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From: Brian Foster <bfoster@redhat.com>
To: linux-fsdevel@vger.kernel.org
Cc: linux-xfs@vger.kernel.org, linux-mm@kvack.org, hch@infradead.org,
	djwong@kernel.org, willy@infradead.org
Subject: [PATCH v3 6/7] iomap: remove old partial eof zeroing optimization
Date: Mon, 14 Jul 2025 16:41:21 -0400	[thread overview]
Message-ID: <20250714204122.349582-7-bfoster@redhat.com> (raw)
In-Reply-To: <20250714204122.349582-1-bfoster@redhat.com>

iomap_zero_range() optimizes the partial eof block zeroing use case
by force zeroing if the mapping is dirty. This is to avoid frequent
flushing on file extending workloads, which hurts performance.

Now that the folio batch mechanism provides a more generic solution
and is used by the only real zero range user (XFS), this isolated
optimization is no longer needed. Remove the unnecessary code and
let callers use the folio batch or fall back to flushing by default.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/iomap/buffered-io.c | 24 ------------------------
 1 file changed, 24 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 194e3cc0857f..d2bbed692c06 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1484,33 +1484,9 @@ iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
 		.private	= private,
 	};
 	struct address_space *mapping = inode->i_mapping;
-	unsigned int blocksize = i_blocksize(inode);
-	unsigned int off = pos & (blocksize - 1);
-	loff_t plen = min_t(loff_t, len, blocksize - off);
 	int ret;
 	bool range_dirty;
 
-	/*
-	 * Zero range can skip mappings that are zero on disk so long as
-	 * pagecache is clean. If pagecache was dirty prior to zero range, the
-	 * mapping converts on writeback completion and so must be zeroed.
-	 *
-	 * The simplest way to deal with this across a range is to flush
-	 * pagecache and process the updated mappings. To avoid excessive
-	 * flushing on partial eof zeroing, special case it to zero the
-	 * unaligned start portion if already dirty in pagecache.
-	 */
-	if (!iter.fbatch && off &&
-	    filemap_range_needs_writeback(mapping, pos, pos + plen - 1)) {
-		iter.len = plen;
-		while ((ret = iomap_iter(&iter, ops)) > 0)
-			iter.status = iomap_zero_iter(&iter, did_zero);
-
-		iter.len = len - (iter.pos - pos);
-		if (ret || !iter.len)
-			return ret;
-	}
-
 	/*
 	 * To avoid an unconditional flush, check pagecache state and only flush
 	 * if dirty and the fs returns a mapping that might convert on
-- 
2.50.0


  parent reply	other threads:[~2025-07-14 20:37 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-14 20:41 [PATCH v3 0/7] iomap: zero range folio batch support Brian Foster
2025-07-14 20:41 ` [PATCH v3 1/7] filemap: add helper to look up dirty folios in a range Brian Foster
2025-07-15  5:20   ` Darrick J. Wong
2025-07-14 20:41 ` [PATCH v3 2/7] iomap: remove pos+len BUG_ON() to after folio lookup Brian Foster
2025-07-15  5:14   ` Darrick J. Wong
2025-07-14 20:41 ` [PATCH v3 3/7] iomap: optional zero range dirty folio processing Brian Foster
2025-07-15  5:22   ` Darrick J. Wong
2025-07-15 12:35     ` Brian Foster
2025-07-18 11:30     ` Zhang Yi
2025-07-18 13:48       ` Brian Foster
2025-07-19 11:07         ` Zhang Yi
2025-07-21  8:47           ` Zhang Yi
2025-07-28 12:57             ` Zhang Yi
2025-07-30 13:19               ` Brian Foster
2025-08-02  7:26                 ` Zhang Yi
2025-07-30 13:17           ` Brian Foster
2025-08-02  7:19             ` Zhang Yi
2025-08-05 13:08               ` Brian Foster
2025-08-06  3:10                 ` Zhang Yi
2025-08-06 13:25                   ` Brian Foster
2025-08-07  4:58                     ` Zhang Yi
2025-07-14 20:41 ` [PATCH v3 4/7] xfs: always trim mapping to requested range for zero range Brian Foster
2025-07-14 20:41 ` [PATCH v3 5/7] xfs: fill dirty folios on zero range of unwritten mappings Brian Foster
2025-07-15  5:28   ` Darrick J. Wong
2025-07-15 12:35     ` Brian Foster
2025-07-15 14:19       ` Darrick J. Wong
2025-07-14 20:41 ` Brian Foster [this message]
2025-07-15  5:34   ` [PATCH v3 6/7] iomap: remove old partial eof zeroing optimization Darrick J. Wong
2025-07-15 12:36     ` Brian Foster
2025-07-15 14:37       ` Darrick J. Wong
2025-07-15 16:20         ` Brian Foster
2025-07-15 16:30           ` Darrick J. Wong
2025-07-14 20:41 ` [PATCH v3 7/7] xfs: error tag to force zeroing on debug kernels Brian Foster
2025-07-15  5:24   ` Darrick J. Wong
2025-07-15 12:39     ` Brian Foster
2025-07-15 14:30       ` Darrick J. Wong
2025-07-15 16:20         ` Brian Foster

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