+ fs-writeback-in-wait_sb_inodes-skip-wait-for-as_writeback_indeterminate-mappings.patch added to mm-unstable branch

+ fs-writeback-in-wait_sb_inodes-skip-wait-for-as_writeback_indeterminate-mappings.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: fs/writeback: in wait_sb_inodes(), skip wait for AS_WRITEBACK_INDETERMINATE mappings
has been added to the -mm mm-unstable branch.  Its filename is
     fs-writeback-in-wait_sb_inodes-skip-wait-for-as_writeback_indeterminate-mappings.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fs-writeback-in-wait_sb_inodes-skip-wait-for-as_writeback_indeterminate-mappings.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: Joanne Koong <joannelkoong@gmail.com>
Subject: fs/writeback: in wait_sb_inodes(), skip wait for AS_WRITEBACK_INDETERMINATE mappings
Date: Fri, 22 Nov 2024 15:23:57 -0800

For filesystems with the AS_WRITEBACK_INDETERMINATE flag set, writeback
operations may take an indeterminate time to complete.  For example,
writing data back to disk in FUSE filesystems depends on the userspace
server successfully completing writeback.

In this commit, wait_sb_inodes() skips waiting on writeback if the inode's
mapping has AS_WRITEBACK_INDETERMINATE set, else sync(2) may take an
indeterminate amount of time to complete.

If the caller wishes to ensure the data for a mapping with the
AS_WRITEBACK_INDETERMINATE flag set has actually been written back to
disk, they should use fsync(2)/fdatasync(2) instead.

Link: https://lkml.kernel.org/r/20241122232359.429647-4-joannelkoong@gmail.com
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: Bernd Schubert <bernd.schubert@fastmail.fm>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/fs-writeback.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/fs-writeback.c~fs-writeback-in-wait_sb_inodes-skip-wait-for-as_writeback_indeterminate-mappings
+++ a/fs/fs-writeback.c
@@ -2681,6 +2681,9 @@ static void wait_sb_inodes(struct super_
 		if (!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK))
 			continue;
 
+		if (mapping_writeback_indeterminate(mapping))
+			continue;
+
 		spin_unlock_irq(&sb->s_inode_wblist_lock);
 
 		spin_lock(&inode->i_lock);
_

Patches currently in -mm which might be from joannelkoong@gmail.com are

mm-add-as_writeback_indeterminate-mapping-flag.patch
mm-skip-reclaiming-folios-in-legacy-memcg-writeback-indeterminate-contexts.patch
fs-writeback-in-wait_sb_inodes-skip-wait-for-as_writeback_indeterminate-mappings.patch
mm-migrate-skip-migrating-folios-under-writeback-with-as_writeback_indeterminate-mappings.patch
fuse-remove-tmp-folio-for-writebacks-and-internal-rb-tree.patch