullstartblock(del.br_startblock)) {
+ error = xfs_bmap_del_extent_delay(ip, XFS_DATA_FORK,
+ &icur, &got, &del);
+ if (error || !xfs_iext_get_extent(ifp, &icur, &got))
+ break;
+ } else {
+ if (!xfs_iext_prev_extent(ifp, &icur, &got))
+ break;
+ }
+ }

return error;
}
--
2.17.0