+ fs-remove-calls-to-set-and-clear-the-folio-error-flag.patch added to mm-unstable branch

+ fs-remove-calls-to-set-and-clear-the-folio-error-flag.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: fs: remove calls to set and clear the folio error flag
has been added to the -mm mm-unstable branch.  Its filename is
     fs-remove-calls-to-set-and-clear-the-folio-error-flag.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fs-remove-calls-to-set-and-clear-the-folio-error-flag.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: fs: remove calls to set and clear the folio error flag
Date: Wed, 7 Aug 2024 20:35:25 +0100

Nobody checks the folio error flag any more, so we can stop setting and
clearing it.  Also remove the documentation suggesting to not bother
setting the error bit.

Link: https://lkml.kernel.org/r/20240807193528.1865100-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 Documentation/filesystems/vfs.rst |    3 +--
 mm/filemap.c                      |    8 --------
 mm/migrate.c                      |    2 --
 mm/page_io.c                      |    4 +---
 4 files changed, 2 insertions(+), 15 deletions(-)

--- a/Documentation/filesystems/vfs.rst~fs-remove-calls-to-set-and-clear-the-folio-error-flag
+++ a/Documentation/filesystems/vfs.rst
@@ -913,8 +913,7 @@ cache in your filesystem.  The following
 	stop attempting I/O, it can simply return.  The caller will
 	remove the remaining pages from the address space, unlock them
 	and decrement the page refcount.  Set PageUptodate if the I/O
-	completes successfully.  Setting PageError on any page will be
-	ignored; simply unlock the page if an I/O error occurs.
+	completes successfully.
 
 ``write_begin``
 	Called by the generic buffered write code to ask the filesystem
--- a/mm/filemap.c~fs-remove-calls-to-set-and-clear-the-folio-error-flag
+++ a/mm/filemap.c
@@ -530,7 +530,6 @@ static void __filemap_fdatawait_range(st
 			struct folio *folio = fbatch.folios[i];
 
 			folio_wait_writeback(folio);
-			folio_clear_error(folio);
 		}
 		folio_batch_release(&fbatch);
 		cond_resched();
@@ -2346,13 +2345,6 @@ static int filemap_read_folio(struct fil
 	unsigned long pflags;
 	int error;
 
-	/*
-	 * A previous I/O error may have been due to temporary failures,
-	 * eg. multipath errors.  PG_error will be set again if read_folio
-	 * fails.
-	 */
-	folio_clear_error(folio);
-
 	/* Start the actual read. The read will unlock the page. */
 	if (unlikely(workingset))
 		psi_memstall_enter(&pflags);
--- a/mm/migrate.c~fs-remove-calls-to-set-and-clear-the-folio-error-flag
+++ a/mm/migrate.c
@@ -640,8 +640,6 @@ void folio_migrate_flags(struct folio *n
 {
 	int cpupid;
 
-	if (folio_test_error(folio))
-		folio_set_error(newfolio);
 	if (folio_test_referenced(folio))
 		folio_set_referenced(newfolio);
 	if (folio_test_uptodate(folio))
--- a/mm/page_io.c~fs-remove-calls-to-set-and-clear-the-folio-error-flag
+++ a/mm/page_io.c
@@ -273,9 +273,7 @@ static void sio_write_complete(struct ki
 		 * memory for allocating transmit buffers.
 		 * Mark the page dirty and avoid
 		 * folio_rotate_reclaimable but rate-limit the
-		 * messages but do not flag PageError like
-		 * the normal direct-to-bio case as it could
-		 * be temporary.
+		 * messages.
 		 */
 		pr_err_ratelimited("Write error %ld on dio swapfile (%llu)\n",
 				   ret, swap_dev_pos(page_swap_entry(page)));
_

Patches currently in -mm which might be from willy@infradead.org are

fs-remove-calls-to-set-and-clear-the-folio-error-flag.patch
mm-remove-pg_error.patch