linux-kernel - [PATCH v3 6/7] dax: add recovery_write to dax_iomap

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Message-Id: <20220111185930.2601421-7-jane.chu@oracle.com>
Date:   Tue, 11 Jan 2022 11:59:29 -0700
From:   Jane Chu <jane.chu@...cle.com>
To:     david@...morbit.com, djwong@...nel.org, dan.j.williams@...el.com,
        hch@...radead.org, vishal.l.verma@...el.com, dave.jiang@...el.com,
        agk@...hat.com, snitzer@...hat.com, dm-devel@...hat.com,
        ira.weiny@...el.com, willy@...radead.org, vgoyal@...hat.com,
        linux-fsdevel@...r.kernel.org, nvdimm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org
Subject: [PATCH v3 6/7] dax: add recovery_write to dax_iomap_iter in failure path

dax_iomap_iter() fails if the destination range contains poison.
Add recovery_write to the failure code path.

Signed-off-by: Jane Chu <jane.chu@...cle.com>
---
 fs/dax.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index e0eecd8e3a8f..c16362d3993c 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1199,6 +1199,8 @@ int dax_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
 }
 EXPORT_SYMBOL_GPL(dax_truncate_page);
 
+typedef size_t (*iter_func_t)(struct dax_device *dax_dev, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i);
 static loff_t dax_iomap_iter(const struct iomap_iter *iomi,
 		struct iov_iter *iter)
 {
@@ -1210,6 +1212,7 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi,
 	ssize_t ret = 0;
 	size_t xfer;
 	int id;
+	iter_func_t write_func = dax_copy_from_iter;
 
 	if (iov_iter_rw(iter) == READ) {
 		end = min(end, i_size_read(iomi->inode));
@@ -1249,6 +1252,17 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi,
 
 		map_len = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size),
 				&kaddr, NULL);
+		if ((map_len == -EIO) && (iov_iter_rw(iter) == WRITE)) {
+			if (dax_prep_recovery(dax_dev, &kaddr) < 0) {
+				ret = map_len;
+				break;
+			}
+			map_len = dax_direct_access(dax_dev, pgoff,
+					PHYS_PFN(size), &kaddr, NULL);
+			if (map_len > 0)
+				write_func = dax_recovery_write;
+		}
+
 		if (map_len < 0) {
 			ret = map_len;
 			break;
@@ -1264,14 +1278,21 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi,
 		 * The userspace address for the memory copy has already been
 		 * validated via access_ok() in either vfs_read() or
 		 * vfs_write(), depending on which operation we are doing.
+		 *	xfer = dax_copy_from_iter(dax_dev, pgoff, kaddr,
+		 *			map_len, iter);
 		 */
 		if (iov_iter_rw(iter) == WRITE)
-			xfer = dax_copy_from_iter(dax_dev, pgoff, kaddr,
-					map_len, iter);
+			xfer = write_func(dax_dev, pgoff, kaddr, map_len, iter);
 		else
 			xfer = dax_copy_to_iter(dax_dev, pgoff, kaddr,
 					map_len, iter);
 
+		if (xfer == (ssize_t) -EIO) {
+			pr_warn("dax_ioma_iter: write_func returns-EIO\n");
+			ret = -EIO;
+			break;
+		}
+
 		pos += xfer;
 		length -= xfer;
 		done += xfer;
-- 
2.18.4