From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 23 May 2018 12:17:11 -0400 From: Brian Foster To: Christoph Hellwig Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 19/34] xfs: simplify xfs_bmap_punch_delalloc_range Message-ID: <20180523161710.GA33498@bfoster.bfoster> References: <20180523144357.18985-1-hch@lst.de> <20180523144357.18985-20-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180523144357.18985-20-hch@lst.de> Sender: owner-linux-mm@kvack.org List-ID: On Wed, May 23, 2018 at 04:43:42PM +0200, Christoph Hellwig wrote: > 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 > --- > fs/xfs/xfs_bmap_util.c | 78 ++++++++++++++---------------------------- > 1 file changed, 25 insertions(+), 53 deletions(-) > > diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c > index 06badcbadeb4..c009bdf9fdce 100644 > --- a/fs/xfs/xfs_bmap_util.c > +++ b/fs/xfs/xfs_bmap_util.c ... > @@ -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; > + 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; > + if (!(ifp->if_flags & XFS_IFEXTENTS)) { > + error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK); > + if (error) > + return error; > + } > > - /* > - * 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 (!xfs_iext_lookup_extent(ip, ifp, start_fsb, &icur, &got)) > + return 0; > > - 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); > - } > + do { > + if (got.br_startoff >= start_fsb + length) > 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 (!isnullstartblock(got.br_startblock)) > + continue; > > - /* > - * 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); > + del = got; > + xfs_trim_extent(&del, start_fsb, length); > + error = xfs_bmap_del_extent_delay(ip, XFS_DATA_FORK, &icur, > + &got, &del); > if (error) > break; > - > - ASSERT(!xfs_defer_has_unfinished_work(&dfops)); > -next_block: > - start_fsb++; > - remaining--; > - } while(remaining > 0); > + if (!xfs_iext_get_extent(ifp, &icur, &got)) > + break; Mostly looks Ok, but I'm not following what this get_extent() call is for..? It also doesn't look like it would always do the right thing with sub-page blocks. Consider a page with a couple discontig delalloc blocks that happen to be the first extents in the file. The first xfs_bmap_del_extent_delay() would do: xfs_iext_remove(ip, icur, state); xfs_iext_prev(ifp, icur); ... which I think sets cur->pos to -1, causes the get_extent() to fail and thus fails to remove the subsequent delalloc blocks. Hm? Brian > + } while (xfs_iext_next_extent(ifp, &icur, &got)); > > return error; > } > -- > 2.17.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html