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Wong" Cc: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH 6/6] xfs: replace zero range flush with folio batch Message-ID: References: <20251016190303.53881-1-bfoster@redhat.com> <20251016190303.53881-7-bfoster@redhat.com> <20251105223715.GI196370@frogsfrogsfrogs> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251105223715.GI196370@frogsfrogsfrogs> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 On Wed, Nov 05, 2025 at 02:37:15PM -0800, Darrick J. Wong wrote: > On Thu, Oct 16, 2025 at 03:03:03PM -0400, Brian Foster wrote: > > Now that the zero range pagecache flush is purely isolated to > > providing zeroing correctness in this case, we can remove it and > > replace it with the folio batch mechanism that is used for handling > > unwritten extents. > > > > This is still slightly odd in that XFS reports a hole vs. a mapping > > that reflects the COW fork extents, but that has always been the > > case in this situation and so a separate issue. We drop the iomap > > warning that assumes the folio batch is always associated with > > unwritten mappings, but this is mainly a development assertion as > > otherwise the core iomap fbatch code doesn't care much about the > > mapping type if it's handed the set of folios to process. > > > > Signed-off-by: Brian Foster > > --- > > fs/iomap/buffered-io.c | 4 ---- > > fs/xfs/xfs_iomap.c | 16 ++++------------ > > 2 files changed, 4 insertions(+), 16 deletions(-) > > > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > > index d6de689374c3..7bc4b8d090ee 100644 > > --- a/fs/iomap/buffered-io.c > > +++ b/fs/iomap/buffered-io.c > > @@ -1534,10 +1534,6 @@ iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero, > > while ((ret = iomap_iter(&iter, ops)) > 0) { > > const struct iomap *srcmap = iomap_iter_srcmap(&iter); > > > > - if (WARN_ON_ONCE((iter.iomap.flags & IOMAP_F_FOLIO_BATCH) && > > - srcmap->type != IOMAP_UNWRITTEN)) > > - return -EIO; > > - > > if (!(iter.iomap.flags & IOMAP_F_FOLIO_BATCH) && > > (srcmap->type == IOMAP_HOLE || > > srcmap->type == IOMAP_UNWRITTEN)) { > > diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c > > index 29f1462819fa..5a845a0ded79 100644 > > --- a/fs/xfs/xfs_iomap.c > > +++ b/fs/xfs/xfs_iomap.c > > @@ -1704,7 +1704,6 @@ xfs_buffered_write_iomap_begin( > > { > > struct iomap_iter *iter = container_of(iomap, struct iomap_iter, > > iomap); > > - struct address_space *mapping = inode->i_mapping; > > struct xfs_inode *ip = XFS_I(inode); > > struct xfs_mount *mp = ip->i_mount; > > xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset); > > @@ -1736,7 +1735,6 @@ xfs_buffered_write_iomap_begin( > > if (error) > > return error; > > > > -restart: > > error = xfs_ilock_for_iomap(ip, flags, &lockmode); > > if (error) > > return error; > > @@ -1812,16 +1810,10 @@ xfs_buffered_write_iomap_begin( > > xfs_trim_extent(&imap, offset_fsb, > > cmap.br_startoff + cmap.br_blockcount - offset_fsb); > > start = XFS_FSB_TO_B(mp, imap.br_startoff); > > - end = XFS_FSB_TO_B(mp, > > - imap.br_startoff + imap.br_blockcount) - 1; > > - if (filemap_range_needs_writeback(mapping, start, end)) { > > - xfs_iunlock(ip, lockmode); > > - error = filemap_write_and_wait_range(mapping, start, > > - end); > > - if (error) > > - return error; > > - goto restart; > > - } > > + end = XFS_FSB_TO_B(mp, imap.br_startoff + imap.br_blockcount); > > + iomap_flags |= iomap_fill_dirty_folios(iter, &start, end); > > + xfs_trim_extent(&imap, offset_fsb, > > + XFS_B_TO_FSB(mp, start) - offset_fsb); > > Hrm, ok. This replaces the pagecache flush with passing in folios and > letting iomap zero the folios regardless of whatever's in the mapping. > That seems to me like a reasonable way to solve the immediate problem > without the huge reengineering ->iomap_begin project. > Yeah.. modulo a potential clean up to have this actually report the COW mapping which might be incrementally cleaner. I'll take a closer look at that when I get back to this.. > The changes here mostly look ok to me, though I wonder how well this all > meshes with all the other iomap work headed to 6.19... > The batch stuff is already in -next I believe. It might be good to get the first patch in sooner, but I don't think the rest should be too bad provided it stays isolated to XFS and zero range. Brian > --D > > > > > goto found_imap; > > } > > -- > > 2.51.0 > > > > >